A guide for planners and managers - IUCN

222 MARINE AND COASTAL
PROTECTED AREAS
Photo by John Clark.
FIGURE II-36.
Visiting party to Perez Island in the Alacranes Reef complex take all
wastes back to the Yucatan mainland.
Colonial breeding of
marine-feeding species on
islands, especially seabirds, leads
to intensive eutrophication of
many island ecosystems. Massive
concentrations of phosphate in
seabird guano deposits on some
islands are valuable for mining
of fertilizer. Following human
contact and settlement, concentrations
of seabirds decline
rapidly, usually because of the
import of predators, especially
rats (Bourne, 1981), and direct
harvest of eggs and birds. The
network of ecological connections
between land and sea is
broken very early on many islands as a direct result of human contact. Fishing and
the exploitation of other marine resources are important elements in the economy
of many island peoples, either for subsistence or for export. This dependence on, and
progressive depletion of, marine creatures at different stages of economic development
is discussed for the Tristan da Cunha Islands by Wace and Holdgate (1976). The recent
extension of ownership of fish stocks to 200 miles offshore has very greatly increased
the marine resources owned and theoretically available to many island states, although
they may find such resources difficult to exploit or conserve (Lawson, 1980; Kearney,
1980).
Because of the importance, both ecologically and economically, of marineterrestrial
interactions, it is particularly important in protecting island habitats to prevent
the disruption on land or the overexploitation at sea of marine-feeding species. These
links between land and sea are fragile, but are best preserved on uninhabited islands
by rigorously preventing the introduction of predators, and on inhabited islands by
encouraging the composting or other local recycling on land of waste products from
fisheries. Soil fertility is better maintained in this way than through a total reliance
on imported synthetic fertilizers.
Establish environmental monitoring and research in the natural sciences as a locally
based activity.
Because of their proximity to continental coasts, many islands are used for
monitoring the atmosphere for synoptic weather analyses and forecasting. Islands with
substantial populations of breeding seabirds have also been used to monitor nearby
seas for pollutants and are increasingly seen as valuable sites for estimating the size
of nearby fish and other seafood stocks (e.g., fulmar counts in the North Atlantic and
penguin counts in the sub-Antarctic islands and the Antarctic Peninsula).