Data from: Buried alive: the behavioural response of the mussels, Modiolus modiolus and Mytilus edulis to sudden burial by sediment

Sedimentation in the sea occurs through natural processes, such as wave and tidal action, which can be exacerbated during storms and floods. Changes in terrestrial land use, marine aggregate extraction, dredging, drilling and mining are known to result in substantial sediment deposition. Research suggests that deposition will also occur due to the modern development of marine renewable energy. The response to individual burial under three depths of sediment, three sediment fractions and five burial durations was investigated in two mussel species, Modiolus modiolus and Mytilus edulis in specialist mesocosms. Both mussel species showed substantial mortality, which increased with duration of burial and burial by finer sediment fractions. M. modiolus was better able to survive short periods of burial than M. edulis, but at longer durations mortality was more pronounced. No mortality was observed in M. modiolus in burial durations of eight days or less but by 16 days of burial, over 50% cumulative mortality occurred. Under variable temperature regimes, M. edulis mortality increased from 20% at 8°C to over 60% at 14.5 and 20°C. Only M. edulis was able to emerge from burial, facilitated by increased byssus production, laid mostly on vertical surfaces but also on sediment particles. Emergence was higher from coarse sediment and shallow burials. Byssus production in M. edulis was not related to the condition index of the mussels. Results suggest that even marginal burial would result in mortality and be more pronounced in warm summer periods. Our results suggest that in the event of burial, adult M. modiolus would not be able to emerge from burial unless local hydrodynamics assist, whereas a small proportion of M. edulis may regain contact with the sediment water interface. The physiological stress resulting in mortality, contribution of local hydrodynamics to survival and other ecological pressures such as mussels existing in aggregations, are discussed.

海洋中的沉积作用由波浪、潮汐作用等自然过程形成，风暴与洪水期间此类过程可能加剧。已知陆地土地利用变化、海洋骨料开采、疏浚、钻探与采矿会引发大量沉积物沉积。研究表明，海洋可再生能源的现代开发同样会导致沉积作用发生。本研究在专业中型实验生态系统（mesocosms）中，针对地中海贻贝（Modiolus modiolus）与紫贻贝（Mytilus edulis）两个物种，探究了其在三种沉积物埋藏深度、三种沉积物组分以及五种埋藏时长下的个体埋藏响应。两种贻贝均出现了显著的死亡率，且死亡率随埋藏时长增加以及细粒沉积物组分的埋藏而升高。地中海贻贝相较于紫贻贝，更能耐受短期埋藏，但在更长埋藏时长下，其死亡率更为显著。地中海贻贝在8天及以内的埋藏时长中未出现死亡，但至16天埋藏时，累积死亡率已超过50%。在可变温度条件下，紫贻贝的死亡率从8℃时的20%升至14.5℃与20℃时的60%以上。仅紫贻贝可通过增加足丝（byssus）分泌实现从沉积物中逃逸，其足丝大多附着于垂直表面，亦可附着于沉积物颗粒。从粗沉积物与较浅埋藏深度中逃逸的个体比例更高。紫贻贝的足丝分泌量与其自身的条件指数无关。研究结果表明，即使是轻微埋藏也会导致贻贝死亡，且在温暖的夏季情况会更为严重。本研究结果显示，遭遇埋藏时，成年地中海贻贝无法自行从沉积物中逃逸，除非借助当地水动力条件辅助；而仅有少量紫贻贝可重新与沉积物-水界面恢复接触。本研究还探讨了导致死亡的生理胁迫机制、当地水动力条件对存活的影响，以及贻贝以集群形式存在等其他生态压力因素。