Seasonal growth in the bivalve Macoma balthica near the southern limit of its range

F.H. Nichols; J.K. Thompson

doi:10.2307/1352108

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Seasonal growth in the bivalve Macoma balthica near the southern limit of its range

F.H. Nichols·J.K. Thompson

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Abstract

Shell-length growth in Macoma balthica from San Francisco Bay, California, as measured on living animals in situ, is highly seasonal despite a mild Mediterranean climate: a long period of near non-growth from May to the following February is followed by a short period of rapid growth between March and May. The rapid-growth period follows the spawning period during January/February and ends as water temperature rises above about 15??C. Despite the shortness of the growth period, M. balthica grows larger at a given age in San Francisco Bay than is recorded elsewhere in the world. Application of a model, developed elsewhere from these same field measurements, shows that (1) measurable growth occurs during the summer/autumn/early winter "nongrowth" period, (2) there is an autumn recruitment, and (3) both spring and autumn recruits combine to form a single "one-year-old" size grouping. None of these features is detectable through growth-ring analysis of field samples, apparently because of indistinct climatic seasons, or through size-frequency histogram analysis because of the combined effects of slow growth and intermittent recruitment. ?? 1982 Estuarine Research Federation.

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F.H. Nichols, J.K. Thompson. 1982. Seasonal growth in the bivalve Macoma balthica near the southern limit of its range. https://doi.org/10.2307/1352108

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