The Plankton of Narragansett Bay


Cover photo by Stephanie Anderson

Dr. Tatiana Rynearson


Phytoplankton Assistant
Stephanie Anderson



Narragansett Bay Rhode Island is a highly productive estuary located on the east coast of North America.  It is the site of two long-term monitoring studies, which provide an unprecedented opportunity to examine decade-scale changes in nutrient cycling, phytoplankton, zooplankton, and fish community dynamics.  Regarded as one of the world’s longest-running plankton time series, samples have been collected weekly since Professor T. Smayda launched the program in the 1950’s.  Data is available to the public beginning in 1999.  Samples are collected once per week -regardless of tidal stage- for temperature, salinity, turbidity, size-fractionated chlorophyll a and nutrients.  Microplankton community composition (size range >10μm, both species identification and abundance) is determined using a light microscope to quantify live samples.  The species list for the >10μm size fraction includes 246 different species or species complexes of protists.  Samples are also collected for the determination of copepod and ctenophore concentrations.

Weekly Sampling Procedure


Thalassiosira rotula by Stephanie Anderson

Weekly surface, bottom and net tow samples are collected from Station II in Narragansett Bay, RI (lat. 41 34.2N; long. 71 23.4W). Previously, equal volumes of surface and bottom water were combined for counting.  Currently, surface and bottom water are counted separately (count type indicated with data). Phytoplankton cells are enumerated under a compound microscope using a Sedgewick-Rafter counting chamber. Samples are counted live and unconcentrated. A 20μm net tow sample is also examined;  species observed in the net sample are recorded as present but not counted.  Species identifications are based on appearance in the Sedgewick-Rafter chamber and supplemented with permanent mounts examined with phase contrast and interference contrast optics. Samples are preserved in 1% Lugol's preservative. The accurate identification of very small and problematic species is not guaranteed.  Quality control of all counts in the database has been conducted on samples collected between
1999 and 2008 and includes analysis of changes in community composition (Windecker, 2010).                 

Cell count data spreadsheets are available (Microsoft Excel; units = cells per liter).   The available data start in January 1999.  See Historical Data (below) for earlier data.


Acartia tonsa & various phytoplankton by Anna Mosby and Caitlyn Lawrence

Weekly vertical net tows are taken from 5 m to surface with a ¼ m diameter, 64μm mesh net from the same station at which phytoplankton are collected. The volume filtered is 0.25 m3.  The sample is preserved immediately in a final concentration of 4% buffered formalin-seawater solution.  Zooplankton are identified and enumerated under a dissecting microscope from a subsample taken with a wide bore pipette calibrated in mls. The subsample volume is chosen to ensure counting of at least 200 organisms. Species identification is made for all copepodite stages of copepods. Copepod nauplii are lumped.  Other taxa are identified to species when known, or if not (as for benthic larvae) to order.  Gelatinous species are collected with a separate vertical tow taken with a ½ m diameter 1 mm mesh net with a flowmeter. Sample volume is 1.1 m3. This sample is returned to the laboratory and live organisms are counted immediately to ensure that ctenophores, which do not withstand preservation, can be accurately enumerated. Diameter of medusae and ctenophores are measured and all are identified to species. Drained volume of the sample is recorded. Sampling began in 1999 but samples were stored and only those from October 2001 to the present have been counted with funding from the National Science Foundation and the Vetleson Foundation Grants to Barbara K. Sullivan.

Zooplankton and data gelatinous zooplankton spreadsheets are available for download (Microsoft Excel).  The available data start in October 2001.

Environmental Data

Lachat Nutrient Analyzer

 Environmental parameters measured include secchi-disk depth, temperature, salinity and nutrient concentrations.  Physical data spreadsheets (including secchi-disk depth, temperature and salinity) are available for download (Microsoft Excel).  The available data begin in 1999.  Water column profiles of temperature, salinity, depth, pH, dissolved oxygen and chlorophyll fluorescence are also recorded.  Please e-mail if you are interested in obtaining water column profile data.  Nutrient concentrations are measured in surface and bottom samples.  Samples are collected, kept on ice and filtered within a few hours of collection.  Filtering is done with an acid washed filtration manifold (60 ml syringe and Millipore filtering tips) using 0.45 mm cellulose filtering membranes. Filtrate is placed in 60 ml polyethelene bottles and frozen at -20ºC until analysis.  For further information on nutrient analysis please see our methods summary.          

Nutrient data spreadsheets are available for download (Microsoft Excel).  The available data begin in 2003.

Nutrient analysis was conducted through support from RI Sea Grant from 2003-2009.


Chaetoceros curvisetus by Stephanie Anderson


The Narragansett Bay time series is an active participant in the following plankton and time series working groups:

  • The IOC-UNESCO International Group for Marine Ecological Time Series (IGMETS)
  • The IOC-UNESCO working group to investigate Climate Change and Global Trends of Phytoplankton in the Ocean (TrendsPO)
  • The ICES Working Group on Phytoplankton and Microbial Ecology (WGPME)
  • SCOR WG137:  Global Patterns of Phytoplankton Dynamics in Coastal Ecosystems (WG137)

An interactive graphical summary of our time series is also available online here. 


Zooplankton material is based upon work supported by the National Science Foundation under Grant No. 0115177. Any opinions, findings, and conclusions or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

For more information on gelatinous zooplankton data,
contact Dr. Barbara Sullivan-Watts.

