|Life history and production of Neomysis integer (Leach, 1814) in the brakish part of the Westerschelde|
Abdulkerim, Z. (1992). Life history and production of Neomysis integer (Leach, 1814) in the brakish part of the Westerschelde. MSc Thesis. University of Gent, Zoology Institute, Marine Biology Section: Gent. 55 pp.
The hyperbenthos of the brackish part of the Westerschelde estuary was sampled on a fortnightly basis from November 1990 to December 1991. The temporal patterns in the hyperbenthic community structure were investigated with several multivariate statistical techniques. The biology and population dynamics of the dominant species, the mysid Neomysis integer were studied in depth. Secondary production of this species was estimated by 3 different approaches. The hyperbenthos is highly dominated by two mysid species: Neomysis integer (throughout the year) and Mesopodopsis slabben (only in summer). The analyses revealed five distinct seasonal communities. The highest number of species was observed in spring and summer. At this time the community contains a number of temporary hyperbenthic species. In winter, the community was poor in species and almost all of these were permanent hyperbenthic species. The observed temporal patterns in the community showed strong correlation with temperature, turbidity and dissolved oxygen concentration of the water. The study of the life history and the composition of the Neomysis integer population of the study area revealed three distinct peaks of reproduction and input of juveniles in the year 1991. This suggests a production of three cohorts per year. The three cohorts showed marked differences in their biology (e.g. density, growth and fecundity). Three different methods for estimating secondary production yielded similar results. The annual production is 322 mg AFDW.m-2.yr-1 with a P/B ratio of about 6.0. The average cohort P/B is about 3.0. The production and growth characteristics of the different cohorts, and of the two sexes within a cohort, varied considerably. The spring cohort accounts for almost half of the annual production.
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