ECOHAB 1997: Project Summaries

Anderson, D.M. (WHOI), D.T. Townsend (U. ME), J.H. Churchill (WHOI), J.J. Cullen (Dalhousie Univ.), G.J. Doucette (NOAA), W.R. Geyer (WHOI), M.D. Keller (Bigelow), T.C. Loder (UNH), D.R. Lynch (Dartmouth), J.L. Martin (DFO Canada), D.J. McGuillicuddy (WHOI), J.E. O’Reilly (NOAA), N.R. Pettigrew (U. ME), R.P. Signell (USGS), A.C. Thomas (U. ME), and J.T. Turner (U. MA, Dartmouth).  8/1/97-3/31/98, NOAA Sea Grant Award NA46RG0470 (first 18 months of 4.5 year award); 6/1/98-5/31/99, NSF Award OCE-9808173.

The overall objective of the ECOHAB-Gulf of Maine project is to understand and model the dynamics of the toxic dinoflagellate Alexandrium in the Gulf of Maine by investigating the physical, biological, chemical, and behavioral mechanisms underlying population abundance and distribution in several key habitats or regimes and by characterizing the transport pathways that link them. Field studies include both moored and shipboard hydrographic observations, nutrient conditions, and population distributions (including benthic resting cysts) within the Casco Bay region, the Eastern Maine Coastal Current, and the southern Bay of Fundy. The Casco Bay region including the Kennebec River plume is an area where initiation of blooms is likely to occur. Inoculation of Alexandrium cells into the plume waters that form the Western Maine Coastal Current explain the southerly transport of vegetative populations along the coasts of southern Maine, New Hampshire, and Massachusetts, but the mechanisms of bloom initiation are not understood. Larger scale offshore surveys extending along the Maine coast from Casco Bay to the Bay of Fundy will determine the coupling of the physics with the Alexandrium biology of the northern Gulf of Maine-Bay of Fundy region and linkages, if any, to southern Gulf of Maine populations initiated near Casco Bay. Field studies will also determine offshore cyst distributions along the Maine coast as well as distributions within several important inshore embayments (e.g., Casco Bay). Field and laboratory excystment experiments will determine the requirements leading to bloom initiation and coupled with the hydrographic data will identify the physical features governing delivery of the inoculum to areas favorable for growth. Laboratory mesocosm studies will also be conducted to determine diel population responses to light and nutrients, critical to resolving nutrition and substrate supply for advected populations. All data will be merged into a physical-biological coupled model for the western Gulf of Maine toward generating a forecasting tool for better understanding of the seasonal population dynamics and the mechanisms for delivery of toxic cells to shellfish within the region.

Lead PI: D.M. Anderson, Biology Department, WHOI, Woods Hole, MA, 02543; danderson@whoi.edu; 508-289-2351

Doucette,G.J. (Medical University of. SC). 9/1/97-8/31/00, Second year of 3 year award. NSF Award OCE-9726260.

The focus of this project is to investigate the possible role of algicidal bacteria in promoting the decline and dissipation of Gymnodinium breve red tides along the Florida Gulf coast. Blooms of G. breve are especially problematic along the Florida coast, where costs associated with these annual events are estimated at about $20 million per episode. As a result, there is a growing interest in exploring strategies for the management, mitigation, and/or control of G. breve blooms, which will rely, in part, on acquiring knowledge of natural mechanisms involved in regulating population growth of this dinoflagellate. Several reports of algicidal bacteria occurring in high concentrations at the onset of bloom termination suggest that such microbes may directly or indirectly lead to the decline of these events, yet the issue of bacterial involvement in terminating harmful algal blooms has not been addressed in U.S. coastal waters. Our approach is to test the hypothesis that algicidal bacteria specific for G. breve are present in microbial assemblages indigenous to the Florida Gulf coast. This effort will involve attempts to isolate bacterial strains from both bloom and non-bloom waters, and screen for their ability to inhibit or preclude the growth of G. breve laboratory cultures. Bacterial isolates showing algicidal activity against G. breve will then be classified using both classical and molecular techniques, the latter yielding 16S rRNA sequence data needed to design strain-specific oligonucleotide probes. Molecular probes will provide a means to track the population dynamics of these bacteria in controlled (e.g., mesocosms) as well as natural systems, thereby helping to assess their involvement in promoting bloom decline. Concurrent laboratory studies will define the algicidal target specificity among phytoplankton taxa closely- and more distantly-related to G. breve, evaluate the conditions promoting algicidal activity of the bacteria, and begin to characterize the algicidal agent and its mechanism of action. The knowledge gained from this study represents an essential first step in evaluating the potential use of algicidal bacteria as a means of controlling or regulating blooms of G. breve.

