Estuaries and Coasts

, Volume 34, Issue 4, pp 701–711 | Cite as

Food Web Structure in a Chesapeake Bay Eelgrass Bed as Determined through Gut Contents and 13C and 15N Isotope Analysis

  • James G. Douglass
  • J. Emmett Duffy
  • Elizabeth A. Canuel


Changes in seagrass food-web structure can shift the competitive balance between seagrass and algae, and may alter the flow of energy from lower trophic levels to commercially important fish and crustaceans. Yet, trophic relationships in many seagrass systems remain poorly resolved. We estimated the food web linkages among small predators, invertebrate mesograzers, and primary producers in a Chesapeake Bay eelgrass (Zostera marina) bed by analyzing gut contents and stable C and N isotope ratios. Though trophic levels were relatively distinct, predators varied in the proportion of mesograzers consumed relative to alternative prey, and some mesograzers consumed macrophytes or exhibited intra-guild predation in addition to feeding on periphyton and detritus. These findings corroborate conclusions from lab and mesocosm studies that the ecological impacts of mesograzers vary widely among species, and they emphasize the need for taxonomic resolution and ecological information within seagrass epifaunal communities.


Mesograzer Diet Seagrass Stable isotope Omnivory Food web 



We thank J. Paul Richardson, Rachael E. Blake, Romuald Lipcius, Paul Gerdes, and others for help and advice with field and lab work, and we thank David Harris and the staff of the UC Davis Stable Isotope Facility for invaluable sample processing services. This work was supported by grant #XXXXXX to J.E. Duffy. This is VIMS contribution #XXXX.


