Temperate coastal marine communities: Biodiversity and threats

Abstract

SYNOPSIS. Temperate marine ecosystems are some of the most productive and diverse of all ecosystems. Over the past century the resources contained within these communities have been subjected to gross mismanagement. They are continually subjected to threats from multiple stresses imposed mostly by human activities, predominantly as a result of increased population growth. The most significant categories of threats derive from: (1) habitat loss and degradation, (2) pollution from numerous sources including sewage, pesticides, pulp mills, thermal effluents, polychlorinated biphenyls, heavy metals, oil and radionuclides, (3) overexploitation, (4) species introductions, (5) global climate change, (6) misguided human perceptions and (7) legal complexities. Furthermore, because subtidal and offshore coastal marine communities are not easily observed, their deterioration often goes mostly unnoticed.Impacts from stresses on coastal marine communities are manifested at the individual species level, but magnify in effect throughout the entire ecosystem because of complex inter-connected relationships between species at different trophic levels, including interactions such as predation, competition and mutualism. Therefore, one missing species or group of species that may be affected by some particular local pollutant, for example, may have unpredictable direct or indirect consequences through secondary effects on the ecosystem, possibly leading to the loss of a few to many species. Rather than striving to maintain some specific level of diversity, we should endeavor to understand the basic ecological processes that control populations, communities and ecosystems so we can best predict what kinds of stresses will cause the most serious alterations to the system and avoid them. In addition, we should be conservative about protecting systems even before we understand the processes fully. © 1994 by the American Society of Zoologists.