RAPID: A subtle epidemic: unique mortality of Mytilus californianus on the Oregon coast

在温带的岩石海岸，贻贝是“基础”物种，作为多种捕食者的猎物，能够过滤大量水中的颗粒，并庇护数百种其他物种，因此在群落功能中起着核心作用。因此，对它们数量和持久性的威胁引起了重大的生态和社会关注。过去的研究表明，贻贝具有高度的弹性，能够很好地适应急性、短期的压力，如冬季风暴或短期变暖的干扰。2023年夏天，在常规的野外研究中发现了一种新的死亡模式：大量的贻贝死亡，许多贻贝的壳中仍有组织，以分散的模式被观察到。也就是说，不是大规模死亡（即大面积的所有贻贝都被杀死），而是单个死亡的贻贝被活的和明显健康的贻贝包围，每平方米有多个死亡的贻贝。该项目调查了死亡事件的原因，初步数据显示可能是有害的藻类繁殖。该项目还通过支持对几名本科生的研究培训来建立能力，并向公众和资源管理人员通报对潮间带岩石生态系统稳定性的新威胁。正在调查的假设是，2023年在俄勒冈州和加利福尼亚北部海岸的8个研究地点发生的“分散”死亡事件，影响了潮间带的岩石优势，加利福尼亚贻贝，可能是有害藻华的不寻常后果。在这次事件中，死贻贝的密度从0.7到10.6/m2不等。这种新模式与典型的生物大规模死亡形成鲜明对比，在这种情况下，特定地点或区域内的所有个体都因（例如）热应力或严重风暴而死亡。分散的死亡模式一直持续到2023年9月下旬。初步的组织学证据表明，贻贝消化食物的能力受到抑制，很可能是由一种水生毒素引起的。为了调查死亡事件的原因，该小组(1)每月收集(a)水样以鉴定鞭毛藻种类；(b)贻贝组织样本以进行消化和肾脏组织的组织学调查，并进行高效液相色谱和质谱分析，以确定藻类来源毒素的存在；(2)继续进行贻贝床调查，确定死亡事件的季节性；(3)在死亡率较高或较低的地点量化冬季风暴对贻贝床的影响。这项研究促进了对社区对强烈环境压力的反应以及这些压力如何影响岩质潮间带生态系统未来的理解。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

On temperate rocky shores, mussels are a “foundation” species, serving as prey for multiple predators, able to filter particles out of huge volumes of water, and harboring hundreds of other species, thereby serving a central role in community function. Hence, threats to their abundance and persistence are of significant ecological and societal concern. Past research has shown that mussels are highly resilient and well-adapted to acute, short-lived stresses such as disturbance from winter storms or short-term warming. In summer 2023, a novel pattern of mortality was discovered during routine field research: high numbers of dead mussels, many with tissue remaining in the shell were observed in a scattered pattern. That is, rather than a mass mortality (i.e., all mussels in a large area are killed), single dead mussels surrounded by live and apparently healthy mussels occurred, with multiple dead individuals per square meter. This project investigates the cause of the mortality event, which preliminary data suggests may be a harmful algal bloom. The project also builds capacity by supporting research training for several undergraduate students and informs the public and resource managers about an emerging threat to the stability of rocky intertidal ecosystems.The hypothesis under investigation is that the 2023 “scattered” mortality event at 8 study sites along the Oregon and northern California coasts affecting the rocky intertidal dominant, Mytilus californianus, may be an unusual consequence of a harmful algal bloom. During this event, densities of dead mussels have ranged from 0.7 to 10.6/m2. This novel pattern contrasts with typical mass mortalities of organisms where all individuals within a specific site or area die due to (e.g.) thermal stress or severe storms. The scattered mortality pattern persisted through late September 2023. Preliminary histological evidence suggests the ability of mussels to digest food is being suppressed, most likely by a water-borne toxin. To investigate the cause of the mortality event, the team is (1) collecting monthly (a) water samples for identification of dinoflagellate species and (b) mussel tissue samples for histological investigation of digestive and kidney tissues and high performance liquid chromatography and mass spectrometry analyses for the presence of algal-derived toxins; (2) continuing mussel bed surveys to determine the seasonality of the mortality event; and (3) quantifying mussel bed persistence through winter storms at sites with higher or lower rates of mortality. This research advances understanding of community responses to intense environmental stresses and how these might influence the future of rocky intertidal ecosystems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.