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Leitão E, Castellanos DF, Park G, Dam HG. Antagonistic interactions of the dinoflagellate Alexandrium catenella under simultaneous warming and acidification. HARMFUL ALGAE 2024; 134:102625. [PMID: 38705619 DOI: 10.1016/j.hal.2024.102625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 03/28/2024] [Accepted: 04/03/2024] [Indexed: 05/07/2024]
Abstract
There is a concern that harmful algal bloom (HAB) species may increase under climate change. Yet, we lack understanding of how ecological interactions will be affected under ocean warming and acidification (OWA) conditions. We tested the antagonistic effects of three strains of the dinoflagellate HAB species Alexandrium catenella on three target species (the chlorophyte Tetraselmis sp., the cryptomonad Rhodomonas salina, and the diatom Thalassiosira weissflogii) at various biomass ratios between species, at ambient (16 °C and 400 µatm CO2) and OWA (20 °C and 2000 µatm CO2) conditions. In these experiments the Alexandrium strains had been raised under OWA conditions for ∼100 generations. All three non-HAB species increased their growth rate under OWA relative to ambient conditions. Growth rate inhibition was evident for R. salina and Tetraselmis sp. under OWA conditions, but not under ambient conditions. These negative effects were exacerbated at higher concentrations of Alexandrium relative to non-HAB species. By contrast, T. weissflogii showed positive growth in the presence of two strains of Alexandrium under ambient conditions, whereas growth was unaffected under OWA. Contrary to our expectations, A. catenella had a slight negative response in the presence of the diatom. These results demonstrate that Alexandrium exerts higher antagonistic effects under OWA compared to ambient conditions, and these effects are species-specific and density dependent. These negative effects may shift phytoplankton community composition under OWA conditions.
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Affiliation(s)
- Ewaldo Leitão
- Department of Marine Sciences, University of Connecticut, 1080 Shennecossett Road, Groton, CT 06340, USA.
| | - Diana F Castellanos
- Biology Department, Pomona College, 175 W. 6th St., Claremont, CA 91711, USA
| | - Gihong Park
- Department of Marine Sciences, University of Connecticut, 1080 Shennecossett Road, Groton, CT 06340, USA
| | - Hans G Dam
- Department of Marine Sciences, University of Connecticut, 1080 Shennecossett Road, Groton, CT 06340, USA
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2
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Kang Y, Gobler CJ. Nitrogen liberated via allelopathy can promote harmful algal blooms. HARMFUL ALGAE 2023; 129:102490. [PMID: 37951604 DOI: 10.1016/j.hal.2023.102490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 08/05/2023] [Accepted: 08/11/2023] [Indexed: 11/14/2023]
Abstract
Allelopathy is a biological mechanism that can promote harmful algal blooms (HAB) via the inhibition of sympatric phytoplankton. While nutrient loading can also promote HABs, the ability of allelopathy to stimulate HABs via the regeneration of nutrients has yet to be explored. To examine the impacts of allelopathically liberated N on HAB species, a series of experiments were performed using multiple allelopathic HAB species including the dinoflagellates Alexandrium catenella and Margalefidinium polykrikoides, and the pelagophyte, Aureoumbra lagunensis. These HAB species were paired with the cosmopolitan dinoflagellate, Akashiwo sanguinea, that was labeled with 15NO3- or 15NH4+, allowing the release and transfer of N to be traced as a time course during allelopathic interactions. During all experiments, the allelopathic inhibition of Akashiwo was accompanied by increases in cell densities, growth rates, and the δ15N content of the HAB species, evidencing the transfer of N liberated from Akashiwo. The cellular transfer of 15N and release of dissolved N was higher when Akashiwo was grown with 15NO3- compared to 15NH4+ suggesting a differential subcellular-compartmentalization of N sources. Regardless of the type of N, HAB species obtained 60 - 100% of their cellular N from lysed Akashiwo cells and there was an enrichment of the δ15N content of the dissolved NH4+ pool post-lysis of Akashiwo. Collectively, the results demonstrate that beyond facilitating species succession, allelopathy can supply HABs with N and, therefore, is likely important for promoting and sustaining HABs. Given that allelopathy is known to be a dose-dependent process, allelopathy may induce a positive feedback loop, whereby competitors are lysed, N is liberated, HABs are intensified and, in turn, become more strongly allelopathic.