Lead PI: G.J. Doucette, Marine Biomedical & Environmental Sciences, Medical University of South Carolina, Charleston, SC 29412; greg.doucette@noaa.gov; 843-762-8528.

Durbin, E.G. (GSO-URI), R.G. Campbell (GSO-URI), and A.D. Cembella (NRC-Canada). 09/15/97 — 08/31/00, NSF Award OCE 9726261.

Toxic Alexandrium spp. dinoflagellates cause paralytic shellfish poison (PSP) outbreaks in the Gulf of Maine each year, posing a public health threat and resulting in economic loss. The population dynamics of Alexandrium spp. are at present poorly understood; in order to understand and model these dynamics basic information on the mechanisms that allow blooms to form must be obtained. This study will determine the role of grazing by the dominant zooplankton (copepods) in the population dynamics of toxic Alexandrium spp. The study will conduct laboratory experiments to elucidate the mechanisms responsible for specific grazing behavior of dominant zooplankton species. Coordinated in situ field studies focusing on the spring period of bloom initiation will also be conducted, at sites where high PSP levels occur early and regularly.

Lead PI: E.G. Durbin, Graduate School Oceanography, University of Rhode Island, Narragansett, RI, 02882; edurbin@gso.uri.edu; 401-874-6580.

Kvitek, R.G. (CSU-Monterey Bay).  02/01/98-01/31/00. NSF Award OCE-9726263.

The purpose of this project has been to test the general hypothesis that the foraging behavior and distribution of high level marine predators (sea otters and shorebirds) under natural conditions are mediated by benthic prey toxicity due to harmful algal blooms (HAB's). The research has had two taxonomic foci (sea otters and shorebirds) in two geographic regions (California and Alaska). In southeast Alaska, the recent and rapid expansion of the sea otter population into the more HAB-prone inside passage provided an ideal opportunity to test the influence of HAB toxins on the distribution and feeding ecology of this important marine predator. The preliminary results from the first Alaska field season show that sea otters generally shun or leave areas where their primary prey (butter clams) are toxic. However, when otters do forage at toxic prey sites, they either shift their diet to less profitable prey (e.g., smaller clams found in deeper water) that are not toxic and ignore the larger more abundant and accessible butter clams, or they capture, open and discard the toxic butter clams. During our second Alaskan field season we will seek to confirm these findings and to determine whether otters discriminate between more and less toxic prey at the level of the individual. That is, are otters that do capture butter clams at toxic sites testing each clam that they capture, and discarding all or part of it depending on the toxin level. The second component of the project focuses on the response of common northern California shore birds (Dowitchers, Godwits, Oystercatchers, Sanderlings, Whimbrels) to the predictable seasonal increase in the paralytic shellfish poisoning toxin (PSPT) content of two major intertidal invertebrate prey (mole crabs and mussels). To test the general hypothesis that the foraging behavior of these avian predators is mediated by PSPT, we are monitoring and correlating seasonal changes in invertebrate prey toxicity with changes in the shorebird behavior and diet over a two year period at several widely separated sites along the California coast. Each paired study site includes rocky habitat where Black Oystercatchers forage on sea mussels, and exposed sandy beach where the other shorebirds forage on mole crabs. During 1998, prey toxicity resulting from PSPT HAB activity was much lower than normal and no change in bird foraging behavior was observed. This condition was likely due to the 1997/98 El Niño event that resulted in very low summer primary productivity. While this situation did not provide an opportunity to compare shore bird foraging under toxic and non-toxic conditions, it did yield an excellent set of low toxicity baseline observations for comparison with the upcoming non-El Niño HAB season in 1999.

