Changes in cyanoprokaryote populations, Microcystis morphology, and microcystin concentrations in Lake Elphinstone (Central Queensland, Australia)

Abstract

Lake Elphinstone is a tropical inland water body in the far north of the Fitzroy Catchment in Central Queensland, Australia, and has experienced recurrent toxic cyanoprokaryote blooms since 1997. This article reports on an examination of the environmental conditions of the lake and the concurrent cyanoprokaryote species together with their toxicity. The lake was sampled three times during periods of high cyanoprokaryote cell concentrations. Successive changes in the dominant Microcystis species were accompanied by variation in the concentration of the hepatotoxin microcystin. Environmental parameters recorded during dominance by both the highly toxic species Microcystis panniformis and the nontoxic M. botrys are provided. Nutrient status, temperature, and light conditions were associated with species change within the blooms. Variation of microcystin concentrations coincided with speciation change (i.e., morphological variation) within the blooms. Also discussed is the environmental impact of toxin production by M. panniformis with respect to influence on cell division, energy states, and toxin photodegradation. Lake Elphinstone is the first Australian location reported to have M. panniformis.

Tropical cyanobacterial blooms: a review of prevalence, problem taxa, toxins and influencing environmental factors

“…Studies that did not document the maximum temperatures for individual water bodies were excluded and thus, there is a certain bias in the results that could have led to this insignificant effect of temperature. However, temperature ranges in the tropics are within 1-8°C for each water body Wang et al, 2002;White et al, 2003;Kotut et al, 2010) and this small increase in temperature, which was within the optimum temperature range of Microcystis toxin production (25-30°C, Van der Westhuizen and Eloff, 1985;Kim et al, 2005), may not significantly affect toxicity.…”

“…1). Blooms in Australian water bodies were tested using mouse bioassays in the 1990s, and later by HPLC for more detailed toxin results (Saker and Griffiths, 2001;Griffiths and Saker, 2003;White et al, 2003;Bor- (Mizuno and Mori, 1970;Lewis 1973Lewis , 1978Green et al, 2004). In the case of tropical Africa, many of the blooms were detected in reservoirs and lakes used for drinking water, highlighting a need for toxicity testing in these countries (Akin-Oriola et al, 2006 o n l y McGregor and Fabbro, 2000;Saker and Griffiths, 2001; o n l y Saker and Griffiths, 2001;Griffiths and Saker, 2003; o n l y .…”

“…There was only one notable Microcystis bloom in trop- ical Australia, recorded from Lake Elphinstone, caused by Microcystis panniformis, with a very high microcystin level of 2500 μg L -1 (White et al, 2003). It is notable that M. panniformis was not found to produce high levels of toxins in tropical Asia (Tab.…”

Impacts of a Toxic Microcystis Bloom on the Macroinvertebrate Fauna of Lake Elphinstone, Central Queensland, Australia

“…Field trips were conducted on 20-22 March, 13-14 May and 22-23 July 2002, to coincide with the expected peak cyanoprokaryote bloom season. Methods relating to the collection and analysis of phytoplankton samples and their toxicity can be found in White et al, 2003. For macroinvertebrate sampling, the lake was divided into 10 areas and six were randomly chosen as sampling sites (Fig. 1b).…”

“…A dense cyanoprokaryote bloom was recorded during March, with peak concentrations following in May, before collapse occurred prior to sampling in July (White et al 2003). Toxin concentrations were variable throughout sampling.…”