Hermit crabs play an important role in the Northern Adriatic Sea due to their abundance, wide range of symbionts, and function in structuring the benthic community. Small-scale (0.25 m2) hypoxia and anoxia were experimentally generated on a sublittoral soft bottom in 24 m depth in the Gulf of Trieste. This approach successfully simulates the seasonal low dissolved oxygen (DO) events here and enabled studying the behaviour and mortality of the hermit crab Paguristes eremita. The crabs exhibited a sequence of predictable stress responses and ultimately mortality, which was correlated with five oxygen thresholds. Among the crustaceans, which are a sensitive group to oxygen depletion, P. eremita is relatively tolerant. Initially, at mild hypoxia (2.0 to 1.0 ml l− 1 DO), hermit crabs showed avoidance by moving onto better oxygenated, elevated substrata. This was accompanied by a series of responses including decreased locomotory activity, increased body movements and extension from the shell. During a moribund phase at severe hypoxia (0.5 to 0.01 ml l− 1 DO), crabs were mostly immobile in overturned shells and body movements decreased. Anoxia triggered emergence from the shell, with a brief locomotion spurt of shell-less crabs. The activity pattern of normally day-active crabs was altered during hypoxia and anoxia. Atypical interspecific interactions occurred: the crab Pisidia longimana increasingly aggregated on hermit crab shells, and a hermit crab used the emerged infaunal sea urchin Schizaster canaliferus as an elevated substrate. Response patterns varied somewhat according to shell size or symbiont type (the sponge Suberites domuncula). Mortality occurred after extended anoxia (~ 1.5 d) and increased hydrogen sulphide levels (H2S ~ 128 μmol). The relative tolerance of crabs and certain symbionts (e.g. the sea anemone Calliactis parasitica) – as potential survivors and recolonizers of affected areas – may influence and promote community recovery after oxygen crises.

中文翻译：

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寄居蟹及其共生体：对沿岸沉积物底部人工诱导缺氧的反应

寄居蟹在亚得里亚海北部发挥着重要作用，因为它们数量丰富、共生体范围广，并且在构建底栖生物群落方面发挥着重要作用。在的里雅斯特湾（Gulf of Trieste） 24 m 深的沿海软底上实验产生了小规模（0.25 m2）的缺氧和缺氧。这种方法成功地模拟了这里的季节性低溶解氧 (DO) 事件，并能够研究寄居蟹 Paguristes eremita 的行为和死亡率。螃蟹表现出一系列可预测的压力反应和最终的死亡率，这与五个氧气阈值相关。在对氧气消耗敏感的甲壳类动物中，P. eremita 相对耐受。最初，在轻度缺氧（2.0 到 1.0 ml l- 1 DO）下，寄居蟹通过转移到含氧更好、升高的基质上来表现出回避行为。这伴随着一系列反应，包括运动活动减少、身体运动增加和从外壳延伸。在严重缺氧（0.5 至 0.01 ml l-1 DO）的垂死阶段，螃蟹大多在翻倒的壳中不动，身体运动减少。缺氧触发了壳中的出现，无壳螃蟹的短暂运动爆发。在缺氧和缺氧期间，正常白天活动的螃蟹的活动模式发生了变化。发生了非典型的种间相互作用：螃蟹 Pisidia longimana 越来越多地聚集在寄居蟹壳上，一只寄居蟹使用出现的动物海胆 Schizaster canaliferus 作为升高的底物。响应模式根据壳大小或共生体类型（海绵 Suberites domuncula）有所不同。长时间缺氧后发生死亡率（~ 1. 5 d) 和增加的硫化氢水平 (H2S ~ 128 μmol)。螃蟹和某些共生体（例如海葵 Calliactis parasitica）的相对耐受性——作为受影响地区的潜在幸存者和重新定居者——可能会影响和促进氧气危机后的社区恢复。