Download Angus Mackenzie - Water Column Effects Harmful Algae Blooms

IN THE MATTER
of the Resource Management Act 1991
AND
IN THE MATTER
of a Board of Inquiry appointed under section 149J of
the Resource Management Act 1991 to consider The
New Zealand King Salmon Co. Limited's private plan
change requests to the Marlborough Sounds Resource
Management Plan and resource consent applications
for marine farming at nine sites located in the
Marlborough Sounds
STATEMENT OF EVIDENCE OF ANGUS LINCOLN MACKENZIE IN
RELATION TO WATER COLUMN EFFECTS: HARMFUL ALGAL BLOOMS
FOR THE NEW ZEALAND KING SALMON CO. LIMITED
JUNE 2012
D A Nolan / J D K Gardner-Hopkins
Phone 64 4 499 9555
Fax 64 4 499 9556
PO Box 10-214
DX SX11189
Wellington
TABLE OF CONTENTS
EXECUTIVE SUMMARY
QUALIFICATIONS AND EXPERIENCE
1 SCOPE OF EVIDENCE
3 THE PROPOSAL
4 HARMFUL ALGAL BLOOMS: AN INTRODUCTION
4 NOTABLE HARMFUL ALGAL BLOOMS IN NEW ZEALAND COASTAL
WATERS
6 PHYTOPLANKTON ECOLOGY AND NUTRIENT CHEMISTRY OF THE
MARLBOROUGH SOUNDS WITH SPECIAL REFERENCE TO HARMFUL
ALGAL BLOOMS
11 OVERSEAS EVIDENCE OF LINKS BETWEEN HABS AND SEA CAGE FISH
FARMING
20 Scotland
21 Chile
22 Korea
24 USA and Canada
24 Japan
25 Scandinavia
26 Baltic Sea
28 A SUMMARY OF THE OVERSEAS EVIDENCE LINKING HARMFUL ALGAL
BLOOMS AND SEA CAGE FISH FARMING
28 POTENTIAL EFFECTS OF FISH FARM EFFLUENTS WITH RESPECT TO
HARMFUL ALGAL BLOOMS IN THE MARLBOROUGH SOUNDS
29 MONITORING RECOMMENDATIONS
36 SUBMISSIONS
36 CONCLUSIONS
39
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
EXECUTIVE SUMMARY
A.
My work in relation to New Zealand King Salmon Company Limited (NZ
King Salmon) has been to undertake an assessment of the effects of the
company's proposal on the potential for harmful algal blooms (HABs) in
the Marlborough Sounds. This includes a discussion of what is
understood internationally about the relationship between sea cage fish
farming and HABs, the New Zealand experience of HABs over the last
several decades, and what this means in relation to NZ King Salmon's
proposed farm sites.
B.
My evidence provides a brief discussion of the ecology of phytoplankton
communities throughout New Zealand and the Marlborough Sounds with
a focus on toxic and noxious species. I discuss the nature of the water
column and associated phytoplankton in different parts of the Sounds and
what this means in relationship to the proposed farms. I also provide a
synopsis of the international literature on the association between the
incidence of HABs and effluents from sea cage fish farming operations.
C.
Frequent blooms of planktonic micro-algae in coastal waters are a natural
and essential ecosystem process. Occasionally blooms of some species
(usually flagellates) affect human interests and so become known as
harmful algal blooms (HABs). There have been many accounts of HABs
in New Zealand coastal waters but few if any of these can be attributed to
anthropogenic effects on water quality.
D.
Globally, increased exploitation and awareness of the ecology of coastal
seas has revealed that the potential for HABs is greater than formerly
realised. HAB events of various types are common in New Zealand and
many that do not cause significant environmental or economic effects go
largely unnoticed.
E.
A link has been made between coastal seawater nutrient enrichment and
eutrophication in some counties although the relationship is complex and
depends on the specific environment and micro-algae involved.
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
The
record of major HABs shows that coastal eutrophication is not a factor in
their incidence in New Zealand.
F.
Effluent emissions from sea cages is often cited as a potential cause of
HABs but there is no evidence from routine phytoplankton monitoring
programmes that salmon cages in the Marlborough Sounds have
contributed to the generation of HABs in this region to date.
G.
Neither is there convincing evidence from the international literature of an
association with HABs and sea cages, except in some shallow, confined
and poorly flushed locations subject to heavy nutrient loads. However it
is acknowledged in several studies that there is an inadequate
understanding of how nutrient discharges from sea cages affect the
structure and function of the wider pelagic ecosystem.
H.
Pelorus and Queen Charlotte Sounds differ most markedly in the
influence that oceanic sea water and freshwater inflows have on the
physical structure and nutrient chemistry of the water column and
phytoplankton communities. Both Sounds usually support dinoflagellate
dominated communities in summer.
I.
Inner Queen Charlotte Sound often experiences higher biomass blooms,
probably due to nutrient enrichment via inflows of upwelled water entering
the sound through Tory Channel. Surface waters in Tory Channel contain
high levels of nitrate throughout the year. The various inlets and bays
where
reduced
flushing
and
strongly
stratified
water
columns
predominate are preferred flagellate habitats and may contain high
numbers of resting cysts in the sediments.
These environments are
sometimes the origin of more widespread HABs.
J.
Inner Pelorus and Kenepuru Sounds are strongly influenced by nutrient
enrichment from the Pelorus and Kaituna Rivers which is the reflected in
the turbidity, high phytoplankton biomass and productivity of inner sound
waters. Outer Pelorus Sound is influenced by oceanic water from Cook
Strait and wind and tide induced upwelling of nutrient enriched waters.
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
K.
With the exception of the Papatua Site (Port Gore) the proposed farms
are sited in deep, high current locations with well mixed water columns
where ambient inorganic nutrient concentrations are naturally high.
These are not the type of environments conducive to HAB development.
Although the Papatua Site does not have high current flows, it is situated
on the margins of Cook Strait and is near regions (Capes Lambert and
Jackson) typified by high current and turbulent well mixed nutrient-rich
waters.
L.
It is not expected that the increased nitrogen loads with their sources
spread over a wide geographic area in naturally nutrient rich
environments will lead to an increase in problems with HABs. The lack of
evidence of an association between HABs and existing salmon farms in
the Marlborough Sounds and Stewart Island suggests the effects of the
proposed increased nutrient inputs will be minimal. An appropriate water
column monitoring programme should be able to detect any significant
changes
in
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
this
regard.
Page 1 of 41
QUALIFICATIONS AND EXPERIENCE
1
My full name is Angus Lincoln MacKenzie.
2
I hold a BSc (Hons) from the University of Otago.
3
I am an elected member of the council of the International Society for the
Study of Harmful Algae (ISSAH) and serve on the editorial board of the
journal, "Harmful Algae".
4
I am currently a Senior Research Scientist at the Cawthron Institute
(Cawthron), in Nelson. I have held this position for the last 32 years. My
work at Cawthron has focused primarily on the ecology, productivity,
physiology,
taxonomy,
biochemistry
and
toxicology
of
marine
phytoplankton and the effects of aquaculture on the marine environment.
5
Prior to working at Cawthron I was employed as a Research Technician at
Freshwater Section of DSIR for three years. My area of work at DSIR
was involved with research on the eutrophication of NZ lakes.
6
My expertise includes aquatic ecology and environmental effects of
aquaculture; phytoplankton systematics, ecology and physiology; microalgal biotoxin analytical methodologies; shellfish metabolism and
physiology;
biogeochemical
processes
in
environments; biosecurity risk assessment.
coastal
and
freshwater
I have authored or co-
authored more than 80 primary publications in refereed journals, and 135
consultancy reports, popular publications and conference papers on
various aspects of coastal marine ecology, harmful algal blooms (HABs),
aquaculture development and biosecurity.
7
I have been contracted as an expert witness on one previous occasion to
provide evidence relating to coastal phytoplankton ecology to a Council
Resource Consent hearing.
8
This evidence is given in support of a request for a change to the
Marlborough Sounds Resource Management Plan and nine resource
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 2 of 41
consent applications, lodged with the Environmental Protection Authority
(EPA) 3 October 2011 and collectively referred to as 'the proposal'.
9
My work in relation to New Zealand King Salmon Company Limited (NZ
King Salmon) has been to undertake an assessment of the effects of the
company's proposal on the potential for harmful algal blooms (HABs) in
the Marlborough Sounds.
This includes a discussion of what is
understood internationally about the relationship between sea cage fish
farming and HABs, the New Zealand experience of HABs over the last
several decades, and what this means in relation to NZ King Salmon's
proposed farm sites.
The work was carried out in collaboration with
Cawthron colleagues Dr Paul Gillespie and Mr Ben Knight. I am one of
the authors of the report1 appended to the proposal application, and refer
to that report in this evidence as the Water Column Effects Report/August
2011. My evidence is an extension of information provided in this report
and references contained therein.
10
In preparing this brief of evidence I have reviewed the evidence of Dr
Paul Gillespie and Mr Ben Knight on the water column effects of the
proposed developments and the international literature on what is known
of the relationships between coastal eutrophication, sea cage fish farming
and HABs. I have also reviewed unpublished material that relates to the
nature and incidence of HABs in New Zealand and the Marlborough
Sounds in particular.
11
I have read the Code of Conduct for Expert Witnesses as contained in the
Environment Court of New Zealand Practice Note 1 November 2011 and I
agree to comply with it. My qualifications as an expert are set out above.
I confirm that the issues addressed in this brief of evidence are within my
area of expertise. I have not omitted to consider material facts known to
me that might alter or detract from the opinions expressed.
1
Gillespie, P., Knight, B.R., MacKenzie, L. 2011. The New Zealand King Salmon Company Limited:
Assessment of Environmental Effects-Water Column. Prepared for the New Zealand King Salmon
Co. Ltd. Cawthron Report No. 1985. 79 p.
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 3 of 41
SCOPE OF EVIDENCE
12
The structure of my evidence is as follows:
12.1
The Proposal
12.2
Harmful Algal Blooms: An Introduction
12.3
Notable Harmful Algal Blooms in New Zealand Coastal Waters
12.4
Phytoplankton
Ecology
and
Nutrient
Chemistry
of
the
Marlborough Sounds With Special Reference to Harmful Algal
Blooms
12.5
Overseas Evidence of Links Between Harmful Algal Blooms and
Sea Cage Fish Farming
12.6
12.5.1
Scotland
12.5.2
Chile
12.5.3
Korea
12.5.4
USA and Canada
12.5.5
Japan
12.5.6
Scandanavia
12.5.7
Baltic Sea
Summary of the Overseas Evidence Linking Harmful Algal
Blooms and Sea Cage Fish Farming
12.7
Potential Effects of Fish Farm Effluents with Respect to Harmful
Algal Blooms in the Marlborough Sounds
12.8
Monitoring Recommendations
12.9
Submissions
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 4 of 41
12.10
Conclusions
THE PROPOSAL
13
I confirm that my evidence is based on the project proposal as described
in chapter 3 of the Sustainably Growing King Salmon Assessment of
Environmental Effects prepared by Boffa Miskell Limited October 2011;
and chapter 3 of the Sustainably Growing King Salmon White Horse Rock
Assessment of Environmental Effects prepared by Boffa Miskell Limited
October 2011.
