Tom Mullaney

School of Biological Earth and Environmental Science
University of New South Wales
Sydney NSW 2052
AUSTRALIA

Phone: +612 9385 2118
Fax: +612 9385 1558

Email: t.mullaney at student.unsw.edu.au

Honours Projects

Tom graduated in early 2004 after completing his undergrad with honours at the end of 2003, researching the feeding ecology of hardyheads (a common estuarine baitfish) in a NSW estuary. Stomach content analyses were used to identify and quantify the common prey items. A measurement of a gut throughput rate and manipulative feeding experiments, using in situ mesocosms, allowed a daily predation rate to be estimated from the volume of prey consumed. Hardyheads consumed zooplankton (predominantly crustacean nauplii and copepods) and benthic fauna (predominantly polychaetes and bivalves). Predation was both selective (15-24 mm TL fish on crustacean nauplii) and opportunistic (25 - 34 mm TL fish on calanoid copepods). There was an ontogenetic shift in diet, with the shift from zooplankton to benthic fauna occurring in the 35-44 mm TL size class. For the hardyhead population as a whole, 25% of biomass uptake came from zooplankton and 75% from benthic fauna at a total rate of 20.6 mm³ of prey per gram of fish per day. In an estuarine system, the transfer of biomass from nutrients to baitfish and finfish populations through the benthos is just as or more important than via pelagic pathways. Understanding the feeding ecology of hardyheads will identify the role they (and other baitfish) play as a resource in estuarine systems.

PhD Project

Tom is currently undertaking a PhD looking at the larval fish assemblages associated with coastal regions, the EAC and the Tasman Front off NSW. Results so far show that the EAC is analogous to the Gulf Stream off eastern USA. Temperate coastal families are entrained into the EAC in northern NSW and transported south. Also as the EAC separates from the coast of NSW, EAC/coastal mixed water is entrained into the Tasman Sea, bringing coastal species with it. This EAC/coastal mixed water often forms a filament between the EAC (now propagating towards NZ) and the Tasman Sea. Cold core eddies also often form in this region and these have shown to be highly productive, with higher concentrations of individuals of both coastal and oceanic origin. This research is also focusing on pilchard (Sardinops sagax) and blue mackerel (Scomber australasicus) and the relationship between larval growth rates and physical properties and/or available resources. The relatively oligotrophic East Australian Current (EAC) and relatively nutrient enriched coastal upwelling regions and cold core eddies were chosen as habitats displaying varying degrees of secondary production. Theoretically, high secondary production in the zooplankton community will lead to more available prey for larval fish and fast larval growth; and fast growth in the larval stage equates to survival and therefore a stronger year class.