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MARINE INVASIVE SPECIES:
AN EMERGING THREAT IN THE
WESTERN INDIAN OCEAN
Indian Ocean Commission
Blue Tower
4th floor, rue de l’Institut
Ebene, Mauritius
Tel : +230 402 6100
MARINE INVASIVE SPECIES:
[email protected]
An emerging threat in the western indian ocean
www.coi-ioc.org
Marine invasive species (MIS) are recognised as one of the four major threats to marine and coas-
Fax : +230 466 0160
tal ecosystems along with land-based sources of marine pollution, overexploitation of living marine
© Indian Ocean Commission
resources and habitat degradation.
Definition: Invasive species are species which proliferate and spread in a manner which threatens
ecosystems, habitats and/or other species, and which potentially cause socio-economic and/or
environmental damage, or harm to human health. The majority of invasive species are alien (non-
Photo credits :
indigenous, exotic): species which have been intentionally or unintentionally introduced to a new
Charles Griffiths, Commission de l’océan Indien, International Maritime Organisation, Marine and
geographic location, area, or region outside of their natural distribution range. However, it is important to
Coastal Management, Mauritius Oceanography Institute, Mercator Media, David Obura, Pierre Peries,
note that indigenous species may also become invasive, usually under altered environmental conditions.
Luc J.D. Ralaimarindaza, Andry Rasolomaharavo, Tamara Shiganova, Patsy Theresine
Alien species can be introduced to new coastal or marine areas via a number of pathways: broadly
defined as the underlying activity or purpose (e.g. mariculture, shipping, oil and gas exploitation,
tourism or aquarium trade) for the intentional or unintentional translocation of species.
Intentional introductions include species which are imported
for fisheries or mariculture ventures, for coastal management
initiatives (eg. erosion control), or display in aquaria. However,
such introductions may also result in unintentional ones as a
result of escape or subsequent deliberate (illegal) release from
the facility, or spread from an unconfined site.
The pathway responsible for the majority of unintentional
introductions is shipping (including small craft as well as
offshore platforms) which transports alien species in ballast
water or as biofouling. The construction of canals linking
previously unconnected water bodies is also important in
some regions (eg. Suez Canal).
This publication has been produced with the assistance of the European Union.
The contents of this publication are the sole responsibility of the author and can
in no way reflect the views of the European Union.
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IMPACT ON FISHERIES: The comb jelly Mnemiopsis leidyi endemic to North America coast - was first recorded in the Black
Sea in 1982. It became well established, occurring in massive
numbers and changing the whole pelagic trophic web, with a
devastating effect on the pelagic fisheries of the Black and Azov
Seas. These fisheries target zooplanktivorous fish species such
as anchovy, horse mackerel, sprat and kilka. Since Mnemiopsis
also feeds on zooplankton, its presence led to a massive decline
in the availability of food for the fish, causing the collapse of
fisheries worth approximately $500 million per year. Landings
of anchovy dropped to one-third of their previous levels, and
many fishermen abandoned fishing. The situation has improved
in recent years as a result of another accidental introduction: a
second species of comb jelly which preys on Mnemiopsis, leading
to a decline in its numbers.
The management of invasive species is based on a hierarchical
approach including the following:
Biofouling : the biological communities which develop on submerged physical structures such as
ship’s hulls, propellers etc, as well as fishing gear, mariculture cages and even marine debris. Slowmoving vessels and those which spend lengthy periods in one location and are cleaned infrequently
are of particular concern as they harbour a greater number of species which can enter new areas by
“jumping ship” or by releasing offspring into the surrounding waters. Biofouling is now recognised as
the biggest source of marine invasives.
Ballast water is used to provide stability to ships which are not carrying a full load of cargo. It is taken
on board at the start of a journey and discharged in the port where the cargo is to be loaded. Most marine
biota have a planktonic stage in their lifecycle and it has been estimated that up to 10 000 species may
be present in ballast water at any given time. The sediments which accumulate in ballast tanks commonly
contain dinoflagellate cysts which, once discharged can result in Harmful Algal Blooms (HABs).