Lead PI: R.G. Kvitek, California State University - Monterey Bay, 100 Campus Center, Seaside, CA, 93955-8001; rikk_kvitek@monterey.edu; 408-582-3529.

Paul, V.J. (UGuam), 12/15/97-12/14/00, EPA Award R82-6220.

Harmful algal blooms (HABs) of many types have increased in abundance and severity in the United States and worldwide in recent years. Of particular concern in coral reef habitats are the frequent and persistent seaweed blooms. These blooms can have many negative impacts including; overgrowing corals, negatively affecting seagrass communities, and washing up on beaches in areas where tourism is economically essential. An additional concern for cyanobacterial blooms are the toxins they produce and their impacts on other reef organisms and humans. The production of deterrent and toxic secondary metabolites by benthic cyanobacteria probably facilitates bloom formation on coral reefs because most generalist grazers avoid this potential food source. Almost nothing is known about the temporal and spatial patterns of bloom formation in reef habitats or about environmental factors affecting bloom formation and persistence. Additionally, secondary metabolite types and concentrations can vary considerably among different collections of cyanobacteria, but environmental factors influencing this chemical variation are not understood. This project will investigate the temporal and spatial patterns of cyanobacterial blooms on Guam, eight reef sites will be monitored biweekly and cyanobacterial populations will be measured. Secondary metabolites associated with these blooms will be isolated by chromatographic methods and characterized by spectroscopic methods including 2D NMR techniques. Effects of these compounds on feeding by herbivores such as fishes and invertebrates will be examined in laboratory and field bioassays. Compounds released by the cyanobacteria into seawater will be characterized and examined for their effects on competitors and other microorganisms in laboratory and field bioassays. Effects of grazing, light, and nutrients (nitrogen, phosphorus, iron) on secondary metabolite production will be examined in a combination of field and laboratory experiments. The results of this research will yield information on the dynamics of cyanobacterial blooms in tropical reef environments; the production and toxicity of their secondary metabolites and effects on herbivores, competitors, and microorganisms.

Lead PI: V.J. Paul, University of Guam Marine Laboratory, Mangilao, GU 96923, USA; vpaul@uog9.uog.edu; 671-735-2186.

Stabile, J.E. (NYU Med. Center), and I.I. Wirgin (NYU Med. Center).  10/01/97-09/30/99, NSF Award OCE 9726262.

