Effects of rising temperature on growth and energy budget of juvenile Eogammarus possjeticus (Amphipoda: Anisogammaridae)

Growth and energy budget of marine amphipod juvenile Eogammarus possjeticus at different temperatures (20 degrees C, 24 degrees C, 26 degrees C, 28 degrees C, 30 degrees C, 32 degrees C and 34 degrees C) were investigated in this study. The results showed that the cumulative mortality rate increased significantly with rising temperature (p<0.01), and exceeded 50% after 24 h when temperature was above 30 degrees C. With the temperature increasing from 20 degrees C to 26 degrees C, the ingestion rate and absorption rate increased, but decreased significantly above 28 degrees C (p<0.01), indicating a decline in feeding ability at high temperatures. The specific growth rate increased with rising temperature, but decreased significantly (p<0.01) after reaching the maximum value at 24 degrees C. Similarly, the oxygen consumption and ammonia emission rates also showed a trend of first increase and then decrease. However, the O:N ratio decreased first and then increased with rising temperature, indicating that the energy demand of E. possjeticus juvenile transferred from metabolism of carbohydrate and lipid to protein. In the energy distribution of amphipods, the proportion of each energy is different. With rising temperature, the ratio of the energy deposited for growth accounted for ingested gross energy showing a trend of decrease, while the energy lost to respiration, ammonia excretion, and feces accounted for ingested gross energy being showed a trend of increase. It seemed that rising temperature increased the metabolism and energy consumption of the amphipods and, meanwhile, decreased the energy used for growth, which may be an important reason for the slow growth and small body size of the amphipods during the summer high-temperature period.

Automated summary

The study investigated the growth and energy budget of marine amphipod juvenile Eogammarus possjeticus at different temperatures. Results showed that rising temperatures led to increased mortality rates, decreased feeding ability at high temperatures, and changes in energy distribution. Rising temperatures appeared to increase metabolism and energy consumption in amphipods while decreasing energy used for growth, resulting in slow growth and small body size during high-temperature summer periods.