A guide for planners and managers - IUCN

6 MARINE AND COASTAL
PROTECTED AREAS
Photo by John Clark.
Critical Areas and Ecosystems
Among the most ecologically critical and threatened resources are fringing coral
reefs, tideflats, coastal wetlands and shallows, especially lagoons and estuaries and
their grass beds and mangrove swamps. These areas provide food and shelter for
waterfowl and for the fishes, crustaceans, and molluscs utilized by an estimated two
thirds of the world’s fisheries including some of the world’s most lucrative fisheries
(e.g., shrimp). Sea grass meadows are vital because they act as “nurseries” (special
habitats that nurture the young of marine and coastal species) and as nutrient
suppliers for economically important fish stocks. Wetlands, floodplains, sea grass beds,
and coral reefs are being degraded, or even destroyed the world over (Carpenter, 1983;
IUCN/UNEP, 1988; Wells and Hanna, 1992; Wilkinson, 1992, 1998), with severe
effects on the economies that depend on them. Coral reef ecosystems are of great,
significance to tropical countries, providing habitats for the seafood on which many
rural communities in developing countries depend.
In addition, coastal wetlands and coral reefs are extremely important for
protecting shorelines and coastal villages against storm waves and shore erosion
(Figure 3). In Sri Lanka, the removal of corals to produce lime was so damaging that
a local fishery collapsed—mangroves, small lagoons, and coconut groves disappeared
because of increased shore erosion, and local wells were contaminated with salt
before protection was implemented through a coastal zone management programme.
FIGURE 3.
A beach damaged by erosion. Beach erosion is often the result of
sand and coral mining for construction materials.
Fisheries
As fisheries for finfish, crustaceans,
and molluscs become
more fully exploited, the effects
of habitat destruction and pollution
will become more evident,
particularly on those species
depending on coastal wetlands
and shallows or on inland wetlands
and floodplains for nutrients
or for spawning grounds
and nurseries.
Most of the world catch
of marine species—87 million
tonnes in 1996—comes from within 320 km of land. The continental shelf directly
leads to high production because it concentrates activity into a thin water layer and
provides a substrate (solid surface) for fixed plants and benthic animals. In addition,
the topography of the shelf stimulates the upwelling of deeper waters carrying
chemical nutrients to the surface.