Aspects of the community structure and reproductive ecology of the common sea-urchin Parechinus angulosus Leske around the Cape Peninsula, South Africa
type: CreativeWork
description: The geographic distributionof Parechinus angulosus according to present II records extend from Umhlali (Zululand) to Luderitz Bay (Day, 1974). The urchins are therefore adapted to a wide range of temperatures. Maximum fluctuations probably occur along the stretches of coastline affected by upwelling, the South-West, and west coasts, with differentials of twelve degrees Centigrade and more. Furthermore, these fluctuations may take place within a matter of a few hours or even less, i.e., almost capriciously Like temperature changes encountered on land but, unlike, the latter, by virtue of movement of different water masses, rather than cooling rate. The importance of temperature as a regulator of reproductive cycles in marine organisms, specifica'ly invertebrates, is discussed in Giese and Pearse's (1974) detailed review on the subject. A local study by Newman (1969) considers the effect of temperature on the spawning behaviour of abalone (Haliotis midae). This study was commenced in the light of this information and subjective preliminary observations underwater, which revealed striking density and relative size differences between urchins on the Atlantic side of the Peninsula and in the warmer False Bay. A detailed in situ record of sea temperatures at two study sites, Robben Island and Millers Point was obtained by installing temperature measuring devices. This monitoring covered a period of one year, while coupled with monthly collections of urchins in the mature size range. The variations of male and female gonad indices were found to be essentially in agreement, though lagging behind sea temperature changes. The spawning periods of urchins at both study sites was similar, occurring in spring and autumn, despite the significantly different water temperature averages. A clear pattern was observed at Millers Point, while being poorly defined at Robben Island. This is in agreement with the findings of Newman (1967, 1969), whose observations included data from St. He…
abstract: The geographic distributionof Parechinus angulosus according to present II records extend from Umhlali (Zululand) to Luderitz Bay (Day, 1974). The urchins are therefore adapted to a wide range of temperatures. Maximum fluctuations probably occur along the stretches of coastline affected by upwelling, the South-West, and west coasts, with differentials of twelve degrees Centigrade and more. Furthermore, these fluctuations may take place within a matter of a few hours or even less, i.e., almost capriciously Like temperature changes encountered on land but, unlike, the latter, by virtue of movement of different water masses, rather than cooling rate. The importance of temperature as a regulator of reproductive cycles in marine organisms, specifica'ly invertebrates, is discussed in Giese and Pearse's (1974) detailed review on the subject. A local study by Newman (1969) considers the effect of temperature on the spawning behaviour of abalone (Haliotis midae). This study was commenced in the light of this information and subjective preliminary observations underwater, which revealed striking density and relative size differences between urchins on the Atlantic side of the Peninsula and in the warmer False Bay. A detailed in situ record of sea temperatures at two study sites, Robben Island and Millers Point was obtained by installing temperature measuring devices. This monitoring covered a period of one year, while coupled with monthly collections of urchins in the mature size range. The variations of male and female gonad indices were found to be essentially in agreement, though lagging behind sea temperature changes. The spawning periods of urchins at both study sites was similar, occurring in spring and autumn, despite the significantly different water temperature averages. A clear pattern was observed at Millers Point, while being poorly defined at Robben Island. This is in agreement with the findings of Newman (1967, 1969), whose observations included data from St. He…
author: Fricke, Alexander Hermann
keywords: Reproductive ecology
date published: 1980
date modified: 2026-07-22T22:23:44Z
provider: University of Cape Town
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Department of Oceanography

PropertyValue
property ID: Handle
value: http://hdl.handle.net/11427/38997