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Affiliation(s)
- Yoonja Kang
- Chonnam National University, Department of Ocean Integrated Science, Yeosu 59626, South Korea
| | - Christopher J Gobler
- Stony Brook University, School of Marine and Atmospheric Sciences, Stony Brook, NY 11794, United States of America.
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Tillmann U, Mitra A, Flynn KJ, Larsson ME. Mucus-Trap-Assisted Feeding Is a Common Strategy of the Small Mixoplanktonic Prorocentrum pervagatum and P. cordatum (Prorocentrales, Dinophyceae). Microorganisms 2023; 11:1730. [PMID: 37512902 PMCID: PMC10384473 DOI: 10.3390/microorganisms11071730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 06/25/2023] [Accepted: 06/27/2023] [Indexed: 07/30/2023] Open
Abstract
Prorocentrum comprises a diverse group of bloom-forming dinophytes with a worldwide distribution. Although photosynthetic, mixoplanktonic phagotrophy has also been described. Recently, the small P. cf. balticum was shown to use a remarkable feeding strategy by crafting globular mucus traps to capture and immobilize potential prey. Here we present evidence showing that two additional related species, the recently described P. pervagatum and the cosmopolitan bloom-forming P. cordatum, also produce large (80-120 µm) mucus traps supporting their mixoplanktonic activity. Prey are captured within the traps either through passive entanglement upon contact with the outside surface, or through active water movement created by rotating Prorocentrum cells eddying particles to the inside surface where trapped live prey cells became immobilized. Entrapment in mucus assisted deployment into the prey of a peduncle extruded from the apical area of the Prorocentrum cell. Phagotrophy by P. pervagatum supported faster growth compared to unfed controls and time series quantification of food vacuoles revealed ingestion rates of ca. 10-12 Teleaulax prey cells day-1. Model calculations show clear advantages of deploying a mucus trap for increasing prey encounter rates. This study demonstrates that the large size and immobilization properties of mucus traps successfully increase the availability of prey for small Prorocentrum species, whose peduncle feeding mode impedes consumption of actively moving prey, and that this strategy is common among certain clades of small planktonic Prorocentrum species.
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Affiliation(s)
- Urban Tillmann
- Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany
| | - Aditee Mitra
- School of Earth and Environmental Sciences, Cardiff University, Park Place, Cardiff CF10 3AT, UK
| | | | - Michaela E Larsson
- Aquatic Science Branch, Department of Water and Environmental Regulation, Joondalup, WA 6027, Australia
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Larsson ME, Bramucci AR, Collins S, Hallegraeff G, Kahlke T, Raina JB, Seymour JR, Doblin MA. Mucospheres produced by a mixotrophic protist impact ocean carbon cycling. Nat Commun 2022; 13:1301. [PMID: 35288549 PMCID: PMC8921327 DOI: 10.1038/s41467-022-28867-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 02/04/2022] [Indexed: 01/04/2023] Open
Abstract
AbstractMixotrophic protists (unicellular eukaryotes) that engage in both phototrophy (photosynthesis) and phago-heterotrophy (engulfment of particles)—are predicted to contribute substantially to energy fluxes and marine biogeochemical cycles. However, their impact remains largely unquantified. Here we describe the sophisticated foraging strategy of a widespread mixotrophic dinoflagellate, involving the production of carbon-rich ‘mucospheres’ that attract, capture, and immobilise microbial prey facilitating their consumption. We provide a detailed characterisation of this previously undescribed behaviour and reveal that it represents an overlooked, yet quantitatively significant mechanism for oceanic carbon fluxes. Following feeding, the mucospheres laden with surplus prey are discarded and sink, contributing an estimated 0.17–1.24 mg m−2 d−1 of particulate organic carbon, or 0.02–0.15 Gt to the biological pump annually, which represents 0.1–0.7% of the estimated total export from the euphotic zone. These findings demonstrate how the complex foraging behaviour of a single species of mixotrophic protist can disproportionally contribute to the vertical flux of carbon in the ocean.
