Population biology of the intertidal snailChilina ovalis sowerby (pulmonata) in the Queule River estuary, South-Central Chile |
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| Authors: | Pedro Quijón Heraldo Contreras Eduardo Jaramillo |
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| Institution: | (1) Graduate Program in Marine Biology, College of Charleston, 205 Fort Johnson Rd., Charleston, SC 29412, USA;(2) Undergraduate College of Natural and Applied Sciences, Coastal Carolina University, PO Box 261954, Conway, SC 29528, USA;(3) National Ocean Service, National Oceanic and Atmospheric Administration, 219 Fort Johnson Rd., Charleston, SC 29412, USA; |
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| Abstract: | The temporal variability in abundance and population structure of the gastropodChilina ovalis Sowerby was studied in the upper intertidal zone of Queule River estuary, south-central Chile (c. 40°S). Snails were collected monthly (September 1995–December 1997) from haphazardly-located quadrats (50×50 cm, n=5 each time), and counted and measured (shell height) in the laboratory. Water and sediment samples were collected at the same time to study the snail's habitat characteristics. Overall mean abundance was 115 individuals m?2 (SD=55). Monthly abundance estimates indicated a clear decrease during 1997. This decrease appeared to be related to the annual recruitment success of the species and at least partially to water temperature and sedimentological variability. Overall size range ofC. ovalis was 1.5–27.5 mm shell height. Growth varied seasonally with highest growth rates observed after recruitment (November–February). Slower growth continued throughout the austral winter months. Despite changes in abundance between 1996 and 1997, no differences were detected when population growth estimates were compared between years. A maximum longevity of approximately 4 yr was estimated from the growth curves of the cohorts, and a life cycle with more than one reproductive period is suggested. |
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