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Larval fishes as biological tracers of latitudinal and cross-shelf connectivity off Western Australia

Millar, N., Holliday, D., Beckley, L.E., Feng, M. and Thompson, P.A. (2009) Larval fishes as biological tracers of latitudinal and cross-shelf connectivity off Western Australia. In: AMSA2009 46th Annual Conference for the Australian Marine Sciences Conference, 5 - 9 July, Adelaide, Australia.

Abstract

The role of the Leeuwin Current in driving latitudinal and cross-shelf transport processes was examined using larval fishes as tracers. Coinciding with peak Leeuwin Current flow (late austral autumn) a multidisciplinary voyage off Western Australia sampled 13 onshore-offshore transects at every degree of latitude from Northwest Cape (22oS) to Cape Leeuwin (34oS). Sampling stations where larval fishes were collected using depth-integrated bongo tows were designed to sample shelf, Leeuwin Current and oceanic waters. Generally, in the cross-shelf direction, there was a decrease in diversity and concentration of larval fishes from inshore (>1.0 /m3) to offshore (<0.50 larvae /m3). However, at some of the oceanic locations, higher larval fish concentrations occurred and these were associated with meso-scale features of the Leeuwin Current. From north to south there was no clear gradient in larval fish concentrations, but diversity of larval fishes decreased reflecting the biogeographic trend of adults. Cross-shelf exchange was persistent for the entire study region and was demonstrated by the offshore occurrence of larvae of reef-dwelling taxa (e.g. Acanthuridae and Blenniidae) and inshore occurrence of meso-pelagic larvae (e.g. Myctophidae and Sternoptychidae). It appears that meso-scale features, such as eddies, disrupt longshore connectivity but mixing associated with these features enhances cross-shelf exchange.

Publication Type: Conference Item
Murdoch Affiliation: School of Environmental Science
URI: http://researchrepository.murdoch.edu.au/id/eprint/12879
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