Unravelling the effects of elevated temperature on the physiological energetics of Bellamya bengalensis

Temperature is one of the key environmental factors affecting the eco-physiological responses of living organisms and is considered one of the utmost crucial factors in shaping the fundamental niche of a species. The purpose of the present study is to delineate the physiological response and changes in energy allocation strategy of Bellamya bengalensis, a freshwater gastropod in the anticipated summer elevated temperature in the future by measuring the growth, body conditions (change in total weight, change in organ to flesh weight ratio), physiological energetics (ingestion rate, absorption rate, respiration rate, excretion rate and Scope for Growth) and thermal performance, Arrhenius breakpoint temperature (ABT), thermal critical maxima (CTmax), warming tolerance (WT) as well as thermal safety margin (TSM) through a mesocosm experiment. We exposed the animals to three different temperatures, 25 °C (average habitat temperature for this animal) and elevated temperatures 30 °C, 35 °C for 30 days and changes in energy budget were measured twice (on 15th and 30th day). Significant changes were observed in body conditions as well as physiological energetics. The total body weight as well as the organ/flesh weight ratio, ingestion followed by absorption rate decreased whereas, respiration and excretion rate increased with elevated temperature treatments resulting in a negative Scope for Growth in adverse conditions. Though no profound impact was found on ABT/CTmax, the peak of thermal curve was considerably declined for animals that were reared in higher temperature treatments. Our data reflects that thermal stress greatly impact the physiological functioning and growth patterns of B. bengalensis which might jeopardize the freshwater ecosystem functioning in future climate change scenario.