Influence of damming on anuran species richness in riparian areas: A test of the serial discontinuity concept

• Published in: Ecology and evolution Vol. 8; no. 4; pp. 2268 - 2279
• Main Authors: Guzy, Jacquelyn C., Eskew, Evan A., Halstead, Brian J., Price, Steven J.
• Format: Journal Article
• Language: English
• Published: England John Wiley & Sons, Inc 01-02-2018; John Wiley and Sons Inc; Wiley
• Subjects: Adults; amphibian; Bayesian analysis; Biodiversity; Breeding seasons; Communities; Dam effects; Dams; Damsites; detection; Discharge; Discontinuity; Downstream; Eggs; Empirical analysis; Environmental conditions; Environmental regulations; Flood predictions; floodplain; Floodplains; flow regulation; Habitats; hierarchical Bayesian analysis; Hydrologic data; Influence; Land use; Landscape; Larvae; Model testing; Occupancy; Original Research; Predictions; Reptiles & amphibians; Riparian environments; Rivers; Species diversity; Species richness; urbanization; Watersheds; Wetlands; United States > US; South Carolina; detection; floodplain; occupancy; downstream; flow regulation; amphibian; hierarchical Bayesian analysis; urbanization
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.3750

Almost all large rivers worldwide are fragmented by dams, and their impacts have been modeled using the serial discontinuity concept (SDC), a series of predictions regarding responses of key biotic and abiotic variables. We evaluated the effects of damming on anuran communities along a 245‐km river corridor by conducting repeated, time‐constrained anuran calling surveys at 42 locations along the Broad and Pacolet Rivers in South Carolina, USA. Using a hierarchical Bayesian analysis, we test the biodiversity prediction of the SDC (modified for floodplain rivers) by evaluating anuran occupancy and species diversity relative to dams and degree of urbanized land use. The mean response of the anuran community indicated that occupancy and species richness were maximized when sites were farther downstream from dams. Sites at the farthest distances downstream of dams (47.5 km) had an estimated ~3 more species than those just below dams. Similarly, species‐specific occupancy estimates showed a trend of higher occupancy downstream from dams. Therefore, using empirical estimation within the context of a 245‐km river riparian landscape, our study supports SDC predictions for a meandering river. We demonstrate that with increasing distance downstream from dams, riparian anuran communities have higher species richness. Reduced species richness immediately downstream of dams is likely driven by alterations in flow regime that reduce or eliminate flows which sustain riparian wetlands that serve as anuran breeding habitat. Therefore, to maintain anuran biodiversity, we suggest that flow regulation should be managed to ensure water releases inundate riparian wetlands during amphibian breeding seasons and aseasonal releases, which can displace adults, larvae, and eggs, are avoided. These outcomes could be achieved by emulating pre‐dam seasonal discharge data, mirroring discharge of an undammed tributary within the focal watershed, or by basing real‐time flow releases on current environmental conditions.
We evaluated the effects of damming on anuran communities along a 245 km river corridor. We test the biodiversity prediction of the Serial Discontinuity Concept by evaluating anuran spatial distributions relative to dams. Our study supports predictions of the Serial Discontinuity Concept and our results indicate that with increasing distance downstream from dams, riparian anuran communities have higher species richness. Photo by Mitchell Pruitt.