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Journal of Plankton Research

Julia M Diaz, Sydney Plummer, Carmelo Tomas, Catharina Alves-de-Souza
Harmful bloom-forming algae include some of the most prolific microbial producers of extracellular reactive oxygen species (ROS). However, the taxonomic diversity of ROS production, the underlying physiological mechanisms and ecophysiological roles of ROS cycling are not completely characterized among phytoplankton taxa that form harmful algal blooms (HABs). This study examines the extracellular production of the ROS superoxide and hydrogen peroxide by five marine HAB species: Chattonella marina , Heterosigma akashiwo , Karenia brevis , Pseudo-nitzschia sp...
November 2018: Journal of Plankton Research
Julia M Diaz, Sydney Plummer
In aquatic environments, phytoplankton represent a major source of reactive oxygen species (ROS) such as superoxide and hydrogen peroxide. Many phytoplankton taxa also produce extracellular ROS under optimal growth conditions in culture. However, the physiological purpose of extracellular ROS production by phytoplankton and its wider significance to ecosystem-scale trophic interactions and biogeochemistry remain unclear. Here, we review the rates, taxonomic diversity, subcellular mechanisms and functions of extracellular superoxide and hydrogen peroxide production by phytoplankton with a view towards future research directions...
November 2018: Journal of Plankton Research
Daffne C López-Sandoval, Antonio Delgado-Huertas, Susana Agustí
Due to the increasing constraints on using the radioactive isotope 14 C to measure primary productivity (14 C-PP), we determined the surface carbon fixation rates in the Mediterranean Sea, using the alternative stable isotope 13 C method (13 C-PP). Rates obtained (13 C-POCp) were compared with simultaneous 14 C-POCp measurements in samples of different volumes (72 mL and 1.2 L). We also tested the variation of the percentage of dissolved primary production (PER), to the total productivity using organic and inorganic filters (14 C method)...
September 2018: Journal of Plankton Research
Sanae Chiba, Sonia Batten, Corinne S Martin, Sarah Ivory, Patricia Miloslavich, Lauren V Weatherdon
Oceanographers have an increasing responsibility to ensure that the outcomes of scientific research are conveyed to the policy-making sphere to achieve conservation and sustainable use of marine biodiversity. Zooplankton monitoring projects have helped to increase our understanding of the processes by which marine ecosystems respond to climate change and other environmental variations, ranging from regional to global scales, and its scientific value is recognized in the contexts of fisheries, biodiversity and global change studies...
September 2018: Journal of Plankton Research
Piotr Maszczyk, Ewa Babkiewicz, Marta Czarnocka-Cieciura, Z Maciej Gliwicz, Janusz Uchmański, Paulina Urban
The vertical distribution of planktonic animals, such as Daphnia , in overlapping gradients of food concentration and risk of visual predation should depend on Daphnia population density and should be the result of the group effect of optimizing decisions taken by each individual (juvenile or adult), trading-off a high growth rate to low mortality risk. We tested this hypothesis by comparing the theoretical distributions from simulations based on an experimentally parameterized, optimizing individual-based model (consistent with the assumptions of the concept of the interference ideal free distribution with costs) with distributions observed in laboratory experiments...
July 2018: Journal of Plankton Research
Scarlett Sett, Kai G Schulz, Lennart T Bach, Ulf Riebesell
An indoor mesocosm experiment was carried out to investigate the combined effects of ocean acidification and warming on the species composition and biogeochemical element cycling during a winter/spring bloom with a natural phytoplankton assemblage from the Kiel fjord, Germany. The experimental setup consisted of a "Control" (ambient temperature of ~4.8 °C and ~535 ± 25 μatm p CO2 ), a "High-CO2 " treatment (ambient temperature and initially 1020 ± 45 μatm p CO2 ) and a "Greenhouse" treatment (~8...
July 2018: Journal of Plankton Research
Alexander Dreshchinskii, Anja Engel
The sea surface microlayer (SML) is the uppermost layer of the water column that links the ocean and atmosphere. It accumulates a variety of biogenic surface-active and buoyant substances, including gelatinous material, such as transparent exopolymer particles (TEP) and Coomassie stainable particles (CSP), potentially affecting air-sea exchange processes. Here, we studied the influence of the annual cycle of phytoplankton production on organic matter (OM) accumulation in the SML relative to the subsurface water (SSW)...
