Anderson Donald M.

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Last Name
Anderson
First Name
Donald M.
ORCID
0000-0002-3983-6388

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  • Preprint
    Dynamics of a mesoscale eddy off Cape Ann, Massachusetts in May 2005
    ( 2011-08-18) Jiang, Mingshun ; Zhou, Meng ; Libby, Scott P. ; Anderson, Donald M.
    Observations and numerical modeling indicate that a mesoscale anti-cyclonic eddy formed south of Cape Ann at the northern entrance of Massachusetts Bay (MB) during May 2005, when large river discharges in the western Gulf of Maine and two strong Nor’easters passing through the regions led to an unprecedented toxic Alexandrium fundyense bloom (red tide). Both model results and field measurements suggest that the western Maine coastal current separated from Cape Ann around May 7-8, and the eddy formed on around May 10. The eddy was trapped at the formation location for about a week before detaching from the coastline and moving slowly southward on May 17. Both model results and theoretical analysis suggest that the separation of the coastal current from the coast and subsequent eddy formation were initiated at the subsurface by an adverse pressure gradient between Cape Ann and MB due to the higher sea level set up by onshore Ekman transport and higher density in downstream MB. After the formation, the eddy was maintained by the input of vorticity transported by the coastal current from the north, and local vorticity generation around the cape by the horizontal gradients of wind-driven currents, bottom stress, and water density induced by the Merrimack River plume. Observations and model results indicate that the anti-cyclonic eddy significantly changed the pathway of nutrient and biota transport into the coastal areas and enhanced phytoplankton including Alexandrium abundances around the perimeter of the eddy and in the western coast of MB.
  • Preprint
    Approaches to monitoring, control and management of harmful algal blooms (HABs)
    ( 2009-04) Anderson, Donald M.
    Virtually every coastal country in the world is affected by harmful algal blooms (HABs, commonly called “red tides”). These phenomena are caused by blooms of microscopic algae. Some of these algae are toxic, and can lead to illness and death in humans, fish, seabirds, marine mammals, and other oceanic life, typically as a result of the transfer of toxins through the food web. Sometimes the direct release of toxic compounds can be lethal to marine animals. Non-toxic HABs cause damage to ecosystems, fisheries resources, and recreational facilities, often due to the sheer biomass of the accumulated algae. The term “HAB” also applies to non-toxic blooms of macroalgae (seaweeds), which can cause major ecological impacts such as the displacement of indigenous species, habitat alteration and oxygen depletion in bottom waters. Globally, the nature of the HAB problem has changed considerably over the last several decades. The number of toxic blooms, the resulting economic losses, the types of resources affected, and the number of toxins and toxic species have all increased dramatically. Some of this expansion has been attributed to storms, currents and other natural phenomena, but human activities are also frequently implicated. Humans have contributed by transporting toxic species in ballast water, and by adding massive and increasing quantities of industrial, agricultural and sewage effluents to coastal waters. In many urbanized coastal regions, these inputs have altered the size and composition of the nutrient pool which has, in turn, created a more favorable nutrient environment for certain HAB species. The steady expansion in the use of fertilizers for agricultural production represents a large and worrisome source of nutrients in coastal waters that promote some HABs. The diversity in HAB species and their impacts presents a significant challenge to those responsible for the management of coastal resources. Furthermore, HABs are complex oceanographic phenomena that require multidisciplinary study ranging from molecular and cell biology to large-scale field surveys, numerical modelling, and remote sensing from space. Our understanding of these phenomena is increasing dramatically, and with this understanding come technologies and management tools that can reduce HAB incidence and impact. Here I summarize the global HAB problem, its trends and causes, and new technologies and approaches to monitoring, control and management, highlighting molecular probes for cell detection, rapid and sensitive toxin assays, remote sensing detection and tracking of blooms, bloom control and mitigation strategies, and the use of large-scale physical/biological models to analyze past blooms and forecast future ones.
  • Preprint
    Interannual variability of Alexandrium fundyense abundance and shellfish toxicity in the Gulf of Maine
    ( 2005-05-03) McGillicuddy, Dennis J. ; Anderson, Donald M. ; Solow, Andrew R. ; Townsend, David W.
