Trophic position of the invasive ctenophore Mnemiopsis leidyi: an experimental approach
Vanhove, B. (2013). Trophic position of the invasive ctenophore Mnemiopsis leidyi: an experimental approach. MSc Thesis. Oceans & Lakes, Interuniversity Master in Marine and Lacustrine Science and Management: Brussel. 33 + annexes pp.
The invasive ctenophore Mnemiopsis leidyi has become a hot topic since its destructive introduction in the Black Sea. Due to its invasive success and its rapid range expansion, there has been much interest in the feeding behavior and the trophic position of M. leidyi. This study aimed to determine some of the basic interactions of M. leidyi with the native pelagic zooplankton in the Belgian part of the North Sea and the Westerscheldt estuary by means of biochemical biomarkers, such as stable isotopes and fatty acids , in combination with grazing experiments and 13C tracer experiments. Our findings showed that M. leidyi is a very efficient predator with very short digestion times that can found in many different environmental conditions and ecosystems. Furthermore, our results emphasized the importance of spatial and temporal variations in the isotopic signature of various taxa when interpreting trophic interactions. This study supported the position of M. leidyi as a secondary consumer. Furthermore, our findings suggest that the native ctenophore Pleurobrachia pileus uses a different ecological niche than M. leidyi and could be positioned at a higher trophic level. This supports the hypothesis that M. leidyi and P. pileus are feeding on different food sources and implies that two ctenophores can co-occur rather than outcompete each other. Finally, this study shows that 13C tracer experiments can be a very helpful tool when identifying potential prey species and has many possible application for future research involving gelatinous zooplankton.
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