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Ferreira GD, Figueira J, Marques SC, Hansen PJ, Calbet A. The strengths and weaknesses of Live Fluorescently Labelled Algae (LFLA) to estimate herbivory in protozooplankton and mixoplankton. MARINE ENVIRONMENTAL RESEARCH 2022; 174:105558. [PMID: 34998128 DOI: 10.1016/j.marenvres.2022.105558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 12/21/2021] [Accepted: 01/01/2022] [Indexed: 06/14/2023]
Abstract
The Live Fluorescently Labelled Algae (LFLA) technique has been used numerous times to estimate microzooplankton herbivory. Yet, it is unknown how mixoplankton (i.e., single-cell organisms that can combine phototrophy and phagotrophy) affect the outcome of this technique. Hence, we conducted a broad-spectrum assessment of the strengths and weaknesses of the LFLA technique, using several mixoplanktonic and protozooplanktonic grazers. Species from different taxonomic groups and different feeding mechanisms were tested in short-term experiments (ca. 5 h) in the laboratory, at different prey concentrations and during light and dark periods of the day. Overall, our findings suggest that the LFLA technique, due to its short-term nature, is an effective tracker of diel ingestion and digestion rates, and can detect new mixoplanktonic predators. We recommend that, irrespective of the prey concentration, incubations to measure grazing rates with this technique should generally be concluded within 1 h (adaptable to the environmental temperature). Nevertheless, our results also call for caution whenever using LFLA in the field: feeding mechanisms other than direct engulfment (like peduncle feeding) may provide severely biased ingestion rates. Furthermore, size and species selectivity are very hard to circumvent. To reduce the effects of selectivity, we propose the combined use of two distinctly coloured fluorochromes (i.e., distinct emission spectra). With this modification, one could either label different size ranges of prey or account for species-specific interactions in the food web.
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Affiliation(s)
- Guilherme Duarte Ferreira
- Institut de Ciències del Mar, CSIC, Pg. Marítim de la Barceloneta, 37-49, 08003, Barcelona, Spain; Marine Biological Section, University of Copenhagen, DK-3000, Helsingør, Denmark
| | - Joana Figueira
- MARE - Marine and Environmental Science Centre, Polytechnic of Leiria, Peniche, Portugal
| | - Sónia Cotrim Marques
- MARE - Marine and Environmental Science Centre, Polytechnic of Leiria, Peniche, Portugal
| | - Per Juel Hansen
- Marine Biological Section, University of Copenhagen, DK-3000, Helsingør, Denmark
| | - Albert Calbet
- Institut de Ciències del Mar, CSIC, Pg. Marítim de la Barceloneta, 37-49, 08003, Barcelona, Spain.
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Long M, Krock B, Castrec J, Tillmann U. Unknown Extracellular and Bioactive Metabolites of the Genus Alexandrium: A Review of Overlooked Toxins. Toxins (Basel) 2021; 13:905. [PMID: 34941742 PMCID: PMC8703713 DOI: 10.3390/toxins13120905] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 12/08/2021] [Accepted: 12/14/2021] [Indexed: 12/04/2022] Open
Abstract
Various species of Alexandrium can produce a number of bioactive compounds, e.g., paralytic shellfish toxins (PSTs), spirolides, gymnodimines, goniodomins, and also uncharacterised bioactive extracellular compounds (BECs). The latter metabolites are released into the environment and affect a large range of organisms (from protists to fishes and mammalian cell lines). These compounds mediate allelochemical interactions, have anti-grazing and anti-parasitic activities, and have a potentially strong structuring role for the dynamic of Alexandrium blooms. In many studies evaluating the effects of Alexandrium on marine organisms, only the classical toxins were reported and the involvement of BECs was not considered. A lack of information on the presence/absence of BECs in experimental strains is likely the cause of contrasting results in the literature that render impossible a distinction between PSTs and BECs effects. We review the knowledge on Alexandrium BEC, (i.e., producing species, target cells, physiological effects, detection methods and molecular candidates). Overall, we highlight the need to identify the nature of Alexandrium BECs and urge further research on the chemical interactions according to their ecological importance in the planktonic chemical warfare and due to their potential collateral damage to a wide range of organisms.