  1. Bobsien, I.C. 2006. The role of small fish species in eelgrass food webs of the Baltic Sea. Dissertation, Christian-Albrechts-Universität zu Kiel, GermanyGoogle Scholar
  2. Canuel, E.A., J.E. Cloern, D.B. Ringelberg, J.B. Guckert, and G.H. Rau. 1995. Molecular and isotopic tracers used to examine sources of organic matter and its incorporation into the food webs of San Francisco Bay. Limnology and Oceanography 40: 67–81.CrossRefGoogle Scholar
  3. Cardinale, B.J., D.S. Srivastava, J.E. Duffy, J.P. Wright, A.L. Downing, M. Sankaran, and C. Jouseau. 2006. Effects of biodiversity on the functioning of trophic groups and ecosystems. Nature 443: 989–992.CrossRefGoogle Scholar
  4. Cerco, C.F., and K. Moore. 2001. System-wide submerged aquatic vegetation model for Chesapeake Bay. Estuaries 24: 522–531.CrossRefGoogle Scholar
  5. Chanton, J.P., and F.G. Lewis. 1999. Plankton and dissolved inorganic carbon isotopic composition in a river-dominated estuary: Apalachicola Bay, Florida. Estuaries 22: 575–583.CrossRefGoogle Scholar
  6. Douglass, J.G., J.E. Duffy, A.C. Spivak, and J.P. Richardson. 2007. Nutrient versus consumer control of community structure in a Chesapeake Bay eelgrass habitat. Marine Ecology Progress Series 348: 71–83.CrossRefGoogle Scholar
  7. Douglass, J.G., J.E. Duffy, and J.E. Bruno. 2008. Herbivore and predator diversity interactively affect ecosystem properties in an experimental marine community. Ecology Letters 11: 598–608.CrossRefGoogle Scholar
  8. Douglass, J.G., K.E. France, J.P. Richardson, and J.E. Duffy. 2010. Seasonal and interannual change in a Chesapeake Bay eelgrass community: insights into biotic and abiotic control of community structure. Limnology and Oceanography 55: 1499–1520.CrossRefGoogle Scholar
  9. Duffy, J.E. 2002. Biodiversity and ecosystem function: the consumer connection. Oikos 99: 201–219.CrossRefGoogle Scholar
  10. Duffy, J.E., and M.E. Hay. 2000. Strong impacts of grazing amphipods on the organization of a benthic community. Ecological Monographs 70: 237–263.CrossRefGoogle Scholar
  11. Duffy, J.E., and A.M. Harvilicz. 2001. Species-specific impacts of grazing amphipods in an eelgrass bed community. Marine Ecology Progress Series 223: 201–211.CrossRefGoogle Scholar
  12. Duffy, J.E., J.P. Richardson, and K.E. France. 2005. Ecosystem consequences of diversity depend on food chain length in estuarine vegetation. Ecology Letters 8: 301–309.CrossRefGoogle Scholar
  13. Eriksson, B.S., L. Ljunggren, A. Sandström, G. Johansson, J. Mattila, A. Rubach, S. Råeberg, and M. Snickars. 2009. Declines in predatory fish promote bloom-forming macroalgae. Ecological Applications 19: 1975–1988.CrossRefGoogle Scholar
  14. Fry, B. 2006. Stable isotope ecology. New York: Springer.CrossRefGoogle Scholar
  15. Haahtela, I. 1984. A hypothesis of the decline of the bladder wrack (Fucus vesiculosus L.) in SW Finland in 1975–1981. Limnologica 15: 345–350.Google Scholar
  16. Hines, A.H., A.M. Haddon, and L.A. Wiechert. 1990. Guild structure and foraging impact of blue crabs and epibenthic fish in a subestuary of Chesapeake Bay. Marine Ecology Progress Series 67: 105–126.CrossRefGoogle Scholar
  17. Hughes, A.R., K.J. Bando, L.F. Rodriguez, and S.L. Williams. 2004. Relative effects of grazers and nutrients on seagrasses: a meta-analysis approach. Marine Ecology Progress Series 282: 87–99.CrossRefGoogle Scholar
  18. Jaschinski, S., N. Aberle, S. Gohse-Reiman, H. Brendelberger, K.H. Wiltshire, and U. Sommer. 2009. Grazer-diversity effects in an eelgrass–epiphyte microphytobenthos system. Oecologia 159: 607–615.CrossRefGoogle Scholar
  19. Jernakoff, P., A. Brearly, and J. Nielsen. 1996. Factors affecting grazer–epiphyte interactions in temperate seagrass meadows. Oceanography and Marine Biology: An Annual Review 34: 109–162.Google Scholar
  20. Kangas, P., H. Autio, G. Haellfors, H. Luther, A. Niemi, and H. Salemaa. 1982. A general model of the decline of Fucus vesiculosus at Tvaerminne, south coast of Finland in 1977–81. Acta Botanica Fennica 118: 1–27.Google Scholar
  21. Kirkman, H. 1978. Growing Zostera capricorni Aschers. in tanks. Aquatic Botany 4: 367–372.CrossRefGoogle Scholar
  22. Kitting, C.L. 1984. Selectivity by dense populations of small invertebrates foraging among seagrass blade surfaces. Estuaries 7: 276–288.CrossRefGoogle Scholar
