New Zealand Journal of Marine and Freshwater Research abstracts

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Dietary composition of Gambusia affinis (Family Poeciliidae) populations in the northern Waikato region of New Zealand

S. MANSFIELD^*

School of Biological Sciences
University of Auckland
Private Bag 92 019
Auckland, New Zealand

B. H. MCARDLE

School of Biological Sciences
University of Auckland
Private Bag 92 019
Auckland, New Zealand

*Present address: Department of Environmental Science, Policy and Management, 201 Wellman Hall, University of California, Berkeley, CA 94720, United States. Email: mansfiel@nature.berkeley.edu

Abstract  Invertebrates were collected and identified from the stomach contents of eight mosquitofish (Gambusia affinis) populations in the northern Waikato region of New Zealand at 3-month intervals from December 1994 to September 1995. To investigate temporal and spatial patterns in dietary composition a novel analysis programme was created that used Gower's similarity coefficient. The analysis found differences in diet among months, lakes, and three size groups of mosquitofish (<15, 15-25, and >25 mm). Smaller mosquitofish fed mostly on zooplankton whereas larger G. affinis ate greater quantities of terrestrial fauna and large invertebrates. These differences are probably correlated with gape size and visual acuity, although ecological factors may also be important.

Keywords  Gambusia affinis; mosquitofish; aquatic insects; prey selection; Gower's similarity coefficient; Waikato

M97061
Received 8 October 1997; accepted 26 February 1998

PDF file of entire paper: medium quality (580K); (scanned from paper original: notes about this process)

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