Environmental Data

Historical Data

Biological and physical data collected by Professor T. Smayda and his lab from the 1959 – 1997 time period has now been made available. These data are also housed here. Please check there for recent updates to this dataset.

Nutrient data spreadsheets are available for download (Microsoft Excel). The available data begin in 1959 and span several years.

Physical data as well as chlorophyll and zooplankton spreadsheets are available for download (Microsoft Excel). The available temperature data span from 1959 through 1997.

As a courtesy to fellow scientists, please e-mail Tatiana Rynearson to indicate how you are using this data so that efforts are not duplicated.  Comments and suggestions as to the website and its data are also welcome.

Additional Resources:

Narragansett Bay Benthic Survey
The Coastal Institute
EPA's Narragansett Bay site
National Estuarine Reserve
Save the Bay
Narragansett Bay Estuary Program

 Previous Students

Sarah Flickinger: September 2013-August 2015
Samantha DeCuollo: January 2013 - August 2013
Kathryn McCuster: September 2011 - December 2012
Caitlyn Lawrence: August 2009 - August 2011
Matt Horn: May 2007 - August 2007
Laura Windecker: August 2006 - May 2007; August 2008 - August 2009
Haley Brew: August 2005 - August 2006
Kelly Henry:  May 2005 - August 2005
Jason Graff: September 2003 - May 2005; May 2007 - August 2008
Angela Allen: May 2003 - Sept. 2003
Kris Joppe-Mercure: September 2001 - May 2003
Malcolm McFarland: September 1999 - August 2001
Andrew Staroscik:  January 1999 - August 1999

  • Beaulieu, W.T., Costello, J.H., Klein-Macphee, G. & Sullivan, B.K., 2013. Seasonality of the ctenophore Mnemiopsis leidyi in Narragansett Bay, Rhode Island. Journal of Plankton Research doi: 10.1093/plankt/fbt041.
  • Borkman, D.G., Smayda, T., 2009. Multidecadal (1959-1997) changes in Skeletonema abundance and seasonal bloom patterns in Narragansett Bay, Rhode Island, USA. Journal of Sea Research 61 (1-2), 84-94.
  • Canesi K, Rynearson TA (2016) Temporal variation of Skeletonema community composition from a long-term time series in Narragansett Bay identified using high-throughput sequencing. Mar Ecol Prog Ser 556:1-16
  • Costello, J.H., Sullivan, B.K., Gifford, D.J., 2006. A physical-biological interaction underlying variable phenological responses to climate change by coastal zooplankton. J. Plankton Res. 28 (11), 1099-1105.
  • Graff, J.R. & Rynearson, T.A. 2011. Extraction method influences the recovery of phytoplankton pigments from natural assemblages. Limnology & Oceanography: Methods 9: pp. 129-139.
  • Hargraves, P.E. 1988. Phytoplankton of Narragansett Bay. pp. 136-143, In: Freshwater and Marine Plants of Rhode Island. R.G. Sheath & M.M. Harlin (eds.). Kendall-Hunt Publ. Co., Dubuque, Iowa. 149 pp. 
  • Karentz, D. & T.J. Smayda. 1984. Temperature and seasonal occurence patterns of 30 dominant phytoplankton species in Narragansett Bay over a 22-year period (1959-1980). Marine Ecology Progress Series 18: 277-293.
  • Karentz, D., Smayda, T.J., 1998. Temporal patterns and variations in phytoplankton community organization and abundance in Narragansett Bay during 1959-1980. J. Plankton Res. 20 (1), 145-168. 
  • Lawrence, C.M., Menden-Deuer, S., 2012. Drivers of protistan grazing pressure: seasonal signals of plankton community composition and environmental conditions. Marine Ecology Progress Series 459 (39-52).
  • Li, Y., Smayda, T.J., 1998. Temporal variability of chlorophyll in Narragansett Bay, 1973‚Äì1990. ICES Journal of Marine Science: Journal du Conseil 55 (4), 661-667.
  • Li, Y., Smayda, T.J., 2001. A Chlorophyll Time Series for Narragansett Bay: Assessment of the Potential Effect of Tidal Phase on Measurement. Estuaries 24 (3), 328-336.
  • Pratt, D.M. 1959. The Phytoplankton of Narragansett Bay. Limnology & Oceanography 4: 425-440. 
  • Smayda, T.J. 1998. Patterns of variability characterizing marine phytoplankton with examples from Narragansett Bay. ICES Journal of Marine Science 55: 562-573.
  • Smayda, T.J. & Borkman, D. 2004. Ecological effects of climate variation in the North Atlantic: Phytoplankton. In: Stenseth, N.C. [Ed.] Marine Ecosystems and Climate Variation -- the North Atlantic. Oxford University Press.
  • Smayda, T.J. & Borkman, D.G. 2008. Nutrient and Plankton Dynamics in Narragansett Bay. In: Desbonnet, A., B.A. Costa-Pierce [Ed.] Science for Ecosystem-based Management. Springer, New York, pp. 431-484.
  • Windecker, L.A. 2010. Ten Years of Phytoplankton Species Abundance Patterns in mid-Narragansett Bay, Rhode Island:1999-2008. Available from Pell Library or in the PDF from the author).