    Six years of oceanographic surveys of Alexandrium fundyense concentrations in the Gulf of Maine are combined with shellfish toxicity records from coastal monitoring stations to assess covariations of these quantities on seasonal to interannual time scales. Annual mean gulf-wide cell abundance varies by less than one order of magnitude during the time interval examined (1993-2002). Fluctuations in gulf-wide annual mean cell abundance and shellfish toxicity are not related in a consistent manner. This suggests that interannual variations in toxicity may be regulated by transport and delivery of offshore cell populations, rather than the absolute abundance of the source populations themselves.
  • Technical Report
    Marine biotoxins and harmful algae : a national plan
    (Woods Hole Oceanographic Institution, 1993-01) Anderson, Donald M. ; Galloway, Sylvia B. ; Joseph, Jeanne D.
    Marine biotoxins and harmful algae represent a significant and expanding threat to human health and fisheries resources throughout the U.S. This problem takes many forms, ranging from massive "red tides" or blooms of cells that discolor the water to dilute, inconspicuous concentrations of cells noticed only because of the harm caused by the highly potent toxins those cells contain. Impacts include mass mortalities of wild and farmed fish, human intoxications and death from contaminated shellfish or fish, alterations of marine trophic structure, and death of marine mammals, seabirds, and other animals. The nature of the problem has changed considerably over the last two decades in the U.S. Where formerly a few regions were affected, now virtally every coastal state is threatened, in many cases over large geographic areas and by more than one harmful species. The U.S. research, monitoring, and regulatory infrastructure is not adequately prepared to meet this expanding threat. In an effort to surmount these problems, a workshop was convened to formulate a National Plan for the prediction, control, and mitigation of the effects of harmful algal blooms on the U.S. marine biota. This report summarizes the status of U.S. research knowledge and capabilties, and identifies areas where research funds should be directed for maximum benefit.
  • Preprint
    Temporal and spatial variations in nutrient stoichiometry and regulation of phytoplankton biomass in Hong Kong waters : influence of the Pearl River outflow and sewage inputs
    ( 2008-01) Xu, Jie ; Ho, Alvin Y. T. ; Yin, Kedong ; Yuan, Xiangcheng ; Anderson, Donald M. ; Lee, Joseph H. W. ; Harrison, Paul J.
    In 2001, the Hong Kong government implemented the Harbor Area Treatment Scheme (HATS) under which 70% of the sewage that had been formerly discharged into Victoria Harbor is now collected and sent to Stonecutters Island Sewage Works where it receives chemically enhanced primary treatment (CEPT), and is then discharged into waters west of the Harbor. The relocation of the sewage discharge will possibly change the nutrient dynamics and phytoplankton biomass in this area. Therefore, there is a need to examine the factors that regulate phytoplankton growth in Hong Kong waters in order to understand future impacts. Based on a historic nutrient data set (1986-2001), a comparison of ambient nutrient ratios with the Redfield ratio (N:P:Si=16:1:16) showed clear spatial variations in the factors that regulate phytoplankton biomass along a west (estuary) to east (coastal/oceanic) transect through Hong Kong waters. Algal biomass was constrained by a combination of low light conditions, a rapid change in salinity, and strong turbulent mixing in western waters throughout the year. Potential stoichiometric Si limitation (up to 94% of the cases in winter) occurred in Victoria Harbor due to the contribution of sewage effluent with high N and P enrichment all year, except for summer when the frequency of stoichiometric Si limitation (48%) was the same as P, owing to the influence of the high Si in the Pearl River discharge. In the eastern waters, potential N limitation and N and P co-limitation occurred in autumn and winter respectively, because of the dominance of coastal/oceanic water with low nutrients and low N:P ratios. In contrast, potential Si limitation occurred in spring and a switch to potential N, P and Si limitation occurred in eastern waters in summer. In southern waters, there was a shift from P limitation (80%) in summer due to the influence of the N-rich Pearl River discharge, to N limitation (68%) in autumn, and to N and P co-limitation in winter due to the dominance of N-poor oceanic water from the oligotrophic South China Sea. Our results show clear temporal and spatial variations in the nutrient stoichiometry which indicates potential regulation of phytoplankton biomass in HK waters due to the combination of the seasonal exchange of the Pearl River discharge and oceanic water, sewage effluent inputs, and strong hydrodynamic mixing from SW monsoon winds in summer and the NE monsoon winds in winter.
  • Article
    Rapid growth and concerted sexual transitions by a bloom of the harmful dinoflagellate Alexandrium fundyense (Dinophyceae)
    (John Wiley & Sons, 2015-09-18) Brosnahan, Michael L. ; Velo-Suarez, Lourdes ; Ralston, David K. ; Fox, Sophia E. ; Sehein, Taylor R. ; Shalapyonok, Alexi ; Sosik, Heidi M. ; Olson, Robert J. ; Anderson, Donald M.
