Feeding ecology of the ctenophore Mnemiopsis leidyi A. Agassiz (Ctenophora, Lobata)

Lindsay J Sullivan, University of Rhode Island

Abstract

Accurate estimates of feeding rate and diet composition of the ctenophore Mnemiopsis leidyi are ultimately important for understanding their population dynamics and predation impacts. While feeding by adult M. leidyi has been well documented in both field and laboratory studies, little attention has been paid to feeding by the ctenophore's early life history stages or to examining its diel feeding rhythms. Feeding and growth rates of newly-hatched larval M. leidyi were measured in a series of controlled laboratory experiments. The newly-hatched larvae consumed significant quantities of both microphytoplankton and microzooplankton prey. The measured rates were sufficiently high that the larvae, when abundant, have the potential to exert a significant predation impact on their prey populations. In addition to feeding, significant growth of larval M. leidyi feeding on in situ microplankton assemblages was observed in controlled laboratory experiments. Larval growth rate was positively correlated with the total standing stock of microplankton prey available. Feeding rates of larval M. leidyi on in situ microplankton assemblages were also measured using gut content analysis. Although there is a significant amount of overlap in the prey categories quantified by gut content analysis and prey removal experiments, rates calculated from gut contents are significantly lower than rates measured in prey removal experiments. Therefore, gut content analysis and prey removal experiments cannot be used interchangeably and it is best to use the method specific to the prey type being examined. Additionally, feeding rates of all life history stages of M. leidyi were measured by direct examination of gut contents at 4-h intervals during 7 separate 24-h periods. Gut content analysis revealed an apparent diel feeding pattern that is driven by the species composition of the prey field rather than by changes in the ctenophore's feeding rates. Understanding of the predation impacts and diet composition of M. leidyi requires documentation of their diet over both the diel cycle and the organism's entire life history. An increased understanding of ctenophore feeding rates will help determine how, when and why ctenophore blooms occur. ^

Subject Area

Biology, Ecology|Biology, Oceanography

Recommended Citation

Lindsay J Sullivan, "Feeding ecology of the ctenophore Mnemiopsis leidyi A. Agassiz (Ctenophora, Lobata)" (2007). Dissertations and Master's Theses (Campus Access). Paper AAI3277008.
http://digitalcommons.uri.edu/dissertations/AAI3277008

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