Population dynamics of the estuarine isopod Sphaeroma rugicauda
In: Estuarine, Coastal and Shelf Science. Academic Press: London; New York. ISSN 0272-7714; e-ISSN 1096-0015, meer
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| Author keywords |
climatic effects; sex ratios; seasonal variation |
| Auteurs | | Top |
- Heath, D.J.
- Khazaeli, A.A.
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| Abstract |
Population density, spatial distribution, size distribution, sex ratio and fecundity were studied in a population over a three-year period. Young are produced in the summer, overwinter, reproduce and then die. Population densities decrease due to mortality from March to June and increase due to natality from July to September. Climate has a significant effect on population density. An abnormally warm summer (1976) led to earlier breeding, reduced fecundity, faster growth and higher mortality of juveniles. This led to fewer, larger, breeding adults in 1977. Two years which were climatically similar showed similar population trends. Egg and offspring number were positively correlated with female size but differed between years. Brood pouch mortality was estimated at 17%. Marked changes in population sex ratio were shown to be artefacts due to differences in swimming activity of the sexes. |
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