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Affiliation(s)
- Marc Long
- IFREMER, Centre de Brest, DYNECO Pelagos, 29280 Plouzané, France;
| | - Bernd Krock
- Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany;
| | - Justine Castrec
- University Brest, CNRS, IRD, Ifremer, LEMAR, 29280 Plouzané, France;
- Station de Recherches Sous-Marines et Océanographiques (STARESO), Punta Revellata, BP33, 20260 Calvi, France
| | - Urban Tillmann
- Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany;
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Karlson B, Andersen P, Arneborg L, Cembella A, Eikrem W, John U, West JJ, Klemm K, Kobos J, Lehtinen S, Lundholm N, Mazur-Marzec H, Naustvoll L, Poelman M, Provoost P, De Rijcke M, Suikkanen S. Harmful algal blooms and their effects in coastal seas of Northern Europe. HARMFUL ALGAE 2021; 102:101989. [PMID: 33875185 DOI: 10.1016/j.hal.2021.101989] [Citation(s) in RCA: 70] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 01/22/2021] [Accepted: 01/24/2021] [Indexed: 06/12/2023]
Abstract
Harmful algal blooms (HAB) are recurrent phenomena in northern Europe along the coasts of the Baltic Sea, Kattegat-Skagerrak, eastern North Sea, Norwegian Sea and the Barents Sea. These HABs have caused occasional massive losses for the aquaculture industry and have chronically affected socioeconomic interests in several ways. This status review gives an overview of historical HAB events and summarises reports to the Harmful Algae Event Database from 1986 to the end of year 2019 and observations made in long term monitoring programmes of potentially harmful phytoplankton and of phycotoxins in bivalve shellfish. Major HAB taxa causing fish mortalities in the region include blooms of the prymnesiophyte Chrysochromulina leadbeateri in northern Norway in 1991 and 2019, resulting in huge economic losses for fish farmers. A bloom of the prymesiophyte Prymnesium polylepis (syn. Chrysochromulina polylepis) in the Kattegat-Skagerrak in 1988 was ecosystem disruptive. Blooms of the prymnesiophyte Phaeocystis spp. have caused accumulations of foam on beaches in the southwestern North Sea and Wadden Sea coasts and shellfish mortality has been linked to their occurrence. Mortality of shellfish linked to HAB events has been observed in estuarine waters associated with influx of water from the southern North Sea. The first bloom of the dictyochophyte genus Pseudochattonella was observed in 1998, and since then such blooms have been observed in high cell densities in spring causing fish mortalities some years. Dinoflagellates, primarily Dinophysis spp., intermittently yield concentrations of Diarrhetic Shellfish Toxins (DST) in blue mussels, Mytilus edulis, above regulatory limits along the coasts of Norway, Denmark and the Swedish west coast. On average, DST levels in shellfish have decreased along the Swedish and Norwegian Skagerrak coasts since approximately 2006, coinciding with a decrease in the cell abundance of D. acuta. Among dinoflagellates, Alexandrium species are the major source of Paralytic Shellfish Toxins (PST) in the region. PST concentrations above regulatory levels were rare in the Skagerrak-Kattegat during the three decadal review period, but frequent and often abundant findings of Alexandrium resting cysts in surface sediments indicate a high potential risk for blooms. PST levels often above regulatory limits along the west coast of Norway are associated with A. catenella (ribotype Group 1) as the main toxin producer. Other Alexandrium species, such as A. ostenfeldii and A. minutum, are capable of producing PST among some populations but are usually not associated with PSP events in the region. The cell abundance of A. pseudogonyaulax, a producer of the ichthyotoxin goniodomin (GD), has increased in the Skagerrak-Kattegat since 2010, and may constitute an emerging threat. The dinoflagellate Azadinium spp. have been unequivocally linked to the presence of azaspiracid toxins (AZT) responsible for Azaspiracid Shellfish Poisoning (AZP) in northern Europe. These toxins were detected in bivalve shellfish at concentrations above regulatory limits for the first time in Norway in blue mussels in 2005 and in Sweden in blue mussels and oysters (Ostrea edulis and Crassostrea gigas) in 2018. Certain members of the diatom genus Pseudo-nitzschia produce the neurotoxin domoic acid and analogs known as Amnesic Shellfish Toxins (AST). Blooms of Pseudo-nitzschia were common in the North Sea and the Skagerrak-Kattegat, but levels of AST in bivalve shellfish were rarely above regulatory limits during the review period. Summer cyanobacteria blooms in the Baltic Sea are a concern mainly for tourism by causing massive fouling of bathing water and beaches. Some of the cyanobacteria produce toxins, e.g. Nodularia spumigena, producer of nodularin, which may be a human health problem and cause occasional dog mortalities. Coastal and shelf sea regions in northern Europe provide a key supply of seafood, socioeconomic well-being and ecosystem services. Increasing anthropogenic influence and climate change create environmental stressors causing shifts in the biogeography and intensity of HABs. Continued monitoring of HAB and phycotoxins and the operation of historical databases such as HAEDAT provide not only an ongoing status report but also provide a way to interpret causes and mechanisms of HABs.