    Transitions between life cycle stages by the harmful dinoflagellate Alexandrium fundyense are critical for the initiation and termination of its blooms. To quantify these transitions in a single population, an Imaging FlowCytobot (IFCB), was deployed in Salt Pond (Eastham, Massachusetts), a small, tidally flushed kettle pond that hosts near annual, localized A. fundyense blooms. Machine-based image classifiers differentiating A. fundyense life cycle stages were developed and results were compared to manually corrected IFCB samples, manual microscopy-based estimates of A. fundyense abundance, previously published data describing prevalence of the parasite Amoebophrya, and a continuous culture of A. fundyense infected with Amoebophrya. In Salt Pond, a development phase of sustained vegetative division lasted approximately 3 weeks and was followed by a rapid and near complete conversion to small, gamete cells. The gametic period (∼3 d) coincided with a spike in the frequency of fusing gametes (up to 5% of A. fundyense images) and was followed by a zygotic phase (∼4 d) during which cell sizes returned to their normal range but cell division and diel vertical migration ceased. Cell division during bloom development was strongly phased, enabling estimation of daily rates of division, which were more than twice those predicted from batch cultures grown at similar temperatures in replete medium. Data from the Salt Pond deployment provide the first continuous record of an A. fundyense population through its complete bloom cycle and demonstrate growth and sexual induction rates much higher than are typically observed in culture.
  • Preprint
    A comparison of eutrophication impacts in two harbours in Hong Kong with different hydrodynamics
    ( 2009-09-03) Xu, J. ; Yin, K. ; Liu, H. ; Lee, Joseph H. W. ; Anderson, Donald M. ; Ho, Alvin Y. T. ; Harrison, Paul J.
    Eutrophication impacts may vary spatially and temporally due to different physical processes. Using a 22-year time series data set (1986-2007), a comparison of eutrophication impacts between two eutrophic harbors, Victoria and Tolo Harbours, in Hong Kong with very different hydrodynamic conditions was conducted. In the highly-flushed Victoria Harbour (Victoria), the highest Chl a (13 μg L-1) occurred due to stratification in summer as a result of the input of the eutrophic Pearl River discharge, but the high flushing rate restricted nutrient utilization and the further accumulation of algal biomass. In other seasons, vertical mixing induced light limitation and horizontal dilution led to low Chl a (< 2 μg L-1) and no spring bloom. Few hypoxic events (DO < 2 mg L-1) occurred due to strong tidal mixing. Therefore, Victoria is resilient to nutrient enrichment. In contrast, in the weakly-flushed Tolo Harbour (Tolo), year long stratification, the long residence times and weak tidal currents favored algal growth, resulting in a spring diatom bloom and high Chl a (up to 30 μg L-1) all year and frequent hypoxic events in summer. Hence, Tolo is susceptible to nutrient enrichment and it responded to nutrient reduction since sewage treatment resulted in a 32-38% decrease in algal biomass in Tolo, but not in Victoria. A significant (11-22%) reduction in bottom DO in the both harbors after sewage treatment was due to a decrease in the organic loading from sewage treatment or the diversion.
  • Article
    Evaluation of sxtA and rDNA qPCR assays through monitoring of an inshore bloom of Alexandrium catenella Group 1
    (Nature Research, 2019-10-10) Murray, Shauna A. ; Ruvindy, Rendy ; Kohli, Gurjeet S. ; Anderson, Donald M. ; Brosnahan, Michael L.
    Alexandrium catenella (formerly A. tamarense Group 1, or A. fundyense) is the leading cause of Paralytic Shellfish Poisoning in North and South America, Europe, Africa, Australia and Asia. The quantification of A.catenella via sxtA, a gene involved in Paralytic Shellfish Toxin synthesis, may be a promising approach, but has not been evaluated in situ on blooms of A. catenella, in which cell abundances may vary from not detectable to in the order of 106 cells L−1. In this study, we compared sxtA assay performance to a qPCR assay targeted to a species-specific region of ribosomal DNA (rDNA) and an established fluorescent in situ hybridization (FISH) microscopy method. Passing-Bablok regression analyses revealed the sxtA assay to overestimate abundances when <5 cell equivalents A. catenella DNA were analysed, but otherwise was closer to microscopy estimates than the rDNA assay, which overestimated abundance across the full range of concentrations analysed, indicative of a copy number difference between the bloom population and a culture used for assay calibration a priori. In contrast, the sxtA assay performed more consistently, indicating less copy number variation. The sxtA assay was generally reliable, fast and effective in quantifying A. catenella and was predictive of PST contamination of shellfish.
