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.
|Number of pages||9|
|Journal||Journal of the Marine Biological Association of the United Kingdom|
|State||Published - 1 Aug 2020|
Bibliographical noteFunding Information:
The authors gratefully acknowledge support from the University of Haifa, the Helmsley Charitable Trust Mediterranean Sea Research Center, and the Maurice and Lady Hatter Fund of the Leon Recanati Institute for Maritime Studies (RIMS) at the University of Haifa.
© Marine Biological Association of the United Kingdom 2020. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited.
- Annual swarms
- Eastern Mediterranean
ASJC Scopus subject areas
- Aquatic Science