Skip to main content
U.S. flag

An official website of the United States government

The missing dead: The lost role of animal remains in nutrient cycling in North American Rivers

January 30, 2019

While leaf litter, wood, and other plant remnants are known to play a central role in lotic ecosystems, animal remains (carcasses, bones, shells) have received less attention. We propose a simple classification scheme for animal remains in rivers based on origin (authochthonous vs. allochthonous) and frequency (pulsed vs continuous). We then present case studies in which we estimate the former biomass of several taxonomic groups that are now diminished in abundance to determine whether their remains could have historically constituted a significant flux of nutrients in rivers of North America. We focus on bones and shells, which decompose slowly and could provide long-term reservoirs of nutrients. We find that carcasses of alligator snapping turtles, once abundant in southeastern rivers, could have provided an amount of phosphorus equivalent to about 1% of total phosphorus (TP) load at median flow, and more at low flows. Mussel shells could have contributed a similar amount (0.8% of TP) but the contribution of beaver carcasses, even at former abundances, was likely small. In contrast, a single documented mass drowning of bison in the Assiniboine River could have contributed half the annual TP load for that river. Such drownings could have been a common occurrence prior to the loss of most wild terrestrial megafauna in North America. We conclude that animal remnants, particularly allochthonous remains from terrestrial animals, formerly played a substantial role in nutrient cycling. Existing models of ecosystem function under reference conditions are incomplete without consideration of these lost animal legacies.

Publication Year 2019
Title The missing dead: The lost role of animal remains in nutrient cycling in North American Rivers
DOI 10.1016/j.fooweb.2018.e00106
Authors Seth J. Wenger, Amanda L. Subalusky, Mary Freeman
Publication Type Article
Publication Subtype Journal Article
Series Title Food Webs
Index ID 70201782
Record Source USGS Publications Warehouse
USGS Organization Patuxent Wildlife Research Center