  • Article
    Pseudo-nitzschia bloom dynamics in the Gulf of Maine: 2012-2016
    (Elsevier, 2019-08-19) Clark, Suzanna ; Hubbard, Katherine A. ; Anderson, Donald M. ; McGillicuddy, Dennis J. ; Ralston, David K. ; Townsend, David W.
    The toxic diatom genus Pseudo-nitzschia is a growing presence in the Gulf of Maine (GOM), where regionally unprecedented levels of domoic acid (DA) in 2016 led to the first Amnesic Shellfish Poisoning closures in the region. However, factors driving GOM Pseudo-nitzschia dynamics, DA concentrations, and the 2016 event are unclear. Water samples were collected at the surface and at depth in offshore transects in summer 2012, 2014, and 2015, and fall 2016, and a weekly time series of surface water samples was collected in 2013. Temperature and salinity data were obtained from NERACOOS buoys and measurements during sample collection. Samples were processed for particulate DA (pDA), dissolved nutrients (nitrate, ammonium, silicic acid, and phosphate), and cellular abundance. Species composition was estimated via Automated Ribosomal Intergenic Spacer Analysis (ARISA), a semi-quantitative DNA finger-printing tool. Pseudo-nitzschia biogeography was consistent in the years 2012, 2014, and 2015, with greater Pseudo-nitzschia cell abundance and P. plurisecta dominance in low-salinity inshore samples, and lower Pseudo-nitzschia cell abundance and P. delicatissima and P. seriata dominance in high-salinity offshore samples. During the 2016 event, pDA concentrations were an order of magnitude higher than in previous years, and inshore-offshore contrasts in biogeography were weak, with P. australis present in every sample. Patterns in temporal and spatial variability confirm that pDA increases with the abundance and the cellular DA of Pseudo-nitzschia species, but was not correlated with any one environmental factor. The greater pDA in 2016 was caused by P. australis – the observation of which is unprecedented in the region – and may have been exacerbated by low residual silicic acid. The novel presence of P. australis may be due to local growth conditions, the introduction of a population with an anomalous water mass, or both factors. A definitive cause of the 2016 bloom remains unknown, and continued DA monitoring in the GOM is warranted.
  • Preprint
    Effects of nutrients, salinity, pH and light:dark cycle on the production of reactive oxygen species in the alga Chattonella marina
    ( 2007-06-03) Liu, Wenhua ; Au, Doris W. T. ; Anderson, Donald M. ; Lam, Paul K. S. ; Wu, Rudolf S. S.
    Experiments were carried out to investigate the effects of nutrients, salinity, pH and light:dark cycle on growth rate and production of reactive oxygen species (ROS) by Chattonella marina, a harmful algal bloom (HAB) species that often causes fish kills. Different nitrogen forms (organic-N and inorganic-N), N:P ratios, light:dark cycles and salinity significantly influenced algal growth, but not ROS production. However, iron concentration and pH significantly affected both growth and ROS production in C. marina. KCN (an inhibitor of mitochondrial respiration) and 3-(3,4-dichlorophenyl)-1,1-dimethylurea (an inhibitor of photosynthesis) had no significant effects on ROS production. Vitamin K3 (a plasma membrane electron shuttle) enhanced ROS production while its antagonist, dicumarol, decreased ROS production. Taken together, our results suggest that ROS production by C. marina is related to a plasma membrane enzyme system regulated by iron availability but is independent of growth, photosynthesis, availability of macronutrients, salinity and irradiance.
  • Preprint
    Using clay to control harmful algal blooms : deposition and resuspension of clay/algal flocs
    ( 2003-12-21) Beaulieu, Stace E. ; Sengco, Mario R. ; Anderson, Donald M.
