Recent invader or indicator of environmental change? A phylogenetic and ecological study of Cylindrospermopsis raciborskii in New Zealand |
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| Institution: | 1. Freshwater and Coastal Group, Cawthron Institute, Nelson, New Zealand;2. School of Biological Sciences, University of Waikato, Hamilton, New Zealand;3. Environment Waikato, Hamilton, New Zealand;1. IASMA Research and Innovation Centre, Istituto Agrario di S. Michele all’Adige – Fondazione E. Mach, Via E. Mach 1, 38010 S. Michele all’Adige (Trento), Italy;2. Department of Biology, University of Florence, Via La Pira 4, 50121 Florence, Italy;1. School of Biological Science, Monash University, Clayton 3800, Victoria, Australia;2. CSIRO Marine and Atmospheric Research, Hobart, Tasmania, Australia;3. Seqwater, PO Box 16146, City East 4002, Queensland, Australia;1. Departamento de Microbiología, Instituto de Investigaciones Biológicas Clemente Estable, Uruguay;2. Sección Limnología, Instituto de Ecología y Ciencias Ambientales, Facultad de Ciencias, UDELAR, Uruguay;3. Grupo de Ecología y Fisiología de Fitoplancton, CSIC, Uruguay;1. Australian Rivers Institute, Griffith University, Nathan, 4111 Queensland, Australia;2. Department of Earth and Environmental Sciences, and the Lamont-Doherty Earth Observatory, Columbia University, Palisades NY, 10964, USA;1. Queensland Department of Health, Forensic and Scientific Services, 39 Kessels Road, Coopers Plains, Qld 4108, Australia;2. Queensland Department of Environment and Science, GPO Box 5078 Brisbane Qld 4001, Australia |
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| Abstract: | Cylindrospermopsis raciborskii is a diazotrophic and potentially toxic cyanobacterium that was initially thought to be confined to tropical freshwaters. Recently it appears to have expanded its range to more temperate regions of the globe. There are contrasting hypotheses to explain this spread including; dispersal of highly adapted strains or localised spread from warm refuges as climatic or environmental conditions change. C. raciborskii was first detected in the isolated island nation of New Zealand in 2003, providing a unique opportunity to explore whether this recent identification is due to a new incursion or resultant from climatic or environmental change. Phylogenetic analysis (nifH, ITS1-L, ITS1-S, and rpoC1) of six strains isolated from two New Zealand lakes showed they were most closely related to those from South America, and suggest that the recent detection of this species was not due to a new incursion. Ten years of environmental data from three lakes (Waaki, Waikare and Whangape) experiencing blooms were analysed to identify potential reasons for recent C. raciborskii blooms. This analysis showed that the relatively recent (within the last 20–30 years) collapses of extensive macrophyte stands in lakes Waaki, Waikare and Whangape have resulted in increased turbidity’, low water column dissolved reactive phosphorus and seasonal shifts in the dissolved inorganic nitrogen availability, all conditions known to facilitate C. raciborskii dominance. Collectively these data indicate that C. raciborskii has always been present in New Zealand, and that recent changes in environmental conditions in these lakes are now facilitating bloom events. |
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| Keywords: | Cylindrospermin Phylogenetics 16S rRNA ITS |
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