The life cycle of Bathyporeia pilosa Lindström (Amphipoda) in a stressful, low salinity environment
Chris Mettam

A population of Bathyporeia pilosa in the upper reaches of the Severn estuary was isolated from downstream populations by extensive stretches of unsuitable substratum and by the timing of its reproductive period and mating. The downstream population had discrete spring and autumn breeding periods. The progeny of its spring breeders mostly followed an annual cycle but the largest, most advanced individuals made up the smaller group of autumn breeders. The progeny of the autumn breeders joined the main overwintering stock, matured and bred in the spring. The upstream population was strictly univoltine, breeding in mid-summer. Individuals generally occurred at lower densities, matured at a smaller size and had fewer eggs. The rate of development at both sites was similar but egg laying appeared to be synchronised with different phases of the lunar cycle. Both populations from the Severn estuary were more restricted in their life cycles than predominantly bivoltine but continuously breeding populations from west Wales at a similar latitude.

Keywords: Amphipoda, life cycle, reproduction, embryonic development.
Contents of this volume Sci. Mar. 53(2-3) : 543-550 Back PDF
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