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  • 1
    Publication Date: 2024-03-22
    Description: The oceans' uptake of anthropogenic carbon dioxide (CO2) decreases seawater pH and alters the inorganic carbon speciation – summarized in the term ocean acidification (OA). Already today, coastal regions experience episodic pH events during which surface layer pH drops below values projected for the surface ocean at the end of the century. Future OA is expected to further enhance the intensity of these coastal extreme pH events. To evaluate the influence of such episodic OA events in coastal regions, we deployed eight pelagic mesocosms for 53 days in Raunefjord, Norway, and enclosed 56–61 m**3 of local seawater containing a natural plankton community under nutrient limited post-bloom conditions. Four mesocosms were enriched with CO2 to simulate extreme pCO2 levels of 1978-2069 μatm while the other four served as untreated controls. Here, we present results from multivariate analyses on OA-induced changes in the phyto-, micro-, and mesozooplankton community structure. Pronounced differences in the plankton community emerged early in the experiment, and were amplified by enhanced top-down control throughout the study period. The plankton groups responding most profoundly to high CO2 conditions were cyanobacteria (negative), chlorophyceae (negative), auto- and heterotrophic microzooplankton (negative), and a variety of mesozooplanktonic taxa, including copepoda (mixed), appendicularia (positive), hydrozoa (positive), fish larvae (positive), and gastropoda (negative). The restructuring of the community coincided with significant changes in the concentration and elemental stoichiometry of particulate organic matter. Results imply that extreme CO2 events can lead to a substantial reorganization of the planktonic food web, affecting multiple trophic levels from phytoplankton to primary and secondary consumers.
    Keywords: Alkalinity, total; Alkalinity, total, standard deviation; Ammonium; Aragonite saturation state; Aragonite saturation state, standard deviation; Bicarbonate ion; Bicarbonate ion, standard deviation; Biogenic silica; Biomass/Abundance/Elemental composition; Calcite saturation state; Calcite saturation state, standard deviation; Calculated using seacarb; Calculated using seacarb after Nisumaa et al. (2010); Calculated using seacarb after Orr et al. (2018); Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, standard deviation; Carbon, organic, particulate; Carbon, organic, particulate/Nitrogen, organic, particulate ratio; Carbon, organic, particulate/Phosphorus, particulate ratio; Carbon, total, particulate; Carbonate ion; Carbonate ion, standard deviation; Carbonate system computation flag; Carbon dioxide; Carbon dioxide, standard deviation; Chlorophyceae indeterminata, biomass as carbon; Chlorophyll a; Chlorophyll a, standard deviation; Chrysophyceae indeterminata, biomass as carbon; Coast and continental shelf; Community composition and diversity; Cryptophyceae indeterminata, biomass as carbon; Cyanophyceae, biomass as carbon; DATE/TIME; Day of experiment; Diatoms indeterminata, biomass as carbon; Dinophyceae indeterminata, biomass as carbon; Entire community; Event label; Field experiment; Fjord; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Fugacity of carbon dioxide in seawater, standard deviation; KOSMOS_2015; KOSMOS_2015_Mesocosm-M1; KOSMOS_2015_Mesocosm-M2; KOSMOS_2015_Mesocosm-M3; KOSMOS_2015_Mesocosm-M4; KOSMOS_2015_Mesocosm-M5; KOSMOS_2015_Mesocosm-M6; KOSMOS_2015_Mesocosm-M7; KOSMOS_2015_Mesocosm-M8; KOSMOS_2015_Mesocosm-M9; KOSMOS Bergen; MESO; Mesocosm experiment; Mesocosm label; Mesocosm or benthocosm; Nitrate; Nitrate and Nitrite; Nitrite; Nitrogen, organic, particulate; Nitrogen, organic, particulate/Phosphorus, organic, particulate ratio; Nitrogen, total, particulate; North Atlantic; OA-ICC; Ocean Acidification International Coordination Centre; Partial pressure of carbon dioxide, standard deviation; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Particulate inorganic carbon/particulate organic carbon ratio; Pelagos; pH; pH, standard deviation; Phosphate; Phosphate, total, particulate; Potentiometric titration; Prasinophyceae indeterminata, biomass as carbon; Primary production/Photosynthesis; Prymnesiophyceae indeterminata, biomass as carbon; Ratio; Salinity; Salinity, standard deviation; Silicate; Temperate; Temperature, water; Temperature, water, standard deviation; Type
    Type: Dataset
    Format: text/tab-separated-values, 18566 data points
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  • 2
    Publication Date: 2024-03-15
    Description: We conducted an experiment with large volume in situ mesocosms (~55–60 m3 and 21 m depth) in Raunefjord (Bergen), Norway in 2015 to investigate how ocean acidification (OA) extreme events affect food web structure and carbon export in a natural plankton community, particularly focusing on the keystone species Oikopleura dioica, a globally abundant appendicularian.