HARMFUL ALGAL BLOOMS: AN INTRODUCTION
14
A high biomass of a single or a limited group of species of planktonic
micro-algae is generally referred to as an algal bloom. Blooms are the
result of the transient dominance by one or a few species over others, due
to favourable physical (e.g. salinity/temperature), chemical (e.g. nutrients)
or biological (e.g. life cycle behaviours) factors that enhance their growth.
Algal blooms are essential to the normal functioning of the marine
ecosystem. For example the spawning of many invertebrates is timed to
take advantage of the extra algal-food resources available during blooms.
15
There are some algal species which through various mechanisms (often
the production of poisonous secondary metabolites),can cause natural
mass mortalities of marine flora and fauna, kill fish in sea cages or
contaminate shellfish with toxins.
HABs are usually natural events,
however, there is a growing scientific consensus (Anderson et al.,
20082;Heisler et. al., 20083) that degraded coastal sea-water quality can
promote the development and persistence of HABs and is one of the
reasons for their apparent global expansion.
2
The Baltic Sea, Aegean
Anderson, D.M. et al., 2008. Harmful algal blooms and eutrophication: Examining linkages from
selected coastal regions of the United States. Harmful Algae 8: 39-53.
3
Heisler J. et al., 2008. Eutrophication and harmful algal blooms: A scientific consensus. Harmful
Algae 8: 3-13.
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 5 of 41
Sea, Northern Adriatic and Black Sea all have regions where increases in
HABs have been coincident with increases in nutrient loading from urban,
industrial and agricultural sources. Comparable situations are not known
in New Zealand and it is unlikely that eutrophication is an important factor
in the incidence of HABs here, except perhaps in some small coastal
impoundments (e.g. Jones & Rhodes 19944)
16
Most HAB species are flagellates, i.e. they belong to a number of different
taxonomic groups that have whip-like flagella which enable them to swim
and rapidly change position within the water column in response to light,
nutrients, temperature and salinity gradients. Non-motile diatoms usually
dominate the highest biomass phytoplankton blooms (usually in late
winter-spring and autumn) which represent the annual productivity
maxima, but few diatoms have harmful effects.
17
Because of their motility, the growth of flagellate dominated phytoplankton
communities are favoured in locations where the water column becomes
strongly stratified in summer, due to the buoyancy of warm surface waters
overlying colder deeper waters. Vertical salinity gradients also play an
important role in the stratification of coastal sea waters. The development
of a strongly stratified water column occurs more frequently in sheltered
embayments with weak current flows, minimal turbulence and long water
residence times.
18
Good quantities of dissolved silica are an essential nutrient for diatoms
because of their silica impregnated cell walls.
Dissolved silica is not
required for the growth of flagellates. Consequently, flagellate growth is
often favoured under conditions where silica becomes a limiting nutrient
for diatoms. Long term changes in the N/P/Si ratios have been shown to
correlate with changes in the ratio of abundance of diatoms and
flagellates in large drowned river valley estuarine systems similar to the
4
Jones, J.B. and Rhodes, L.L. (1994) Suffocation of pilchards (Sardinopssagax) by a green
microalgal bloom, Wellington Harbour,New Zealand, December 1993. New Zealand Journal of
Marine and Freshwater Research 28. 379-384
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 6 of 41
Marlborough Sounds (Smayda & Borkman 20055 ).
It has been
suggested that because the nutrient inputs from sea cage farms are rich
in nitrogen and phosphorus, but deficient in silica, these effluents can
favour the growth of flagellate dominated HABs.
NOTABLE HARMFUL ALGAL BLOOMS IN NEW ZEALAND COASTAL
WATERS
19
Harmful algal blooms in New Zealand can be localised events occupying
only a small bay or inlet, or very extensive phenomena where cells are
transported, and resident populations established, around much of the
coastline of either main island. Blooms originating in the North Island
have been observed to cross Cook Strait and intrude into the Marlborough
Sounds.
There are a few locations where resident populations of
particular species result in the formation of HABs every year and other
locations which are rarely, if ever, affected. Some species may for a
period of several years become a major component of the phytoplankton
only to eventually decline in abundance and disappear. The ability to form
long-lived resting cysts that reside in the sediments is an important feature
of the life cycle of some HAB species that enables their establishment and
long term residence. Over the last 20 years there have been numerous
minor HAB blooms that have required some response from the
aquaculture industry or food safety regulators, and a number of very large
events which have had significant economic and social consequences.
The most important major events that have been documented are listed
below:
19.1
In the years of 1860, 1900-1901, 1956, 1960, 1964, 1979, and
1981 there were recorded accounts of Tasman Bay slime
blooms, which were caused by dinoflagellate mucilage exudates
5
Smayda, T., Borkman, D. 2005. Multi-decadal changes in the diatom:flagellate ratio and Si:N and
Si:P ratios in Narragansett Bay, and influence of Si:N supply ratios on diatom species competition.
In Proceedings of the Open Science Meeting on HABs and Eutrophication, 7-10 March 2005,
Baltimore Maryland, USA.p 60 of abstracts.
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 7 of 41
associated with massive fish kills and a hindrance to fishing
activities (MacKenzie et al., 20026).
19.2
In the summer of 1982-83, an intense and persistent diatom
bloom (Ceratulina pelagica) on the North Island east coast
caused widespread shellfish and some fish mortalities, probably
through anoxia (Taylor et al., 19857)
19.3
In January 1989 in Big Glory Bay, Stewart Island a Heterosigma
bloom occurred, that resulted in a loss of more than 600 tonnes
of farmed salmon.
This was a costly blow to the developing
industry (Chang et al., 19908; MacKenzie, 19919). The bloom
took place after an unusually long period of fine calm weather
which reduced flushing and water exchange. It is not possible to
say whether the salmon farm effluents played a significant role in
stimulating this bloom, but it was noted at the time that high
nutrient concentrations occurred in Paterson Inlet which was
attributed to incursions of fertile oceanic water.
To our
knowledge there has been no repetition of major algal bloom
events in Big Glory Bay since 1989, although a routine
phytoplankton monitoring programme with weekly sampling has
been in place ever since and salmon production is now around
3,000 tonnes per year.
19.4
During the 1992-93 summer a dinoflagellate bloom (Karenia sp.)
in Northland and the Hauraki Gulf contaminated shellfish with
brevetoxins and a large number of people became ill from eating
them. There were reports of marine fauna mass mortalities in
6
MacKenzie, L., Sims, I., Beuzenberg, V., Gillespie, P. 2002: Mass accumulation of mucilage caused
by dinoflagellate polysaccharide exudates in Tasman Bay, New Zealand. Harmful Algae 1. 69-84.
7
Taylor, F.J., Taylor, N.J., Walsby, J.R. 1985.A bloom of the planktonic diatom Cerataulinapelagica,
off the coast of Northeastern New Zealand in 193, and its contribution to an associated mortality of
fish and benthic fauna. Internationale Revue der gesamten Hydrobiologie und Hydrographie. 70(6):
773-795.
8
Chang, F. H., C. Anderson and N. C. Boustead 1990: First record of a Heterosigma
(Raphidophyceae) bloom with associated mortality of cage-reared salmon in Big Glory Bay, New
Zealand. New Zealand Journal of Marine and Freshwater Research 24: 461-469.
9
MacKenzie, A.L. 1991. Toxic and noxious phytoplankton in Big Glory Bay, Stewart Island, New
Zealand. Journal of Applied Phycology 3: 19-34.
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 8 of 41
Northland and prolonged closures of shellfish harvesting nationwide (MacKenzie et al., 199510).
This event resulted in the
commencement of the national marine shellfish biotoxin and toxic
phytoplankton monitoring programmes.
19.5
In 1993-1994 blooms of the toxic dinoflagellate Alexandrium
minutum in outer Pelorus Sound resulted in extensive and
prolonged closures of mussel harvesting within the sound,
resulting in significant losses to growers, processors and their
employees. These were relatively minor events but unreliable
and inaccurate toxin testing methods used at the time made them
appear more serious than they were.
19.6
During the summers of 1993-94 and 1995-96 blooms of Karenia
selliformis contaminated Foveaux Strait oysters with a toxin (now
known as gymnodimine) and caused widespread mortalities of
fish and shellfish in Southland and the east coast of the South
Island, possibly as far north as Port Underwood (MacKenzie et
al., 199611).
19.7
In March-April 1996 and 1997 the first blooms of the saxitoxin
producing dinoflagellate, Alexandrium catenella were identified in
the Bay of Plenty associated with high levels of saxitoxins in surf
clams.
Since then blooms of A. catenella and shellfish
contamination have become common on the North Island east
coast from the Bay of Islands to the Bay of Plenty, most recently
in January 2012.
19.8
During March 1998 a bloom of Karenia brevisulcata in Wellington
Harbour caused mass mortalities of marine fauna and flora and
10
MacKenzie A. L., L. L. Rhodes, D. Till, F. H. Hoe Chang, H. Kaspar, A. Haywood, J. Kapa and B.
Walker 1995: A Gymnodinium sp. bloom and the contamination of shellfish with lipid soluble toxins
in New Zealand, Jan - April 1993. In P. Lassus, E. Erard, P. Gentien and C. Marcaillou [Eds]
Harmful Marine Algal Blooms Lavoisier Science Publishers, Paris pp. 795-800.
11
MacKenzie, L., A. Haywood, J. Adamson, P. Truman, D. Till, M. Satake and T. Yasumoto. 1996.
Gymnodimine Contamination of Shellfish in New Zealand. In: Yasumoto,T., Oshima, Y., and
Fukuyo, Y. (Eds) Harmful and Toxic Algal Blooms. Intergovernmental Oceanographic Commission
of UNESCO. pp 97-100.
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 9 of 41
adversely affected the Mahanga Bay shellfish hatchery (Chang,
199912). The bloom was preceded by reports of dead fish (tuna,
bill-fish) abalone, seals and penguins along the Wairarapa coast.
19.9
In May 2000 the toxic dinoflagellate, Gymnodinium catenatum
was first identified in samples from the North Island west coast.