During the past decade blooms of the brown tide microalgae, Aureococcus anophagefferens, have occurred sporadically in Peconic Bay and Great South Bays of Long Island, N.Y. Blooms of the brown tide vary annually in the timing of their onset, duration and intensity. We hypothesize that temporal and spatial variability in bloom characteristics is due to underlying genetic variation among populations of A. anophagefferens. This hypothesis was tested by DNA sequence analysis of the two internal transcribed spacer regions (ITS1 and ITS2), the 5.8S subunit and the first hypervariable region of the large subunit of rDNA. Brown tide PCR primers were developed and used to amplify A. anophagefferens DNA directly from pre-bloom and bloom water samples and from cultured isolates. PCR products were cloned into the pCR2.1 >plasmid vector and 20 recombinants per water sample or cultured isolate were sequenced. Sequence data were obtained from 1995 summer bloom water samples from West Neck Bay and Flanders Bays in the Peconic Bay system and cultured isolates CCMP 1784 (L.I., N.Y.), CCMP 1785 (L.I., N.Y.), CCMP 1790 (L.I., N.Y.) and CCMP 1794 (Barnegatt Bay, N.J.). Extremely high levels of ITS1 sequence variability were observed among and within water samples and cultured isolates of the brown tide microorganism. A total of 25 polymorphic nucleotide sites were observed among 191 bp of ITS1 DNA sequence. Cloned PCR fragments were assigned ITS1 composite types on the basis of unique combinations of polymorphic nucleotides. A total of 37 different ITS1 types were observed among the 120 cloned fragments. Cultured isolates of A. anophagefferens were observed to have between 6-16 different ITS1 types. Water samples were observed to have ITS1 types not found in the current cultured isolates. CCMP 1794 from Barnegatt Bay had unique ITS1 types suggesting the presence of geographic differentiation between the New Jersey and Long Island sites. High levels of sequence variability were also observed in ITS2, 5.8S and the large subunit of rDNA. However, variability in these regions was less than that of ITS1. We are currently working on alternative methods to more clearly evaluate the spatial and temporal variability of the brown tide microorganism.

Lead PI: J. Stabile, New York University Medical Center, Nelson Laboratory for Environmental Medicine, Long Meadow Road, Tuxedo, NY 10987; jstabile@iona.edu; 914-633-2253.

Steidinger, K.A. (FMRI), J.J. Walsh (USF), C.R. Tomas (USF), J.H. Landsberg (USF), G.A. Vargo (USF), R.H. Pierce (Mote), G.J. Kirkpatrick (Mote), J.D. Buck (Mote), R.H. Weisburg (USF), J. Fournie (EPA), F. VanDolah (NOAA), P.A. Tester (NOAA), T. Whitledge (U. AK), R. Wanninkhof (NOAA), G. Janowitz (NCSU), D. Kamykowski (NCSU), T. Hopkins (NCSU), T. Wolcott (NCSU), D. Wolcott (NCSU), G. Fahnenstiel (NOAA), D.F. Millie (USDA), O.M. Schofield (Rutgers), K.A. Fanning (USF), S.E. Lohrenz (U. S. Miss.), and D.G. Redalje (U. S. Miss.).  09/01/97-03/31/99, first 1.5 years of 4.5 year project, NOAA Grant NA960P0084. EPA Awards R826792 to G. Vargo, 06/01/98-05/31/01 and R827085 to K. Steidinger, 10/15/98-10/14/01.

ECOHAB: Florida is a multidisciplinary project to determine biological and physical factors that lead to recurrent blooms of NSP-producing Gymnodinium breve on Florida’s western shelf. Using moored instrumentation for collection of in situ physical data, routine hydrographic surveys, intensive field and laboratory studies on the ecology, physiology, toxicity, and behavior of the organism, and robust mathematical modeling, the research will determine those factors like responsible for transport and accumulation of Gymnodinium in the region, as well as trophodynamics and toxin transfer in the coastal food web. Biological measurements include life cycle measurements with flow cytometry, diel vertical migration studies in controlled and field environments, optical characteristics of coastal waters and populations, assemblage and species-specific productivity, nutrient uptake, toxicity and toxin distributions, and grazing rates of planktonic herbivores. The study is now being used as a base for many other regional and targeted studies on Gymnodinium (e.g., roles of bacteria and viruses in bloom dynamics) and circulation in the Gulf, including complementary remote sensing projects with multi- and hyperspectral sensors.

Lead PI: K.A. Steidinger, Florida Department of Environmental Protection, Florida Marine Research Institute, 100 8^th Ave., SE, St. Petersburg, FL, 33701-5095; steidinger_k@epic7.dep.state. Fl.us; 813-896-8626.

Wells, M.L. (UCSC), D.L. Garrison (NSF), and R. Tjeerdema (UCSC). 01/01/98-12/31/01, EPA Award R82-6306.

