Interspecific differences in respiration and energy storage reserves in two freshwater predatory leeches from ecosystems of contrasting stability

Abstract

1. 1. Interspecific differences in respiration and energy storage reserves of Nephelopsis obscura typically found in environments with wide seasonal and diurnal variations and Erpobdella montezuma from a stable and homogenous environment were determined. 2. 2. N. obscura had significantly lower rates of resting ( R m ) and active ( R a ) respiration and aerobic scope than E. montezuma. 3. 3. E. montezuma had significantly higher total lipid (TL), glycogen (GN), triacylglycerols (TAGS) concentrations and active phosphorylase (PHO-A) activity than N. obscura. 4. 4. While R m > and R a decreased with increase in body size, TL, TAGS and PHO-A in both N. obscura and E. montezuma and GN in E. montezuma increased with increase in body size. 5. 5. Both N. obscura and E. montezuma showed positive net relative accumulation values for TL, TAGS and GN indicating reserve utilization never exceeded deposition. 6. 6. Despite experiencing winter stresses with expected increases in the metabolic costs of repair, R m of N. obscura was lower than that of E. montezuma suggesting the higher levels of energy surplus experienced by E. montezuma result in lower respiratory efficiency. 7. 7. N. obscura had significantly lower accumulations of energy reserves than E. montezuma which faces shorter temporal mismatches between energy demand and food supply suggesting that the levels of energy reserves are more directly correlated with immediate energy surplus than with energy deficits potentially encountered later.