Biomass export of salamanders and anurans from ponds is affected differentially by changes in canopy cover

JULIA E. EARL,
THOMAS M. LUHRING,
BETHANY K. WILLIAMS,
RAYMOND D. SEMLITSCH
Article first published online: 11 AUG 2011
Freshwater Biology
How to Cite
EARL, J. E., LUHRING, T. M., WILLIAMS, B. K. and SEMLITSCH, R. D. (2011), Biomass export of salamanders and anurans from ponds is affected differentially by changes in canopy cover. Freshwater Biology. doi: 10.1111/j.1365-2427.2011.02672.x
Author Information
Division of Biological Sciences, University of Missouri, Columbia, MO, U.S.A.
*Correspondence: Julia E. Earl, Division of Biological Sciences, University of Missouri, 212 Tucker Hall, Columbia, MO 65211, U.S.A. E-mail: jee9rb@mail.mizzou.edu
Present address: Bethany K. Williams, Columbia Environmental Research Center, U.S. Geological Survey, 4200 New Haven Road, Columbia, MO 65201, U.S.A.

Publication History
Article first published online: 11 AUG 2011
(Manuscript accepted 16 July 2011)

Summary
1.  Previous research shows that canopy-associated shifts from an algal to a detritus-based food web can affect anuran tadpoles negatively. This may not be true of salamander larvae, however, because they are predators.

2.  To investigate the influence of canopy cover on the survival and growth of salamanders, and on the subsequent export of biomass from ponds, we conducted a mesocosm experiment examining effects of shading (high or low) and litter (leaves or grass) on Ambystoma maculatum (a forest specialist) and A. texanum (a habitat generalist). Additionally, we reanalysed data from Williams, Rittenhouse & Semlitsch (2008) to examine the effects of shading and litter on biomass export of three anurans: Rana sphenocephala, Pseudacris crucifer and Hyla versicolor.

3.  In contrast to previous studies, we found that salamanders performed better in mesocosms with the characteristics of closed canopy ponds (high shade and leaf litter), which resulted in a greater export of biomass. Salamanders grew larger under closed canopy conditions, probably because of differences in prey abundance among treatments. Anurans responded differently to canopy cover than caudates. The biomass export of R. sphenocephala and P. crucifer was reduced under closed canopy conditions (although differently affected by litter and shading), while the biomass of H. versicolor was not affected.
 




This and other studies suggest that changes in canopy cover may induce a shift in the amphibians emerging from ponds, from primarily anurans in open canopy ponds to primarily salamanders in closed canopy ponds. Additional multispecies studies will determine whether these trends hold true for more diverse amphibian assemblages. Further investigation into the effects of canopy cover on salamanders will be important for understanding aquatic-terrestrial linkages.