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Chaetognatha: distribution and abundance in the Leeuwin Current system

Buchanan, P.J. and Beckley, L.E. (2013) Chaetognatha: distribution and abundance in the Leeuwin Current system. In: AMSA2013 Golden Jubilee Conference, 7 - 11 July, Gold Coast, Qld, Australia.


Recent experiments have shown that chaetognaths (arrow worms) are the preferred prey of the pelagic phyllosoma larvae of the Western Rock Lobster. Little is known about the chaetognaths of the Leeuwin Current system though it is the dominant oceanographic feature of the southeast Indian Ocean, exerts strong influences on the marine biota and is heavily implicated in annual recruitment of the Western Rock Lobster. An extensive survey of the Leeuwin Current system collected plankton samples using 355 μm nets (down to 150 m depth) over shelf (50-100 m), Leeuwin Current (200-300 m) and oceanic (1000-5000 m) stations from 22°S to 34°S. Sampling was conducted in May 2007 to coincide with peak Leeuwin Current flow and biological activity. It is anticipated that at least 20 of the 121 globally recognised chaetognath species will be identified from these samples. To date, the genera Flaccisagitta, Mesosagitta, Serratosagitta and Pterosagitta appear to dominate temperate samples and two species previously unrecorded from waters off Western Australia, Aidanosagitta neglecta and Eukrohnia minuta, have been identified. This study encompasses tropical, subtropical and warm temperate waters and the anomalous Leeuwin Current system is predicted to strongly influence the chaetognath assemblages. Links between assemblages and environmental factors, such as meso-scale features, water masses, primary production, nutrient concentrations and biology, are being explored. This study will improve understanding of the prey field available to planktonic lobster larvae and possibly assist with explaining the continued and unexpected decline in recruitment since 2006/07.

Item Type: Conference Item
Murdoch Affiliation(s): School of Veterinary and Life Sciences
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