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Affiliation(s)
- Bengt Karlson
- Swedish Meteorological and Hydrological Institute, Research and Development, Oceanography, Sven Källfelts gata 15, SE-426 71 Västra Frölunda, Sweden.
| | - Per Andersen
- Aarhus University, Marine Ecology, Vejlsøvej 25, 8600 Silkeborg, Denmark
| | - Lars Arneborg
- Swedish Meteorological and Hydrological Institute, Research and Development, Oceanography, Sven Källfelts gata 15, SE-426 71 Västra Frölunda, Sweden
| | - Allan Cembella
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany
| | - Wenche Eikrem
- University of Oslo, Department of Biosciences, P. O. Box 1066 Blindern, Oslo 0316, Norway; Norwegian Institute for Water Research. Gaustadalleen 21, 0349 Oslo, Norway
| | - Uwe John
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany; Helmholtz Institute for Functional Marine Biodiversity, Ammerländer Heerstraße 231, 26129 Oldenburg, Germany
| | - Jennifer Joy West
- CICERO Center for International Climate Research, P.O. Box 1129, 0318 Blindern, Oslo Norway
| | - Kerstin Klemm
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany
| | - Justyna Kobos
- University of Gdansk, Institute of Oceanography, Division of Marine Biotechnology, Marszalka Pilsudskiego 46, 81-378 Gdynia; POLAND
| | - Sirpa Lehtinen
- Finnish Environment Institute (SYKE), Marine Research Centre, Agnes Sjöbergin katu 2, 00790 Helsinki, Finland
| | - Nina Lundholm
- Natural History Museum of Denmark, University of Copenhagen, Øster Farimagsgade 5, 1353 Copenhagen K, Denmark
| | - Hanna Mazur-Marzec
- University of Gdansk, Institute of Oceanography, Division of Marine Biotechnology, Marszalka Pilsudskiego 46, 81-378 Gdynia; POLAND
| | - Lars Naustvoll
- Institute of Marine Research, Flødevigen Marine Research Station, N-4817 His, Norway
| | - Marnix Poelman
- Wageningen UR, Wageningen Marine Research, P.O. box 77, 4400 AB, Yerseke, The Netherlands
| | - Pieter Provoost
- Intergovernmental Oceanographic Commission, Project Office for IODE, Wandelaarkaai 7/61 - 8400 Oostende, Belgium
| | - Maarten De Rijcke
- Flanders Marine Institute (VLIZ), Wandelaarkaai 7, B-8400 Oostende, Belgium
| | - Sanna Suikkanen
- Finnish Environment Institute (SYKE), Marine Research Centre, Agnes Sjöbergin katu 2, 00790 Helsinki, Finland
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Kremp A, Hansen PJ, Tillmann U, Savela H, Suikkanen S, Voß D, Barrera F, Jakobsen HH, Krock B. Distributions of three Alexandrium species and their toxins across a salinity gradient suggest an increasing impact of GDA producing A. pseudogonyaulax in shallow brackish waters of Northern Europe. HARMFUL ALGAE 2019; 87:101622. [PMID: 31349884 DOI: 10.1016/j.hal.2019.101622] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 05/28/2019] [Accepted: 05/29/2019] [Indexed: 06/10/2023]
Abstract
Blooms of Alexandrium spp. are a well-known phenomenon in Northern European waters. While A. tamarense/catenella, and A. pseudogonyaulax have been reported from marine waters, high densities of A. ostenfeldii are mainly observed at lower salinities in North Sea estuaries and the Baltic Sea, suggesting salinity as a driver of Alexandrium species composition and toxin distribution. To investigate this relationship, an oceanographic expedition through a natural salinity gradient was conducted in June 2016 along the coasts of Denmark. Besides hydrographic data, phytoplankton and sediment samples were collected for analyses of Alexandrium spp. cell and cyst abundances, for toxin measurement and cell isolation. Plankton data revealed the predominance of A. pseudogonyaulax at all transect stations while A. ostenfeldii and A. catenella generally contributed a minor fraction to the Alexandrium community. High abundances of A. pseudogonyaulax in the shallow enclosed Limfjord were accompanied by high amounts of goniodomin A (GDA). This toxin was also detected at low abundances along with A. pseudogonyaulax in the North Sea and the Kattegat. Genetic and morphological characterization of established strains showed high similarity of the Northern European population to distant geographic populations. Despite low cell abundances of A. ostenfeldii, different profiles of cycloimines were measured in the North Sea and in the Limfjord. This field survey revealed that salinity alone does not determine Alexandrium species and toxin distribution, but emphasizes the importance of habitat conditions such as proximity to seed banks, shelter, and high nutrient concentrations. The results show that A. pseudogonyaulax has become a prominent member of the Alexandrium spp. community over the past decade in the study area. Analyses of long term monitoring data from the Limfjord confirmed a recent shift to A. pseudogonyaulax dominance. Cyst and toxin records of the species in Kiel Bight suggest a spreading potential into the brackish Baltic Sea, which might lead to an expansion of blooms under future climate conditions.