Over subsequent months a major bloom developed that spread
along the entire coast of the North Island, through Cook Strait
and up the east coast as far as Hawke Bay. The bloom impinged
on the Marlborough Sounds but did not become established in
this area. The contamination of juvenile mussels collected on
Ninety Mile Beach (‘Kaitaia Spat’) with resting cysts of G.
catenatum, halted the transport of this valuable resource to the
Marlborough Sounds. This had a major effect on the productivity
of the mussel industry (MacKenzie & Taylor 2004)13.
Annual
blooms occurred in Hawke Bay until 2004, after which it gradually
dwindled in abundance and eventually disappeared.
The last
cells of G. catenatum were seen in Hawke Bay in 2007.
19.10
During the spring of 2002 Karenia spp.blooms (K. mikimotoi, K.
brevisulcata, K. concordia) caused mass mortalities of fish
(flounder, mullet etc.) in the Hauraki Gulf and the total loss of
cultured abalone on a farm in Kennedys Bay, Coromandel
Peninsular (Chang et al., 200114).
19.11
June 2010 a Pseudochattonella verruculosa bloom in inner
Queen Charlotte Sound caused substantial mortalities (>200
tonnes)
of
salmon
at
the
Ruakaka
Bay
salmon
farm.
Commercially this was the most serious fish kill event since the
12
Chang, F.H., 1999. Gymnodnium brevisulcatum sp. nov.(Gymnodiniales, Dinophyceae), a new
species isolated from the 1998 summer bloom in Wellington harbour, New Zealand.Phycologia
38(5): 377-384.
13
MacKenzie, A.L., Taylor, M. 2004. Risk assessment of the transfer of Kaitaia spat contaminated
with Gymnodiniumcatenatum cysts. A report for the NZ Mussel Industry Council, Cawthron Report
No. 868.
14
Chang, F.H. et al., 2001. Occurrence and distribution of Karenia brevisuclata (Dinophycae) during
the summer toxic outbreaks on the central east coast of New Zealand. Phycologia 40: 215-222.
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 10 of 41
1989 Big Glory Bay bloom (MacKenzie et al., 2011a15).
The
bloom was generated in the Grove Arm and throughout its
duration was confined to the inner sound, with its seaward limit
extending onto the farm at Ruakaka Bay.
19.12
During
February-April
2011the
first
recorded
bloom
of
Alexandrium catenella occurred in Tory Channel which eventually
spread to other regions of Queen Charlotte Sound and resulted
in shellfish harvest closures of up to three months (MacKenzie et
al.,2011b16). A sampling survey of seafloor sediments showed
that A. catenella resting cysts, were widely distributed around the
Sound with highest densities in Opua Bay, Tory Channel.
In
February 2012 a bloom of A. catenella again developed in Opua
Bay but inclement weather during early autumn prevented the
bloom from becoming more widespread.
19.13
An example of a chronic HAB phenomena, is the annual
appearance of the resident toxic dinoflagellate, Dinophysis
acuminata in Port Underwood. Without exception over 20 years
of monitoring, blooms of this species have occurred very year,
usually in spring or late summer. Fortunately the toxicity of this
species is relatively mild and only occasionally have harvest
closures been necessary when cell numbers have become
exceptionally high.
15
MacKenzie, L., Smith, K. F., Rhodes, L. L., Brown, A., Langi, V., Lovell, G., Preece, M. 2011a.
Mortalities of sea cage salmon (Oncorhynchustshawytscha) due to a bloom of Pseudochattonella
verruculosa (Dictyophyceae) in Queen Charlotte Sound, New Zealand. Harmful Algae 11: 45-53.
16
MacKenzie, L., Harwood, T., Boundy, M., Smith, K, Knight, B., Jiang, Weimin, McNabb, P.,
Selwood, A., van Ginkel, R., Langi, V., Edgar, M., Moisan, C. 2011b. An Alexandrium catenella
bloom and associated saxitoxin contamination of shellfish, Queen Charlotte Sound, March-June
2011. A report for MAF Food Safety. Cawthron Report No. 1945. 38pp.
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 11 of 41
PHYTOPLANKTON ECOLOGY AND NUTRIENT CHEMISTRY OF THE
MARLBOROUGH SOUNDS WITH SPECIAL REFERENCE TO HARMFUL
ALGAL BLOOMS
20
The Marlborough Sounds with their numerous sheltered inlets and bays,
broad open reaches and proximity to the deep turbulent waters of Cook
Strait provide a diversity of physical and chemical water column conditions
that shape the species composition, successional patterns and biomass of
the phytoplankton.
Although phytoplankton communities are highly
dynamic, there are consistent seasonal patterns in phytoplankton biomass
and species succession that are experienced in the Sounds and
throughout the wider region (MacKenzie & Gillespie 198617; Gibbs & Vant,
1997; 18) that are typical of temperate latitudes elsewhere (Figure. 1).
21
There are also consistent spatial differences in the hydrodynamic
properties, residence time, light and nutrient conditions of different
locations that control the biomass and species composition of
phytoplankton communities. The index (ISL) devised by Knight (Gillespie
et al., 201119) as a guide to the optimum location of fish farms in the
Sounds (i.e. those with a high index value) provides a good illustration of
locations where flagellate dominated phytoplankton blooms are most likely
to occur (i.e. those with a low index indicative of poor flushing
characteristics). The model clearly identifies the sound entrances and
channel regions as the most suitable for finfish aquaculture in terms of
currents and water depth. These areas are also those which are least
likely to experience stable water column conditions conducive to the
development of nuisance algal blooms. They are also locations where
there is the maximum potential for dilution and dispersion of nutrients
emanating from the farms.
17
Mackenzie A. L. and P. A. Gillespie 1986: Plankton ecology and productivity, nutrient chemistry
and hydrography of Tasman Bay, New Zealand, 1982-1984. New Zealand Journal of Marine and
Freshwater Research 20: 365-395.
18
Gibbs M.M., Vant, W.N. 1997. Seasonal changes in factors controlling phytoplankton growth in
Beatrix Bay, New Zealand. NZ Journal of Marine and Freshwater Research 31: 237-248.
19
Gillespie, P., Knight, B.R., MacKenzie, L. 2011. The New Zealand King Salmon Company Limited:
Assessment of Environmental Effects-Water Column. Prepared for the New Zealand King Salmon
Co. Ltd. Cawthron Report No. 1985. 79p.
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 12 of 41
Figure 1.
Seasonal changes in (A) water column temperature, (B) nutrients (nitrate + nitrite),
and (C) phytoplankton biomass in the Marlborough Sounds. This figure is based on
observational data from Tennyson Inlet, Pelorus Sound but these patterns are typical
of processes in other embayments throughout the Sounds. The patterns are generally
maintained from year to year although the timing, magnitude and species involved
vary.
22
Light limitation in late autumn/early winter generally leads to a slowdown
in
phytoplankton
growth
and
nutrient
demand.
Consequently
concentrations of oxidised forms of nitrogen (nitrate and nitrite), formed by
the re-mineralisation of organic nitrogen and nitrification of reduced forms
of nitrogen (e.g. ammonium) in the sediments and water column,
accumulate and reach their annual maximum. Concurrently during this
period water column stratification that has been maintained throughout the
summer and autumn breaks down.
23
Diatoms respond rapidly to water column mixing and increases in nitrate
(Carter 200420), and in late winter to early spring the annual productivity
maximum caused by diatom blooms usually takes place. Throughout the
20
Carter, C.M. 2004. Spatial and Temporal Dynamics of Phytoplankton communities in a Coastal
Ecosystem.PhD Thesis. University of Canterbury. 177p.
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 13 of 41
spring a succession of diatom blooms may occur until early summer,
when warming surface waters stabilise the water column, preventing
mixing,
and
favouring
phytoplankton
communities
dominated
by
flagellates that can take advantage of vertical gradients of light and
nutrients.
Flagellate communities usually become established at the
density interface (pycnocline), typically at 9-12 metres depth, between
deeper, darker, cooler, higher-salinity, nutrient rich layers and warmer,
lower-salinity, nutrient depleted but illuminated layers in the upper water
column.
Because flagellates are able to move between these layers
throughout the day and night, they are able to optimise their access to
nutrients and light. Often there is a secondary productivity maximum in
late summer/autumn, when zooplankton grazing pressure that has built up
over the spring and summer is relaxed.
24
Superimposed on this general seasonal pattern are nutrient enrichment
and water column mixing episodes brought on by floods, storms,
upwelling events and complex biological interactions (competition for
nutrients, grazing, allelopathy etc.) that also play important roles in
structuring phytoplankton communities. Carter (2004)20 provided evidence
that long term El-Nino Southern Oscillation(ENSO) changes in upwelling
along the Cook Strait continental shelf can impact phytoplankton
dynamics in Pelorus Sound and during strong El-Nino phases this can
cause diatoms to persist during the summer. Conversely during strong La
Niña phases dinoflagellates tend to become dominant in summer.
Changes in ENSO also relate to changes in the magnitude of river inflows,
and oceanic and riverine nitrogen sources that underpin phytoplankton
productivity are complementary in Pelorus Sound (Zeldis et al., 200821).
25
Pelorus and Queen Charlotte Sounds differ most markedly in the
influence that freshwater runoff has on the water column.
This is a
function of the relative size of freshwater catchment areas of each sound.
The ratio of catchment to sea surface area is much greater in Pelorus
21
Zeldis, J.R., Howard-Williams, C., Carter, C.M., Schiel, D.R. 2008. ENSO and riverine control of
nutrient loading phytoplankton biomass and mussel aquaculture yield in Pelorus Sound, New
Zealand. Marine Ecology Progress Series 371: 131-142.
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 14 of 41
Sound than Queen Charlotte Sound.
These differences in freshwater
inflow are reflected in the water chemistry of the Sounds, especially with
respect to salinity fields and the amounts and ratios of essential nutrients
(Figure 2).
For example, the ratios of inorganic nitrogen to dissolved
reactive silicates (essential for diatom growth) are higher in Queen
Charlotte Sound than Pelorus Sound (Carter 200422, Mackenzie
unpublished data).
26
Because of its importance to the mussel farming industry, most research
has been focused on the Pelorus Sound system and there are numerous
published papers that deal with various aspects of the hydrology, nutrient
chemistry and plankton ecology (e.g. Gibbs et al., 199223; Gibbs and Vant,
199724; Gibbs et al., 200225). It is apparent from some of this research
(e.g. Ogilvie et al., 200026) that food depletion during periods of low
phytoplankton productivity resulting from nitrogen limitation can be a
constraint on mussel productivity in some part of Pelorus Sound. There
has been less equivalent research on Queen Charlotte Sound and most
existing material is contained in unpublished reports and data sets (e.g.
the MSQP phytoplankton/biotoxin monitoring database).
