| one publication added to basket [14406] | Effects of pollutants on marine ecosystems
Gray, J.S. (1982). Effects of pollutants on marine ecosystems. Neth. J. Sea Res. 16: 424-443
In: Netherlands Journal of Sea Research. Netherlands Institute for Sea Research (NIOZ): Groningen; Den Burg. ISSN 0077-7579; e-ISSN 1873-1406, meer
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| Abstract |
Effects of continuous gross pollution lead to dominance by small-sized individuals that have life-history characteristics allowing rapid recolonization of disturbed habitats. Acute short-term pollution, such as oil accidents, can recover to normal conditions in 3 to 10 years depending largely on exposure. Moderate pollution on planktonic systems is thought to lead to dominance by microflagellates, small copepods, ctenophores and medusae whereas in unpolluted systems diatoms, large copepods and fish dominate. Close analysis of data on which such hypoothesis are based suggests that there are a few strong trophic links in planktonic systems. The species that dominate under moderate pollution are tolerant species with life-history characteristics that allow them to increase. In the absence of potentially competitively superior diatoms, microflagellates increase, and lacking large copepods, small copepods increase. Unstructured systems will not show food-chain accumulation of heavy metals or organochlorines, as is demonstrated with data on caesium, mercury and DDT levels. A hypothesis is erected that structured food web systems exist only where the predator or herbivore can completely control prey or plant density. In planktonic and soft-sediment systems this structure will be restricted to small patches in space or time over large areas or long time scales unstructured systems will be the rule. The lognormal distribution is suggested as a model for the distribution of individuals among species for such unstructured systems. Pollution has the effect of simplifying the system and giving it structure with defined groups of species dominating. Thus pollution can structure communities over large areas. |
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