Domoic acid-producing diatoms belonging to the genus Pseudo-nitzschia cause serious toxic algal blooms on the west coast of the United States that have resulted in deaths of seabirds in California water and human poisonings in Oregon and Washington. Presently, little is known about the growth requirements of the individual species and the environmental conditions that promote toxicity. This proposal addresses the need for detailed information on how Pseudo- nitzschia species respond to various levels of macro- and micronutrients. These data are fundamental to developing the capability of predicting where and when these toxic blooms are likely to develop. We are specifically testing the hypotheses that 1) domoic acid production changes as a function of silicate (Si)/nitrogen(N) limitation of the organisms, varying for different species in conjunction with their N and SI metabolic requirements; 2) cellular production and release rates of domoic acid vary systematically with the iron (Fe) nutrient status of organisms, with rates being high under Fe deficient conditions and low in iron replete conditions; and 3) Pseudo-nitzschiaspecies have a high Fe requirement, so that toxic blooms in coastal waters are probably restricted to regions and times when Fe concentrations in surface waters are high. In addition, we will examine the novel idea that domoic acid has a roles in trace metal uptake. This information could provide a predictive capability for assessing the conditions that allow toxic species to bloom and out compete those species which lack the ability to produce domoic acid. To determine nutrient requirements of Pseudo-nitzschiaspecies, nutrient uptake kinetics, and to assess the effect of nutrients on domoic acid production, we will use a variety of continuous and batch culture approaches, utilizing locally-isolated cultures. The proposed research will make s significant contribution to management strategies for future domoic acid blooms in coastal waters of the Pacific and elsewhere. Being able to predict where and when blooms of toxigenic Pseudo-nitzschia species are likely to develop, would lead to considerably more efficient monitoring strategies and an enhanced ability to plan appropriate responses. If our hypotheses are correct, serious toxic bloom problems may be restricted to specific regions of the coast system where micro- or macronutrient concentrations are sufficiently high to support the development of high-density blooms. These same conditions may also affect the levels of toxin produced by bloom species.

Lead PI: M.L. Wells, Institute of Marine Sciences, University of California, Santa Cruz, Santa Cruz, CA 95064; mwells@cats.ucsc.edu; 408-459-3877.

Wikfors, G.H. (NEFSC, NOAA), C. Martin (NEFSC, NOAA), S.E. Shumway (Bigelow), D.G. Dam (UConn), G. McManus (UConn), and R.M. Smolowitz (UPenn). 01/15/98-07/14/99, NOAA FOP and EPA Award R826219-01-0.

Most HAB dinoflagellates grow relatively slowly; therefore, accumulation of their biomass (a bloom) is likely attributable in large part to reduced grazing. Among the grazing organisms that normally limit phytoplankton biomass accumulation are pelagic consumers, such as protozoans, copepods, and larvae of benthic invertebrates, as well as benthic filter-feeders, chiefly the bivalve mollusks. Knowledge of direct, harmful effects of an algal species upon consumers would explain the mechanism by which a bloom of that alga can occur, and provide predictive capability of the types of ecosystems, dominated by benthic or pelagic consumers, that are most susceptible to blooms of that alga. We propose to investigate systematically, under controlled laboratory conditions, effects of two cultured HAB dinoflagellates, Prorocentrum minimum and Gyrodinium aureolum, upon a suite of representative consumer organisms, including three protozoans, two copepods, and a larval and post-set bivalve. Effects of these dinoflagellates, both alone and in various combinations with " good food" algae, upon feeding, behavior, population dynamics, and histological condition of individual organisms will be documented. This work will benefit from a team approach utilizing, in all experiments, identical algal cultures produced in the unique Milford Microalgal Mass Culture Facility. Results will provide information critical to interpretation of field studies of HAB dynamics and food-web effects.

Lead PI: G.H. Wikfors, North East Fishery Science Center, NMFS, NOAA, Milford, CT., 06460; Gary.Wikfors@NOAA.gov; 203-783-4217.