November 2017: Journal of Plankton Research
Andrea Bozman, Josefin Titelman, Stein Kaartvedt, Ketil Eiane, Dag L Aksnes
We tested the hypothesis that the coronate jellyfish Periphylla periphylla distributes vertically according to a preferential range of absolute light intensities. The study was carried out in Lurefjorden, Norway, a fjord characterized by mass occurrences of this jellyfish. We collected data on the vertical distribution of P. periphylla medusa during day, dusk and night periods from video observations by a remotely operated vehicle in relation to estimated ambient light levels. Our results suggest that large P...
March 2017: Journal of Plankton Research
Michael Blackett, Cathy H Lucas, Katherine Cook, Priscilla Licandro
We applied the concept of source-sink dynamics to investigate a recent (1999-2013) increase in the occurrence of the siphonophore Muggiaea atlantica in Scottish coastal waters. Our aim was to determine whether this change represented the establishment of resident populations (i.e. "sources"), or transient populations reliant on immigration (i.e. "sinks"). First, we show that local production was not always sufficient to account for recruitment (a "source" prerequisite), suggesting reliance on immigration (a "sink" prerequisite)...
January 2017: Journal of Plankton Research
J Paczkowska, O F Rowe, L Schlüter, C Legrand, B Karlson, A Andersson
It is well-known that nutrients shape phytoplankton communities in marine systems, but in coastal waters allochthonous dissolved organic matter (ADOM) may also be of central importance. We studied how humic substances (proxy of ADOM) and other variables influenced the nutritional strategies, size structure and pigment content of the phytoplankton community along a south-north gradient in the Baltic Sea. During the summer, the proportion of mixotrophs increased gradually from the phosphorus-rich south to the ADOM-rich north, probably due to ADOM-fueled microbes...
January 2017: Journal of Plankton Research
Andrew P Rees, Karen Tait, Claire E Widdicombe, Graham D Quartly, Andrea J McEvoy, Lisa Al-Moosawi
Trichodesmium, a colonial cyanobacterium typically associated with tropical waters, was observed between January and April 2014 in the western English Channel. Sequencing of the heterocyst differentiation (hetR) and 16S rRNA genes placed this community within the Clade IV Trichodesmium, an understudied clade previously found only in low numbers in warmer waters. Nitrogen fixation was not detected although measurable rates of nitrate uptake and carbon fixation were observed. Trichodesmium RuBisCO transcript abundance relative to gene abundance suggests the potential for viable and potentially active Trichodesmium carbon fixation...
May 2016: Journal of Plankton Research
Jennifer Marie Questel, Leocadio Blanco-Bercial, Russell R Hopcroft, Ann Bucklin
The genus Pseudocalanus (Copepoda, Calanoida) is among the most numerically dominant copepods in eastern North Pacific and Pacific-Arctic waters. We compared population connectivity and phylogeography based on DNA sequence variation for a portion of the mitochondrial cytochrome oxidase I gene for four Pseudocalanus species with differing biogeographical ranges within these ocean regions. Genetic analyses were linked to characterization of biological and physical environmental variables for each sampled region...
May 2016: Journal of Plankton Research
Boris Espinasse, Sünnje L Basedow, Vigdis Tverberg, Tore Hattermann, Ketil Eiane
High Calanus finmarchicus abundances were recorded in wintertime in Vestfjorden, close to the main cod breeding grounds off Lofoten and Vesterålen, northern Norway. The mean abundance for locations with water depth >500 m was ∼37000 ind. m(-2) (range: 26700-49000 ind. m(-2)). To our knowledge, this is the first report of massive overwintering of C. finmarchicus on the Norwegian shelf. Because of the observed size and location of this population, we argue that local overwintering on the northern Norwegian shelf can contribute significantly to sustain a C...
May 2016: Journal of Plankton Research
Shunyan Cheung, Xiaomin Xia, Cui Guo, Hongbin Liu
Oxygen minimum zones (OMZs), characterized by depleted dissolved oxygen concentration in the intermediate depth of the water column, are predicted to expand under the influence of global warming. Recent studies in the Eastern Tropical South Pacific Ocean and Arabian Sea have reported that heterotrophic nitrogen fixation is active in the OMZs. In this study, we investigated the community structure of diazotrophs in the OMZ of the Costa Rica Dome (CRD) upwelling region in the Eastern Tropical North Pacific Ocean, using 454-pyrosequencing of nifH gene amplicons...
