Low oxygen alters food web interactions by affecting distributions, predator feeding rates and prey escape:
Laboratory experiments, field sampling, and individual based modeling indicate that low dissolved oxygen (hypoxia) can strongly affect predator attack rates, prey escape behavior, and encounter rates between predators and their prey. As a result, the relative strength of the various predator-prey interactions in estuarine food webs can be altered by the presence of low dissolved oxygen – even if it is restricted to bottom waters. Our results indicate that these changes will increase the flow of carbon to gelatinous zooplankton in the Patuxent River, a subestuary of Chesapeake Bay.
Sample publications:
Grove, M. and D.L. Breitburg. 2005. Growth and reproduction of gelatinous zooplankton exposed to low dissolved oxygen. Marine Ecology Progress Series. 301:185-198.
Breitburg, D.L., A. Adamack, S.E. Kolesar, M.B. Decker, K.A. Rose, J.E. Purcell, J.E. Kiester, and J.H. Cowan, Jr. 2003. The pattern and influence of low dissolved oxygen in the Patuxent River, a seasonally hypoxic estuary. Estuaries 26:280-297.
Breitburg, D.L., K.H. Rose, and J.A. Cowan, Jr. 1999. Linking water quality to survival of larval fishes: predation mortality of fish larvae in an oxygen-structured water column. Marine Ecology Progress Series. 178:39-54.
Breitburg, D.L., T. Loher, C.A. Pacey, A. Gerstein. 1997. Varying effects of low dissolved oxygen on trophic interactions in an estuarine food web. Ecological Monographs. 67:489-507.
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Intraguild food webs, hypoxia, and the importance of ctenophore predation:
Intraguild food webs – food webs in which two species interact through both predator-prey and competitive interactions – are common in aquatic systems. Our laboratory is exploring the idea that the Chesapeake Bay can be thought of as a system of overlapping intraguild predation food webs. Factors that shift dominance to the ctenophore Mnemiopsis leidyi instead of the scyphomedusae Chrysaora quinquecirrha are destabilizing because M. leidyi is both a superior competitor to fish larvae for zooplankton prey, and predator of fish larvae.
< Blue arrows indicate dominant predator prey interactions
 Former graduate student, Sarah Kolesar, studied the effect of hypoxia on the intraguild food web that includes ctenophores, fish larvae and zooplankton. She found that ctenophores were effective predators on fish eggs and larvae at low dissolved oxygen concentrations, and that the intraguild structure of the food web determined survival rates of fish larvae at all oxygen concentrations at which these species co-occur.
See: Kolesar, S.E. (2006) The effects of hypoxia on predation interactions between Mnemiopsis leidyi ctenophores and larval fish in the Chesapeake Bay ecosystem. University of Maryland, Center for Environmental Science. PhD Dissertation. >>
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