Salamander Poster Separc2012

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Surasinghe, T. D. and Baldwin, R. F. (2012). Exploitative competition among stream salamanders along a land-use gradient. The Annual meeting of the Southeastern Partners in Amphibian and Reptile Conservation, Pikesville, TN.

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Salamander Poster Separc2012

  1. 1. EXPLOITATIVE COMPETITION AMONG STREAM SALAMANDERS ALONG A LAND-USE GRADIENT Thilina Surasinghe, Mark McAllister, Robert Baldwin Dept of Biological Sciences, School of Agricultural, Forest, and Environmental Sciences, Clemson University, SC Objectives Study spatial occupancy of D. quadramaculatus & D. fuscus under four riparian land-uses: forested, urban, agricultural, residential areas. Study competition between D. quadramaculatus and D. fuscus. 100 100 Agricultural Riparian Land-Use Urban Riparian Land-Use 90 BB with ND 90 Black-Bellied Northern Dusky BB with ND 80 salamander Salamander 80 ND with BB ND with BB 70 BB only 70 BB only Percentage Occurrence Percentage OccurrenceIntroduction 60 ND only 60 ND onlyTarget species: Two species of stream salamanders- the Black-bellied salamander (Desmognathus quadramaculatus) and the Northern Dusky 50 50Salamander (Desmognathus fuscus). 40 40D. fuscus is a small-sized subordinate species among stream salamanders (SVL: 50-60 mm ). 30 30D. Quadramaculatus is a large bodied (SVL: 70-80 mm ) species hypothesized to dominate stream salamander communities 20 20 10 20 20 10 Agricultural Riparain Land-Use 18 18 0 Urban Riparain Land-Use Bank Crevices Channel Bottom Channel-Bank Interface Bank Surface 0 16 16 Microhabitat Types Bank Crevices Channel Bottom Channel-Bank Interface Bank Surface Microhabitat Types 14 14 100 120 12 12 Residential Riparain Land-Use Type Short Wall short wall 10 10 90 Forested Riparian Land-Use 8 8 100 80 BB with ND BB with ND 6 6 70 4 4 ND with BB ND with BB 80 Percentage Occurrence 2 2 60 Percentage Occurrence BB only BB only 0 0 0 5 10 15 20 25 30 35 40 45 50 0 5 10 15 20 25 30 35 40 45 50 Long wall 50 ND only Long wall ND only 60 Blabk-bellied Northern-dusky Black-bellied Northern-dusky 40 20 20 30 40 Residential Riparain Land-Use 18 18 Forested Riparain Land-Use 20 16 16 14 14 10 20 Short Wall 12 12 Short Wall 0 10 10 Bank Crevices Channel Bottom Channel-Bank Interface Bank Surface 0 8 8 Microhabitat Types Bank Crevices Channel Bottom Channel-Bank Interface Bank Surface 6 6 Microhabitat Types 4 4 2 2 Microhabitat selectivity of the Black-bellied salamander (Desmognathus quadramaculatus) and the Northern Dusky Salamander 0 0 0 5 10 15 20 25 30 35 40 45 50 0 5 10 15 20 25 30 35 40 45 50 Long wall Long wall (Desmognathus fuscus) along the riparian land-use gradient Northern-dusky Black-bellied Black-bellied Northern-dusky Results & ConclusionMethodology D. quadramaculatus: In each land-use simulation, occupied the stream banks and chose rock crevices as their preferred microhabitat.The experiment simulated four riparian land-use types : forested, agricultural, residential, and urban. Showed high site fidelity.The artificial streams were filled with native stream substrates and water. Air pumps were used to mimic the streams oxygen conditions. D. fuscus: Broad microhabitat selectivity including interstitial space beneath rocks and logs, leaf litter, sand and gravel. Mostly occupiedThe target species were captured from the wild. the stream channel, notably in the forested tank. Observed in areas of the bank unoccupied by D. quadramaculatus in other land-useOnly males of the same SVL size class were used (50 - 60 mm for D. fuscus and 70 - 80 mm for D.qudramaculatus). simulations,The salamanders were fed with live invertebrates (mealworms, red worms, bloodworms, and crickets). No aggression or predation was observed.Observations were made under species co-existence and species isolation, each phase phase lasted 5 days. No evidence on D. fuscus competitively displacing D. quadramaculatus.Each land use type was duplicated in the same channel with different individuals. Once D. quadramaculatus is removed from the tanks, D. fuscus moved to the microhabitats previously occupied by D. quadramaculatus20 min Observations were made daily in every third hour (0900 to 2100 hours). indicating that they are dominant in competition for space and microhabitat.Records were taken on salamander’s aggressive behavior on an ordinal scale. The study is still continuing and more replications will be done in future.The microhabitat occupied and the precise location of all the animals in the artificial streams were recorded.

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