Climate Change: Thermal Physiology of Endemic Freshwater Fishes

We are seeking a motivated Honours student to help characterize the metabolic physiology of some of South West Australia’s iconic freshwater fishes.  The SW is a region of global significance for its extraordinary Biodiversity, yet it is also one of the areas most threatened by climate change. The student will be taking advantage of a brand new cutting-edge respirometry system and swim tunnel funded by the School of Veterinary Science to quantify metabolic rates in freshwater cobbler and Pygmy Perch.  The project will be a “hands-on” experience and include the student both working with fish in the field and the lab. The work will suit a student with an interest in the fields of eco-physiology and equip the successful applicant with the necessary skills to investigate climate change effects in fishes and other ectothermic vertebrates. 

For more information contact Stephen Beatty (s.beatty@murdoch.edu.au)

Parasites and changing climates: quantifying the threats by multiple stressors

Changing climates are not just changing temperatures, but are also set to change many other biotic and abiotic factors which will impact organisms. Parasites in particular can have substantial impacts on the biology of their hosts, including reduced growth and slower reproductive output. Much like Australia’s terrestrial ecosystems, aquatic systems are increasingly being invaded by exotic species, including parasites. Lernaea cyprinacea, an anchor-worm, has been found in numerous native fishes. We are seeking a student with interests in either parasitology and/or ecophysiology to investigate the interactive effects of climate change and parasite presence in native fish, using a state of the art respirometry system. The project will be a “hands-on” experience and include the student both working with fish in the field and the lab.

For more information contact Stephen Beatty (s.beatty@murdoch.edu.au)

How well do fish swim?

River barriers, such as dams and weirs, are a major threat to the unique freshwater fish fauna of Western Australia, because they prevent feeding and spawning migrations and may lead to disconnected populations. Fishways are structures which may enable fishes to negotiate these barriers and we are involved in a number of projects to design and construct fishways throughout the state. Effective fishway design, however, requires knowledge of the swimming performance of the target fishes and this information is currently very limited for native freshwater fishes in Western Australia.

This study will use a swim tunnel, recently installed in our laboratory, to measure the swimming performance of freshwater fishes and relate swimming performance to parameters such as fish age, size and sex, water temperature and parasitic infection. The data that are obtained will have immediate applications because they will be related to water flow measurements from current fishways and used to design improved fishways in the future.

For more information contact Stephen Beatty (s.beatty@murdoch.edu.au)

Freshwater Crocodiles: habitat use in small riverine pools of the Kimberley

The freshwater crocodile (Crocodylus johnstoni) is an iconic species in the rivers of northern Australia. There is much concern that freshwater crocodiles will be severely impacted in the Kimberley by the invasion of the introduced cane toad (Bufo marinus). This project will assess the habitat ulitisation, home range and movement patterns of this large freshwater predator in pools of the Fitzroy River. This will be achieved through acoustic tracking and mark-recapture of the species. The project will suit a candidate that likes field work in remote areas and will involve Indigenous Ranger groups.

For more information contact David Morgan (d.morgan@murdoch.edu.au)

Dwarf Sawfish: recruitment and movement patterns in the Kimberley

The dwarf sawfish (Pristis clavata) is critically endangered (IUCN) and is considered to be one of the world’s rarest species. The Kimberley is a hotspot for the species, yet very little is known about its biology. The candidate will be assisting in developing an acoustic tracking (passive) study in the Fitzroy River estuary and King Sound to examine the movement patterns and habitat usage of the species, and will also determine likely conservation threats. The project will suit a candidate that likes field work in remote areas and will involve Indigenous Ranger groups.

For more information contact David Morgan (d.morgan@murdoch.edu.au)

Study the healing process in fish gills after toxic insults

Water has 30,000x less oxygen than air. Hence, fast swimming fish are very susceptible to gill damage. Algae blooms may produce substances toxic to tissues including gills.  Algae blooms can be very transient, with clinical signs presenting in affected fish only 1-2days after the blooms have been washed away by currents or tides. This often makes the diagnosis of the cause of gill damage difficult without a good understanding of how gills response and heal in the period following toxic insults. Surprisingly while many published papers report on the gill damage caused by various toxic chemicals, none could be found describing the healing process that follows. The question remains: do fish gills response to toxic damage much like lung tissues in mammals and birds?

This study will require you to:

•      Design live fish experiments to study the healing process in fish gills post exposure to toxic compounds

•      Carry out histopathological evaluation of gills sampled over time

•      Undertake ultrastructural evaluation using electron microscopy

For more information contact Susan Kueh (s.kueh@murdoch.edu.au)

Evaluation of in-feed essentials oils as a control for ‘Big Belly’, a gut bacterial disease of Lates calcarifer (barramundi)

‘Big Belly’ (aka Pot Belly) is a significant bacterial disease of barramundi fry at the hatchery level in Southeast Asia. ‘Big Belly’ can cause mortalities of 80 to 100%. It is caused by intracellular coccobacilli and is difficult to treat. The disease may persist as a chronic gut infection in grow-out barramundi.

In this study, we are interested in incorporating the essential oils extracted from garlic, ginger, clove or cinnamon into feed as a potential means of controlling ‘Big Belly’. Similar trials carried out in rainbow trout and tilapia have shown beneficial effects including better resistance to disease.

You will be involved in the following: field & laboratory trials based in Singapore; design of experimental field trials to evaluate in-feed essential oils; evaluate the effects of these supplements via examination of test versus control fish tissues.

For more information contact Susan Kueh (s.kueh@murdoch.edu.au)

How many freshwater mussels do we have in south-western Australia?

Only one species of freshwater mussel, Carter’s freshwater mussel or Westralunio carteri, is thought to occur in the south-west of Western Australia. A recently completed PhD project by Dr Michael Klunzinger found that W. carteri has undergone a massive reduction in range over the last 50 years, principally because of salinization and drying of rivers. The same project found some tantalizing evidence that certain populations of these mussels are genetically differentiated, to the extent that they may not belong to the same species.

The aim of this study is to use molecular genetic and morphological analyses to determine whether there are one or more species of freshwater mussels in the south-west of Western Australia. Answering this question will have important consequences for conservation management, because it will affect both the conservation status and future management plans for freshwater mussels in the region.

For more information contact Alan Lymbery (a.lymbery@murdoch.edu.au)

Are mussels keystone species for freshwater ecosystems?

Mussels play important roles in the functioning of freshwater ecosystems throughout the world, particularly because their filter feeding activities influence water chemistry and clarity, and the amount and kind of suspended particles in the water. Nothing is known, however, of the extent to which Carter’s freshwater mussel influences water quality in Western Australian rivers.

Mussel densities can be very high (³ 100 m-2) in pools which form over summer in many of the ephemeral rivers in the south-west. These pools are important refuge sites for native freshwater fishes and we hypothesise that mussels contribute to the survival of fishes in the pools through their filter feeding activities, which may reduce algal density, enhance water quality and prevent lethal deoxygenation. The aim of this study is to test this hypothesis using a combination of field observations and manipulation of mussel and fish densities in experimental ponds.

For more information contact Alan Lymbery (a.lymbery@murdoch.edu.au)