Is Crangon crangon (L. 1758, Decapoda, Caridea) food limited in the Wadden Sea?

摘要

Dry weight condition (dry weight at length), caloric content and RNA·DNA~(-1)-ratio of brown shrimp Crangon crangon were monitored in temperature controlled starvation experiments and field samples. A significant decrease of dry weight and RNA·DNA~(-1) was observed within the experiments in all length classes (20,30,45 and 60 mm) and at all temperatures (9,12,17 and 20 ℃). The highest weight loss of -1.9% · d~(-1) occurred at 20 ℃. Dry weight condition and RNA·DNA~(-1) in field samples from the Wadden Sea (2005-2007) peaked in summer and were lowest in winter, while caloric content increased during winter, possibly indicating vitellogenesis. The results of the starvation experiments were used to interpret observed field conditions suggesting that at least 25% of the shrimp population is food-limited. Food limitation was most pronounced in the period November until April, where up to 75% of the population exhibited signs of starvation or food limitation.