title: Diversity and toxicity of the diatomPseudo-nitzschiaPeragallo in the Gulf of Maine, Northwestern Atlantic Ocean.
abstract: Multiple species in the toxic marine diatom genusPseudo-nitzschiahave been identified in the Northwestern Atlantic region encompassing the Gulf of Maine (GOM), including the Bay of Fundy (BOF). To gain further knowledge of the taxonomic composition and toxicity of species in this region,Pseudo-nitzschiaisolates (n=146) were isolated from samples collected during research cruises that provided broad spatial coverage across the GOM and the southern New England shelf, herein referred to as the GOM region, during 2007-2008. Isolates, and cells in field material collected at 38 stations, were identified using electron microscopy (EM). Eight species (P. americana, P. fraudulenta, P. subpacifica, P. heimii, P. pungens, P. seriata, P. delicatissimaandP. turgidula), and a novel form,Pseudo-nitzschiasp. GOM, were identified. Species identity was confirmed by sequencing the large subunit of the ribosomal rDNA (28S) and the internal transcribed spacer 2 (ITS2) for six species (36 isolates). Phylogenetic analyses (including neighbor joining, maximum parsimony, and maximum likelihood estimates and ITS2 secondary structure analysis) and morphometric data supported the placement ofP. sp. GOM in a novel clade that includes morphologically and genetically similar isolates from Australia and Spain and is genetically most similar toP. pseudodelicatissimaandP. cuspidata. Seven species (46 isolates) were grown in nutrient-replete batch culture and aliquots consisting of cells and growth medium were screened by Biosense ASP ELISA to measure total domoic acid (DA) produced (intracellular + extracellular);P. americanaandP. heimiiwere excluded from all toxin analyses as they did not persist in culture long enough for testing. All 46 isolates screened produced DA in culture and total DA varied among species (e.g., 0.04 to 320 ng ml-1forP. pungensandP. sp. GOM isolates, respectively) and among isolates of the same species (e.g., 0.24 - 320 ng ml-1forP. sp. GOM). The 15 most toxic isolates corresponded toP. seriata, P. sp. GOM andP. pungens, and fg DA cell-1was determined for whole cultures (cells and medium) using ELISA and liquid chromatography (LC) with fluorescence detection (FLD); for seven isolates, toxin levels were also estimated using LC - with mass spectrometry and ultraviolet absorbance detection.Pseudo-nitzschia seriatawas the most toxic species (up to 3,500 fg cell-1) and was observed in the GOM region during all cruises (i.e., during the months of April, May, June and October).Pseudo-nitzschiasp. GOM, observed only during September and October 2007, was less toxic (19 - 380 fg cell-1) thanP. seriatabut more toxic thanP. pungensvar.pungens(0. 4 fg cell-1). Quantitation of DA indicated that concentrations measured by LC and ELISA were positively and significantly correlated; the lower detection limit of the ELISA permitted quantification of toxicity in isolates that were found to be nontoxic with LC methods. The confirmation of at least seven toxic species and the broad spatial and temporal distribution of toxicPseudo-nitzschiaspp. have significant implications for the regional management of nearshore and offshore shellfisheries resources.
authors.affiliation: Universidade Federal do Paraná, Centro Politécnico, Department of Botany, Curitiba, Paraná, CEP 81531-990, Brazil.
authors.forename: Luciano F
authors.initials: LF
authors.lastname: Fernandes
authors.affiliation: Woods Hole Oceanographic Institution, Department of Biology, MS-32, Woods Hole, MA 02536, USA ; Fish and Wildlife Research Institute, Florida Fish and Wildlife Conservation Commission, 100 8 Ave SE, St. Petersburg, FL, 33701, USA.
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Hubbard
authors.affiliation: Woods Hole Oceanographic Institution, Department of Biology, MS-32, Woods Hole, MA 02536, USA.
authors.forename: Mindy L
authors.initials: ML
authors.lastname: Richlen
authors.affiliation: Woods Hole Oceanographic Institution, Department of Biology, MS-32, Woods Hole, MA 02536, USA.
authors.forename: Juliette
authors.initials: J
authors.lastname: Smith
authors.affiliation: Fisheries and Oceans Canada, Gulf Fisheries Centre, 343 av. Université, Moncton, NB, E1C 9B6, Canada.
authors.forename: Stephen S
authors.initials: SS
authors.lastname: Bates
authors.affiliation: Digital Microscopy Facility, Mount Allison University, Sackville, NB, E4L 1G7, Canada.
authors.forename: James
authors.initials: J
authors.lastname: Ehrman
authors.affiliation: Fisheries and Oceans Canada, Gulf Fisheries Centre, 343 av. Université, Moncton, NB, E1C 9B6, Canada.
authors.forename: Claude
authors.initials: C
authors.lastname: Léger
authors.affiliation: Universidade Federal do Paraná, Center for Marine Studies, Pontal do Paraná, PR, 83255-976, Brazil.
authors.forename: Luiz L
authors.initials: LL
authors.lastname: Mafra
authors.affiliation: Woods Hole Oceanographic Institution, Department of Biology, MS-32, Woods Hole, MA 02536, USA.
authors.forename: David
authors.initials: D
authors.lastname: Kulis
authors.affiliation: National Research Council of Canada, Biotoxin Metrology, Measurement Science and Standards, 1411 Oxford Street, Halifax, Nova Scotia B3H 3Z1, Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: Quilliam
authors.affiliation: Woods Hole Oceanographic Institution, Department of Biology, MS-32, Woods Hole, MA 02536, USA.
authors.forename: Katie
authors.initials: K
authors.lastname: Libera
authors.affiliation: Woods Hole Oceanographic Institution, Department of Biology, MS-32, Woods Hole, MA 02536, USA.
authors.forename: Linda
authors.initials: L
authors.lastname: McCauley
authors.affiliation: Woods Hole Oceanographic Institution, Department of Biology, MS-32, Woods Hole, MA 02536, USA.
authors.forename: Donald M
authors.initials: DM
authors.lastname: Anderson
keywords: Amnesic Shellfish Poisoning; Bay of Fundy; Georges Bank; Gulf of Maine; Pseudo-nitzschia; domoic acid; harmful algal blooms; species diversity