Dr Kirsten Benkendorff, School of Biological Sciences, Flinders University

	School of Biological Sciences Faculty of Science & Engineering

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Dr Kirsten Benkendorff

Research Activities

Molluscan and intertidal reef biodiversity

Dr Benkendorff with student

Understanding the biodiversity of organisms in their natural ecosystems should underpin all bioprospecting research in the marine environment. Sustainable collection for chemical studies requires a good understanding of which organisms live where and how widely distributed and abundant the species are, as well as their basic life history, in particular the potential for their populations to recruit and recover after collection. This basic species inventory data can also provide the foundation for conservation and management of marine habitats. Unfortunately, we currently have inadequate inventory data for the management of most Australian marine habitats and this is certainly true of intertidal reefs in South Australia.

I have developed methods for rapid biodiversity assessment of molluscs on rocky intertidal reefs. These procedures were first developed to locate species rich hotspots and breeding sites along the Illawarra coast of NSW and more recently have been applied to intertidal reef assessment along metropolitan and remote coasts in South Australia. I am currently undertaking an assessment of the physical characteristics and biological communities of intertidal reefs along the Fleurieu Peninsula in a project funded by the SA Department of Environment and Heritage. This should facilitate adequate representation of all intertidal reefs communities in a system of aquatic reserves. We are also developing an intertidal reef monitoring program for South Australia in collaboration with ReefWatch and the SA Conservation Council.

Of course the notion “biodiversity” not only encompasses the range of different species and ecosystems that occur on earth, but also the genetic variability within and between populations of each species. Consequently, my research lab is also undertaking research into the genetic diversity of some molluscan groups. In particular, Ph.D. student Ana Glavinic is investigating the phylogeny and phylogeography of rare endemic bivalves, commonly known as brooch shells (Neotrigonia). I am also investigating the possible use of chemical markers in molluscan taxonomy. In particular, a phylogenetic analysis of species in the Family Muricidae will be mapped against the presence of brominated secondary metabolites as component of Patrick Laffy’s Ph.D. project.

Bioprospecting, bioresources and molluscan secondary metabolites

Silicate column extraction of mollusc extract

Silicate column extraction of mollusc extract

I am interested in developing Australian marine molluscs as novel bioresources, particularly in relation to their medicinal properties. To date I have screened a large number of species and their egg masses for antimicrobial (antibiotic) and anticancer activities. The haemolymph (blood) and lipid extracts from the majority of species tested appear to have interesting antimicrobial activity against a broad spectrum of pathogenic bacteria, but limited cytotoxicity towards human cell lines. The active compounds are yet to be identified in most of these species. The main exception is the predatory marine gastropod Dicathais orbita (pdf), from which several bioactive compounds have been identified, including a potent antibiotic and a novel anticancer agent. Consequently, this species is being further investigated for potential development as a functional food and/or as the source of a novel nutriceutical agent (natural health product). In collaboration with Dr Catherine Abbott and Postdoctoral Research Fellow Cassandra McIver we are investigating potential applications in the prevention of colorectal cancer. PhD students Chantel Westley and Patrick Laffy have also been investigating the biosynthetic origin and enzymes used by Dicathais orbita to synthesize the bioactive compounds (brominated indoles and choline esters).

The egg capsules of Dicathais orbita are also proving to be a good model for the investigation of natural antifouling defenses. Surface biofouling has enormous economic consequences for the shipping and aquaculture industries. Antibiotic resistant biofilms can also be responsible for persistent infection in hospitals. Consequently, there is a serious need to develop new treatments aimed at disrupting microbial biofilms. Understanding of the ways that natural organisms regulate fouling of their surfaces could trigger novel ideas for anti-fouling technology. The egg masses of some marine molluscs have also been found to have interesting sun-screening properties with potential for cosmaceutical applications. I have identified a number of UV absorbing pigments in the egg capsules of Dicathais orbita and Ph.D. student Rachel Przeslawski has documented the composition of mycosporine-like amino acids in a wide range of gastropod egg masses.

Molluscan aquaculture and immune health

Taking blood from an abalone

To prevent overexploitation, research on the population biology, life history and aquaculture potential of novel marine bioresources must be prioritized. Consequently, we have been investigating the life cycle (pdf) of Dicathais orbita and maintain a breeding population within marine aquaria on campus to complement our medicinal research on this species. The development of methods for successful larval culture and settlement of Dicathais orbita forms the major focus for Warwick Noble’s Ph.D. project.

Knowledge on the immune health of molluscs is also very important for understanding and reducing mortality in aquaculture. The effects of environmental and procedural stressors can be examined by monitoring immune parameters, such as antibacterial activity and haemocytes (blood cells). In a collaborative FRDC project with researchers at Melbourne University, we are investigating the baseline variation in immune parameters and the effects of stress on abalone.

The effects of spawning and temperature on the immune health of the Pacific Oyster is also being investigated by Ph.D. student Yan Li, in attempt to explain summer mortality.

Chantel Westley's PhD project also involves the investigation of a potentially novel immune mechanism in the Muricidae.

Posters of whelk research

Overview of projects (pdf)
Dicathais life cycle (pdf)
Chantel Westley - biochemistry (pdf)
Patrick Laffy - bioinformatics (pdf)
Warwick Noble - larval culture (1 MB pdf)
Norman Lim - antifouling (pdf)

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