    Keywords: Abundance per volume; Alkalinity, total; Animalia; Aragonite saturation state; Area/locality; Bicarbonate ion; Biomass/Abundance/Elemental composition; Calcite saturation state; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbon, organic, particulate, flux; Carbon, organic, particulate, suspended; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Chordata; Coast and continental shelf; Community composition and diversity; Counting; DATE/TIME; Day of experiment; Elemental analyser; Entire community; Event label; Field experiment; Flow cytometry Accuri C6; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Growth/Morphology; KOSMOS_2015; KOSMOS_2015_Mesocosm-M1; KOSMOS_2015_Mesocosm-M2; KOSMOS_2015_Mesocosm-M3; KOSMOS_2015_Mesocosm-M4; KOSMOS_2015_Mesocosm-M5; KOSMOS_2015_Mesocosm-M6; KOSMOS_2015_Mesocosm-M7; KOSMOS_2015_Mesocosm-M8; KOSMOS Bergen; Length; MESO; Mesocosm experiment; Mesocosm label; Mesocosm or benthocosm; Microphytoplankton, biomass as carbon; Nanophytoplankton, biomass as carbon; North Atlantic; OA-ICC; Ocean Acidification International Coordination Centre; Oikopleura dioica; Other studied parameter or process; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Pelagos; pH; Phosphate; Picophytoplankton, biomass as carbon; Salinity; Silicate; Single species; Species, unique identification; Species, unique identification (Semantic URI); Species, unique identification (URI); Temperate; Temperature, water; Treatment: partial pressure of carbon dioxide; Type of study; Zooplankton
    Type: Dataset
    Format: text/tab-separated-values, 5405 data points
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  • 3
    Publication Date: 2023-02-08
    Description: Invasive alien species continue to arrive in new locations with no abatement in rate, and thus greater predictive powers surrounding their ecological impacts are required. In particular, we need improved means of quantifying the ecological impacts of new invasive species under different contexts. Here, we develop a suite of metrics based upon the novel Relative Impact Potential (RIP) metric, combining the functional response (consumer per capita effect), with proxies for the numerical response (consumer population response), providing quantification of invasive species ecological impact. These metrics are comparative in relation to the eco-evolutionary baseline of trophically analogous natives, as well as other invasive species and across multiple populations. Crucially, the metrics also reveal how impacts of invasive species change under abiotic and biotic contexts. While studies focused solely on functional responses have been successful in predictive invasion ecology, RIP retains these advantages while adding vital other predictive elements, principally consumer abundance. RIP can also be combined with propagule pressure to quantify overall invasion risk. By highlighting functional response and numerical response proxies, we outline a user-friendly method for assessing the impacts of invaders of all trophic levels and taxonomic groups. We apply the metric to impact assessment in the face of climate change by taking account of both changing predator consumption rates and prey reproduction rates. We proceed to outline the application of RIP to assess biotic resistance against incoming invasive species, the effect of evolution on invasive species impacts, application to interspecific competition, changing spatio-temporal patterns of invasion, and how RIP can inform biological control. We propose that RIP provides scientists and practitioners with a user-friendly, customisable and, crucially, powerful technique to inform invasive species policy and management.
