Effects of Temperature and Salinity on Larval Development of Pagurus bemhardus (Decapoda, Paguridae)

Abstract

The hermit crab Pagurus bernhardus L. was reared from egg to first crab stage at 6 'C, 12 "C and 18 "C. At 6 "C, development was completed after 107 to 112 d ; at 12 ' C , after 49 to 54 d; at 18 "C, after 33 to 35 d following hatching, Survival rates were 6.7 O/O both at 6" and 18 "C; they were 20 '/V at 12 "C. A simple graphical model was constructed which predcts occurrence, presence and settling of P. bernhardus larvae in the field. According to h s model, in Helgoland waters (North Sea), duration of larval development lasts about 35 to 62 d, depending on the water temperature during and after hatching. Shortest development (about 35 d) is postulated for larvae hatching at the beginning of August. Complete rearing to metamorphosis was accomplished in 20/w and 30/m S (18 "C). In 1O0/m S, Zoea 1 larvae exhibit 10O0/o mortality 2 to 5 d after hatching. No differences in development duration, mortality, etc. were noticed at 20 '/m and 30 '/m S. The observation that a salinity of 20 O/M does not cause recognizable stress is discussed in relation to local larval distribution.