    Harmful algal blooms (HABs) may be legitimate targets for direct control or mitigation, due to their impacts on commercial fisheries and public health. One promising control strategy is the rapid sedimentation of HABs through flocculation with clay. The objective of this study was to evaluate flow environments in which such a control strategy might be effective in removing harmful algae from the water column and depositing a layer of clay/algal flocs on the sea floor. We simulated the natural environment in two laboratory flumes: a straight-channel “17-m flume” in which flocs settled in a still water column and a “racetrack flume” in which flocs settled in flow. The 17-m flume experiments were designed to estimate the critical bed shear stress for resuspension of flocs that had settled for different time periods. The racetrack flume experiments were designed to examine the deposition and repeated resuspension of flocs in a system with tidal increases in flow speed. All flume runs were conducted with the non-toxic dinoflagellate Heterocapsa triquetra and phosphatic clay (IMC-P4). We repeated the experiments with a coagulant, polyaluminum hydroxychloride (PAC), expected to enhance the removal efficiency of the clay. Our experiments indicated that at low flow speeds (≤ 10 cm s-1), phosphatic clay was effective at removing algal cells from the water column, even after repeated resuspension. Once a layer of flocs accumulated on the bed, the consolidation, or dewatering, of the layer over time increased the critical shear stress for resuspension (i.e. decreased erodibility). Resuspension of a 2-mm thick layer that settled for 3 hours in relatively low flow speeds (≤ 3 cm s-1) would be expected at bed shear stress of ~0.06-0.07 Pa, as compared to up to 0.09 Pa for a layer that was undisturbed for 9 or 24 hours. For the same experimental conditions, the addition of PAC decreased the removal efficiency of algal cells in flow and increased the erodibility of flocs from the bottom. By increasing the likelihood that flocs remain in suspension, the addition of PAC in field trials of clay dispersal might have greater impact on sensitive, filter-feeding organisms. Overall, our experiments suggest that the flow environment should be considered before using clay as a control strategy for HABs in coastal waters.
  • Preprint
    Ocean urea fertilization for carbon credits poses high ecological risks
    ( 2008) Glibert, Patricia M. ; Azanza, Rhodora ; Burford, Michele ; Furuya, Ken ; Abal, Eva ; Al-Azri, Adnan ; Al-Yamani, Faiza ; Andersen, Per ; Anderson, Donald M. ; Beardall, John ; Berg, Gry M. ; Brand, Larry E. ; Bronk, Deborah ; Brookes, Justin ; Burkholder, JoAnn M. ; Cembella, Allan D. ; Cochlan, William P. ; Collier, Jackie L. ; Collos, Yves ; Diaz, Robert ; Doblin, Martina ; Drennen, Thomas ; Dyhrman, Sonya T. ; Fukuyo, Yasuwo ; Furnas, Miles ; Galloway, James ; Graneli, Edna ; Ha, Dao Viet ; Hallegraeff, Gustaaf M. ; Harrison, John A. ; Harrison, Paul J. ; Heil, Cynthia A. ; Heimann, Kirsten ; Howarth, Robert W. ; Jauzein, Cecile ; Kana, Austin A. ; Kana, Todd M. ; Kim, Hakgyoon ; Kudela, Raphael M. ; Legrand, Catherine ; Mallin, Michael ; Mulholland, Margaret R. ; Murray, Shauna A. ; O’Neil, Judith ; Pitcher, Grant C. ; Qi, Yuzao ; Rabalais, Nancy ; Raine, Robin ; Seitzinger, Sybil P. ; Salomon, Paulo S. ; Solomon, Caroline ; Stoecker, Diane K. ; Usup, Gires ; Wilson, Joanne ; Yin, Kedong ; Zhou, Mingjiang ; Zhu, Mingyuan
    The proposed plan for enrichment of the Sulu Sea, Philippines, a region of rich marine biodiversity, with thousands of tonnes of urea in order to stimulate algal blooms and sequester carbon is flawed for multiple reasons. Urea is preferentially used as a nitrogen source by some cyanobacteria and dinoflagellates, many of which are neutrally or positively buoyant. Biological pumps to the deep sea are classically leaky, and the inefficient burial of new biomass makes the estimation of a net loss of carbon from the atmosphere questionable at best. The potential for growth of toxic dinoflagellates is also high, as many grow well on urea and some even increase their toxicity when grown on urea. Many toxic dinoflagellates form cysts which can settle to the sediment and germinate in subsequent years, forming new blooms even without further fertilization. If large-scale blooms do occur, it is likely that they will contribute to hypoxia in the bottom waters upon decomposition. Lastly, urea production requires fossil fuel usage, further limiting the potential for net carbon sequestration. The environmental and economic impacts are potentially great and need to be rigorously assessed.