22
Carter, C.M. 2004. Spatial and temporal dynamics of phytoplankton communities in a coastal
ecosystem. PhD Thesis. University of Canterbury. 177p.
23
Gibbs, M. M., Pickmere, S.E., Woods, P.H., Payne, G.W., James, M.R., Hickman, R.W.,
Illingworth, J. 1992. Nutrient and chlorophyll a variability at six stations associated with mussel
farming in Pelorus Sound, 1984-85. NZ Journal of Marine and Freshwater Research 26: 197-211.
24
Gibbs, M.M., Vant, W.N., 1997. Seasonal changes in factors controlling phytoplankton growth in
Beatrix Bay, New Zealand. NZ Journal of Marine and Freshwater Research 31: 237-248.
25
Gibbs, M., Ross, A., Downes, M. 2002. Nutrient cycling and fluxes in Beatrix bay, Pelorus Sound,
New Zealand. NZ Journal of Marine and Freshwater Research 36: 675-697.
26
Ogilvie, S.C., Ross, A.H., Schiel, D.R. 2000. Phytoplankton biomass associated with mussel farms
in Beatrix bay, New Zealand. Aquaculture 181: 71-80.
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 15 of 41
Figure 2.
A typical profile of salinity and nitrate concentrations sampled at stations along the
axis of Pelorus Sound from Havelock to Cook Strait. The ticks on the isobars are
oriented towards increasing concentrations.
The arrow marks the location of the
proposed farms at White Horse Rock, Post Office Point, Tapipi and Richmond in the
Waitata Reach/outer Pelorus Sound. These data are from observations and analyses
carried out in April 1987. The figures show the intrusion of high salinity seawater
(>34.5 psu) containing elevated concentrations of nitrate (>1.0 mmol m-3) in bottom
waters throughout the inner sound, broaching the surface in the outer sound.
The
proposed farm sites in Waitata Reach are situated where inner sound waters of an
estuarine character meet oceanic waters from Cook Strait.
27
The influence of the Pelorus River on the salinity of near surface waters
can extend to the entrance of the sound (Figure 2) where high salinity,
nitrate-enriched waters from Cook Strait are lifted to the surface by wind
induced upwelling and tidal mixing processes. Relatively high levels of
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 16 of 41
nitrate-N (> 2.0 mmol m-3) can be found in surface waters in this area
during summer, when euphotic waters within the rest of the sound are
nitrogen depleted.
28
Toxic and noxious algal blooms are uncommon in Pelorus Sound and few
shellfish harvest closures have been necessary. Occasionally low levels
of domoic acid (produced by planktonic diatoms in the genus
Pseudonitzchia) are identified, predominately in the inner Sounds.
Closures due to yessotoxin contamination occurred in Kenepuru Sound in
2004. The most extensive and lengthy closures occurred in 1993 and
1994 as the result of blooms of the toxic dinoflagellate Alexandrium
minutum in Anakoha Bay. Given this history the risk of serious problems
with HABs is regarded as low though the future appearance and
establishment of nuisance species, previously unknown in the sound, is
always a possibility.
29
From
a
water
column
perspective
there
are
biogeographical zones in Queen Charlotte Sound.
several
distinct
These include the
inner sound and bays south west of Tory Channel terminating in the
Grove Arm, Tory Channel itself, the various bays which extend off Tory
Channel (e.g. Onapua Bay, Oyster Bay, Deep Bay), and the large northeastern region of the sound opening on to Cook Strait. Within this latter
region East Bay and Endeavour Inlet can probably also be regarded as
discrete units. From the limited amount of physical and biological data
that is available it is clear that the physical properties, nutrient chemistry
and hence the phytoplankton ecology of these regions are usually rather
different. The hydrodynamics of Queen Charlotte Sound is complicated
by having two entrances that differ in tidal phase which affects estimates
of the water residence times.
30
Most of the detailed water column analysis that has taken place in Queen
Charlotte Sound has been in the Grove Arm since this area has a history
of frequent toxic micro-algal blooms (MacKenzie et al., 199827) and
27
MacKenzie L., P. Truman, M. Satake, T. Yasumoto, J. Adamson, D. Mountfort and D. White 1998:
Dinoflagellate blooms and associated DSP-toxicity in shellfish in New Zealand. In B. Reguera, J.
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 17 of 41
research has been focussed there.
There is a new data set being
established by the Marlborough District Council which contains data from
four sites in the main channel of Queen Charlotte Sound and one site in
Tory Channel.
This data set provides useful information on nutrient
chemistry and water column structure.
31
High salinities, typical of oceanic waters, are common within the inland
reaches of the Grove Arm and the area usually supports a high
phytoplankton biomass. Inorganic nutrient concentrations generally follow
a predictable seasonal pattern, although bottom waters usually contain
high levels of nitrate throughout the year and nutrient enrichment
episodes associated with intrusions of nutrient rich oceanic water have
been identified.
The mechanism of these intrusions is not completely
understood. It may involve the onset of estuarine-like circulation during
heavy rainfall periods and tidally driven jets of deep bottom water from
Tory Channel.
During summer a dinoflagellate dominated community
prevails for long periods and toxic dinoflagellate blooms have occurred
here on numerous occasions in the past28. The area may function as an
incubator where blooms develop and are dispersed to other areas. There
is good evidence (MacKenzie et al., 2011a29) that the flagellate bloom
(Pseudochattonella verruculosa) responsible for killing fish at the Ruakaka
farm in June 2010 originated in the Grove Arm, under the influence of a
bottom water intrusion event, and spread from there throughout the inner
sound.
32
In contrast to the inner sound, Tory Channel is a turbulent and dynamic
environment. This is reflected in the biomass and species composition of
the phytoplankton which (in the Channel proper) is usually relatively low
and dominated by diatoms at most times. High nitrate levels exist in the
Blanco, M. L. Fernandezand T. Wyatt [Eds], Harmful Algae Xunta de Galicia and
Intergovernmental Oceanographic Commission of UNESCO pp. 74-77.
28
MacKenzie, L., Beuzenberg, V., Holland, P., McNabb, P., Selwood, A. 2004. Solid phase adsorption
toxin tracking (SPATT): A new monitoring tool that simulates the biotoxin contamination of filter
feeding bivalves. Toxicon 44: 901-918
29
MacKenzie, L., Smith, K. F., Rhodes, L. L., Brown, A., Langi, V., Lovell, G., Preece, M. 2011a.
Mortalities of sea-cage salmon (Oncorhynchustshawytscha) due to a bloom of
Pseudochattonellaverruculosa (Dictyophyceae) in Queen Charlotte Sound, New Zealand. Harmful
Algae 11: 45-53.
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 18 of 41
surface waters of Tory Channel throughout the year (Figure 3A) because
of persistent upwelling off the eastern coast in the vicinity of Tory Channel
entrance (Figure 3B). High levels of nitrate persist throughout the water
column of Tory Channel during summer when the photic zone in other
parts of the sound is usually depleted of inorganic nitrogen. The longer
retention time, water column stability and high fertility of the various
embayments that extend off Tory Channel gives these areas a different
character where flagellate dominated communities flourish in summer.
Figure 3.
A) Dissolved inorganic nitrogen (DIN) in surface waters of Queen Charlotte Sound.
B) Satellite image of sea surface temperatures showing cold (~ 10°C), high nitrate,
upwelling water off the east coast of the Marlborough Sounds on 18 Feb 2012.).
33
A recent example of this was a bloom of the toxic dinoflagellate,
Alexandrium catenella (MacKenzie et al., 2011b19) that began and
persisted for more than two months (March-May 2011) within the southern
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 19 of 41
Tory Channel bays (Onapua/Opua Bay, Oyster Bay). There is evidence
suggesting these bays acted as incubators from which the bloom was
dispersed through the Sound, leading to widespread shellfish biotoxin
contamination and prolonged harvesting closures.
34
Less is known about the water column and plankton ecology of the
northern part of Queen Charlotte Sound, except that it is characterised
deeper mixing than the inner sound, and the phytoplankton composition
more closely resembles that of Tory Channel. It is expected however that
East Bay and Endeavour Inlet will have unique characteristics of their
own.
Figure 4.
Distribution of benthic resting cysts of the toxic dinoflagellate Alexandrium catenella in
the Marlborough Sounds.
35
Recent research (MacKenzie unpub.) on the dinoflagellate resting cyst
communities within the sediments of Pelorus and Queen Charlotte
Sounds has shown these provide a good indicator of fundamental
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 20 of 41
differences in the nature of the phytoplankton communities in these
different regions. The sediments within the numerous embayments off
Queen Charlotte Sound support more abundant and diverse cyst
communities (Figure 4) than similar environments in Pelorus Sound. This
probably reflects the different salinity regimes and sources and ratios of
inorganic nutrient (N,P and Si ) that provide more favourable dinoflagellate
habitats in Queen Charlotte Sound.
36
Fish kills due to algal blooms are not a new phenomenon in Queen
Charlotte Sound.
The earliest known written record is of a fish kill
associated with discoloured water in the Grove Armin 1962.
(1982)30 recorded:
Hurley
“Quantities of fish both dead and otherwise were
reported to be present on the beaches.
Discussion was held with
caretaker of the Domain at Ngakuta Bay, and the following information
was obtained. The exact date of the occurrence is not clear but given as
approximately the second week in April (1962). During this period the
waters were calm and the surface appeared as a reddish brown colour
almost bloodlike, no smell being apparent from this substance.
Fish
(spotties, gurnard, flounders, snapper, dogfish) were reported as being
ashore literally gasping and showing evidence of general distress.”
OVERSEAS EVIDENCE OF LINKS BETWEEN HABS AND SEA CAGE FISH
FARMING
37
The following evidence has been obtained from searches of the
international literature pertaining to the effects of fish farming on coastal
sea water quality and the incidence of HABs.
30
Hurley, D.E 1982. The ‘Nelson Slime’ observations on past occurrences. NZOI Oceanographic
Summary No. 20 October 1982
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 21 of 41
Scotland
38
Over several decades there was a large increase in farmed salmon
production in Scotland, from 598 tonnes in 1980 to 159,000 tonnes in
2001 (‘Marine Scotland’ statistics),accompanied by a concomitant
increase in annual N and P waste loadings from fish farms. The Scottish
salmon industry is the 3rd largest in the world after Norway and Chile.