March 2016: Journal of Plankton Research
Michael R Landry, Karen E Selph, Moira Décima, Andrés Gutiérrez-Rodríguez, Michael R Stukel, Andrew G Taylor, Alexis L Pasulka
We investigated phytoplankton production rates and grazing fates in the Costa Rica Dome (CRD) during summer 2010 based on dilution depth profiles analyzed by flow cytometry and pigments and mesozooplankton grazing assessed by gut fluorescence. Three community production estimates, from (14)C uptake (1025 ± 113 mg C m(-2) day(-1)) and from dilution experiments analyzed for total Chla (990 ± 106 mg C m(-2) day(-1)) and flow cytometry populations (862 ± 71 mg C m(-2) day(-1)), exceeded regional ship-based values by 2-3-fold...
March 2016: Journal of Plankton Research
Michael R Stukel, Claudia R Benitez-Nelson, Moira Décima, Andrew G Taylor, Carolyn Buchwald, Michael R Landry
The Costa Rica Dome is a picophytoplankton-dominated, open-ocean upwelling system in the Eastern Tropical Pacific that overlies the ocean's largest oxygen minimum zone. To investigate the efficiency of the biological pump in this unique area, we used shallow (90-150 m) drifting sediment traps and (234)Th:(238)U deficiency measurements to determine export fluxes of carbon, nitrogen and phosphorus in sinking particles. Simultaneous measurements of nitrate uptake and shallow water nitrification allowed us to assess the equilibrium balance of new and export production over a monthly timescale...
March 2016: Journal of Plankton Research
Stephen B Baines, Xi Chen, Benjamin S Twining, Nicholas S Fisher, Michael R Landry
Mineral limitation of mesozooplankton production is possible in waters with low trace metal availability. As a step toward estimating mesozooplankton Fe and Zn requirements under such conditions, we measured tissue concentrations of major and trace nutrient elements within size-fractioned zooplankton samples collected in and around the Costa Rica Upwelling Dome, a region where phytoplankton growth may be co-limited by Zn and Fe. The geometric mean C, N, P contents were 27, 5.6 and 0.21 mmol gdw(-1), respectively...
March 2016: Journal of Plankton Research
Moira Décima, Michael R Landry, Michael R Stukel, Lucia Lopez-Lopez, Jeffrey W Krause
We investigated standing stocks and grazing rates of mesozooplankton assemblages in the Costa Rica Dome (CRD), an open-ocean upwelling ecosystem in the eastern tropical Pacific. While phytoplankton biomass in the CRD is dominated by picophytoplankton (<2-µm cells) with especially high concentrations of Synechococcus spp., we found high mesozooplankton biomass (∼5 g dry weight m(-2)) and grazing impact (12-50% integrated water column chlorophyll a), indicative of efficient food web transfer from primary producers to higher levels...
March 2016: Journal of Plankton Research
Melanie L Jackson, Sharon L Smith
A variety of ecological strategies for tolerance of low-oxygen conditions within the Costa Rica Dome (CRD) area of the Eastern Tropical Pacific are documented for the copepod family Eucalanidae. During the summer of 2010, we compared the ecological strategies used by the Eucalanidae inside and outside the central CRD region. We compared the vertical and horizontal distributions of five species, Eucalanus inermis, Subeucalanus subtenuis, Subeucalanus subcrassus, Subeucalanus pileatus and Pareucalanus attenuatus together with Rhincalanus species, in the epipelagic (upper 200 m) among four locations, which we grouped into a section roughly crossing the core CRD area (inside-outside core CRD)...
March 2016: Journal of Plankton Research
Joaquim I Goes, Helga do Rosario Gomes, Karen E Selph, Michael R Landry
The Costa Rica Dome (CRD) is a unique open-ocean upwelling system, with picophytoplankton dominance of phytoplankton biomass and suppressed diatoms, yet paradoxically high export of biogenic silica. As a part of Flux and Zinc Experiments cruise in summer (June-July 2010), we conducted shipboard incubation experiments in the CRD to examine the potential roles of Si, Zn, Fe and light as regulating factors of phytoplankton biomass and community structure. Estimates of photosynthetic quantum yields revealed an extremely stressed phytoplankton population that responded positively to additions of silicic acid, iron and zinc and higher light conditions...
March 2016: Journal of Plankton Research
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