ESTONIAN ENVIRONMENTAL REVIEW 2009

Proliferation of macroalgae
Costal sea bottom biological communities are impacted
by the general level of eutrophication of the Baltic Sea as
well as by local sources of pollution. The higher nutrient
concentration is responsible for the massive proliferation
of ephemeral filamentous macroalgae (map 8.2). Proliferation
of algae in turn has a strong impact on light conditions
and leads to competition for space as a result of which
mats of filamentous algae may suffocate higher plant and
perennial algal (bladder wrack) communities.
Oil pollution
The Baltic Sea is an area of very busy shipping traffic
– passengers, goods, oil and other hazardous cargoes are
transported on this body of water. In recent years, shipping
traffic has increased along with the likelihood of oil
spills and the number of intentional pollution events O .
In 2008, the border guard discovered 69 spills, in 2007,
99 and in 2006, 62.
The impact of oil spills is specific to each species.
For example in the case of bladder wrack communities,
species of algae and fauna that are related to the bladder
wrack community bear the brunt of the pollution. The
sensitivity of the kelp itself to short-term oil pollution
is low, yet in areas sheltered from waves, mineralized
oil may asphyxiate the communities in their entirety,
including the bladder wrack. As a consequence of severe
oil spills, the whole bottom-dwelling biota is generally
destroyed. In terms of feeder groups, filter feeders in the
sedimentary layer are the first to experience the most
severe harm. As the hydrocarbons are broken down, the
sedimentary layers closest to the surface become clearer
and the animals living within the sediment are affected.
Herbivores disappear from the polluted area due to the
toxic effects of the oil.
Besides oil spills, construction activity and mineral
extraction in coastal waters, and hazardous material
contamination are potential risks and factors impacting
bottom-dwelling biotic communities.
Invasion of alien species to the Baltic Sea has increased
exponentially and above all it is caused by more intensified
shipping traffic and is related to environmental
instability, which in turn is caused by climate change
and eutrophication.
8.4.4. Protection
It is not possible to apply working measures on the
local level to combat present eutrophication in the Baltic
Sea. At the same time, if all of the countries bordering the
Baltic Sea were to contribute to lessening the local impact,
it would be effective on a wider scale. Possible measures
to reduce the impact of pollution of coastal origin include
retracting influx, channelling and better treatment of
waste water. More sustainable use of water would also
help. In the case of construction activity, dredging and
dumping, the implementation of restrictions in special
conservation areas and in the immediate vicinity are
important; in some cases, ship speed restrictions are
necessary to avoid disruption of habitats on the seabed. In
the case of oil pollution, prevention and implementation
of navigational restrictions and pollution control play the
most important roles.
Marine alien species may enter a new area in many
ways, but above all on ships – in ballast water or attached
to the ship’s hull. Human-made canals also have an
important role. Individual animals may also escape into
nature from home aquariums and aquaculture farms. Thus
prevention is the most important thing for preserving
local diversity and preventing invasion of alien species
(including carrying out the recommendations of the
International Maritime Organization).
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O
Kaugseire Eestis. (Remote sensing in Estonia.) (2008) / Ed. K. Väljataga, K. Kaukver. Tallinn : EEIC. [WWW] http://www.keskkonnainfo.ee/index.php?lan=EE&sid=65&tid=67
(Õlireostuse tuvastamine SAR kujutistelt (Identifying oil spills from SAR images), p 195)