|Chemical defences and the structure of subtidal epibenthic communities|
Dyrynda, P.E.J. (1985). Chemical defences and the structure of subtidal epibenthic communities, in: Gibbs, P.E. (Ed.) Proceedings of the 19th European Marine Biology Symposium, Plymouth, Devon, UK, 16-21 September 1984. pp. 411-423
In: Gibbs, P.E. (Ed.) (1985). Proceedings of the 19th European Marine Biology Symposium, Plymouth, Devon, UK, 16-21 September 1984. Cambridge University Press: Cambridge. ISBN 0-521-30294-3. 541 pp., more
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In common with modular sessile organisms in general, poriferans, colonial cnidarians, bryozoans, and colonial ascidians colonizing hard-substrates are particularly vulnerable to interspecific interactions of micro- or macro-biotic endobiosis, epibiosis, or predation, i.e. sequestrational resource capture. They are also comparable in that an appreciable proportion of species are known to accumulate toxic secondary metabolites, which may, as allelochemicals, serve as part of the array of defences each species possesses, complementing or replacing the more evident physical or physico-chemical defensive options. In order to evaluate the potential for chemical defence in temperate communities, a range of species from the above four groups, occurring together in the same high-occupancy subtidal assemblages off southern Britain, have been assayed for the presence of potential toxins which may act against the above risk categories. A proportion of representatives from each group provided strong positive outcomes with some of the test species, but not others, providing evidence of interspecific variability, both in the occurrance of toxins between the defending sessile species, and of susceptibility among the potentially offending biota. Possession of complex chemical defences by sessile species requires equally complex counteractive measures in successful offenders, a requirement leading to specificity of association, as exemplified by many associations between resistant offenders and sessile species known to contain toxins. The presence of chemical defences within even a small proportion of sessile biota in a community, mayby influencing patterns of grazing, larval settlement, and adult inter-relationships have consequences for gross community structure.