A guide for planners and managers - IUCN

24 MARINE AND COASTAL
PROTECTED AREAS
Photo by John Clark.
where organisms are less tied to the solid bottom than are land organisms to the earth.
But, more important because of the fluid nature of the seas, whole biological
communities exist as floating plankton-based entities distributed horizontally and
vertically through broad ocean spaces. Ocean currents are great mixers, transporting
organic nutrients produced at one site to distant locations and carrying planktonic
eggs and larvae of organisms to colonize distant habitats. In addition, many marine
species migrate long distances, like tunas, turtles, whales, and eels, and yet other
creatures, such as seabirds, depend on these. Since marine organisms are in closer
chemical contact with their surrounding medium than land organisms, they are
jeopardized more by pollution.
Conservation management of such large-scale ecosystems is a difficult challenge
and for the most part we must focus our protected area efforts on concrete situations.
For example, among the most ecologically critical and threatened areas are coastal
wetlands and shallows, especially lagoons and estuaries and their mangrove swamps.
Coral reef ecosystems are of more local, but nonetheless great, significance, providing
habitats for the fish on which many rural communities in developing countries
depend.
Wetlands, sea grass beds, and coral reefs are being degraded (Figure I-8), or even
destroyed the world over (Carpenter, 1983; IUCN/UNEP, 1991; Wells and Hanna,
1992; Wilkinson, 1992, 1998), with severe effects on the economies that depend on
them. In Sri Lanka, the removal of corals to produce lime was so extensive that a local
fishery collapsed.
FIGURE I-8.
Reef fishes need healthy coral reef
ecosystems to prosper.
MPAs help maintain ecosystem
productivity; safeguarding essential ecological
processes by controlling activities that
disrupt them or that physically damage
the environment. Some of these processes
are physical, such as the movement of
water, food, and organisms by gravity,
waves, and currents. Others are chemical,
such as concentration and exchange of
gases and minerals, and biological, such as
nutrient transfer from one trophic level to
another. Some, such as nutrient cycling, are
of all three types. It is these processes that
maintain ecosystem integrity and productivity.
Lake lchkeul in Tunisia is an example
of an MPA where ecosystem processes are
maintained (see Box I-1).