Rydberg et al., (2002)31 estimated that the total annual N and P loads into
Scottish waters from fish farming in 2001 were 7,900 and 1,580 tonnes
respectively. Because of emerging problems with a variety of toxic algal
bloom phenomena in the 1990s, the focus came on the fish farming
industry as a contributor to these problems and several studies (e.g.
Smayda 200632) were initiated to investigate this. There were three major
concerns which these studies addressed:
38.1
Plant nutrients from fish farms were leading to an increase in
algal blooms.
38.2
Plant nutrients from fish farms had disturbed the natural ratios of
nutrient elements so favouring the occurrence of toxic over nontoxic species.
38.3
Plant nutrients from fish farms had made potentially toxic algae
more poisonous.
39
A report for the Scottish Executive Central Research Unit (2002)33
concluded that the lack of long term monitoring data made it difficult to
judge whether the perceived increase in HABs was real and related to
expansion in the fish farming industry. The sporadic data that existed did
not show conclusively that there has been a wide scale increase in the
abundance of organisms responsible for HABs in Scottish waters.
31
Rydberg, L., Sjöberg, B., Stigebrandt, A. 2002. The interaction between fish farming and algal
communities of Scottish waters: a review. Draft report to the Scottish Environmental Protection
Authority. (cited by Smayda 2006)
32
Smayda, T.J. 2006. Harmful algal Bloom Communities in Scottish coastal Waters: Relationship to
Fish Farming and Regional Comparisons: A review. A report for Scottish Executive Environment
Group, Natural Scotland Paper 2006/3 168 pp.
33
Scottish Executive Central Research Unit, 2002.Review and Synthesis of the environmental
impacts of aquaculture. http://www.scotland.gov.uk/Resource/Doc/46951/0030621.pdf
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 22 of 41
Although the number of incidents of toxicity had increased, this was
believed to be probably the result of increased monitoring associated with
the expansion of shellfish cultivation. The study concluded, that except in
a few enclosed sea-lochs, nutrient enrichment by fish farms was too little
relative to natural levels to have the led to an increase in HAB
occurrences and that the supply of nutrients to the marine environment
was unlikely to be a factor limiting fish farm production in the future.
40
A follow up study was based on a review and analysis of Scottish regional
phytoplankton monitoring data carried out by Smayda (2006)29.
He
concluded that the increase in N and P loads entering coastal waters due
to fish farms was not accompanied by an increase in phytoplankton
blooms, either of benign or harmful species. Smyada went on to conclude
that:
40.1
“There is no evidence of a significant increase in nutrient levels,
altered phytoplankton behaviour or an increase in harmful algal
blooms in Scottish waters.”
40.2
“Blooms of harmful species present in Scottish waters are not
dependent on aquacultural stimulation; all harmful species bloom
in habitats not influenced by fish farm wastes.”
40.3
“..the observed phytoplankton behaviour in Scottish coastal
waters does not appear to differ significantly from the natural and
variable behaviour expected of an indigenous phytoplankton flora
exposed to the ‘open system’ features of boreal waters.”
Chile
41
Despite problems in recent years with a viral disease (Infectious Salmon
Anaemia) the Chilean salmon industry remains the 2nd largest in the
world. In 2010 between 250,000 and 300,000 tonnes were harvested,
down from 400,000 tonnes in 2009 and a peak of 650,000 tonnes in 2008.
The potential induction of HABs as a result of salmon aquaculture is a
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 23 of 41
major concern in Chile where highly toxic dinoflagellate blooms (especially
of Alexandrium catenella) are common in the extensive areas of enclosed
waters in the south of the country. A laboratory study (Arzul et al., 200134)
showed salmon excretion products had no effect on the growth of toxic
Alexandrium species, although Buschmann et al. (2006)35 found
dinoflagellate growth was stimulated and diatom growth inhibited when
fish farm effluents were used to fertilise large volume tanks. A limited field
study showed that in the presence of salmon pens, significant increases in
dinoflagellate densities occurred in pulses (Vegara, 200136). A. catenella
has been associated with mass mortalities of salmon (>1,800 tonnes) on
salmon farms in southern Chile (Fuentes et al., 200837).
42
Buschmann et al. (2007)38, in a major study of the nutrient impacts of
farmed Atlantic Salmon on the pelagic ecosystem in Chile, stated that
“there is little scientific evidence that nutrient loading from salmon farms is
sufficient to initiate and sustain harmful algal blooms…”, though they
acknowledged that “… nearly all the rigorous pelagic ecosystem science
related to HABs has occurred outside the areas directly influenced by
salmon farms”. They recommended that further field studies are needed
“to answer concerns that elevated nutrients within densely-crowded
salmon farming areas with limited flushing can promote the establishment
of new harmful algal bloom seed areas.”
34
Arzul, G., Seguel, M., Clement, A. 2001.Effect of marine animal excretions on differential growth of
phytoplankton species. ICES Journal of Marine Science58: 386-390.
35
Buschmann, A.H., Riquelme, V. A., Hernandez-Gonzalez, M. C., Varela, D., Jimenez, J.E.,
Henriquez, L. A., Vergara, P. A., Guinez, R., Filun, L. 2006. A review of the impacts of salmonid
farming on marine coastal ecosystems in the southeast Pacific. ICES Journal of Marine Science
63: 1338-1345.
36
Vegara, P. 2001. Efectosambientales de la salmonicultura: El caso de Bahia Metri, Chile {in
Spanish]. Master thesis, Universidad de Los Lagos, Osorno, Chile, 188pp. (Quoted by Buschmann
et al., 2007).
37
Fuentes, C., Clement, A., Aguilera, A 2008. Summer Alexandrium catenella bloom and the impact
on fish farming in the XI Aysen region, Chile. Moestrup, O. et al., [Eds] 12th International
Conference on Harmful Algae, Copenhagen, Denmark 4-8 Sept 2006. I.O.C. UNESCO Pub.p.183186.
38
Buschmann, A.H., Costa-Pierce, B. A., Cross, S., Iriarte, J. L., Olsen, Y., Reid, G. 2007. Nutrient
impacts of framed Atlantic salmon (Salmosalar) on pelagic ecosystems and implications for
carrying capacity. Report of the Technical Working group (TWG) on Nutrients and Carrying
Capacity of the Salmon Aquaculture Dialogue.30 August 2007, 68pp.
http://www.worldwildlife.org/what/globalmarkets/aquaculture/WWFBinaryitem8844.pdf
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 24 of 41
Korea
43
Some HAB species have caused long term problems for aquaculture in
Korean waters (Kim et al., 2010a39).
The dinoflagellate Cochlodinium
polykrikoides was for many years a persistent bloom former that severely
impacted fish farms in enclosed or semi enclosed embayments in South
Eastern Korea. It caused massive fish kills and economic losses of more
than $100 million in the 1990s: Kudela & Gobler 201240).This species
went from being a minor to a major component of the phytoplankton for
about a decade before disappearing again. In Korea and other regions
where C. polykrikoides blooms have caused major problems, blooms
generally originate offshore as the result of large scale oceanographic
processes and there is no strong evidence that implicates coastal
eutrophication in their origin and development (Kudela et al., 200841).
However, there is evidence that their growth is stimulated when offshore
blooms intrude into areas where freshwater inflows and intensive fish or
shrimp farming has caused localised coastal water enrichment and
eutrophication (Ahn et al., 200642, Kim et al., 2010b43).
USA and Canada
44
Since at least the 1980s there have been chronic problems with algal
blooms causing finfish mortalities in the northeast Pacific regions of
Canada and the United States. One species in particular (Heterosigma
akashiwo) is notorious for its effects on fish farms in the region. The
northwest coast of North America is characterised by regions of intense
39
Kim, H-G 2010a.An Overview on the Occurrences of Harmful Algal Blooms (HABs) and Mitigation
Strategies in Korean Coastal Waters. In: Ishimatsu, A., Lie, H-J. [Eds] Coastal Environmental and
Ecosystem Issues of the east China Sea. Pub. TERRAPUB and Nagasaki University pp. 121-131.
40
Kudela, R.M., Gobler, C.J. 2012. Harmful dinoflagellate blooms caused by Cochodinium sp. Global
expansion and ecological strategies facilitating bloom formation. Harmful Algae 14: 71-86.
41
Philippine Journal of Science. 139(2): 139-147.
Kudela, R.M., Ryan, J.P., Blakely, M.D., Lane, J.Q., Peterson, T.D. 2008. Linking the physiology and
ecology of Cochlodinium to better understand harmful algal bloom events: A comparative
approach. Harmful Algae 7: 278-292.
42
Ahn, Y-H., Shanmugam, P., Ryu, J-H., Jeong, J-C. 2006. Satellite detection of harmful algal bloom
occurrences in Korean waters. 5: 213-231.
43
Kim, C-H., Park, T-G., Lee, C. 2010b.Harmful dinoflagellates and mitigation strategies in
Korea.Philippine Journal of Science. 139(2): 139-147.
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 25 of 41
upwelling and in the enclosed waters of Puget Sound and adjacent areas
light, not nutrient supply, generally limits phytoplankton production.
45
Rensel (2007)44 in a review of the ecology and impacts of H. akashiwo
blooms in Puget Sound states: “It is evident that fish farms do not cause
Heterosigma akashiwo blooms in marine waters of Western Washington
and the data suggest that it is unlikely they exacerbate booms.” The
blooms generally arise in areas remote from fish farms from where they
are transported by tides, winds and estuarine circulation processes.
Blooms of H. akashiwo were recorded in the region well before any fish
farms were established. In Washington State fish farms are required to
be located in regions of naturally high dissolved inorganic nitrogen levels
(Newton et al., 200245) and they make a very small contribution to the
natural nitrogen loads carried by the waters in these regions. Discharge
from major river systems play an important role in the establishment of a
vertically stratified water column favourable to the development of blooms
and their distribution by estuarine circulation.
Heterosigma akashiwo
blooms are typically late spring events coinciding with periods of warm
weather and strong basin-wide water column stratification.
Japan
46
In the 1950-1960s algal bloom outbreaks frequently caused mass
mortalities of marine fauna in the Seto Inland Sea, associated with
industrial and urban development and eutrophication of coastal waters
(Okaichi, 199746). This eutrophication was largely due to inputs of N and
P from industrial (2,200 manufacturing plants) and domestic sources (30
million population), although the rapid development of sea cage finfish
44
Rensel, J. E. 2007. Fish kills from the harmful alga Heterosigmaakashiwo in Puget Sound: Recent
blooms and review. A technical report Sponsored by the National Oceanic and atmosphere
administration; Centre for Sponsored Coastal Ocean Research 58pp.
45
Newton, J.A, Alberton, S.L., Van Voorhis, K., Maloy, C., Siegel, E. 2002. Washington State Marine
Water Quality, 1998 through 2000. Washington State Department of Ecology Publication No. 0202-056.
