| Popis: |
The influence of temperature on larval survival and development was studied in the edible crab, Cancer pagurus, from a population off the Island of Helgoland, North Sea. In rearing experiments conducted at six different temperatures (6°, 10°, 14°, 15°, 18°, 24° C), zoeal development was only completed at 14° and 15° C. Instar duration of the Zoea I was negatively correlated with temperature. A model relating larval body mass to temperature and developmental time suggests that successful larval development is possible within a narrow temperature range (14° ± 3° C) only. This temperature optimum coincides with the highest citrate synthase (CS) activity found at 14° C. A comparison for intraspecific variability among freshly hatched zoeae from different females (CW 13 - 17cm, N = 8) revealed that both body mass and elemental composition varied significantly. Initial larval dry weight ranged from 12.1 to 17.9 µg/individual, the carbon content from 4.6 to 5.8 µg/individual, nitrogen from 1.1 to 1.3 µg/individual, and the C:N ratio from 4.1 to 4.4. A narrow larval temperature tolerance range of C. pagurus as well as the indication of intraspecific variability in female energy allocation into eggs may indicate a potential vulnerability of this species to climate change. Large-scale studies on the ecological and physiological resilience potential of this commercially fished predator are needed. |
