title: 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.
authors.affiliation: Department of Geography McGill University 805 Sherbrooke Street West Montréal QC H3A 0B9 Canada.
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Price
authors.affiliation: School of Earth and Ocean Sciences University of Victoria OEASB A405 PO Box 1700 STN CSC Victoria BC V8W 2Y2 Canada.
authors.forename: Vera
authors.initials: V
authors.lastname: Pospelova
authors.affiliation: Department of Biology University of Prince Edward Island Charlottetown PEI C1A 4P3 Canada.
authors.forename: Michael R S
authors.initials: MR
authors.lastname: Coffin
authors.affiliation: US Environmental Protection Agency Office of Research and Development Narragansett Rhode Island 02882 USA.
authors.forename: James S
authors.initials: JS
authors.lastname: Latimer
authors.affiliation: Department of Geography McGill University 805 Sherbrooke Street West Montréal QC H3A 0B9 Canada.
authors.forename: Gail L
authors.initials: GL
authors.lastname: Chmura
keywords: Coastal waters; Prince Edward Island; estuary type; northeast USA; palynology; phytoplankton; water quality