Population dynamics of the krill Meganyctiphanes norvegica (M. Sars, 1857) (Crustacea: Euphausiacea) in the Ligurian Sea (NW Mediterranean Sea). Size structure, growth and mortality modelling
The seasonal abundance, population structure and dynamics of the euphausiid Meganyctiphanes norvegica were studied from samples taken year round in the NW Mediterranean Sea. Length-frequency distributions were generally bimodal: the first mode was interpreted as the born-in-the-year cohort (0+) and...
| Published in: | Journal of Plankton Research |
|---|---|
| Main Authors: | , |
| Format: | Text |
| Language: | English |
| Published: |
Oxford University Press
1996
|
| Subjects: | |
| Online Access: | http://plankt.oxfordjournals.org/cgi/content/short/18/12/2295 https://doi.org/10.1093/plankt/18.12.2295 |
| Summary: | The seasonal abundance, population structure and dynamics of the euphausiid Meganyctiphanes norvegica were studied from samples taken year round in the NW Mediterranean Sea. Length-frequency distributions were generally bimodal: the first mode was interpreted as the born-in-the-year cohort (0+) and the second as a combination of the older age classes (1+). To describe growth, a bilinear function provides the best fit. A growth rate of 0.052mm day−1 (1.56mm month−1 was calculated for the first part of the growth function and 0.0034 mm day−1 for the second part. A negative exponential mortality function was fitted, giving a mortality rate of 0.0034 day−1 (1.25 year A numerical simulation of the size structure of the Ligurian population was performed and the validity of the model was checked using a multifactorial analysis. The demographic characteristics of the Ligurian population were compared to those of other areas and were interpreted as a functional adaptation of M.norvegica to the southern part of the geographical distribution of the species. |
|---|