Marine Invasive Species may have a variety of impacts:
•
•
1. Prevention or minimization of introductions
2. Prevention of establishment and spread through early
MOST DESIRABLE
detection and rapid response
3. Eradication (where possible)
4. Containment
5. Ongoing control of established invasives.
Prevention is the preferred and most cost-effective option
particularly in the marine environment where eradication is
extremely difficult and ongoing control very costly. Prevention
measures can be applied to pathways and/or around borders
and include:
Pre-border: in the case of deliberate introductions for eg.
mariculture, - Environmental Impacts Assessments to assess
Ecological impacts: they can displace indigenous species through predation, competition, habitat
the risk of invasion; for shipping – management of biofouling
alteration and changes to the food-web. They can also disrupt ecological processes and compromise
and on-board treatment of ballast water;
ecosystem services.
Border: compliance inspections, quarantine and/or treatment;
Economic impacts: they can cause closure of recreational/coastal amenities as well as reductions in
Post-border: monitoring for priority species (early detection)
productivity of fisheries (see below) and efficiency of shipping – the latter due to biofouling which
and rapid response plans.
LEAST DESIRABLE
also causes problems for coastal infrastructure, mariculture operations and industrial installations.
Moreover, there are significant costs associated with their prevention and management.
•
Health impacts: pathogens such as cholera and phytoplankton cysts which form Harmful Algal
Blooms are commonly found in ballast water and sediments. For example, a cholera outbreak in
South America in 1991 was linked to ballast water discharges from a ship from Asia.
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MARINE INVASIVE SPECIES : AN EMERGING THREAT IN THE WESTERN INDIAN OCEAN
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Marine invasive species
in the Western IndIan Ocean
Several species of red algae including Kappaphycus spp, Eucheuma denticulatum and Gracilaria
Salicornia – are utilised for seaweed mariculture in a number of WIO countries.
Tanzania is the biggest producer, but they are also cultivated in Kenya, Madagascar,
Mauritius and Mozambique. They include both introduced (eg. Kappaphycus from the
Philippines) and local species. They are all considered invasive in some parts of the
world (eg. Hawaii) and as such are considered a serious danger to coral reefs and
other benthic communities. There are reports of these species spreading outside of
the farmed areas in the region and it is important that they are monitored.
The Crown of Thorns Starfish (Acanthaster planci) is
a large (up to 80cm in diameter) indigenous species which
can become highly invasive under certain conditions. It feeds
mainly on hard corals and when there
are dense aggregations it can cause
significant damage to coral reefs. It
is of particular concern where there is
already damage due to other factors
such as coral-bleaching. Outbreaks
have increased in recent years and
have been linked to nutrient loading,
El Nino events and a reduction in
predators. They have been reported
from Comoros, Madagascar, Mauritius, Reunion and Seychelles.
Efforts to manage COTS should be coordinated at regional level.
Bugula neritina is a bryozoan which is an
abundant fouling organism that colonises any
freely available substratum, including ships,
piers, buoys and other
man-made marine surfaces
and structures. B. neritina
populations
tolerate
high levels of pollution
(including copper) which
increases their competitive
advantage and thus their
potential to be a fouling
pest. It has been reported in Kenya and Seychelles.
SOMALIA
KENYA
Harmful Algal Blooms (HABs) are caused by a variety of species including dinoflagellates,
diatoms, cyanobacteria or other types of micro-algae some of which can have acute impacts
on biodiversity or human health as a result of toxicity or oxygen depletion. Dinoflagellates are
commonly carried in the sediments of ballast tanks and, although some
are indigenous, there are many examples of translocation. HAB events
have been recorded off the coasts of Kenya, Mauritius, Somalia, South
Africa and Tanzania and some 60 potentially toxic species were recorded
in the region in a UNESCO-IOC led survey. Dinoflagellates included
Amphidinium carterae, Dinophysis acuminata, Gambierdiscus toxicus and
Protocentrum arenarium.
