Temperature-driven oxygen consumption in Loxoconcha elliptica (Ostracoda: Podocopida), with limited differences among sexes and late ontogenetic stages

Ostracods are ecologically important indicators of aquatic ecosystem conditions because of their broad distribution and sensitivity to environmental change. As ectotherms, they are especially responsive to temperature variation, and climate-driven warming may alter their metabolic dynamics in aquatic ecosystems worldwide. Oxygen consumption rate (OCR) is a widely used proxy for metabolic demand, yet few studies have examined the combined effects of temperature, sex, and ontogenetic stage in ostracods. Here, we provide the first estimates of OCR for the euryhaline ostracod Loxoconcha elliptica , and assess its thermal response at 10, 20, and 30 °C in three groups: adult females, adult males, and subadults. Individuals were collected from Font Salada, a coastal spring pond in Valencia (Spain), and OCR was quantified using optical respirometry. Oxygen consumption increased with temperature in all groups, reaching maximum values at 30 °C. Subadults tended to show higher mass-specific OCR and greater thermal sensitivity than adults; however, generalized linear models (GLMs) identified temperature as the only significant predictor. Our findings establish the first physiological baseline for L. elliptica and contribute to understanding the sensitivity of euryhaline ostracods under future warming scenarios.