Download Land-based pollution

Drivers of change
Fact sheet series
VECTORS
Vectors of change in European Marine
Ecosystems and their Environmental
and Socio-Economic Impacts
The VECTORS project seeks to develop
integrated, multidisciplinary research - based
understanding of changes taking place in our
marine environment, the mechanisms for
them and the ecological impacts expected
from them. VECTORS will examine how
these changes may affect the range of goods
and services provided by the oceans, the
ensuing socio - economic impacts and some
of the measures that could be developed to
reduce or adapt to these changes.
Regional seas vectors and drivers
This VECTORS report identifies and
disseminates the current understanding of
drivers, pressures and vectors of change
that could be affecting the main areas
of concern to VECTORS: outbreaks,
invasives, changes in species distribution
and productivity.
The full 220 page report, created through
a desktop review exercise, is available to
download from the VECTORS website,
www.marine-vectors.eu. A series of twelve
fact sheets, including this one, have been
produced to summarise the key findings
for each of the nine drivers studied and
each of the three Regional Seas (Western
Mediterranean, North Sea and Baltic Sea)
that act as case studies for the VECTORS
project.
Land-based pollution
Key points
Eutrophication is a common problem in all three seas considered by
VECTORS; the North Sea, the Western Mediterranean and the Baltic
Sea. In the Baltic sea it is mainly related to waterborne nutrient run - off
from farming and managed forestry. In the western Mediterranean Sea,
eutrophic conditions have been increasingly reported in the last decades
in coastal and transitional waters, leading to dystrophic crises and benthic
and fish kills. Some regions of the North Sea receive large quantities of
anthropogenic nutrients through large rivers, and to a lesser extent from
atmospheric deposition and discharges from plants that treat wastewater.
The main areas affected by
hypoxia in the Mediterranean
sea are coastal zones and
lagoons
where
the
key
environmental features are:
low depth, high productivity,
organic matter enrichment and
low hydrodynamic forces. In the
Baltic Sea hypoxia is widespread
in large areas both in the open
deeper parts and at coastal
sites. A side effect is increased
release of phosphorous from
sediments, causing further eutrophication. In the North Sea, hypoxia can
occur seasonally particularly under stratified conditions in areas with high
rates of production by phytoplankton.
Hazardous substance concentrations in the Baltic used to be at levels where
there were effects on marine mammals and other top predators, with some
species such as the white tailed eagle even close to extinction. These
hazardous substances are now seen to be decreasing in the Baltic.
Biological contamination is caused by natural processes such as circulation,
upwelling relaxation, and river flow; combined with anthropogenic loadings
leading to eutrophication and toxic harmful algal blooms or transport of
pathogens from wastewater and aquaculture.
General effects
Land-based pollution can cause eutrophication (an excess of nutrients), hypoxia (reduced oxygen in the water and
sea-bed sediment), changes in turbidity, chemical and biological contamination. Eutrophication causes benthic algal
blooms and affects regulation by grazers, favouring invading amphipods and polychaetes. Eutrophication can also
influence the development and persistence of harmful algal blooms in the plankton, caused both by toxic and nuisance
algae. Hypoxia in the water affects the behaviour, distribution and productivity of fish, through mass mortality or loss of
habitat. On the other hand, prolonged hypoxia may favour species, such as jellyfish, which are known to tolerate lower
dissolved oxygen concentrations in seawater. Hypoxia in sediment changes the penetration of oxygen altering the redox
potential discontinuity depth and causing release of hydrogen sulphide in sediments. This can have huge impacts on
bottom fauna, and when re - oxidation occurs, opportunistic species can be favoured in the changing areas.
Turbidity in the water is increased by planktonic algal blooms, and can affect prey/predator behaviour in fish, as
well as mating habits. Shadow effects of increased turbidity can alter habitats of macro algae and vascular plants
(Zostera). Chemical contamination from both “classical” and novel contaminants can favour invading species with
less sensitivity to contaminants, e.g. polychaetes and mud snails. Persistent toxic substances are especially worrying
because of both their persistence and their toxic effects on animal and plant life if concentrations exceed certain
thresholds. Biological contamination is less studied, often related to aquatic farms or wastewater outlets it can be linked
to increasing infectious diseases in cetaceans.
