BIOLOGICAL POLLUTION - Marine Pollution: What Everyone Needs to Know - page 198

the spread of this invader, which is able to reproduce while in
a fragmented state. Thus, trying to remove it by cleaning off
fouled surfaces and dredging probably aids the spread of this
species unless it can be contained and totally removed from
the water.
What are some invasive seaweeds and what harm do they do?
Large areas of seabed in the northern Mediterranean are now
carpeted by Caulerpa taxifolia , an invasive seaweed that pushes
out native marine life, disrupts ecosystems, and affects fish-
ermen's livelihoods. In the late twentieth century it was very
popular in the aquarium trade. The public aquarium in Monaco
apparently released small amounts of the seaweed into the
wild. After remaining as a patch in front of the aquarium for
a while, it expanded and covered the seabed along 190 km of
coast. By 2001, it had spread to many other harbors around the
Mediterranean on boat anchors or fishing nets. It starts out by
overgrowing and shading native seaweeds or seagrasses, and
then affects animals that rely on the native species for food.
Animals that cannot move away quickly, such as shellfish, are
smothered. This seaweed protects itself by producing a toxin,
so there are relatively few species that can eat it. One species
that does is the Mediterranean bream, which accumulates the
toxins but is not directly harmed.
Japanese kelp or wakame ( Undaria pinnatifidia) is native to
Japan, China, and Korea, where it is harvested for food. It tol-
erates a wide range of conditions and can grow on any hard
surface, including rope, boat hulls, bottles, mollusk shells, and
other seaweeds. It may form dense forests outcompeting native
species for space and light. It was intentionally introduced
into France for commercial use and then spread to the United
Kingdom, Spain, and Argentina. It was unintentionally intro-
duced into Australia, New Zealand, and Italy. It can interfere
with aquaculture by attaching to cages or ropes, either slowing
the growth of or displacing the farmed species.