Reciprocal subsidies between temporary ponds and riparian forests

Aquatic habitats are closely linked to surrounding terrestrial systems via reciprocal subsidies. Much of the research on aquatic-terrestrial subsidies has focused on streams and lakes, while subsidies across aquatic-terrestrial boundaries of other systems, like temporary ponds, have received less attention. To address the lack of information regarding cross-habitat subsidies of temporary ponds, we quantified leaf litter inputs, amphibian egg inputs, terrestrial insect inputs, and amphibian metamorph and aquatic insect emergence for eight temporary ponds. We compared the relative magnitude of cross-habitat biotic subsidies of temporary ponds to identify potentially important yet overlooked subsidies. Terrestrial insect inputs to ponds were the second largest subsidy (mean 15.3 g m(-2) yr(-1)), exceeding combined emergence of amphibians and aquatic insects (mean 4.0 g m(-2) yr(-1)), yet these high-quality subsidies are generally unaccounted for in similar studies. Across the wetland complex, total amphibian emergence (8929.3 g yr(-1)) was nearly four times higher than total aquatic insect emergence (2491.9 g yr(-1)). Aquatic insect emergence was similar to that of lakes and streams while amphibian emergence was generally higher. Although larger ponds produced greater total fluxes to terrestrial habitats, smaller ponds were often more productive per unit area. Therefore, a mosaic of small ponds may produce greater or equivalent subsidies to terrestrial food webs than a single large pond. Given continued threats to temporary ponds and their connections to surrounding forests, management and restoration of these systems, as well as future studies, should take holistic approaches that account for the many aquatic-terrestrial linkages, and factors that influence them.

Automated summary

Research has found that terrestrial insect inputs are the second largest subsidy for temporary ponds, but are often unaccounted for in similar studies. While larger ponds produce greater total fluxes to terrestrial habitats, smaller ponds are often more productive per unit area.