Contact
Project coordinator: Mel Austen
Project manager: Jenny Lockett
VECTORS Project Office
VECTORS
V1: Feb 2013
Coordinated by Plymouth Marine Laboratory
[email protected], www.marine-vectors.eu
Western Mediterranean
In recent decades, increased anthropogenic input of nitrogen and
phosphorus has led to severe eutrophication problems through Europe,
inducing higher phytoplankton primary production in many coastal areas. In
the western Mediterranean Sea, the process of eutrophication also increases
the frequency and intensity of phytoplankton and macroalgal growth, which
can generate hypoxia / anoxia and high turbidity conditions particularly in
the shallow coastal areas and lagoons. Land - based pollution may result in
the enrichment of the marine environment both in nutrients and in organic
matter. The former can cause eutrophication in the water column while the
latter reduces the depth of the redox potential discontinuity in sediments.
Hypoxia, turbidity and eutrophication in Europe. Hypoxia (oxygen< 2 mg / l) is shown as yellow dots, turbidity (> 0.5 g / l of
suspended particles) as orange dots and eutrophication as red dots.
Baltic Sea
The Baltic Sea is characterised by a low water exchange rate, making it sensitive
to eutrophication. Eutrophication forms the basis for increasing algal blooms,
which in turn increases turbidity and hypoxia, followed by shallowing of the
redox potential discontinuity and sulphide release from the sediment. Combined
with chemical and biological contamination, tolerant invading species can gain
footholds and suppress local species in parts of the Baltic Sea. The increased
turbidity and change in algae composition can change foraging and habitats of
fish and fish - larvae, as well as mating patterns hence disturbing the distribution
and productivity of fish. From the 1960s to present time, improvements in
chemical contaminants have resulted in improvements in the health of top
predators such as marine mammals and white tailed eagles, but eutrophication
and hypoxia are still wide - spread.
Eutrophication status
Good
HELCOM 2010
Bad
HELCOM integrated assessment of eutrophication status, based on Ecosystem
Health of the Baltic Sea, HELCOM 2010. Areas in blue / green are areas “not affected
by eutrophication”, yellow / red areas “affected by eutrophication”. Large circles
indicate open basins and small circles represent coastal assessment sites.
North Sea
Nutrient discharges causing eutrophication and hypoxia have declined in the last 25
years but problem areas exist seasonally within larger river plumes, particularly in
eastern waters. Eutrophication can alter phytoplankton species composition and cause
seasonal hypoxia particularly within bottom waters in strongly stratified areas. Pelagic
animals more tolerant to low dissolved oxygen, such as jellyfish, may become more
prevalent and benthic community composition will be impacted by benefiting animals
that can cope with the shallowing of the redox potential discontinuity layer in sediments.
Adverse effects of chemicals present within sediments have been documented on
organisms, particularly along shipping routes. Only a few coastal areas exceed threshold
bacteria concentrations outlined in specific water quality directives but direct impacts of
biological pollution on flora and fauna can occur in close proximity to sewage outflows
including eutrophication - like effects as well as the transmission of faecal viruses and bacteria
via suspended particulate matter (SPM) to shellfish and other filter feeders. Chemical and
biological pollutants are often associated with SPM which occurs at higher concentrations
in southern vs. northern waters and in coastal areas that are routinely dredged.
Eutrophication status in the period 2001–2005 for the North Sea region. These areas are also
largely problem areas for hypoxia in the North Sea: This figure was taken from the Ospar 2010
Quality Status Report. http://qsr2010.ospar.org/en/ch04_04.html#eutrophication).
VECTORS
VECTORS is a European project (26455) supported within
Themes 2, 5, 6 and 7 of the European Commission
Seventh Framework Programme
Further information
The leader for this driver and fact sheet creator is Paolo Domenici
(CNR-IAMC, [email protected]) with input from Martin M.
Larsen, Myron Peck and the Regional Seas review contributors.