Date of Award

1999

Degree Name

Biological Sciences

College

College of Science

Type of Degree

M.S.

Document Type

Thesis

First Advisor

Thomas K. Pauley

Second Advisor

Michael E. Seidel

Third Advisor

Donald C. Tarter

Abstract

This study observed a population of Ambystoma opacum in Kanawha State Forest, Kanawha County, five miles south of Charleston, West Virginia. Data were collected from September 1995 to November 1997. Reproductive biology and salamander development were examined. Predation of A. opacum and potential predators were also noted. Like other species in the genus Ambystoma, adult A. opacum are mostly fossorial and rarely seen above ground outside of the breeding season. During the breeding season, adults make their way to the breeding pools. Males ventured to the breeding pool first in early September and ranged in size from 49 to 75mm snout-vent length (SVL). Females arrive a few days later and ranged in size from 59 to 77mm SVL. In this study, two females were found over 160 meters from the breeding pool. During courtship a male deposits a spermatophore on the substrate and the female clips the sperm packet off the top with the lips of her cloaca. Two spermatophores were collected and described. Successful courtship can occur at the breeding pond, or during the migration to the pond. Ambystoma opacum differs from other West Virginia ambystomatids in three ways: 1) breeding occurs in the fall, 2) the female lays eggs in a terrestrial habitat and 3) females generally brood the eggs for some time, but will abandon the nest if disturbed. This habit of brooding may increase viability of the eggs by deterring potential predators and decreasing the chance of fungal growth on the eggs. A clutch of eggs is comprised of eggs laid singly in a crudely excavated nest found mostly under logs in this study. Clutch size ranged from 61 to 113 eggs. Eggs were laid directly on the soil in most nests. Ambystoma opacum eggs are well adapted to a terrestrial habitat and readily dehydrate/hydrate while the embryo develops inside. This was witnessed on numerous occasions. Eggs hatch when the nest is inundated with water and will do so while the embryo is at various stages of development; from early stages with a great deal of the yolk sac remaining to well-developed, late-stage larvae. In this population, newly hatched larvae possessed well-developed forelimbs and were approximately 17.0mm total length. Once hatched, larvae are mostly nocturnal, but could be observed on cloudy, overcast days. Stratification of larvae was not witnessed. Larvae attained total lengths of over 45mm by mid-May but were not observed to transform. Literature reports numerous predators of A. opacum eggs and larvae, many of which were observed at the study site. Predation was observed by rusty blackbirds. Larvae at this time were approximately 30mm TL. Although no oophagy was witnessed, a red-spotted newt was observed on an unbrooded nest.

Subject(s)

Salamanders - West Virginia.

Ambystoma opacum - West Virginia.

Salamanders - Larvae - West Virginia.

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