Dataset Information

Biogeography of dinoflagellate cysts in northwest Atlantic estuaries.

ABSTRACT: Few biogeographic studies of dinoflagellate cysts include the near-shore estuarine environment. We determine the effect of estuary type, biogeography, and water quality on the spatial distribution of organic-walled dinoflagellate cysts from the Northeast USA (Maine to Delaware) and Canada (Prince Edward Island). A total of 69 surface sediment samples were collected from 27 estuaries, from sites with surface salinities >20. Dinoflagellate cysts were examined microscopically and compared to environmental parameters using multivariate ordination techniques. The spatial distribution of cyst taxa reflects biogeographic provinces established by other marine organisms, with Cape Cod separating the northern Acadian Province from the southern Virginian Province. Species such as Lingulodinium machaerophorum and Polysphaeridinium zoharyi were found almost exclusively in the Virginian Province, while others such as Dubridinium spp. and Islandinium? cezare were more abundant in the Acadian Province. Tidal range, sea surface temperature (SST), and sea surface salinity (SSS) are statistically significant parameters influencing cyst assemblages. Samples from the same type of estuary cluster together in canonical correspondence analysis when the estuaries are within the same biogeographic province. The large geographic extent of this study, encompassing four main estuary types (riverine, lagoon, coastal embayment, and fjord), allowed us to determine that the type of estuary has an important influence on cyst assemblages. Due to greater seasonal variations in SSTs and SSSs in estuaries compared to the open ocean, cyst assemblages show distinct latitudinal trends. The estuarine context is important for understanding present-day species distribution, the factors controlling them, and to better predict how they may change in the future.

SUBMITTER: Price AM

PROVIDER: S-EPMC4983581 | biostudies-literature | 2016 Aug

REPOSITORIES: biostudies-literature

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Biogeography of dinoflagellate cysts in northwest Atlantic estuaries.

Price Andrea M AM Pospelova Vera V Coffin Michael R S MR Latimer James S JS Chmura Gail L GL

Ecology and evolution 20160719 16

Few biogeographic studies of dinoflagellate cysts include the near-shore estuarine environment. We determine the effect of estuary type, biogeography, and water quality on the spatial distribution of organic-walled dinoflagellate cysts from the Northeast USA (Maine to Delaware) and Canada (Prince Edward Island). A total of 69 surface sediment samples were collected from 27 estuaries, from sites with surface salinities >20. Dinoflagellate cysts were examined microscopically and compared to enviro ...[more]

PMID: 27547344

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Project description:BackgroundDinoflagellate cysts (i.e., dinocysts) are biologically and ecologically important as they can help dinoflagellate species survive harsh environments, facilitate their dispersal and serve as seeds for harmful algal blooms. In addition, dinocysts derived from some species can produce more toxins than vegetative forms, largely affecting species through their food webs and even human health. Consequently, accurate identification of dinocysts represents the first crucial step in many ecological studies. As dinocysts have limited or even no available taxonomic keys, molecular methods have become the first priority for dinocyst identification. However, molecular identification of dinocysts, particularly when using single cells, poses technical challenges. The most serious is the low success rate of PCR, especially for heterotrophic species.MethodsIn this study, we aim to improve the success rate of single dinocyst identification for the chosen dinocyst species (Gonyaulax spinifera, Polykrikos kofoidii, Lingulodinium polyedrum, Pyrophacus steinii, Protoperidinium leonis and Protoperidinium oblongum) distributed in the South China Sea. We worked on two major technical issues: cleaning possible PCR inhibitors attached on the cyst surface and designing new dinoflagellate-specific PCR primers to improve the success of PCR amplification.ResultsFor the cleaning of single dinocysts separated from marine sediments, we used ultrasonic wave-based cleaning and optimized cleaning parameters. Our results showed that the optimized ultrasonic wave-based cleaning method largely improved the identification success rate and accuracy of both molecular and morphological identifications. For the molecular identification with the newly designed dinoflagellate-specific primers (18S634F-18S634R), the success ratio was as high as 86.7% for single dinocysts across multiple taxa when using the optimized ultrasonic wave-based cleaning method, and much higher than that (16.7%) based on traditional micropipette-based cleaning.DiscussionThe technically simple but robust method improved on in this study is expected to serve as a powerful tool in deep understanding of population dynamics of dinocysts and the causes and consequences of potential negative effects caused by dinocysts.

