Assessment of the Threat of Toxic Microalgal Species to the Great Barrier Reef World Heritage Area

Literature Review

Compiled by Samantha Garrard, Kirsten Heimann and David Blair

School of Marine and Tropical Biology, James Cook University

ISBN 9781921359033
Published March 2008

MTSRF Project 2.6.1 - Identification and impact of invasive species in the Great Barrier Reef

Overview

Prerequisites for the assessment of the threat of introduced and invasive marine pests to a particular ecosystem are knowledge of species present, their current distributions and abundances.  This information, however, largely does not exist for microalgal communities in the Great Barrier Reef World Heritage Area (GBRWHA).  The need for such baseline information was recognised by the Australian Ballast Water Management Advisory Council, the Standing Committee on Agriculture and Resource Management, and the Australian and New Zealand Environment and Conservation Council.  In recognition of these problems, baseline studies through port surveys have been conducted in Australia to define the state of introductions and occurrences of non-indigenous species.  These efforts were coordinated largely by the CSIRO Centre for Research on Introduced Marine Species and also involved several State agencies and research organisations.

Despite these surveys, knowledge on current microalgal community structure, occurrences and abundances of toxic microalgae in the GBRWHA remains scarce and incomplete, in particular in regard to introductions and invasiveness, which is defined in this review as range-expansions of existing microalgae due to habitat change.  The main reasons for the paucity of information on toxic microalgae in the GBRWHA lies in the restriction of sampling efforts for only certain species, the sporadic and short term nature of port surveys, and the fact that samples were only analysed by traditional morphology-based techniques, which yield no information regarding toxicity of certain microalgal species.  Taxonomical analysis based on morphology alone is also insufficient because the identification is often tentative at best, which is partially due to morphological plasticity within many microalgal species.

Due to the lack of developed molecular probes for fast and unambiguous identification of Great Barrier Reef (GBR)-specific microalgae, several issues and questions remain and may become more pressing under climate change scenarios.  These are: 

This review will provide an overview of current knowledge of toxic microalgae with a focus on toxic dinoflagellates.  It will briefly describe dinoflagellate characteristics, which impede identification and molecular tool development, provide an overview of microalgal toxins and associated human health issues, and summarise information available on the distribution of toxic microalgae in the GBRWHA and Australasia and their threats to the region.  At the end, this review will also introduce suitable molecular techniques that need to be developed and utilised for GBR-specific toxic microalgal identifications in order to effectively predict the risks and threats that these organisms pose to the GBRWHA and the local human population now and under future temperature regimes.