Fish rely on scyphozoan hosts as a primary food source: evidence from stable isotope analysis
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Predation of fish on their scyphozoan hosts has not been clearly defined using analysis of gut contents because gelatinous prey are difficult to visually detect and are dissolved by fixative solutions. Therefore, scyphomedusae have been generally considered not relevant in fish diet. To determine the contribution of their scyphozoan host tissue to the assimilated diet of age-0 Chloroscombrus chrysurus, we determined δ13C and δ15N of fish, their hosts (scyphomedusae Aurelia sp. and Drymonema larsoni) and their potential prey—small plankton (<200 μm) and mesozooplankton (>200 μm)—in the coastal waters of Alabama, USA. The diet of C. chrysurus was defined using the Bayesian mixing model Stable Isotope Analysis in R (SIAR). Models indicated that the scyphozoan hosts contributed on average ~90 % to fish assimilated diet. In contrast with previous dietary assessments based on analysis of gut contents, these results highlight that scyphozoans are important to the diet of fish associated with them. Because several ecologically and economically important fish species live in association with scyphomedusae, a redefinition of trophic links in marine food webs may be needed in light of the findings in this study.
KeywordsStable Isotope Analysis Fork Length Early Life Stage Trophic Link Bell Diameter
Funding for this study was provided by the National Oceanographic and Atmospheric Agency (NOAA)—R.C. Shelby Center for Ecosystem-Based Fisheries Management, and the National Science Foundation NSF-RAPID (OCE-1043413) to WMG. We thank the Biological Oceanography and FOCAL laboratories at the Dauphin Island Sea Lab (Alabama, USA) for plankton collection. C. Culpepper, J. Herrmann, L. Linn, R. Shipplett, and K. Weiss provided invaluable help in the field. We appreciated the comments by Drs C. Harrod and JDR Houghton, which improved the submitted manuscript. This paper is dedicated to our dear friend and colleague Hermes Mianzan, who searched for jellyfish in fish stomachs during his whole but short life.
- Bjorndal K (1997) Foraging ecology and nutrition of sea turtles. In: Lutz PL, Musick JA, Wyneken J (eds) The biology of sea turtles. CRC Press, New York, pp 199–231Google Scholar
- D’Ambra I (2012) Application of stable isotopes in the analysis of trophic interactions between jellyfish and fish. Dissertation, University of South AlabamaGoogle Scholar
- Davenport J (1998) Sustaining endothermy on a diet of cold jelly: energetics of the leatherback turtle Dermochelys coriacea. Br Herpetol Soc Bull 62:4–8Google Scholar
- Purcell JE, Brown ED, Slokesbury KDE, Haldorson LH, Shirley TC (2000) Aggregations of the jellyfish Aurelia labiata: abundance, distribution, association with age-0 walleye pollock, and behaviors promoting aggregation in Prince William Sound, Alaska. Mar Ecol Prog Ser 195:145–158CrossRefGoogle Scholar
- Shaw RF, Drullinger DL (1990) Early-life-history profiles, seasonal abundance, and distribution of four species of Carangid larvae off Louisiana, 1982 and 1983. NOAA Technical Report NMFS 89:44Google Scholar