Since the mid-1980s, swarms of the rhizostome Rhopilema nomadica have been an annual phenomenon in Israeli Mediterranean coastal waters during the summer months. Despite its annual prominence and the potential impact on food webs and ecosystem services, studies concerning its feeding ecology and its interactions with other biota in the marine food web have not been conducted. During summer 2015 gut contents of 41 R. nomadica were analysed as well as ambient plankton assemblages. More than 60% of the medusae diet was found to consist of microzooplankton <150 μm. Size correlations revealed that larger R. nomadica consumed faster swimming prey while smaller medusae relied more on the slower swimming taxa. The medusan diet reflected most of the ambient plankton taxa, but no statistically significant correlations between the relative abundance in diet and ambient plankton were found. As summer progressed, there was a gradual decrease in both mean medusa bell diameter (from 42.2–16 cm) and integrity of feeding structures. These findings suggest that R. nomadica, at least at the time of its appearance in Israeli coastal waters, may exert less predatory pressure on the plankton than we might otherwise expect.

中文翻译：

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以色列近海根茎Rhopilema nomadica的饮食组成及摄食生态学观察

自 1980 年代中期以来，成群的根茎游牧草蜉蝣在夏季的几个月里，以色列地中海沿岸水域每年都会出现这种现象。尽管它每年都占有重要地位并且对食物网和生态系统服务具有潜在影响，但尚未进行有关其摄食生态学及其与海洋食物网中其他生物群相互作用的研究。2015 年夏季肠道内容物 41R. nomadica分析了环境浮游生物组合。发现超过 60% 的水母饮食由 <150 μm 的微型浮游动物组成。尺寸相关性表明，较大的R. nomadica消耗更快游泳的猎物，而较小的水母则更多地依赖游动较慢的类群。美杜莎饮食反映了大部分环境浮游生物类群，但没有发现饮食中的相对丰度与环境浮游生物之间存在统计学上的显着相关性。随着夏季的进行，美杜莎钟的平均直径（从 42.2-16 厘米）和喂养结构的完整性逐渐减小。这些发现表明R. nomadica，至少在它出现在以色列沿海水域时，它对浮游生物的掠夺性压力可能比我们预期的要小。