46
Okaichi, T. 1997. Red tides in the Seto Inland Sea. In Okaichi, T. and Yanagi, T. [Eds]
Sustainable Development in the Seto Inland Sea Japan from a fisheries point of
view.Terra Scientific Publishing Company, Tokyo.329 pp.
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Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 26 of 41
aquaculture at this time was also suspected to be a contributing factor.
The main micro-algae species involved in these blooms were the
raphidophyte, Chattonella antiqua which appeared in 1969 and the
dinoflagellate, Gymnodinum mikimotoi which was mainly involved in the
1990s (Imai et al., 2006)47.
Extreme blooms in 1972 caused mass
mortality of approximately 14 million cultured yellowtail. This resulted in
aquaculturalists
taking
lawsuits
against
cities
and
industries
for
compensation. As a result, the Japanese authorities instituted the Seto
Inland Sea Law that established environmental water quality standards
specifying acceptable N and P levels in seawater (0.2-0.6 mg/l and 0.020.05 mg/l respectively), measures to reduce the N and P levels in urban
and industrial effluents and controls on reclamation projects. After the
imposition of these controls the numbers and intensity of “red tides”
decreased rapidly. Ironically, as the waters became less eutrophic a shift
in community composition occurred, resulting in a greater incidence of
species responsible for shellfish poisoning. In this case effluent controls
reduced the number of ‘red-tide’ blooms but did not result in fewer HAB
impacts (Anderson et al., 200248).
Scandinavia
47
Toxic and noxious algal blooms affecting aquaculture are a frequent
problem in the coastal waters of Norway and Sweden, although the
species responsible for these effects have changed over time. In the
1960s dinoflagellate blooms (Gymnodinium aureolum, Prorocentrum
minutum) caused fish kills and shellfish toxicity. In the 1980s there were a
series of blooms of the haptophyte, Chrysochromulina polylepis that had a
large impact on the sea cage salmon farming industry in the southern
Skagerrak-Kattegat region (Graneli et al., 1993)49.
47
The cause of the
Imai, I., Yamaguchi, M., Hori, Y. 2006.Eutrophication and occurrences of harmful algal blooms in
the Seto Inland Sea. Plankton and Benthos Research 1(2): 71-84.
48
Anderson, D.M., Glibert, P.M., Burkholder, J.M. 2002. Harmful Algal Blooms and Eutrophication:
Nutrient Sources, Composition and Consequences. Estuaries 25 (4b): 704-726.
49
Graneli, E., Paasche, E. Maestrini, S. 1993. Three years after the Chrysochromulinapolylepis bloom
in Scandinavian waters in 1988: Some conclusions of recent research and monitoring. In Smayda
T.J. and Shimizu, Y. [Eds] Toxic phytoplankton Blooms in the Sea. Elsevier p23-32.
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 27 of 41
unusually extensive and intense blooms of C. polylepis was attributed to
oceanographic processes that lead to the introduction of nitrate enriched
waters into the Kattegat from the Baltic Sea and from eutrophic waters
within the German Bight. It was found that low salinities reduced the toxic
effect of the algae on fish, so sea- cages were towed from bloom exposed
coastal areas into brackish waters of the inner parts of the fjords to
mitigate their effect. In April-May 1998 a mass occurrence of Chattonella
(now Pseudochattonella) verruculosa caused significant mortalities in
salmon sea cages along the southwest coast of Norway and mass
mortalities of wild fish populations on the west coast of Demark. The
introduction of waters rich in nitrate (and with abnormally high N:P ratios)
from the southern North Sea were considered to be a primary cause of
the high phytoplankton biomass that became established in the region at
the time (Aureet al. 200150). These nutrients were believed to be largely
anthropogenic in origin originating from continental river discharges into
the German Bight.
48
In 2011 a risk assessment report was made of the environmental impacts
of Norwegian aquaculture (Taranger et al., 201151). This report focused
on disease dispersal, genetic impact of escapees and the release of
nutrient salts, organic waste and drugs. It did not mention the issue of
HABs although it made reference to the impact on phytoplankton in
general. The Norwegian fin-fish culture industry has an annual production
of about 950,000 tonnes per annum distributed at many locations on a
very long (approximately 1,900 miles) coastline.
The total annual
discharge of dissolved nutrients from this level of production is estimated
to be approximately 9,800 tonnes of nitrogen and 1,600 tonnes of
phosphorus. Acknowledging that the effect of nutrient additions depend
on the sea surface area, residence time and current regime in the different
growing areas, the authors reached the conclusion that the risk of regional
50
Aure, J., Danielssen, D.S., Skogen, M., Svendsen, E., Soland, H., Pettersson, L. 2001.
Environmental conditions during the Chattonella bloom in the North Sea and Skagerrak in May
1998. In Harmful Algal Blooms 2000 Hallegraeff et al., [Eds] IOC UNESCO Pub. p82-85.
51
Taranger, G.L., Boxaspen, K.K., Madhun, A.S., Svasand, T. [Eds] Risk assessment-environmental
impacts of Norwegian aquaculture. A report by the Institute of Marine Research, Norway August
2011. 48 pp. http://www.imr.no/filarkiv/2011/08/risk_assessment_engelsk_versjon.pdf/en
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 28 of 41
eutrophication in all areas was low although they could not rule out local
impacts when fish farms were located in areas with poor water exchange.
The report suggested that on-going monitoring and water quality
assessments would provide better knowledge of areas that may be at risk
of eutrophication.
Baltic Sea
49
A study of the environmental effects of fish farm effluents in the Gulf of
Bothnia (Baltic Sea off Finland) mainly found significant effects on nutrient
enrichment (especially elevated levels of dissolved phosphorus) and
phytoplankton standing crop in small (0.5-0.7 km2) shallow (3-4 m depth)
embayments with water retention times of 2-6days supporting production
of about 70 tonnes per year (Nordvarg & Johansson, 200252). One larger
deeper embayment (8km2, mean depth 6 m) with a water retention time of
eight days, which contains a large fish farm producing over 800-1000
tonnes per year, also had some evidence of nutrient enrichment and
elevated phytoplankton biomass.
A SUMMARY OF THE OVERSEAS EVIDENCE LINKING HARMFUL ALGAL
BLOOMS AND SEA CAGE FISH FARMING
50
Concerns regarding sea cage fish farming frequently refer to the potential
for coastal eutrophication and stimulation of HABs as a high risk factor.
However, my search of the international literature does not reveal a strong
relationship between HABs and fish farming, except in the most confined,
poorly flushed and grossly polluted situations where the nutrient loads
from the farms far exceed the assimilative capacity of the water body (e.g.
Romdhane et al., 199853).
There is scant evidence that chlorophyll a
concentrations (i.e. phytoplankton biomass) are enhanced by nutrient
52
Nordvarg, L., Johansson, T. 2002. The effects of fish farm effluents on the water quality in the Åland
archipelago, Baltic Sea. Aquaculture Engineering 25: 253-279.
53
Romdhane, M.S., Eilertsen, H.C., Yahia O.K.D., Yahia, M.N.D. 1998. Toxic dinoflagellate blooms in
Tunisian lagoons: cause and consequences for aquaculture. In: Reguera et al., [Eds] Harmful
Algae IOC UNESCO. p.80-83.
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 29 of 41
inputs from fish farm cages (Beveridge et al., 199454; Pitta et al., 199955;
Wu et al., 199456), even when these farms are in enclosed inland
locations with restricted water exchange (e.g. Navarro et al., 200857).
Most usually it seems that the fish farm operations encounter other water
quality and health problems associated with overstocking (disease,
parasites, sulphides, de-oxygenation etc.) before HABs become a major
issue.
Most, if not all, major HAB events that result in shellfish toxin
problems and/or mass mortalities of wild or cultivated marine species are
entirely natural.
POTENTIAL EFFECTS OF FISH FARM EFFLUENTS WITH RESPECT TO
HARMFUL ALGAL BLOOMS IN THE MARLBOROUGH SOUNDS
51
In the preceding evidence I have presented material that shows that there
is a documented history of many types of naturally occurring HABs in New
Zealand’s coastal waters. I have discussed the phytoplankton ecology of
the Marlborough Sounds in the context of the physical and nutrient
chemistry environment, and reviewed the international literature for
evidence of an association between fish farming and HABs.
In the
following section I will discuss ways in which fish farm effluents could
potentially increase problems with HABs. I will explain why, in the light of
the present state of our knowledge of the Marlborough Sounds water
column, and the history of salmon farming in New Zealand to date I
believe these effects will be no more than minor.
52
Potential effects of the salmon farm effluent discharges include:
54
Beveridge, M.C.M., Ross, L.G., Kelly. L.A. 1994. Aquaculture and Biodiversity.Ambio 23: 497-502.
Pitta, P., Karakassis, I., Tsapakis, M., Zivanovic, S. 1999. Natural vsmariculture induced variability
in nutrients and plankton in the eastern Mediterranean. Hydrobiologia 391: 181-194.
56
Wu R.S.S. Lam, K.S., Mackay, D.W., Lau, T.C., Yam, V. 1994. Impact of marine fish farming on
water quality and bottom sediment: A case study in the sub-tropical environment. Marine Environ.
Res. 38: 115-145.
57
Navarro, N., Leakey, R.J.G., Black, K.D. 2008. Effect of salmon cage aquaculture on the pelagic
environment of temperate coastal waters: seasonal changes in nutrient and microbial community.
Marine Ecology Progress Series. 361: 47-58.
55
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 30 of 41
52.1
Increases of growth limiting nutrients entering the Marlborough
Sounds may lead to an elevated phytoplankton biomass and
encourage a greater incidence of HABs;
52.2
These nutrient inputs will be at their maximum during summer
when the upper water column is often substantially deleted of
nutrients
and
when
flagellate
dominated
phytoplankton
communities are most common;
52.3
These nutrients are “unbalanced” in that they are rich in N and P
but do not contain the silica essential for diatom growth, and
hence are potentially preferential for the growth of harmful
flagellates.
53
These potential effects are dealt with in the discussion that follows. The
focus of this discussion is on the inputs of combined nitrogen to the
system as this is generally acknowledged as the major limiting nutrient in
coastal marine ecosystems, including the Marlborough Sounds58.
54
The increases in nitrogen concentrations and their dispersion from the
proposed farm sites has been modelled, and is presented in the evidence
of Mr Ben Knight.
