Geoscience Reference
In-Depth Information
2.3 Impacts of human use of ocean areas
Themarineenvironment,eveninthedeepsea,isnolongerpristineanduntouched,andpres-
sures on ecosystems and species are increasing (van den Hove and Moreau,
2007
). Accord-
ing to the Global Coral Reef Monitoring Network (GCRMN), the world has effectively lost
19% of its original area of coral reefs; 15% are seriously under threat of loss within the next
10-20years;andanadditional 20%in20-40years(Wilkinson,
2008
).Seagrasseshavebeen
disappearing at a rate of 110 km
2
yr
−1
since 1980, and 29% of the known areal extent has
disappeared since seagrass areas were initially recorded in 1879 (Waycott
et al
.,
2009
). Oys-
ter reefs have declined by more than 90% from historic levels in 70% of bays and 63% of
the world's marine ecoregions. Most of these declines are due to direct human exploitation,
habitat degradation, and clearance for development, and pollution.
The deep sea has also been impacted by human activities, in particular fisheries. Many
deep water habitats, such as cold-water coral reefs and seamounts show impacts from bot-
tom fishing activities. The biological resources of seamounts have been the target of in-
tensive exploitation, resulting in overfishing and major crashes in stocks on some (Clark
and Koslow,
2007
), along with large impacts on the benthic communities of many studied
seamounts, caused mainly by bottom fishing, particularly demersal trawling (Collie
et al
.,
cold-water coral reefs have been damaged by bottom fishing activities, but the extent of this
damage has not been quantified (Hourigan,
2008
).
Withadvancesintechnology,humancapacitytoreachremoteareashasincreased,lead-
ing to growing threats that include unsustainable fishing and shipping activities, pollution,
ocean dumping, and oil, gas, and mineral exploration. In addition, climate change and ocean
acidification increasingly threaten oceans and polar areas.
