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Title: Effects of environmental stress on some functions of marine molluscs
Author: Thomas, N.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1987
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The relationship between environmental factors and the general 'health' of several common marine molluscs was investigated at stations along the coast of south-west Wales and in the laboratory, utilising locally collected molluscs whose 'health' was rated by numerical scales covering condition factor, dry tissue weight, total lipid content etc. In addition, an attempt was made to relate degree of motility with environmental stress amongst motile gastropods. Lamellibranch molluscs were monitored in situ over an extended period, revealing variations in condition criteria in connection with location, vertical position, age, season and the presence or intensity of pollution. Alcohols of varying isomeric forms were presented as pollutants to specimens of the gastropod L. littorea; the toxic influences were, in some cases, found to be reversible and the toxicity order was found to be similar to that reported in higher mammals. A degree of tolerance was evident towards crude oil; the influence of the substratum was found to be relevant. Molluscs were monitored under laboratory conditions with varying feeding regimes, to investigate the influence on total lipid level etc. Some food-stuffs were found to be more acceptable than others, but little direct fatty-acid incorporation was evident. Elevated temperatures were found to have a profound influence on fatty acid metabolism. L. littorea specimens were observed under field and laboratory conditions, a natural tidal-related behaviour being evident. This rhythmic behaviour proved resilient to environmental pollutants but tended to fade after prolonged constant conditions. Spontaneous re-emergence of the rhythm was detected, but attempts by artificial means to produce the same result met with only partial success. Under field conditions behaviour was found to be influenced by season and vertical position. Various species of gastropod revealed differing behaviour patterns. One aspect of man's role in the degradation of the marine environment was thus determined.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available