Biological processes are not factored into these
models. For over a decade a large, multi-million dollar, interdisciplinary
programme run by the Woods Hole Oceanographic Institute has been in
progress on the east coast of the USA (Gulf of Maine) to develop a bloom
simulation model of the toxic dinoflagellate Alexandrium fundyense
(Anderson et al. 201059). This has to date been the only serious attempt
to develop a numerical model to provide seasonal forecasts of any type of
HAB anywhere. The simulation model has shown some promise but is far
from infallible and is specifically applicable only to the Gulf of Maine. To
simulate the effect of the salmon farm effluents using a biophysical
phytoplankton productivity and community composition model that would
be able to predict the probability of an increase in HABs in the
58
Gibbs, N., Ross, A., Downes, M. 2002. Nutrient cycling and fluxes in Beatrix Bay, Pelorus Sound,
New Zealand. New Zealand Journal of Marine and Freshwater research 36: 675-697.
59
Anderson, et al. 2010. Bloom dynamics of the red tide dinoflagellate Alexandrium fundyense in the
Gulf of Maine a synthesis and progress towards a forecasting capability. IECES CM 201/N:01.
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 31 of 41
Marlborough Sounds, would be an extremely large, expensive and difficult
task, if it was possible at all. It is doubtful that it would result in predictions
that are any better than that which can be achieved by deduction from
existing data and experience.
55
An important mitigating factor is that the sites selected for the proposed
farms are all in areas of naturally high ambient levels of inorganic
nutrients (especially nitrate) as they are close to regions which frequently
experience oceanic upwelling of deep nutrient-enriched waters. Recent
analyses of seawater in Queen Charlotte Sound by the Marlborough
District Council clearly show the importance of Tory Chanel as a source of
oceanic nutrients for the sound (Table 1, Figure 3). The concentrations of
inorganic nitrogen (mainly nitrate-N) in Tory Channel are always high
(approximately 6mmol-N m-3 = 84 mg-N m-3) in surface waters (Figure
3A), even in midsummer when the levels in euphotic waters around the
rest of the sound are depleted.
56
Similarly, as referred to earlier in this evidence, upwelling of nutrient
enriched waters is known to take place in mid-summer at the entrance to
Pelorus Sound and elsewhere along the outer coast of the Marlborough
Sounds (Figure 2). These upwelling phenomena have been associated
with northwest winds resulting from a negative phase of ENSO (Zeldis et
al., 200860). However other field and satellite observations of sea surface
temperature (MacKenzie unpub.) clearly show that upwelling also occurs
under positive phase (La Nina) conditions and the frequency and
mechanism of these events has yet to be properly identified.
57
Although high levels of nutrient loading may be associated with increases
in phytoplankton biomass, it is not the case that this necessarily results in
an increase in the incidence of HABs. Two examples in New Zealand
where this is demonstrated is the Firth of Thames and Big Glory Bay,
Stewart Island.
60
Zeldis, J.R., Howard-Williams, C., Carter, C.M., Schiel, D.R. 2008. ENSO and riverine control of
nutrient loading phytoplankton biomass and mussel aquaculture yield in Pelorus Sound, New
Zealand. Marine Ecology Progress Series 371: 131-142.
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 32 of 41
58
The Firth of Thames is a shallow body of water that receives high nitrogen
loads (~ 5,000 tonnes N yr-1) from the rivers draining an intensively
farmed catchment (Zeldis et al., 201061). River inflow contributes up to
70% of the dissolved inorganic nitrogen load
62
but it is estimated that
denitrification removes a very large amount (~10,800 tonnes N y-1) of fixed
nitrogen from the system in the form of nitrogen gas.
Weekly
phytoplankton monitoring has been in place in the Coromandel area
adjacent to the Firth of Thames since 1993. Although HAB blooms have
been detected from time to time they are not a major problem in this area.
The most notable HAB blooms (MacKenzie et al., 199563) have been large
scale events associated with upwelling over the Hauraki Gulf shelf break
(Sharples & Grieg 199864).
59
Salmon farming has been in progress in Big Glory Bay since the early
1980s.
Big Glory is a small (11.9 km2; mean depth~20 m), enclosed
embayment with poor flushing characteristics (10-14 days water
exchange). As referred to earlier in this evidence, in 1989 a bloom of
Heterosigma akashiwo had a catastrophic effect on the farms and a large
amount of stock (~600 tonnes) was lost within a few days. At the time
annual production in the bay was around 1500 tonnes with an annual
soluble nitrogen load of around 200 tonnes (Pridmore & Rutherford
199265). The effect of the salmon farms were estimated to have increased
the mean nitrogen content by about 30%, however it was believed that the
nitrogen concentrations in the bay were more likely controlled by the
concentrations in the adjoining much larger embayment of Paterson Inlet,
which in turn was subject to oceanographic upwelling processes.
61
Zeldis, J., Broekhuizen, N., Forsythe, A., Morrisey, D., Stenton-Dozey, J. 2010. Waikato Marine
Finfish Farming: Production and Ecological Guidance. A report prepared for MFish Aquaculture
Unit. NIWA Client Report CHC2010-147. 111p.
62
Zeldis, J. 2008. Exploring the carrying capacity of the Firth of Thames for finfish farming: a nitrogen
mass-balance approach. A report for Environment Waikato. NIWA Client Report CHC2008-02.
28pp.
63
MacKenzie A. L., L. L. Rhodes, D. Till, F. H. Hoe Chang, H. Kaspar, A. Haywood, J. Kapa and B.
Walker 1995: A Gymnodinium sp. bloom and the contamination of shellfish with lipid soluble toxins
in New Zealand, Jan - April 1993. In P. Lassus, E. Erard, P. Gentien and C. Marcaillou [Eds]
Harmful Marine Algal Blooms Lavoisier Science Publishers, Paris pp. 795-800.
64
Sharples, J. Grieg, M.J.N. 1998. Tidal currents, mean flows and upwelling on the north-east shelf of
New Zealand. New Zealand Journal of Marine and Freshwater Research 32: 215-231.
65
Pridmore R.D., and Rutherford, J.C. 1992. Modelling phytoplankton abundance in a small enclosed
bay used for salmon farming. Aquaculture and Fisheries Management. 23: 525-542.
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 33 of 41
60
As a result of the 1989 bloom, weekly phytoplankton monitoring was
initiated to provide an early warning of a repeat of this bloom.
This
monitoring continues to the present day and is now in its 23rd year.
Throughout this time there has been no algal bloom which has caused
significant mortalities although salmon farming has continued in the bay,
to a current production of about 3000 tonnes per year. The nitrogen loads
in Big Glory Bay relative to the volume and exchange velocity of the
receiving waters are far in excess of those of the proposed Marlborough
Sounds sites.
61
Because of the size and economic importance of the aquaculture industry,
the Marlborough Sounds is the most intensively monitored region in New
Zealand for HAB activity. The Marlborough Shellfish Quality Programme
(MSQP) samples the water column and shellfish for phytoplankton and
shellfish toxin analysis from 17 sites every week. This monitoring has
been in progress continuously since 1993. A number of MSQP’s routine
sampling sites are near NZKS’s existing farms in Pelorus and Queen
Charlotte Sounds. In addition the company itself has carried out routine
phytoplankton monitoring at the farm sites since their establishment, to
provide an early warning of blooms that may affect their fish. From this
monitoring there is a very large body of data on the occurrence of HAB
species in the Sounds. There is no indication from the phytoplankton or
biotoxin data of unusual HAB activity associated with the farms (Hopkins
et al., 200466) and in fact many HAB events have been at locations far
removed from them.
62
There have been two recent HAB events in Queen Charlotte Sound that
have had important economic consequences. These have been referred
to earlier in this evidence. The bloom of Pseudchattonella verruculosa
that caused fish kills on the Ruakaka Bay farm in June 2010 is believed to
have originated in the inland reaches of the Grove Arm and throughout its
66
Hopkins, G., Forrest, B., Clarke, M. 2004. Environmental Impacts of the Otanerau Bay Salmon
Farm, Marlborough Sounds. A report for The New Zealand King Salmon Co. Ltd. Cawthron Report
No. 824.
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 34 of 41
duration remained confined to the inner sound67.
The bloom was
associated with the shoaling of high salinity water containing high levels of
nitrate in inner Grove Arm. The mechanism of this upwelling is not known
for sure but may relate to a period of high rainfall that set up an estuarine
circulation pattern in the inner sound.
63
The bloom of the toxic dinoflagellate, Alexandrium catenella that caused
lengthy closures of shellfish harvesting in the sound in 2011, almost
certainly had its origin in Opua Bay, an enclosed, isolated bay off Tory
channel68. Investigations over the last year have confirmed that Opua
Bay has a resident population of the dinoflagellate that blooms in late
summer, and analysis of cyst populations in sediment cores suggests that
this population has existed for at least several decades.
Opua Bay
frequently supports a high phytoplankton biomass and is apparently
fertilised by the intrusion of nutrient rich bottom water from Toy Channel,
possibly under the influence of south easterly winds. There is a concern
that A. catenella is in the process of expanding its range throughout the
Sounds and its ecology is the subject of on-going research.
64
The two bloom events discussed above were driven by identifiable,
natural, nutrient enrichment processes and are illustrative of the preferred
flagellate habitats (especially dinoflagellate) of inner Queen Charlotte
Sound and the bays off Tory Channel. These blooms developed due to
the physical and biological nature of these environments (well stratified,
weak current flows, long residence times, established populations) in
combination with the abundance and quality of the inorganic nutrients in
the oceanic waters from Cook Strait that fertilise these areas.
67
MacKenzie, L., Smith, K. F., Rhodes, L. L., Brown, A., Langi, V., Lovell, G., Preece, M. 2011a.
Mortalities of sea-cage salmon (Oncorhynchustshawytscha) due to a bloom of
Pseudochattonellaverruculosa (Dictyophyceae) in Queen Charlotte Sound, New Zealand. Harmful
Algae 11: 45-53.
68
MacKenzie, L., Harwood, T., Boundy, M., Smith, K, Knight, B., Jiang, Weimin, McNabb, P.,
Selwood, A., van Ginkel, R., Langi, V., Edgar, M., Moisan, C. 2011b. An Alexandrium catenella
bloom and associated saxitoxin contamination of shellfish, Queen Charlotte Sound, March-June
2011. A report for MAF Food Safety. Cawthron Report No. 1945. 38pp.
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 35 of 41
Table 1.
Seasonal and depth averaged dissolved inorganic nutrient concentrations and ratios in
Marlborough Sounds and adjacent coastal waters. DRSi (dissolved reactive silicates);
DIN (dissolved inorganic nitrogen); DRP (dissolved reactive phosphorus).
DRSi
Tasman Bay
Water column
DIN
DRP
mmol m-3
5.3
1.4
0.4
Wedge Pt. QC Sound.
