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IS INTERSPECIFIC COMPETITION A PRIMARY DRIVER OF SEGREGATION BETWEEN LARVAL SALAMANDERS (DESMOGNATHUS AMPHILEUCUS AND PSEUDOTRITON RUBER) IN APPALACHIAN STREAMS?

Abstract

Habitat separation among species can be due to innate habitat preference or interspecific competition, a biotic force that has often been cited as a contributing factor to segregation among adult salamanders in Appalachian streams. However, there has been very little research on the segregation of aquatic larvae of those salamanders. In this study, we focused on habitat segregation between two species, the Southern Black-bellied Salamander (Desmoganthus amphileucus) and the Red Salamander (Pseudotriton ruber), which are both common inhabitants of Appalachian headwater streams. Desmognathus amphileucus larvae have small gills and are found in areas of rapid water movement in riffles, whereas large-gilled P. ruber larvae typically occur in the calm water of pools. We tested the alternative hypotheses of innate preference for water disruption versus competitive interaction on habitat choice by placing larval salamanders in a 1-m metal trough holding water at a depth of 2 cm. At one end of the trough, we placed an air-stone bubbler to simulate the water disruption that occurs naturally in riffles. When tested alone, D. amphileucus larvae remained close to the air stone. In the presence of P. ruber, larval D. amphileucus sat slightly but not significantly farther from the air stone. Pseudotriton ruber larvae tended to stay in quiet water well away from the air stone, both during the lone trials and in the presence of D. amphileucus. Our results show that the larvae of these two species do not choose their respective habitat due to interspecific competition but rather chose certain abiotic conditions, specifically the presence or absence of water disruption. We hypothesize that D. amphileucus larvae choose riffles due to their small gills, which results in greater reliance on cutaneous respiration and a need for water disruption to break up hypoxic zones that build up along the skin.

Acknowledgements

Piedmont University Department of Natural Sciences

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