Aspects of the ecology of the lamellibranch Mercenaria mercenaria (L.) in British waters
In: Hydrobiological Bulletin. Netherlands Hydrobiological Society: Amsterdam. ISSN 0165-1404; e-ISSN 2214-708X, more
Also appears in:(1974). Proceedings of the International Symposium on Ecology and Physiology of the Brackish Environment, Amsterdam, September 4-7, 1973. Organized by the Netherlands Hydrobiological Society in honour of the Dutch hydrobiologist Dr. H.C. Redeke (1873-1945). Hydrobiological Bulletin, 8(1-2). Netherlands Hydrobiological Society: Amsterdam. 252 pp., more
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| Keywords |
Mercenaria mercenaria (Linnaeus, 1758) [WoRMS]
Marine/Coastal |
| Abstract |
(1) It seems possible that the naturalised population of Mercenaria in Southampton Water and the Solent is the result of the deliberate introduction of this sp into the River Test in 1925. (2) Mercenari is found in sediments ranging from almost pure shell gravel and sand to sand/gravel/mud mixtures, but is apparently unable to colonise firm clay, possibly because of its inability to burrow in such sediment. (3) Mercenaria in Southampton Water and the Solent occurs in salinities of 24 ppt to 35 ppt which falls within the range of this sp in America. (4) The densities of commercial sized Mercenaria recorded for Southampton Water (up to 160/m super(2)) are much higher than those reported for American Waters, and it is suggested that this may in part be due to the elimination of competing native sp by severe winters. (5) The absence of Mercenaria down the west side of Southampton Water and in the West Solent may be due both to the possible toxic effects of industrial effluents entering the east side of Southampton Water and to the easterly bias of the tidal currents flowing down the estuary. (6) It is suggested that the present distribution of Mercenaria is the result of recruitment from the spawning of the beds of this sp in the River Test, and that the present population is unlikely to expand further unless another spawning colony becomes established in a harbour to the east of Southampton Water. (7) The Mercenaria in Southampton Water appear to have become physiologically adapted to spawn at a lower temp (18°C to 20°C) than is reported for this sp in American waters (22°C+). (8) It is suggested that years with exceptional recruitment may be correlated with low river flows in the summer which leads to a reduced flushing of the larvae down the estuary. Thus in these years the period of retention of the larvae in upper Southampton Water in conditions of optimal temp and salinity for growth and subsequent successful settlement is increased. (9) Recent reclamation work in Southampton Water together with an increase in the commercial exploitation of Mercenaria may lead to changes in the distribution, density and population structure of this species. |
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