Water column
5.2
4.3
0.7
8:6:1
Pelorus Sound/Tennyson
Inlet
Water column
15.4
2.8
0.5
30 : 6 : 1
Tory Channel QC Sound*
Surface
Deep
nd
nd
6.0
5.2
0.4
0.4
nd : 15 : 1
nd : 13 : 1
**Redfield ratio
DRSi:DIN:DRP
13 : 3 : 1
15 : 16 : 1
nd = not determined
*Data courtesy of the Marlborough District Council
**The Redfield ratio (Si:N:P = 15:16:1) is the optimum ratio of inorganic macro-nutrients for
phytoplankton growth. This ratio is a constant in deep ocean waters throughout the world. Deviations
from this ratio in euphotic waters indicate potential growth limitation though lack of an essential
nutrient. For example a ratio of 30:6:1 (Pelorus Sound) shows that there is an excess of Si relative to
P but N concentrations will probably limit phytoplankton growth.
65
Most streams and rivers naturally carry high loads of dissolved silica,
which is an essential nutrient for the growth of diatoms. It is likely that an
important factor in the propensity for Queen Charlotte Sound to
experience a greater incidence of flagellate blooms than Pelorus Sound
relates to the oceanic origin of the seawater and the relatively small
amounts of freshwater that flow into it. As a consequence the salinity is
high and quantities of dissolved silica that enter into the sound may
become substantially exhausted after diatom blooms. This is shown by
the low ratio of dissolved silica to N and P (compared with the Redfield
ratio) in seawater within the Grove Arm (Wedge Point) of Queen Charlotte
Sound and the high ratios found in Pelorus Sound seawater (Table 1.).
Unfortunately there are no available silica analyses from Tory Channel but
the oceanic origin of the water in this area is shown by the high N:P ratio
that is close to the Redfield ratio. Although the salmon farm effluents are
high in N and P but contain essentially no silica their input into the highly
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
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dynamic, rapidly exchanging and nutrient rich environment of Tory
Channel is unlikely to promote a nutrient imbalance within the Sound over
and above that exists naturally.
66
An important feature of Pelorus Sound is the estuarine circulation pattern
whereby low salinity surface waters from the inland reaches moves
seaward to be replaced by deeper higher salinity ocean water from the
outer region. This circulation transports lower salinity near-surface water
as far as the outer Pelorus Sound/Waitata Reach region, carrying with it
elevated concentrations of dissolved silica. In all areas of greater Pelorus
and Kenepuru Sounds dissolved silica is usually present well in excess of
the optimum requirements for diatom growth. The effluent discharges for
the proposed farms into the Waitata reach are unlikely to be sufficient to
make any detectable change in the ambient inorganic nutrient ratios and
hence to the structure of phytoplankton communities.
MONITORING RECOMMENDATIONS
67
Monitoring with regard to water column effects, including effects of
nutrient loading on primary production (and potentially HABs) is covered
by the evidence of Dr Paul Gillespie and includes a recommendation that
NZ King Salmon contribute to and strengthen existing programmes (e.g.
that of MSQP).aimed at monitoring and understanding HABs and water
quality conditions in the Sounds
SUBMISSIONS
68
I am aware that the NZ King Salmon application has attracted a large
number of public submissions. While I have not read all of them, my
attention has been drawn to a number of submissions (32) that are
relevant to my area of expertise.
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
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69
Many of these submissions raise concerns about the general issue of the
potential promotion of HABs due to fish farm effluents, for example:
69.1
“…increased risk of harmful fish toxic and/or shellfish toxic algal
blooms (HABs).” (Submission 0061)
69.2
“The extra nutrients from fish waste may also increase the risk of
poisonous algal bloom.” (Submission 0361)
69.3
“…the increased nutrient loading…increasing the potential for
toxic and non-toxic algal blooms.” (Submission 0415)
69.4
“local mineral enrichment leading potentially to algal blooms”
(Submission 0345)
69.5
“…increased nutrification….(and)….the effect this may have on
increasing the frequency and length of toxic algal blooms…”
(Submission 1000)
69.6
“Increased risk of algal blooms as a result of high nitrogen
loading..” (Submission 1036)
69.7
And a number of other submissions containing similarly generic
statements.
70
The issue of HABs in New Zealand in general and in the Marlborough
Sounds in particular and the international evidence linking sea cage fish
farming with HABs is covered in some detail throughout the body of my
evidence.
71
Some submissions have raised specific issues which have been dealt with
in the evidence but perhaps need more clarification here, I address these
below:
71.1
Issue 1: The submission of Sustain our Sounds Inc. (EPA No.
0061) at paragraph 21 contains the statement: “The shellfish
sampling programme results for the Marlborough Sounds
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 38 of 41
showing that the Ruakaka area (at least) is showing a lack of
resilience and is susceptible to algal blooms.” This statement
implies there is evidence that the Ruakaka farm has degraded
water quality in this area which has led to an increase in HABs.
In fact there is no evidence from the Marlborough Sounds
Shellfish Quality Programme (MSQP) database or from the
routine sampling that NZKS itself carries out that this is the case.
In over 20 years of operation at this site we know of only one
HAB event (the Pseudochattonella bloom in June 2010; Section
21.11 which has impacted the farm. There is good evidence that
this bloom originated in the Grove Arm and was advected onto
the farm.
As has been discussed at some length in the my
evidence (paragraphs 28-37) the inner part of Queen Charlotte
Sound and the embayments off Tory Channel are naturally
favourable flagellate habitats during the warmer months of the
year and blooms are common in these areas. Ruakaka Bay is
situated where inner sound, often strongly stratified water, meets
well mixed more oceanic waters from Tory Channel and the outer
sound and is influenced more or less by both at different times.
71.2
Issue 2: The submission of Lees (EPA No. 0602) contains the
statement: “In Scotland algal blooms are a frequent result of
untreated wastes from salmon farms; prior to the expansion of
salmon farming in the 1980s there had been no incidence of toxic
algal blooms in those areas.”
As discussed in my evidence
(paragraphs 39-41), Scotland is one of the few countries where
there has been rigorous studies that have focussed on this
question.
These studies have failed to find any relationship
between the incidence of HABs and sea cage fish farming.
71.3
Issue 3: Five of the submissions (EPA Nos. 0342, 0559, 0645,
0738 and 1053) make reference to the potential for the
generation of blooms in enclosed or ‘blind’ bays.
This is a
legitimate concern because the weak current flows, long
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 39 of 41
retention
time
and
strongly
stratified
water
columns
characteristics of these environments are preferred flagellate
habitats. However this is precisely why NZKS has chosen sites
on relatively open coastlines, exposed to high current flows of
naturally nutrient replete waters so that nutrient enrichment of
enclosed water bodies will be minimised. In the specific case of
Deep Bay in Tory Channel (Submissions No.0342 and No. 0645)
the water in the bay probably already has high levels of nitrate
because of its close proximity to Tory Channel however the
monitoring of enclosed embayments such as this in close
proximity to the proposed farms should be a priority.
71.4
Issue 4: Two submissions (EPA No. 1072 and EPA No. 0111)
raise the issue of a shift in phytoplankton species composition
from diatom to dinoflagellate dominated communities as a result
of increased nitrogen enrichment. I have dealt with this issue in
my evidence (paragraphs 66-67) and I believe that within the
context of the different nutrient chemistry conditions that prevail
in Pelorus and Queen Charlotte Sounds it is unlikely to be
important. In any case it is probably worth reiterating here that
dinoflagellate dominated communities are natural and common in
the Sounds. Dinoflagellates are an important component of the
phytoplankton upon which most other marine life in the Sounds
depend for their nutrition.
CONCLUSIONS
72
The dynamics of algal blooms are determined by rapidly changing and
complex interactions between physical, chemical and biological factors.
We have a general understanding of how phytoplankton productivity is
controlled by physical factors and seasonal and episodic nutrient supply in
the Sounds. But except for few localities where resident populations of
some species exist we cannot predict with any certainty (except by
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 40 of 41
monitoring) how selection processes will lead to the transient dominance
of a ‘harmless’ species or one that has some property which puts it into
the category of a ‘harmful algal bloom’.
73
HABs are relatively common in Queen Charlotte Sound but less so in
Pelorus Sound, probably due to basic differences in the water chemistry
of these regions. Seawater in Queen Charlotte Sound is oceanic in origin
whereas seawater throughout much of Pelorus Sound is influenced by
large freshwater inflows at the head of the sound and is more estuarine in
character. Sheltered inlets with longer water retention times and stratified
water columns in both Sounds are prime habitats for the establishment of
flagellate dominated communities, including HAB species.
74
A thorough search of the international scientific literature did not provide
evidence of a strong relationship between HABs and sea cage fish
farming, except in the most confined, poorly flushed situations where the
nutrient loads from the farms far exceed the assimilative capacity of the
water body.
75
The fact that the nutrient inputs from the farms can be considered
‘unbalanced’ because of the lack of silica for diatom growth is not
considered to be an important issue. Queen Charlotte Sound waters are
probably naturally silica limited at times and the salmon farm effluents will
not make a difference to the current situation. Whereas in Pelorus Sound
silica is usually present in excess and so is unlikely to be limiting.
76
Effluents from the proposed sea cages will increase the nitrogen load on
the system. However, these inputs need to be seen in the context of the
ambient nutrient environment and the high rates of dilution, dispersion,
assimilation and recycling that take place in the water column and
sediments. The location of the farms in Tory Channel, Port Gore and
outer Pelorus Sound where upwelling results in naturally high ambient
nutrient levels, alleviates potential concerns that maximum rates of
nutrient loading will take place in summer when the upper water column in
the Sounds is generally nutrient depleted.
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012
Page 41 of 41
77
The proposed sites have been chosen to maximise the rapid dilution and
dispersion of nutrients and minimise the potential for HAB development.
The farms will be situated in deep, high current areas, with well mixed
water
columns
and
naturally
high
ambient
inorganic
nutrient
concentrations. These conditions are not conducive to the development
of flagellate dominated blooms.
78
It is not expected that the increase in nitrogen loads with their sources
spread over a wide geographic area will lead to an increase in problems
with HABs, or in fact, given the high natural variability, easily measurable
increases in phytoplankton biomass (see evidence of Mr Ben Knight).
The lack of evidence of an association between HABs and existing
salmon farms in the Marlborough Sounds and Stewart Island suggests the
effects of the proposed increased nutrient loads will be minimal.
Name: Angus Lincoln MacKenzie
Signature:
Date: 21 June 2012
Statement Of Evidence In Relation To Water Column Effects: Harmful Algal Blooms
Of Angus Lincoln MacKenzie For The New Zealand King Salmon Company Limited June 2012