UNITED
REPUBLIC
OF
TANZANIA
ZANZIBAR
SEYCHELLES
COMOROS
MOZAMBIQUE
MAURITIUS
The Asian Mussel (Musculista senhousia) is a small mussel native to east Asia which has a
history of invasion in various parts of the world. It can grow rapidly and settles in aggregations
forming mats on the sediment. It can thus cause marked habitat
alteration and dominate benthic communities. M. senhousia also
deposits large amounts of organic matter in the sediment, which can
result in the accumulation of toxic metabolites such as sulfide, which
can have adverse effects on other species. It has been reported in
Madagascar, Mauritius and Tanzania.
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MARINE INVASIVE SPECIES : AN EMERGING THREAT IN THE WESTERN INDIAN OCEAN
MADAGASCAR
A number of species of oyster, including the
Pacific oyster (Crassostrea gigas), have
been introduced to Mauritius for mariculture
purposes. C.gigas has a history of invasiveness
in other parts of the world (Europe and North
America) and is reported to settle into dense
aggregations which exclude native intertidal
species, destroy habitats and cause eutrophication of the water bodies it invades.
While it may not be as significant a threat in tropical areas, it should be carefully
monitored.
REUNION
White spot syndrome is a viral disease which occurs in penaeid shrimps. It is
SOUTH
AFRICA
highly lethal and contagious and has decimated cultured populations around the
world. A variety of invertebrates can be vectors and there
have been at least two outbreaks of the disease in the
region – in Mozambique (2011) and Madagsacar (2012).
Such events have major implications for the shrimp
farming industry and appropriate precautions need to be
put in place to try and prevent them.
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Marine Invasive Species in the Western Indian Ocean
An additional factor which is likely to heighten the risk of invasions is climate change. An analysis
Relatively few alien marine species have been recorded in the countries of the WIO Region apart from
tolerance range for environmental parameters such as salinity and temperature, as well as high
South Africa, and in this case, many of the records are from the western part of the country and there-
reproductive capacities. This gives them a competitive advantage in the face of climate change and
fore outside of the WIO region. Even fewer of those recorded in the WIO have a history of invasiveness.
environmental disturbances caused by other factors such as pollution.
of species which tend to invade suggests that they have a number of specific traits, including a wide
On the other hand, a number of indigenous or cryptogenic species (i.e. those whose natural distribution
range is unclear) showing invasive behaviour have been reported. Examples of both alien and indigenous invasives in the region are shown on the map on the previous page.
To a large extent, this can be attributed to the low number of targeted surveys in the region. This is
supported by the fact that the growing interest in the subject has resulted in a number of new records
between 2012 when an assessment was done under ASCLME and 2015 (Baseline assessment for the
Biodiversity Project). Moreover, it is anticipated that the risk of introductions to the region is likely to
Regulation of marine invasive species
Increasing recognition of the impacts of marine invasive species over the past few decades has led to
the development of a relatively comprehensive international regulatory regime which comprises the
following:
•
The Convention on Biological Diversity (CBD, 1992) - the only global instrument to provide a
comprehensive basis for measures to protect all components of biodiversity against invasive alien
increase with the expansion of activities related to the primary pathways for marine species.
species (IAS);
•
The United Nations Convention on the Law of the Sea (UNCLOS) (1982)
•
The International Convention for the Control and Management of Ship’s Ballast Water and Sediments
(BWM Convention) (2004)
Seaborne trade in the region, for example, has
and this trend is likely to continue particularly
in light of the recent discoveries of oil and gas
(2010 – 2014) in the areas off of Tanzania and
•
Trade volumes
through WIO ports
increased significantly over the past few years
(2001).
In addition, the following voluntary agreements are relevant:
10,000,000
•
Mozambique – and the potential for further such
finds in the region. Commercial vessels as well as
offshore rigs increase the risk of introductions via
International Convention on the Control of Harmful Anti-fouling Systems on Ships (AFS Convention)
The IMO Voluntary Guidelines on Biofouling (2011) – which may eventually provide the basis for a
new legal instrument; and
•
5,000,000
An FAO Framework for the management of intentional introductions which includes provisions of
the 1995 Code of Conduct for Responsible Fisheries.
biofouling and ballast water.