  • Preprint
    Development of microsatellite markers in the toxic dinoflagellate Alexandrium minutum (Dinophyceae)
    ( 2006-01-22) Nagai, Satoshi ; McCauley, Linda A. R. ; Yasuda, N. ; Erdner, Deana L. ; Kulis, David M. ; Matsuyama, Y. ; Itakura, S. ; Anderson, Donald M.
    Outbreaks of paralytic shellfish poisoning caused by the toxic dinoflagellate Alexandrium minutum (Dinophyceae) are a worldwide concern from both the economic and human health points of view. For population genetic studies of A. minutum distribution and dispersal, highly polymorphic genetic markers are of great value. We isolated 12 polymorphic microsatellites from this cosmopolitan, toxic dinoflagellate species. These loci provide one class of highly variable genetic markers, as the number of alleles ranged from 4 to 12, and the estimate of gene diversity was from 0.560 to 0.862 across the 12 microsatellites; these loci have the potential to reveal genetic structure and gene flow among A. minutum populations.
  • Article
    Global transcriptional profiling of the toxic dinoflagellate Alexandrium fundyense using Massively Parallel Signature Sequencing
    (BioMed Central, 2006-04-25) Erdner, Deana L. ; Anderson, Donald M.
    Dinoflagellates are one of the most important classes of marine and freshwater algae, notable both for their functional diversity and ecological significance. They occur naturally as free-living cells, as endosymbionts of marine invertebrates and are well known for their involvement in "red tides". Dinoflagellates are also notable for their unusual genome content and structure, which suggests that the organization and regulation of dinoflagellate genes may be very different from that of most eukaryotes. To investigate the content and regulation of the dinoflagellate genome, we performed a global analysis of the transcriptome of the toxic dinoflagellate Alexandrium fundyense under nitrate- and phosphate-limited conditions using Massively Parallel Signature Sequencing (MPSS).
  • Preprint
    Alexandrium fundyense cyst viability and germling survival in light vs. dark at a constant low temperature
    ( 2013-05) Vahtera, Emil ; Crespo, Bibiana G. ; McGillicuddy, Dennis J. ; Olli, Kalle ; Anderson, Donald M.
    Both observations and models suggest that large-scale coastal blooms of Alexandrium fundyense in the Gulf of Maine are seeded by deep-bottom cyst accumulation zones (“seed beds”) where cysts germinate from the sediment surface or the overlying near-bottom nepheloid layers at water depths exceeding 100 m. The germling cells and their vegetative progeny are assumed to be subject to modest mortality while in complete darkness as they swim to illuminated surface waters. To test the validity of this assumption we investigated in the laboratory cyst viability and the survival of the germling cells and their vegetative progeny during prolonged exposure to darkness at a temperature of 6°C, simulating the conditions in deep Gulf of Maine waters. We isolated cysts from bottom sediments collected in the Gulf of Maine under low red light and incubated them in 96-well tissue culture-plates in culture medium under a 10:14h light: dark cycle and under complete darkness. Cyst viability was high, with excystment frequency reaching 90% in the illuminated treatment after 30 days and in the dark treatment after 50 days. Average germination rates were 0.062 and 0.038 d-1 for light and dark treatments, respectively. The dark treatment showed an approximately two-week time lag in maximum germination rates when compared to the light treatment. Survival of germlings was considerably lower in the dark treatment. In light treatments, 47% of germinated cysts produced germlings that were able to survive for 7 days and produce vegetative progeny, i.e. there were live cells in the well along with an empty cyst at least once during the experiment. In the dark treatments 12% of cysts produced germlings that were able to survive. When dark treatments are scaled to take into account non-darkness related mortality, approximately 28% of cysts produced germlings that were able to survive for at least 7 days. Even though cysts are able to germinate in darkness, the lack of illumination considerably reduces survival rate of germling cells. In addition to viability of cysts in surface sediments and the near-bottom nepheloid layer, survivability of germling cells and their vegetative progeny at aphotic depths is an important consideration in assessing the quantitative role of deep-coastal cyst seed beds in bloom formation.
  • Article
    A novel immunofluorescence flow cytometry technique detects the expansion of brown tides caused by Aureoumbra lagunensis to the Caribbean Sea
    (American Society for Microbiology, 2014-06-06) Koch, Florian ; Kang, Y. ; Villareal, Tracy A. ; Anderson, Donald M. ; Gobler, Christopher J.