  23. Lipcius, R.N., and W.T. Stockhausen. 2002. Concurrent decline of the spawning stock, recruitment, larval abundance, and size of the blue crab Callinectes sapidus in Chesapeake Bay. Marine Ecology Progress Series 226: 45–61.CrossRefGoogle Scholar
  24. Mansour, R.A. (1992). Foraging ecology of the blue crab, Callinectes sapidus Rathbun in lower Chesapeake Bay. Dissertation, Virginia Institute of Marine Science, College of William and Mary, VirginiaGoogle Scholar
  25. Nelson, W.G. 1979. Experimental studies of selective predation on amphipods: consequences for amphipod distribution and abundance. Journal of Experimental Marine Biology and Ecology 38: 225–245.CrossRefGoogle Scholar
  26. Nelson, W.G. 1980. A comparative study of amphipods in seagrasses from Florida to Nova Scotia. Bulletin of Marine Science 30: 80–89.Google Scholar
  27. Orth, R.J., K.L. Heck Jr., and J. van Montfrans. 1984. Faunal communities in seagrass beds: a review of the influence of plant structure and prey characteristics in predator–prey relationships. Estuaries 7: 339–350.CrossRefGoogle Scholar
  28. Perkins-Visser, E., T.G. Wolcott, and D.L. Wolcott. 1996. Nursery role of seagrass beds: enhanced growth of juvenile blue crabs (Callinectes sapidus Rathbun). Journal of Experimental Marine Biology and Ecology 198: 155–173.CrossRefGoogle Scholar
  29. Peterson, B.J., and B. Fry. 1987. Stable isotopes in ecosystem studies. Annual Review of Ecology and Systematics 18: 293–320.CrossRefGoogle Scholar
  30. Phillips, D.L. 2001. Mixing models in analyses of diet using multiple stable isotopes: a critique. Oecologia 127: 166–170.CrossRefGoogle Scholar
  31. Phillips, D.L., and G.W. Gregg. 2003. Source partitioning using stable isotopes: coping with too many sources. Oecologia 136: 261–269.CrossRefGoogle Scholar
  32. Short, F.T., D.M. Burdick, and J.E. Kaldy. 1995. Mesocosm experiments quantify the effects of eutrophication on eelgrass, Zostera marina. Limnology and Oceanography 40: 740–749.CrossRefGoogle Scholar
  33. Stoner, A.W., and B.A. Buchanan. 1990. Ontogeny and overlap in the diets of four tropical Callinectes species. Bulletin of Marine Science 46: 3–12.Google Scholar
  34. Tagatz, M.E. 1968. Biology of the blue crab, Callinectes sapidus Rathbun, in the St. Johns River, Florida. Fisheries Bulletin 67: 17–33.Google Scholar
  35. Teixeira, R.L., and J.A. Musick JA. 1994. Trophic ecology of two congeneric pipefishes (Syngnathidae) of the lower York River, Virginia. Environmental Biology of Fishes 43: 295–309.CrossRefGoogle Scholar
  36. Thayer, G.W., P.L. Parker, M.W. LaCroix, and B. Fry. 1978. The stable carbon isotope ratio of some components of an eelgrass, Zostera marina, bed. Oecologia 35: 1–12.CrossRefGoogle Scholar
  37. Valentine, J.F., and J.E. Duffy. 2006. The central role of grazing in seagrass ecology. In Seagrasses: biology, ecology and conservation, ed. A.W.D. Larkum, R.J. Orth, and C.M. Duarte, 463–501. Dordrecht: Springer.CrossRefGoogle Scholar
  38. van Montfrans, J., R.L. Wetzel, and R.J. Orth. 1984. Epiphyte–grazer relationships in seagrass meadows: consequences for seagrass growth and production. Estuaries 7: 289–309.CrossRefGoogle Scholar
  39. Virnstein, R.W. 1978. Predator caging experiments in soft sediments: caution advised. In Estuarine interactions, ed. M.L. Wiley, 261–273. New York: Academic.Google Scholar
  40. Wetzel, R.L., and H.A. Neckles. 1986. A model of Zostera marina L. photosynthesis and growth: simulated effects of selected physical–chemical variables and biological interactions. Aquatic Botany 26: 307–323.CrossRefGoogle Scholar
  41. Williams, S.W., and K.L. Heck Jr. 2001. Seagrass communities. In Marine community ecology, ed. M. Bertness, S. Gaines, and M. Hay, 317–337. Sunderland: Sinauer.Google Scholar
  42. Zimmerman, R., R. Gibson, and J. Harrington. 1979. Herbivory and detritivory among gammaridean amphipods from a Florida seagrass community. Marine Biology 54: 41–47.CrossRefGoogle Scholar

Copyright information

© Coastal and Estuarine Research Federation 2011

Authors and Affiliations

  • James G. Douglass
    • 1
  • J. Emmett Duffy
    • 2
  • Elizabeth A. Canuel
    • 2
  1. 1.Northeastern University Marine Science CenterNahantUSA
  2. 2.Virginia Institute of Marine ScienceGloucester PointUSA

Personalised recommendations