Interactive Effects of Elevated Temperature and Moderate Hypoxia on a Shallow‐Water Bivalve, Fulvia mutica

Amid progressing climate change, this study investigated the interactive effects of water temperature, dissolved oxygen (DO), and shell length on Fulvia mutica , a shallow‐coastal water bivalve, focusing on the combined impacts of elevated temperature and moderate hypoxia. Factorial tank experiments were conducted using a total of 420 individuals across two distinct size classes (mean shell lengths: 14.6 mm and 43.2 mm), under 17 environmental conditions combining various water temperatures (25°C–32°C) and DO levels (2, 4, and > 6 mg L −1 ). Based on the experimental results, a Generalized Linear Mixed Model (GLMM) and Accelerated Failure Time (AFT) models were constructed to estimate temperature‐dependent survival probabilities and lethal thresholds (LC 50 and LT 50 , respectively), projecting these values across the examined size range (20, 30, and 40 mm). The results indicated a significant interaction where sensitivity to hypoxia was amplified with increasing water temperatures. Notably, under moderate hypoxia (DO 4 mg L −1 ), within the 25°C–28°C range, the rate of increase in LC 50 averaged 0.25 ± 0.06 mg L −1 °C −1 , whereas the decline in LT 50 averaged 8.5 ± 0.9 days°C −1 across all size classes examined. These findings suggest a potential synergistic threat of coastal warming and oxygen depletion, indicating that F. mutica may be increasingly vulnerable to moderate hypoxia under future warming conditions.