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Affiliation(s)
- Anke Kremp
- Leibniz Institut für Ostseeforschung Warnemünde, Seestr. 15, 18119 Rostock, Germany; Finnish Environment Institute, Marine Research Centre, Agnes Sjöbergin katu 2, 00790 Helsinki, Finland.
| | - Per Juel Hansen
- University of Copenhagen, Marine Biological Section, Strandpromenaden 5, 3000 Helsingør, Denmark
| | - Urban Tillmann
- Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Am Handelshafen 12, D-27570 Bremerhaven, Germany
| | - Henna Savela
- Finnish Environment Institute, Marine Research Centre, Agnes Sjöbergin katu 2, 00790 Helsinki, Finland; Department of Biochemistry/Biotechnology, University of Turku, Kiinamyllynkatu 10, 20520 Turku, Finland
| | - Sanna Suikkanen
- Finnish Environment Institute, Marine Research Centre, Agnes Sjöbergin katu 2, 00790 Helsinki, Finland
| | - Daniela Voß
- Institut für Chemie und Biologie des Meeres (ICBM), Schleusenstr. 1, 26382 Wilhelmshaven, Germany
| | - Facundo Barrera
- Departamento de Química Ambiental, Facultad de Ciencias. Centro de Investigación en Biodiversidad y Ambientes Sustentables. Universidad Católica de la Santísima Concepción. Alonso de Ribera 2850, 4090541, Concepción, Chile
| | - Hans Henrik Jakobsen
- University of Århus, Institute for Bioscience, Frederiksborgvej 399, 4000 Roskilde, Denmark
| | - Bernd Krock
- Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Am Handelshafen 12, D-27570 Bremerhaven, Germany
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Strub PT, James C, Montecino V, Rutllant JA, Blanco JL. Ocean circulation along the southern Chile transition region (38°-46°S): Mean, seasonal and interannual variability, with a focus on 2014-2016. PROGRESS IN OCEANOGRAPHY 2019; 172:159-198. [PMID: 33204044 PMCID: PMC7668349 DOI: 10.1016/j.pocean.2019.01.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Satellite and atmospheric model fields are used to describe the wind forcing, surface ocean circulation, temperature and chlorophyll-a pigment concentrations along the coast of southern Chile in the transition region between 38° and 46°S. Located inshore of the bifurcation of the eastward South Pacific Current into the equatorward Humboldt and the poleward Cape Horn Currents, the region also includes the Chiloé Inner Sea and the northern extent of the complex system of fjords, islands and canals that stretch south from near 42°S. The high resolution satellite data reveal that equatorward currents next to the coast extend as far south as 48°-51°S in spring-summer. They also display detailed distributions of forcing from wind stress and wind stress curl near the coast and within the Inner Sea. Between 38°-46°S, both winds and surface currents during 1993-2016 change directions seasonally from equatorward during summer upwelling to poleward during winter downwelling, with cooler SST and greater surface chlorophyll-a concentrations next to the coast during upwelling, opposite conditions during downwelling. Over interannual time scales during 1993-2016, there is a strong correlation between equatorial El Niño events and sea level and a moderate correlation with alongshore currents. Looking more closely at the 2014-2016 period, we find a marginal El Niño during 2014 and a strong El Niño during 2015 that connect the region to the tropics through the oceanic pathway, with some atmospheric connections through the phenomenon of atmospheric blocking (as noted by others). The period also includes a Harmful Algal Bloom of the dinoflagellate Alexandrium catenella during early-2016 that occurred during a sequence of physical conditions (winds, currents and temperatures) that would favor such a bloom. The most anomalous physical condition during this specific bloom is an extreme case of atmospheric blocking that creates a long period of calm in austral autumn after strong upwelling in austral summer. The blocking is related to the 2015-2016 El Niño and an unusual coincident positive phase of the Southern Annular Mode.
