Ocean warming (OW) and ocean acidification (OA) are increasing threats to marine biodiversity. This study investigated the effects of these climate stressors on the ecology and physiology of the predatory gastropod Stramonita haemastoma in the Canary Islands. Field surveys across the archipelago identified regional warming hotspots around the eastern islands and cooler areas around central and western islands. Abundance declined significantly with increasing sea surface temperature (SST) anomalies, while shell size was peaking under moderate warming before decreasing at higher SST anomalies. To evaluate the physiological mechanisms underlying these patterns, laboratory experiments measured the metabolic rate of S. haemastoma using intermittent-flow respirometry. Individuals were exposed to a factorial combination of temperature (ambient 18°C and future-projected 26°C) and pH (ambient 8.1 and acidified 7.5), and oxygen consumption (VO₂) was measured. Under ambient pH conditions, warming caused a significant increase in metabolic rate, with a Q₁₀ value of 4.27, indicating high thermal sensitivity. Acidified conditions increased oxygen consumption by approximately 70%. When warming and acidification were combined, thermal sensitivity was reduced (Q₁₀ = 1.7). Overall, the results suggest that future OW and OA may reduce abundance and limit the resilience of S. haemastoma populations to future ocean conditions in the Canary Islands.
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