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Ecology of Marine SedimentsFrom Science to Management$
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John S. Gray and Michael Elliott

Print publication date: 2009

Print ISBN-13: 9780198569015

Published to Oxford Scholarship Online: November 2020

DOI: 10.1093/oso/9780198569015.001.0001

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PRINTED FROM OXFORD SCHOLARSHIP ONLINE (oxford.universitypressscholarship.com). (c) Copyright Oxford University Press, 2021. All Rights Reserved. An individual user may print out a PDF of a single chapter of a monograph in OSO for personal use. date: 17 October 2021

Human Impacts on Soft-Sediment Systems—Pollution

Human Impacts on Soft-Sediment Systems—Pollution

(p.133) Chapter 9 Human Impacts on Soft-Sediment Systems—Pollution
Ecology of Marine Sediments

John S. Gray

Michael Elliott

Oxford University Press

A widely accepted definition of marine pollution is“the introduction by man, directly or indirectly, of substances or energy into the marine environment (including estuaries) resulting in such deleterious effects as harm to living resources, hazards to human health, hindrance to marine activities including fishing, impairment of the quality for use of seawater, and reduction of amenities”.(Wells et al. 2002).This differs from contamination since it results in biological damage, whether to the natural or human system, whereas contamination can be regarded merely as the introduction of substances by human activities (McLusky and Elliott 2004). Furthermore, pollution and pollutants can refer to biological and physical materials as well as chemicals (Gray 1992, Elliott 2003). In the case of the benthos, there is an extensive literature indicating that every type of pollutant has an effect on the benthos and so it is not surprising that the benthos is the mainstay of any monitoring and investigative programme. Pollution can affect organisms living in sediments by physical variables associated with the pollution source, such as increased sedimentation of particles, which leads to smothering of the fauna. In such cases the effect can in fact be regarded as a disturbing factor if the effects lead to mortality of individuals (Gray 1992). Alternatively, pollution can affect the fauna by toxicity where increased concentrations of contaminants lead to biochemical and physiological effects and ensuing mortality if certain thresholds for adaptation are exceeded. Here, however, we first treat the effects of the most widespread form of pollution affecting the marine environment— increased organic matter in sediments. Excess organic matter enters the marine environment principally as sewage, although it can also include waste from paper pulp mills or changed river run-off, for example. Excess organic matter causes physical effects such as smothering and also leads to reduced oxygen concentrations in the water column or pore-water in sediments. Sewage discharged into confined bodies of water frequently leads to the well-known symptoms termed eutrophication, resulting, in the most extreme cases, in a total lack of oxygen and the presence of hydrogen sulfide in the sediment, with a corresponding absence of fauna (e.g. de Jonge and Elliott 2001).

Keywords:   crustaceans, currents, deep sea, macrobenthos, marine sediments, mortality, multivariate statistics, mussels, nematodes, oil industry, oligochaetes, ophiuroids, opportunist species, ordination analysis (MDS), organic enrichment, organic matter, organic pollution, organisms, polar regions, pollutants, pollution, polychaetes, predation, sewage, smothering, soft-sediment, species, storms, stress-tolerant species, stressors, system changes, temperature, toxicity, trophic systems

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