After reading this article you will learn about the organisms as bio indicators to oil spill.
The selection of a suitable organisms is one of the first tasks in the preparation of a monitoring survey for pollutants, once the decision to use a biological indicator has been made.
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The basic prerequisites for this sort of study are:
(a) The organisms should accumulate the pollutant without being killed by the levels encountered in the environment.
(b) The organisms should be sedentary in order to be representative of the study area.
(c) The organisms should be abundant throughout the study area.
(d) The organism should be sufficiently long-lived to allow the sampling of more than one year class, if desired.
(e) The organisms should be of reasonable size, giving adequate tissue for analysis.
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(f) The organism should be easy to sample and hardy enough to survive in the laboratory, allowing defecation before analysis and laboratory studies of pollutant uptake.
(g) The Organism should tolerate brackish water.
(h) A simple correlation should exist between the pollutant content of the organism and the average pollutant concentration in the surrounding water.
(i) All organisms of a given species used in a survey should exhibit the same correlation between their pollutant content and the average pollutant concentration in the surrounding water, at all locations studies, under all conditions.
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(j) It is also vital to examine the kinetics of pollutants in an organism which is being considered as a candidate for an indicator survey.
Whilst phytoplankton have attracted considerable interest in respect of their response to the toxic action of trace metals or organochlorines, they have been rarely used as true indicators for the comparison of pollutant abundance at more than one location.
The principal reasons for this appear to be the difficulty in obtaining reasonable sample amounts free from other material or other organisms (zooplankton) and the acknowledged importance of species composition in the accumulation of pollutants by phytoplankton.
Although the indicator ability of phytoplankton is suspected because of the effects of species composition the uptake of pollutants from sea-water by phytoplankton’s is extremely important in the cycling of these chemicals through the ecosphere as it represents a bio concentration and hence dictates the amounts of each pollutant passed on to higher organisms through the food chain.
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As the macro algae satisfy many of the basic requirements to be an indicator organism, it has been often used for detection of trace metals particularly.
Ascidians and Annelids can often be used as indicators for trace metals. Molluscs have certainly been the most commonly used indicators to date at least for trace metals; these are as monitors of organochlorines has not been as widespread as that of finfish.
Research into pollutant kinetics in finfish has been widespread and the use of finfish species to monitor trace elements and organochlorines has been no less common. The major reason for this emphasis has undoubtedly been the economic importance of finfish to man.
Bryan (1976) in his excellent review of trace metals in marine ecosystems, stated that the evidence to that point suggested that Cu, Mb, Zn, at least were regulated over a range of ambient concentrations in finfish. Several marine mammals-viz., seals, dolphins and sea-lions-has potential significance to be a bio indicator with reference to trace metals or to organochlorines.