Source : the WIO State of the Coast Report (2015)
Chapter 26 and UNCTAD Reviews of Maritime
Transport.
0
Another important document is the CBD’s Strategic Plan for Biodiversity 2011- 2020, which includes
2003
2004
2010
2011
2012
a number of targets, of which Aichi Target 9 states that: “By 2020, invasive alien species and
pathways are identified and prioritized, priority species are controlled or eradicated, and measures
are in place to manage pathways to prevent their introduction and establishment.”
Although Tanzania is one of the top mariculture
producers
in
Africa
(mainly
red
seaweeds),
production from other countries in the region is
relatively low. Once constraints to growth – such
as the lack of skills, technology and infrastructure
- have been addressed, it is anticipated that it will
expand throughout the region. Another driver for
mariculture development is the growing decrease
in returns from capture fisheries.
Source : the WIO State of the Coast Report (2015)
Chapter 22.
Role of the Nairobi Convention
The UNEP Regional Seas Programmes have historically been used as platforms to implement a number
of international conventions, including the CBD, IMO Conventions on pollution from ships, and the FAO
Code of Conduct for the Responsible Management of Fisheries. Since invasive alien species are, by definition, transboundary, they are naturally best addressed by harmonizing management efforts at the regional level. While the Nairobi Convention itself does not include articles dealing with invasive species,
Article 7 of the Protocol Concerning Protected Areas and Wild Fauna and Flora in the Eastern African
Region states that: “The Contracting Parties shall take all appropriate measures to prohibit the intentional or accidental introduction of alien or new species which may cause significant or harmful changes
to the Eastern African region.” It is proposed that this be strengthened to provide a sound basis for the
management of marine invasive species and the achievement of Aichi Target 9 in the WIO Region.
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MARINE INVASIVE SPECIES : AN EMERGING THREAT IN THE WESTERN INDIAN OCEAN
9
IOC Biodiversity Project
The Eastern and Southern Africa and the Indian Ocean (ESA-IO) region includes island and coastal
states with rich and vulnerable biodiversity. These natural resources underpin important sectors of
the economies of the countries in the region, particularly fisheries and tourism, and provide livelihood
opportunities and income for local communities. However in recent decades these ecosystems have
been degraded as a result of increasing pressure from human population expansion and uncontrolled,
sometimes inappropriate, coastal development.
In this context, the Indian Ocean Commission (IOC) signed a financing agreement with the European
Union in January 2013, to implement the Biodiversity Project “Coastal, Marine and Island Specific
Biodiversity Management in ESA-I0 Coastal States”. The countries participating in the Biodiversity
project are: Comoros, Madagascar, Mauritius, Seychelles, Kenya and Tanzania with Reunion Island
participating using its own resources.
The project document refers to the need to “implement mechanisms to harmonise policies and
regulations at regional level pertaining to (…) alien invasive species, (…) in association with on-going
initiatives at national level”. Initially the intention was to focus on terrestrial invasive alien species.
However, during the first Biodiversity Project Technical Meeting, in July 2014, the representatives of
the participating countries expressed an interest in complementing the terrestrial IAS activities with
a marine IAS component. The IOC therefore recruited consultants to update an existing MIS baseline
assessment and organise a regional workshop to agree on priorities for a second phase. Proposed
activities include:
•
Liaison with the Nairobi Convention to strengthen its provisions relating to MIS;
•
Development of awareness-raising materials;
•
Capacity development through a port baseline survey
Partners
IOC The Indian Ocean Commission, through the Biodiversity programme, is one of the first
institutions that deals with the marine invasive species (MIS) in the region. It encourages
synergy and policy harmonization between countries of the East Africa and members of the
IOC.
EU
European Union supports financially the Biodiversity programme through the 10th EDF
(European Development Funds) up to 15 million EUR.
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MARINE INVASIVE SPECIES : AN EMERGING THREAT IN THE WESTERN INDIAN OCEAN
Indian Ocean Commission
Blue Tower, 4th floor, rue de l’Institut
Ebene, Mauritius
Tel : +230 402 6100
Fax : +230 465 6798
[email protected]
www.coi-ioc.org