    During the past 3 decades, brown tides caused by the pelagophytes Aureococcus anophagefferens and Aureoumbra lagunensis have caused ecological and economic damage to coastal ecosystems across the globe. While blooms of A. lagunensis had previously been confined to Texas, in 2012, an expansive brown tide occurred on Florida's East Coast, causing widespread disruption within the Indian River and Mosquito Lagoons and generating renewed interest in this organism. A major impediment to detailed investigations of A. lagunensis in an ecosystem setting has been the absence of a rapid and reliable method for cell quantification. The combination of their small size (3 to 5 μm) and nondescript extracellular features makes identification and enumeration of these cells with conventional methods a challenge. Here we report the development of an immunological-based flow cytometry method that uses a fluorescently labeled antibody developed against A. lagunensis. This method is species specific, sensitive (detection limit of 1.5 × 103 cells ml−1), precise (1% relative standard deviation of replicated samples), and accurate (108% ± 8% recovery of spiked samples) over a wide range of cell concentrations. Furthermore, this method effectively quantifies A. lagunensis in both glutaraldehyde- and formalin-preserved samples, yields a high throughput of samples (∼35 samples h−1), and is cost-effective, making it an ideal tool for managers and scientists. This method successfully documented the recurrence of a brown tide bloom in Florida in 2013. Bloom densities were highest in June (>2.0 × 106 cells ml−1) and spanned >60 km from the Ponce de Leon inlet in the northern Mosquito Lagoon south to Titusville in the Indian River Lagoon. Low levels of A. lagunensis cells were found >250 km south of this region. This method also quickly and accurately identified A. lagunensis as the causative agent of a 2013 brown tide bloom in Guantanamo Bay, Cuba, and thus should prove useful for both quantifying the dynamics of ongoing blooms of A. lagunensis as well as documenting new outbreaks of this harmful alga.
  • Preprint
    Dynamics of Alexandrium fundyense blooms and shellfish toxicity in the Nauset Marsh System of Cape Cod (Massachusetts, USA)
    ( 2011-08) Crespo, Bibiana G. ; Keafer, Bruce A. ; Ralston, David K. ; Lind, Henry ; Farber, Dawson ; Anderson, Donald M.
    Paralytic Shellfish Poisoning (PSP) toxins are annually recurrent along the Massachusetts coastline (USA), which includes many small embayments and salt ponds. Among these is the Nauset Marsh System (NMS), which has a long history of PSP toxicity. Little is known, however, about the bloom dynamics of the causative organism Alexandrium fundyense within that economically and socially important system. The overall goal of this work was to characterize the distribution and dynamics of A. fundyense blooms within the NMS and adjacent coastal waters by documenting the distribution and abundance of resting cysts and vegetative cells. Cysts were found predominantly in three drowned kettle holes or salt ponds at the distal ends of the NMS - Salt Pond, Mill Pond, and Town Cove. The central region of the NMS had a much lower concentration of cysts. Two types of A. fundyense blooms were observed. One originated entirely within the estuary, seeded by cysts in the three seedbeds. These blooms developed independently of each other and of the A. fundyense population observed in adjacent coastal waters outside the NMS. The temporal development of the blooms was different in the three salt ponds, with initiation differing by as much as 30 days. These differences do not appear to reflect the initial cyst abundances in these locations, and may simply result from higher cell retention and higher nutrient concentrations in Mill Pond, the first site to bloom. Germination of cysts accounted for a small percentage of the peak cell densities in the ponds, so population size was influenced more by the factors affecting growth than by cyst abundance. Subsurface cell aggregation (surface avoidance) limited advection of the vegetative A. fundyense cells out of the salt ponds through the shallow inlet channels. Thus, the upper reaches of the NMS are at the greatest risk for PSP since the highest cyst abundances and cell concentrations were found there. After these localized blooms in the salt ponds peaked and declined, a second, late season bloom occurred within the central portions of the NMS. The timing of this second bloom relative to those within the salt ponds and the coastal circulation patterns at that time strongly suggest that those cells originated from a regional A. fundyense bloom in the Gulf of Maine, delivered to the central marsh from coastal waters outside the NMS through Nauset Inlet. These results will guide policy decisions about water quality as well as shellfish monitoring and utilization within the NMS and highlight the potential for “surgical” closures of shellfish during PSP events, leaving some areas open for harvesting while others are closed.
  • Article
    Identification and characterization of three differentially Expressed genes, encoding S-adenosylhomocysteine hydrolase, methionine aminopeptidase, and a histone-like protein, in the toxic dinoflagellate Alexandrium fundyense
    (American Society for Microbiology, 2000-05) Taroncher-Oldenburg, Gaspar ; Anderson, Donald M.
