Natural diet and predation impacts of Pelagia noctiluca on fish eggs and larvae in the NW Mediterranean

12 pages, 2 figures, 6 tables, supplemental material http://plankt.oxfordjournals.org/content/38/5/1243/suppl/DC1

Jellyfish are important predators of fish eggs and larvae and predation is believed to be the main factor determining fish recruitment. The diet of different life stages of Pelagia noctiluca and their potential predation impact on ichthyoplankton were investigated in the NW Mediterranean Sea. In June, the spatial distribution of jellyfish and fish larvae, particularly those of anchovy, overlapped in the study area. Gut content analyses showed relatively high abundance of ichthyoplankton in large medusae, while siphonophores were the most numerous prey of ephyrae. Gut contents, digestion times (DT), and prey and predator abundances were used to estimate predation effects (% of standing stock consumed time−1) of P. noctiluca. Medusae consumed 0.1–0.9% h−1 of the anchovy larvae, while ephyrae consumed 1.5–2.7% h−1 of all fish larvae and 1.5–10.4% h−1 of anchovy larvae. We estimate that medusae and ephyrae consumed 0.02–3.2% h−1 and 0.4–7.1% h−1 of fish eggs, respectively. P. noctiluca can reach extremely high numbers and in a bloom situation it can be an important predator of fish larvae, in particular anchovy. Hence it may play an important role in the planktonic food web with a possible impact on anchovy populations

Supported by the project MAR-CTM2010-18874

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