We analyzed surface sediments from 23 northeast USA estuaries, from Maine to Delaware, and nine estuaries from Prince Edward Island (PEI, Canada), to determine how dinoflagellate cyst assemblages varied with nutrient loading. Overall the abundance of cysts of heterotrophic dinoflagellates correlates with modeled nitrogen loading, but there were also regional signals. On PEI cysts of Gymnodinium microreticulatum characterized estuaries with high nitrogen loading while the sediments of eutrophic Boston Harbor were characterized by high abundances of Spiniferites spp. In Delaware Bay and the Delaware Inland Bays Polysphaeridium zoharyi correlated with higher temperatures and nutrient loading. This is the first study to document the dinoflagellate cyst eutrophication signal at such a large geographic scale in estuaries, thus confirming their value as indicators of water quality change and anthropogenic impact.
Bibliographical noteFunding Information:
The Natural Sciences and Engineering Research Council of Canada (NSERC), the Canadian Association of Palynology (CAP) and the Geological Society of America (GSA) provided partial funding for this research through student research awards to AMP. This research was partially supported by NSERC Discovery grants to VP and GLC. MRSC was partially funded by an NSERC CREATE (Collaborative Research and Training Experience) grant to the Canadian Rivers Institute WATER (Watershed and Aquatics Training in Environmental Research) program and the Canadian Watershed Research Consortium . We thank Cindy Crane and the PEI Department of Communities, Land and Environment for providing nitrogen loads for PEI estuaries. We would also like to thank all those who provided information or water quality data from estuaries in this study: Alison Branco (Peconic Estuary Program, SCDHS South Shore Bays Water Quality), Barbara Warren (Salem Sound Coastwatch), Brad Hubeny (Salem State University – Geological Sciences), Ron Huber (Friends of Penobscot Bay), Christopher Deacutis (RIDEM Div. of Fish and Wildlife, Narragansett Bay Water Quality Monitoring Network), Jane Disney (Frenchman Bay Partners), Kevin Brinson (Delaware Environmental Observing System), Peter Milholland (Friends of Casco Bay Citizen Stewards Water Quality Monitoring Program), Tony Williams (Buzzards Bay Coalition), Bebe Moulton (Friends of Blue Hill Bay), Mark Tedesco (EPA), William Hastback (NYSDEC – Bureau of Marine Resources), Matthew Sclafani (Cornell University), Pierce Rafferty (Henry L. Ferguson Museum), Warren Prell (Brown University). Chris Pickerell (Marine Program Director, Cornell), Jaime Vaudrey (University of Connecticut), Provincetown Center for Coastal Studies, Blue Hill Bay Coastal Monitoring Program - Marine Environmental Research Institute, and the many citizen scientists that are part of these organizations who volunteer their time to collect water quality measurements. The US grain size data used article were produced by the U.S. Environmental Protection Agency (EPA) through its Environmental Monitoring and Assessment Program (EMAP). The US samples were made available through the EPA's National Coastal Assessment program. We thank Jingyi Zhang and Artur Plis (McGill University) for assistance in biogenic silica sample preparation, Maureen Soon (University of British Columbia) for the biogenic silica analysis, and Lee van Ardenne (McGill University) for assistance with regression analyses.
- Environmental indicators
- Nutrient loading
- Prince Edward Island
- Water quality