School of Life Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, United Kingdom; Department of Biology and Environmental Science, College of Science, University of the Philippines Cebu, Gorordo Avenue, Lahug, Cebu City 6000, Philippines.
Centre for Environment, Fisheries and Aquaculture Science (CEFAS), Barrack Road, The Nothe, Weymouth, Dorset DT4 8UB, United Kingdom.
Sci Total Environ. 2023 Sep 20;892:164485. doi: 10.1016/j.scitotenv.2023.164485. Epub 2023 May 29.
Warming could facilitate the intensification of toxic algal blooms, two important stressors for marine organisms that are predicted to co-occur more frequently in the future. We investigated the immediate and delayed effects of a heatwave and a simulated bloom (3 × 10 cells L of the diarrhetic shellfish toxin (DST)-producing benthic dinoflagellate Prorocentrum lima on the survival, physiology (oxygen consumption rate, condition index, immune parameters), and toxin accumulation in the Pacific rock oyster Magallana (Crassostrea) gigas. Oysters exposed to both stressors contained higher mean DST concentrations (mean ± 1 SE: 173.3 ± 19.78 μg kg soft tissue) than those exposed to P. lima bloom alone (120.4 ± 20.90 μg kg) and exceeded the maximum permitted levels for human consumption. Exposure to individual stressors and their combination modified the physiology of M. gigas. Oysters exposed to heatwave alone had significantly higher oxygen consumption rates (0.7 ± 0.06 mg O h g) than the control (0.3 ± 0.06 mg O h g). However, this was not observed in oysters exposed to both heatwave and P. lima (0.5 ± 0.06 mg O h g). This alteration of the metabolic response to warming in the presence of P. lima may affect the ability of rock oysters to adapt to environmental stressors (i.e., a heatwave) to ensure survival. Immunomodulation, through changes in total hemocyte count, was observed in oysters exposed to P. lima alone and in combination with warming. Individual stressors and their combination did not influence the condition index, but one mortality was recorded in oysters exposed to both stressors. The findings of this study highlight the vulnerability of rock oysters to the predicted increased frequency of heatwaves and toxic algal blooms, and the increased likelihood of shellfish containing higher than regulatory levels of DST in warming coasts.
升温可能会促进有毒藻类大量繁殖，这是两种对海洋生物有重要影响的压力源，预计它们在未来会更频繁地同时出现。我们研究了热浪和模拟赤潮（3×10 个产生腹泻性贝类毒素（DST）的底栖甲藻夜光藻 Prorocentrum lima 细胞/L）对太平洋石蚝 Magallana（Crassostrea）gigas 存活率、生理机能（耗氧量、条件指数、免疫参数）和毒素积累的即时和延迟影响。同时暴露于两种压力源的牡蛎体内的 DST 浓度平均值（平均值±1 SE：173.3±19.78μg 软组织/kg）高于仅暴露于夜光藻赤潮的牡蛎（120.4±20.90μg 软组织/kg），且超过了人类可食用的最大允许水平。单独暴露于压力源及其组合会改变 M. gigas 的生理机能。仅暴露于热浪的牡蛎的耗氧量（0.7±0.06mg O h g）显著高于对照组（0.3±0.06mg O h g）。然而，在同时暴露于热浪和夜光藻的牡蛎中未观察到这种情况（0.5±0.06mg O h g）。在存在夜光藻的情况下，这种对变暖的代谢反应的改变可能会影响石蚝适应环境压力源（即热浪）以确保生存的能力。仅暴露于夜光藻和同时暴露于压力源的牡蛎体内的总血细胞计数发生了免疫调节变化。单独的压力源及其组合并未影响条件指数，但有一只牡蛎在同时暴露于两种压力源时死亡。这项研究的结果强调了石蚝在预测的热浪和有毒藻类大量繁殖频率增加的情况下的脆弱性，以及在变暖的海岸，贝类体内 DST 含量高于监管水平的可能性增加。