Project description:Previous analyses have shown how diversity among unicellular cyanobacteria inhabiting island-like hot springs is structured relative to physical separation and physiochemical differences among springs, especially at local to regional scales. However, these studies have been limited by the low resolution provided by the molecular markers surveyed. We analyzed large datasets obtained by high-throughput sequencing of a segment of the photosynthesis gene psaA from samples collected in hot springs from geothermal basins in Yellowstone National Park, Montana, and Oregon, all known from previous studies to contain populations of A/B'-lineage Synechococcus. The fraction of identical sequences was greater among springs separated by <50 km than among springs separated by >50 km, and springs separated by >800 km shared sequence variants only rarely. Phylogenetic analyses provided evidence for endemic lineages that could be related to geographic isolation and/or geochemical differences on regional scales. Ecotype Simulation 2 was used to predict putative ecotypes (ecologically distinct populations), and their membership, and canonical correspondence analysis was used to examine the geographical and geochemical bases for variation in their distribution. Across the range of Oregon and Yellowstone, geographical separation explained the largest percentage of the differences in distribution of ecotypes (9.5% correlated to longitude; 9.4% to latitude), with geochemical differences explaining the largest percentage of the remaining differences in distribution (7.4-9.3% correlated to magnesium, sulfate, and sulfide). Among samples within the Greater Yellowstone Ecosystem, geochemical differences significantly explained the distribution of ecotypes (6.5-9.3% correlated to magnesium, boron, sulfate, silicon dioxide, chloride, and pH). Nevertheless, differences in the abundance and membership of ecotypes in Yellowstone springs with similar chemistry suggested that allopatry may be involved even at local scales. Synechococcus populations have diverged both by physical isolation and physiochemical differences, and populations on surprisingly local scales have been evolving independently.

Project description:While harmful algal blooms caused by the ichthyotoxic dinoflagellate, Cochlodinium (Margalefidinium) polykrikoides, are allelopathic and may have unique associations with bacteria, a comprehensive assessment of the planktonic communities associated with these blooms has been lacking. Here, we used high-throughput amplicon sequencing to assess size fractionated (0.2 and 5 ?m) bacterial (16S) and phytoplankton assemblages (18S) associated with blooms of C. polykrikoides during recurrent blooms in NY, USA. Over a three-year period, samples were collected inside ('patch') and outside ('non-patch') dense accumulations of C. polykrikoides to assess the microbiome associated with these blooms. Eukaryotic plankton communities of blooms had significantly lower diversity than non-bloom samples, and non-bloom samples hosted 30 eukaryotic operational taxonomic units (OTUs) not found within blooms, suggesting they may have been allelopathically excluded from blooms. Differential abundance analyses revealed that C. polykrikoides blooms were significantly enriched in dinoflagellates (p<0.001) and the experimental enrichment of C. polykrikoides led to a significant increase in the relative abundance of eight genera of dinoflagellates but a significant decline in other eukaryotic plankton. Amoebophrya co-dominated both within- and near- C. polykrikoides blooms and was more abundant in bloom patches. The core bacterial microbiome of the >0.2?m fraction of blooms was dominated by an uncultured bacterium from the SAR11 clade, while the >5?m size fraction was co-dominated by an uncultured bacterium from Rhodobacteraceae and Coraliomargarita. Two bacterial lineages within the >0.2?m fraction, as well as the Gammaproteobacterium, Halioglobus, from the >5?m fraction were unique to the microbiome of blooms, while there were 154 bacterial OTUs only found in non-bloom waters. Collectively, these findings reveal the unique composition and potential function of eukaryotic and prokaryotic communities associated with C. polykrikoides blooms.

Dataset Information

Biogeography of dinoflagellate cysts in northwest Atlantic estuaries.

Publications

Biogeography of dinoflagellate cysts in northwest Atlantic estuaries.

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