|Distribution, dynamics and productivity of a colonizing (Polydora quadrilobata) and an established (P. ligni) polydorid polychaete in Lake Grevelingen: an enclosed estuary in the SW Netherlands|
Lambeck, R.H.D.; Valentijn, P. (1987). Distribution, dynamics and productivity of a colonizing (Polydora quadrilobata) and an established (P. ligni) polydorid polychaete in Lake Grevelingen: an enclosed estuary in the SW Netherlands. Neth. J. Sea Res. 21(2): 143-158
In: Netherlands Journal of Sea Research. Netherlands Institute for Sea Research (NIOZ): Groningen; Den Burg. ISSN 0077-7579, more
|Authors|| || Top |
- Lambeck, R.H.D.
- Valentijn, P.
The enclosure of the Grevelingen estuary in May 1971 (from then on saline lake Grevelingen) did not result in an immediate population response of Polydora ligni, known as an opportunist. A large summer settlement (2 to 5000 ind·m-2) and a subsequent high mortality occurred at one station in the period 1972 to 1975; abundance fluctuations at a second station were much smaller. In 1977 densities were very low. The congeneric P. quadrilobata (a species new to Dutch waters) was not observed in 1971-1975, but an average density of 760 ind·m-2 (with a biomass of 0.1 g ADW·m-2) was found in the lake in April 1977. Its abundance was low in shallow water (< 2.5 m); in the rest (54%) of the lake no preference for depth, substrate or species association could be detected. Seasonal maxima occurred in spring. These opposing population developments can be explained from the different life histories of the two polydorids in combination with a changed seasonal pattern in food supply. The maximum life span of P. quadrilobata was 1 to 1 1/2 years with one main cohort a year. Maximum values for its biomass and density at the stations were 1.42 g ADW·m-2 and 6900 ind·m-2. Based on reconstructed survivorship curves, annual minimum and maximum values for production were calculated. The (conservative) estimates varied from 0.2 to 2.6 g ADW·m-2·a-1 for different stations and years, with P/B values varying from 1.5 to 8.2.