Life on a gradient : activity levels of the seastar Patiriella exigua in different abiotic conditions

Sankar, Kishan

Life on a gradient : activity levels of the seastar Patiriella exigua in different abiotic conditions

Bachelor Thesis

2005

Publisher

University of Cape Town

Department

Department of Biological Sciences

Faculty

Faculty of Science

Abstract

Two morphs of Patiriella exigua occur in South Africa. These morphs occur on opposite sides of a temperature divide present at Cape Point. The green morph occurring on the West Coast (cold temperate) and the mottled morph occurring on the South Coast (warm temperate). In a previous study by Katherine Dunbar these two morphs were shown to be the same species. This project tests if there is a physiological difference between the two morphs of P. exigua. This was achieved by observing the activity coefficient of righting response of the two morphs of P. exigua under different temperatures and dissolved oxygen concentrations. The green morph was collected from Green Point (West Coast) and the mottled morph from Kalk Bay (South Coast). The results of a general linear model indicated that temperature and dissolved oxygen were significant factors determining righting time of P. exigua with P-values of less than 0.05. AT-test indicated that there was a significant difference between the righting times of the two morphs of P. exigua with the green morph turning at a faster rate than the mottled morph when placed under similar conditions.

Keywords

Marine Biology

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