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Affiliation(s)
- P. Ted Strub
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, 104 CEOAS Admin. Bldg, Corvallis, OR 97331-5503, United States
| | - Corinne James
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, 104 CEOAS Admin. Bldg, Corvallis, OR 97331-5503, United States
| | - Vivian Montecino
- Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago, Chile
| | - José A. Rutllant
- Departamento de Geofísica, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Casilla 2777, Santiago, Chile
- Center for Advanced Studies in Arid Zones (CEAZA), Coquimbo, Chile
| | - José Luis Blanco
- Bluewater Consulting Company, Ramalab Laboratory, O’Higgins 464, Castro, Chile
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Armstrong CT, Erdner DL, McClelland JW, Sanderson MP, Anderson DM, Gobler CJ, Smith JL. Impact of nitrogen chemical form on the isotope signature and toxicity of a marine dinoflagellate. MARINE ECOLOGY PROGRESS SERIES 2018; 602:63-76. [PMID: 31762524 PMCID: PMC6874107 DOI: 10.3354/meps12619] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Despite a global interest in the relationship between harmful algal blooms (HABs) and eutrophication, the impact of natural versus anthropogenic nutrient sources on species composition or toxicity of HABs remains unclear. Stable isotopes are used to identify and track nitrogen (N) sources to water bodies, and thus can be used to ascertain the N source(s) used by the phytoplankton in those systems. To focus this tool for a particular species, the fundamental patterns of N isotope fractionation by that organism must first be understood. While literature is available describing N isotope fractionation by diatoms and coccolithophores, data are lacking regarding dinoflagellates. Here we investigated the effects of N chemical form on isotope fractionation (Δ) and toxin content using isolates of the autotrophic dinoflagellate, Alexandrium catenella, in single-N and mixed-N experiments. Growth of A. catenella exclusively on nitrate (NO3 -), ammonium (NH4 +), or urea, resulted in Δ of 2.7±1.4‰, 29±9.3‰, or 0.3±0.1‰, respectively, with the lowest cellular toxicity reported during urea utilization. Cells initially utilized NH4 + and urea when exposed to mixed-N medium, and only utilized NO3 - after NH4 + decreased below 2-4 μM. This pattern of N preference was similar across all N treatments, suggesting that there is no effect of preconditioning on N chemical preference by A. catenella. In NO3 - and urea-rich environments, the δ15N of Alexandrium catenella would resemble the source(s) of N utilized, supporting this tool's utility as a tracer of N source(s) facilitating bloom formation, however, caution is advisable in NH4 + rich environments where the large Δ value could lead to misinterpretation of the signal.
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Affiliation(s)
- C Taylor Armstrong
- Virginia Institute of Marine Science, Gloucester Point, VA 23062 USA , ,
| | - Deana L Erdner
- University of Texas-Marine Science Institute, Port Aransas, TX 78373 USA ,
| | - James W McClelland
- University of Texas-Marine Science Institute, Port Aransas, TX 78373 USA ,
| | - Marta P Sanderson
- Virginia Institute of Marine Science, Gloucester Point, VA 23062 USA , ,
| | | | | | - Juliette L Smith
- Virginia Institute of Marine Science, Gloucester Point, VA 23062 USA , ,
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