    Genes showing differential expression related to the early G1 phase of the cell cycle during synchronized circadian growth of the toxic dinoflagellate Alexandrium fundyense were identified and characterized by differential display (DD). The determination in our previous work that toxin production in Alexandrium is relegated to a narrow time frame in early G1 led to the hypothesis that transcriptionally up- or downregulated genes during this subphase of the cell cycle might be related to toxin biosynthesis. Three genes, encoding S-adenosylhomocysteine hydrolase (Sahh), methionine aminopeptidase (Map), and a histone-like protein (HAf), were isolated. Sahh was downregulated, while Map and HAf were upregulated, during the early G1 phase of the cell cycle. Sahh and Map encoded amino acid sequences with about 90 and 70% similarity to those encoded by several eukaryotic and prokaryotic Sahh and Map genes, respectively. The partial Map sequence also contained three cobalt binding motifs characteristic of all Map genes. HAf encoded an amino acid sequence with 60% similarity to those of two histone-like proteins from the dinoflagellate Crypthecodinium cohnii Biecheler. This study documents the potential of applying DD to the identification of genes that are related to physiological processes or cell cycle events in phytoplankton under conditions where small sample volumes represent an experimental constraint. The identification of an additional 21 genes with various cell cycle-related DD patterns also provides evidence for the importance of pretranslational or transcriptional regulation in dinoflagellates, contrary to previous reports suggesting the possibility that translational mechanisms are the primary means of circadian regulation in this group of organisms.
  • Book chapter
    Improving the accuracy and utility of harmful algal bloom forecasting systems
    ( 2006-05) Anderson, Donald M. ; Keafer, Bruce A. ; McGillicuddy, Dennis J. ; Solow, Andrew R. ; Kleindinst, Judith L.
    One of the goals of harmful algal bloom (HAB) research has been to develop predictive capabilities for blooms. Major steps have been made towards this goal, including the development of physical-biological models of HAB species that simulate bloom dynamics in specific regions. In the Gulf of Maine region of the northeastern U.S., models have been developed that have considerable skill in simulating blooms of Alexandrium fundyense, the causative organism for paralytic shellfish poisoning (PSP) outbreaks in the region. This model is now being used for both short-term and long-term forecasts. This paper describes several ongoing activities that will improve the accuracy and usefulness of the model and forecasts. These include efforts to streamline or minimize the sampling and analysis requirements of annual A. fundyense cyst surveys, efforts to quantitatively describe or characterize the severity of predicted outbreaks, and plans to obtain real-time data on Alexandrium cell abundance and toxicity that can be assimilated into the models. Together, these and other activities are moving us towards an operational forecasting system for Alexandrium blooms in the region.
  • Article
    Impact of sea-ice dynamics on the spatial distribution of diatom resting stages in sediments of the Pacific Arctic region
    (American Geophysical Union, 2021-06-17) Fukai, Yuri ; Matsuno, Kohei ; Fujiwara, Amane ; Suzuki, Koji ; Richlen, Mindy L. ; Fachon, Evangeline ; Anderson, Donald M.
    The Pacific Arctic region is characterized by seasonal sea-ice, the spatial extent and duration of which varies considerably. In this region, diatoms are the dominant phytoplankton group during spring and summer. To facilitate survival during periods that are less favorable for growth, many diatom species produce resting stages that settle to the seafloor and can serve as a potential inoculum for subsequent blooms. Since diatom assemblage composition is closely related to sea-ice dynamics, detailed studies of biophysical interactions are fundamental to understanding the lower trophic levels of ecosystems in the Pacific Arctic. One way to explore this relationship is by comparing the distribution and abundance of diatom resting stages with patterns of sea-ice coverage. In this study, we quantified viable diatom resting stages in sediments collected during summer and autumn 2018 and explored their relationship to sea-ice extent during the previous winter and spring. Diatom assemblages were clearly dependent on the variable timing of the sea-ice retreat and accompanying light conditions. In areas where sea-ice retreated earlier, open-water species such as Chaetoceros spp. and Thalassiosira spp. were abundant. In contrast, proportional abundances of Attheya spp. and pennate diatom species that are commonly observed in sea-ice were higher in areas where diatoms experienced higher light levels and longer day length in/under the sea-ice. This study demonstrates that sea-ice dynamics are an important determinant of diatom species composition and distribution in the Pacific Arctic region.