Extreme temperatures impair survival and growth through elevated metabolic demand in tropical Strombus canarium larvae

Temperature is a key driver of larval performance in marine invertebrates, yet the effects of thermal extremes remain poorly resolved for tropical species, particularly during early life stages critical for population persistence. This gap is especially pronounced for marine gastropods inhabiting shallow coastal environments where temperatures frequently approach or exceed physiological limits. Here, we examined the effects of temperature (28, 30, 32, and 34 °C) on survival, growth, and oxygen consumption of Strombus canarium larvae, a key grazer in tropical seagrass ecosystems. Survival was highest at 28–30 °C and declined by ~30% and ~48% at 32 °C and 34 °C, respectively, relative to 30 °C. Shell growth showed a similar pattern, with maximum performance at 30 °C and reduced growth at both lower and higher temperatures, although specific growth rate did not differ among treatments. In contrast, oxygen consumption increased rapidly with temperature, rising approximately tenfold from 28 °C to 34 °C, indicating elevated metabolic demand under thermal stress. Together, these results suggest that high temperatures increase metabolic costs without corresponding gains in growth, consistent with a mismatch between metabolic demand and performance. This imbalance likely constrains energy available for growth and survival, thereby impairing larval performance under thermal extremes. Our findings provide new insights into the thermal sensitivity of an ecologically and economically important tropical gastropod and highlight potential vulnerabilities of early life stages under ongoing ocean warming, with implications for both population dynamics, aquaculture and fishery management.