title: Alexandrium fundyensecysts in the Gulf of Maine: long-term time series of abundance and distribution, and linkages to past and future blooms.
abstract: Here we documentAlexandrium fundyensecyst abundance and distribution patterns over nine years (1997 and 2004-2011) in the coastal waters of the Gulf of Maine (GOM) and identify linkages between those patterns and several metrics of the severity or magnitude of blooms occurring before and after each autumn cyst survey. We also explore the relative utility of two measures of cyst abundance and demonstrate that GOM cyst counts can be normalized to sediment volume, revealing meaningful patterns equivalent to those determined with dry weight normalization. Cyst concentrations were highly variable spatially. Two distinct seedbeds (defined here as accumulation zones with > 300 cysts cm-3) are evident, one in the Bay of Fundy (BOF) and one in mid-coast Maine. Overall, seedbed locations remained relatively constant through time, but their area varied 3-4 fold, and total cyst abundance more than 10 fold among years. A major expansion of the mid-coast Maine seedbed occurred in 2009 following an unusually intenseA. fundyensebloom with visible red-water conditions, but that feature disappeared by late 2010. The regional system thus has only two seedbeds with the bathymetry, sediment characteristics, currents, biology, and environmental conditions necessary to persist for decades or longer. Strong positive correlations were confirmed between the abundance of cysts in both the 0-1 and the 0-3 cm layers of sediments in autumn and geographic measures of the extent of the bloom that occurred the next year (i.e.,cysts→blooms), such as the length of coastline closed due to shellfish toxicity or the southernmost latitude of shellfish closures. In general, these metrics of bloom geographic extent did not correlate with the number of cysts in sediments following the blooms (blooms→cysts). There are, however, significant positive correlations between 0-3 cm cyst abundances and metrics of the preceding bloom that are indicative of bloom intensity or vegetative cell abundance (e.g., cumulative shellfish toxicity, duration of detectable toxicity in shellfish, and bloom termination date). These data suggest that it may be possible to use cyst abundance to empirically forecast the geographic extent of the forthcoming bloom and, conversely, to use other metrics from bloom and toxicity events to forecast the size of the subsequent cyst population as the inoculum for the next year's bloom. This is an important step towards understanding the excystment/encystment cycle inA. fundyensebloom dynamics while also augmenting our predictive capability for this HAB-forming species in the GOM.
authors.affiliation: Woods Hole Oceanographic Institution, Woods Hole, MA 02543 USA.
authors.forename: Donald M
authors.initials: DM
authors.lastname: Anderson
authors.affiliation: Woods Hole Oceanographic Institution, Woods Hole, MA 02543 USA.
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Keafer
authors.affiliation: Woods Hole Oceanographic Institution, Woods Hole, MA 02543 USA.
authors.forename: Judith L
authors.initials: JL
authors.lastname: Kleindinst
authors.affiliation: Woods Hole Oceanographic Institution, Woods Hole, MA 02543 USA.
authors.forename: Dennis J
authors.initials: DJ
authors.lastname: McGillicuddy
authors.affiliation: Fisheries and Oceans Canada, Biological Station, St. Andrews, NB E5B 2L9, Canada.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Martin
authors.affiliation: Woods Hole Oceanographic Institution, Woods Hole, MA 02543 USA.
authors.forename: Kerry
authors.initials: K
authors.lastname: Norton
authors.affiliation: School for Marine Science and Technology, Univ. of Massachusetts Dartmouth, New Bedford, MA 02744 USA.
authors.forename: Cynthia H
authors.initials: CH
authors.lastname: Pilskaln
authors.affiliation: Woods Hole Oceanographic Institution, Woods Hole, MA 02543 USA.
authors.forename: Juliette L
authors.initials: JL
authors.lastname: Smith
authors.affiliation: US Geological Survey, Woods Hole, MA 02543 USA.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Sherwood
authors.affiliation: US Geological Survey, Woods Hole, MA 02543 USA.
authors.forename: Bradford
authors.initials: B
authors.lastname: Butman
keywords: Alexandrium fundyense; Gulf of Maine, harmful algal bloom; HAB; cysts, resuspension; paralytic shellfish poisoning; red tide