title: Trophic state and geographic gradients influence planktonic cyanobacterial diversity and distribution in New Zealand lakes.
abstract: Cyanobacteria are commonly associated with eutrophic lakes, where they often form blooms and produce toxins. However, they are a ubiquitous component of phytoplankton in lakes of widely varying trophic status. We hypothesised that cyanobacterial diversity would vary among lakes of differing trophic status, but that the relative importance of geographical and hydromorphological characteristics driving these patterns would differ across trophic groups. DNA from 143 New Zealand lakes that spanned a range of geographic, hydromorphological and trophic gradients was analysed using automated rRNA intergenic spacer analysis and screened for genes involved in cyanotoxin production. Statistical analysis revealed significant delineation among cyanobacterial communities from different trophic classes. Multivariate regression indicated that geographical features (latitude, longitude and altitude) were significant in driving cyanobacterial community structure; however, partitioning of their effects varied among trophic categories. High-throughput sequencing was undertaken on selected samples to investigate their taxonomic composition. The most abundant and diverse (71 operational taxonomic units) taxon across all lake types was the picocyanobacteria genus Synechococcus Cyanotoxins (microcystins n = 23, anatoxins n = 1) were only detected in eutrophic lowland lakes. Collectively, these data infer that increasing eutrophication of lakes will have broad-scale impacts on planktonic cyanobacteria diversity and the prevalence of cyanotoxins.
authors.affiliation: Cawthron Institute, Nelson 7010, New Zealand susie.wood@cawthron.org.nz.|Environmental Research Institute, University of Waikato, Hamilton 3240, New Zealand.
authors.forename: Susanna A
authors.initials: SA
authors.lastname: Wood
authors.affiliation: Cawthron Institute, Nelson 7010, New Zealand.|Faculty of Biology, University of Konstanz, Konstanz, D-78457, Germany.
authors.forename: Marcia Y
authors.initials: MY
authors.lastname: Maier
authors.affiliation: Cawthron Institute, Nelson 7010, New Zealand.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Puddick
authors.affiliation: Cawthron Institute, Nelson 7010, New Zealand.|Institute of Marine Science, University of Auckland, Auckland 1142, New Zealand.
authors.forename: Xavier
authors.initials: X
authors.lastname: Pochon
authors.affiliation: Cawthron Institute, Nelson 7010, New Zealand.|Marine Science and Technology Center, Klaipeda University, Klaipeda LT-92294, Lithuania.
authors.forename: Anastasija
authors.initials: A
authors.lastname: Zaiko
authors.affiliation: Faculty of Biology, University of Konstanz, Konstanz, D-78457, Germany.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Dietrich
authors.affiliation: Environmental Research Institute, University of Waikato, Hamilton 3240, New Zealand.
authors.forename: David P
authors.initials: DP
authors.lastname: Hamilton
mesh_terms: D000458:Cyanobacteria / Q000145:classification / Q000235:genetics / Q000254:growth & development*; D004784:Environmental Monitoring; D005068:Eutrophication; D020387:Food Chain; D014644:Genetic Variation; D060106:Lakes / Q000382:microbiology*; D052998:Microcystins; D009520:New Zealand; D010839:Phytoplankton / Q000145:classification; D010933:Plankton / Q000145:classification / Q000235:genetics / Q000254:growth & development*; D014871:Water Microbiology
chemical_list: D052998:Microcystins; C078588:microcystin
keywords: altitude; anatoxin; biodiversity gradient; cyanotoxins; high-throughput sequencing; latitude; liquid chromatography-mass spectrometry; longitude; microcystin; operational taxonomic unit; saxitoxin