Effects of temperature and salinity on survival and growth of the amphipod Hyale crassicornis (Gammaridea, Hyalidae)

Abstract

This study explored the survival and growth of the marine amphipod Hyale crassicornis under different conditions of ambient temperature and salinity in the laboratory. In 96‐h exposure experiments at a salinity of 30, H. crassicornis tolerated temperatures between 6 and 28°C (>90% survival). The 96‐h LT₅₀ value (median lethal temperature) at high temperature range for the amphipod was 32°C. The values at low temperature range for adults and juveniles were 3.2 and 4.2°C, respectively, indicating that adults have a higher tolerance to low temperature than juveniles. At 25°C, the amphipods tolerated salinities between 10 and 50 (with >80% survival in 96 h). The 96‐h LS₅₀ values at high and low salinity ranges were 56 and 2, respectively. Growth of the juveniles from instars 1 to 6 was determined under different combinations of temperature and salinity. Growth rate of juveniles cultured at 25°C and a salinity of 20 was the highest (0.114 mm day⁻¹) among the combinations of 15–25°C and 10–40 salinity. The moult increment of body length was affected by both temperature and salinity. Yet the intermoult duration of the amphipods was affected by temperature only but not by salinity.

Keywords:

• Amphipod
• Hyale crassicornis
• Gammaridea
• Hyalidae
• temperature
• salinity
• growth
• survival

Acknowledgements

We express our sincere gratitude to X. Q. Ren (The Institute of Oceanology, The Chinese Academy of Sciences, Qingdao, China) for identification of the amphipod species. We thank P. G. Moore (University of Glasgow) and C. K. Wong (The Chinese University of Hong Kong) for their comments on the manuscript. Some results of this study constitute part of a thesis submitted by K. H. Tsoi as partial fulfilment of the requirement for the degree of Master of Philosophy, Division of Biology, The Chinese University of Hong Kong.