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through the ballast water. The main problem is the transportation of
species over physical barriers that separate communities and
ecosystems.
Impact of fisheries on the marine environment
Fishing is responible for considerable pressures
on the marine
environment. The main challenges of fishing are at
present
the
overexploitation of fish stocks , the discard poblem , and the destruction
of benthic habitats.
The consequences are depletion of main predator
and prey species , threat to sea birds and marine mammal populations ,
impacts on the marine food web , loss of sensitive benthic communities
, but also loss of income
and
the destruction of important food
resources.
Another problem of present fishing practices is the high quantities of
fish and other species which are caught unintentionally (bycatch) and
discarded , and consequently wasted.
Fishing activities can also harm the marine ecosystem directly . bottom
trawls are responsible for causing severe damage to the benthic habitats.
Lost fishing gear can also harm the marine environment , as seen in
ghost fishing or the entangling of marine species in lost nets or net
fragments.
(source : coastal marine conservation .2004.p : 77,89)
Exercise : Fill in the gaps with the right words :
1- Marine organisms are ………………………impacted
by human
activities occuring in the ocean.
2- Shipping can harm marine organisms in different ways , some of
the substances released by ships such as …………………….can
lead
to ………………………….., an ……………………..of
water nutrients that can destroy the marine ecosystem .
3- The release of chemical substances into the atmosphere can cause
………………which in turns lead to ocean acidification.