American Alligator Digestion Rate of Blue Crabs and Its Implications for Stomach Contents Analysis

Authors

James C. Nifong, Department of Biology, University of FloridaFollow
Adam E. Rosenblatt, Department of Biological Sciences, Marine Sciences Program, Florida International UniversityFollow
Nathan A. Johnson, United States Geological Survey, Southeast Ecological Science Center
William Barichivich, United States Geological Survey, Southeast Ecological Science Center
Brian R. Silliman, Department of Biology, University of FloridaFollow
Michael R. Heithaus, School of Environment, Arts and Society, Florida International UniversityFollow

Abstract

Stomach contents analysis (SCA) provides a snap-shot observation of a consumer's diet. Interpretation of SCA data can be complicated by many factors, including variation in gastric residence times and digestion rates among prey taxa. Although some SCA methods are reported to efficiently remove all stomach contents, the effectiveness of these techniques has rarely been tested for large irregular shaped prey with hard exoskeletons. We used a controlled feeding trial to estimate gastric residency time and decomposition rate of a large crustacean prey item, the Blue Crab (Callinectes sapidus), which is consumed by American Alligators (Alligator mississippiensis), an abundant apex predator in coastal habitats of the southeastern United States. The decomposition rate of C. sapidus in the stomachs of A. mississippiensis followed a predictable pattern, and some crab pieces remained in stomachs for at least 14 days. We also found that certain portions of C. sapidus were prone to becoming caught within the stomach or esophagus, meaning not all crab parts are consistently recovered using gastric lavage techniques. However, because the state of decomposition of crabs was predictable, it is possible to estimate time since consumption for crabs recovered from wild alligators. This information, coupled with a detailed understanding of crab distributions and alligator movement tactics could help elucidate patterns of cross-ecosystem foraging by the American Alligator in coastal habitats.

Comments

This material is based upon work supported by the National Science Foundation through the Florida Coastal Everglades Long-Term Ecological Research program under Cooperative Agreements #DBI-0620409 and #DEB-9910514. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Recommended Citation

Nifong, J., A.E. Rosenblatt, N. Johnson, W. Barichivich, B. Silliman, M.R. Heithaus. 2012 . American alligator digestion rate of blue crabs and its implications for stomach contents analysis. Copeia (3) pp. 419-423.