Distribution and abundance of toxic microalgae on the central Great Barrier Reef
Project Leader: Prof David Blair & Dr Kirsten Heimann, JCU
Climate change-induced increases in natural disturbance events are predicted to lead to phase shifts to macroalgal dominance on coral reefs world-wide. Macroalgae, dead corals and coral rubble serve as substrates for toxic epiphytic and benthic dinoflagellates, known to cause ciguatera (CFP), paralytic (PSP), diarrheic (DSP), and amnesic shellfish poisoning (ASP). Hence, as substrate availability increases, toxic dinoflagellates are likely to expand their ranges simultaneously with substrate availability. Information on benthic toxic dinoflagellate abundance patterns and community composition for the Great Barrier Reef is sparse. There is an urgent need to collect and collate these data in order to evaluate the impact of climate change on these toxin producers, as they affect human health. This MTSRF-funded project collected preliminary data on abundance patterns and community composition of epiphytic toxic dinoflagellates in coastal, inshore and mid-reefal habitats of the central Great Barrier Reef. Three sites in the Orpheus Island seasonal study (Lodestone Reef, Pioneer Bay and John Brewer Reef) were examined over three seasons. Preliminary results in November 2008 showed relatively high abundance of dinoflagellates, followed by a decrease in March 2009, with numbers increasing again in August 2009 at these sites. No clear patterns in community structure have yet emerged, although Prorocentrum spp dominated the community structure at all three sites in November 2008, and at all seasons at Lodestone Reef. Ostreopsis was the predominant genus at Pioneer Bay in March 2009, but by August Prorocentrum again dominated the toxic microalgal community there. Differences in community structure and species richness may be related to environmental conditions, as Pioneer Bay is tidal inshore, whilst Lodestone and John Brewer Reefs are submerged sites. During November 2008 inshore reefs appear to be dominated by Prorocentrum, whereas Ostreopsis prevailed at submerged reef sites. Sites at Magnetic Island showed the same pattern. Gambierdiscus spp were present, but not prevalent, at all sites in November with the highest number (14%) recorded at John Brewer Reef. These findings are being compiled into an Atlas of Marine Microalgae for the Great Barrier Reef, which also contains descriptions of 22 species of toxic dinoflagellate and 15 substrate macroalgal species.
Ciguatera fish poisoning on the Great Barrier Reef
Project Leader: Dr Kirsten Heimann, JCU
Exotic fish species have become increasingly established and dominant in north Queensland freshwater ecosystems in recent years. Research has shown that exotic species have become most abundant in degraded aquatic habitats, in which naturally low levels of dissolved oxygen (DO) have typically further declined. Earlier work funded through this MTSRF project (Webb 2008) showed that the greater tolerance of exotic fishes to water quality variables such as low DO and high temperature were major contributors to the invasion success of exotic species that had established breeding populations in north Queensland freshwaters. Researchers tested tolerance to low DO in a range of exotic species from those that have established in freshwaters of north Queensland, those that have been found in freshwaters in north Queensland (though not established) and those that are regularly sold in aquarium shops and may thus be released into the environment in the future. Species tested were from four fish families that are freshwater-derived taxa, that is, they have very long evolutionary histories in freshwater, where low DO is more prevalent, compared to most Australian native fish families, which mostly have relatively recent marine ancestry. Fish from the families tested in this study are also commonly used as aquarium fish (the main source of introduced fish species). As expected, it was found that the exotic fishes had significantly greater DO tolerances than most native fish species they would be likely to encounter in north Queensland’s aquatic ecosystems. In addition, we have identified several new species that threaten to invade north Queensland from Papua New Guinea, which are from the families Anabantidae (eg, climbing perch), Channidae (eg, snakeheads) and Osphronemidae (eg, gouramis), all of which are capable of breathing oxygen directly from the air and can stay out of water for considerable periods. Their pre-adaptation for tolerating very low DO confers a considerable risk for their establishment in north Queensland.
Part 1 of a joint progress report by James Cook University - June 2009.
Part 2 of a joint progress report by James Cook University - June 2009.
Project 2.6.1 JCU Heimann, K. et al. (2009) March Interim Report - Part 1 - Laboratory culture of marine microalgae of the Great Barrier Reef toxic dinoflagellate cultures established by the North Queensland Algal Identification/Culturing Facility (NQAIF)
Part 1 of a joint progress report by James Cook University - March 2009.
Project 2.6.1 JCU Blair, D. et al. (2009) March Interim Report - Part 2 - Review of genetic probe development for invasive marine species, with a focus on choice of target gene and on DNA amplification technology
Part 2 of a joint progress report by James Cook University - March 2009.
Literature Review by James Cook University researchers.
Literature Review by James Cook University researchers.