    Type: Article , PeerReviewed
    Format: text
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  • 4
    Publication Date: 2023-02-08
    Description: Lipids, in their function as trophic markers in food webs and organic matter source indicators in the water column and sediments, provide a tool for reconstructing the complexity of global change effects on aquatic ecosystems. It remains unclear how ongoing changes in multiple environmental drivers affect the production of key lipid biomarkers in marine phytoplankton. Here, we tested the responses of sterols, alkenones and fatty acids (FAs) in the diatom Phaeodactylum tricornutum, the cryptophyte Rhodomonas sp. and the haptophyte Emiliania huxleyi under a full-factorial combination of three temperatures (12, 18 and 24 ∘C), three N : P supply ratios (molar ratios 10 : 1, 24 : 1 and 63 : 1) and two pCO2 levels (560 and 2400 µatm) in semicontinuous culturing experiments. Overall, N and P deficiency had a stronger effect on per-cell contents of sterols, alkenones and FAs than warming and enhanced pCO2. Specifically, P deficiency caused an overall increase in biomarker production in most cases, while N deficiency, warming and high pCO2 caused nonsystematic changes. Under future ocean scenarios, we predict an overall decrease in carbon-normalized contents of sterols and polyunsaturated fatty acids (PUFAs) in E. huxleyi and P. tricornutum and a decrease in sterols but an increase in PUFAs in Rhodomonas sp. Variable contents of lipid biomarkers indicate a diverse carbon allocation between marine phytoplankton species in response to changing environments. Thus, it is necessary to consider the changes in key lipids and their consequences for food-web dynamics and biogeochemical cycles, when predicting the influence of global change on marine ecosystems.
    Type: Article , PeerReviewed
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  • 5
    Publication Date: 2023-02-08
    Description: A mesocosm approach was used to investigate the effects of ocean acidification (OA) on a natural plankton community in coastal waters off Norway by manipulating CO2 partial pressure ( pCO2). Eight enclosures were deployed in the Raunefjord near Bergen. Treatment levels were ambient (~320 µatm) and elevated pCO2 (~2000 µatm), each in 4 replicate enclosures. The experiment lasted for 53 d in May-June 2015. To assess impacts of OA on the plankton community, phytoplankton and protozooplankton biomass and total seston fatty acid content were analyzed. In both treatments, the plankton community was dominated by the dinoflagellate Ceratium longipes. In the elevated pCO2 treatment, however, biomass of this species as well as that of other dinoflagellates was strongly negatively affected. At the end of the experiment, total dinoflagellate biomass was 4-fold higher in the control group than under elevated pCO2 conditions. In a size comparison of C. longipes, cell size in the high pCO2 treatment was significantly larger. The ratio of polyunsaturated fatty acids to saturated fatty acids of seston decreased at high pCO2. In particular, the concentration of docosahexaenoic acid (C 22:6n3c), essential for development and reproduction of metazoans, was less than half at high pCO2 compared to ambient pCO2. Thus, elevated pCO2 led to a deterioration in the quality and quantity of food in a natural plankton community, with potential consequences for the transfer of matter and energy to higher trophic levels
    Type: Article , PeerReviewed
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  • 6
    Publication Date: 2023-02-08
    Description: Territorial protandry, or early season male-biased settlement at breeding sites, is a widespread phenomenon in a range of animal breeding systems. While protandry is common across several avian lineages and has been linked with increased reproductive success of earlier breeding males in terrestrial species, the selective advantage of breeding protandry has only rarely been studied in seabirds. We assessed the seasonal changes in the sex ratio at the breeding site and sexspecific correlates of arrival date with reproductive success during 2 breeding seasons of a colonial seabird, the Australasian Gannet (Morus serrator), at Cape Kidnappers, New Zealand.We found no biases in overall sex ratios of adults and fledglings but detected a male sex bias during nest site establishment, and a significantly higher probability of reproductive success for earlier-settling males. In contrast, the reproductive success of females did not correlate with the timing of arrival. Our findings provide an assessment of the sex differences in reproductive correlates of the timing of breeding settlement in gannets and are consistent with selective advantages as suggested by indirect selection hypotheses. This study contributes to our understanding of the fitness benefits of protandry, and its linkages with sex differences in breeding philopatry and mate fidelity, in a long-lived seabird species with obligate and extended biparental care.
    Type: Article , PeerReviewed
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  • 7
    Publication Date: 2023-02-08
    Description: The copepod Acartia tonsa is a key component of a wide range of marine ecosystems, linking energy transfer from phytoplankton to higher trophic levels, and has a central role in productivity and biogeochemistry. The interaction of end-of-century global warming and ocean acidification scenarios with testing moderate temperature effects on a seminatural copepod community is needed to understand future community functioning. Here, we deployed a mesocosm experimental set-up with a full factorial design using two temperatures (13°C and 19°C) crossed with a pCO2 gradient ranging from ambient (550 μatm) to 3000 μatm. We used the natural bacteria, phyto- and microzooplankton species composition and biomass of the Kiel Bight and tested the response of A. tonsa development, carbon growth, mortality, size and condition. The tested traits were differently affected by the interaction of temperature and acidification. Ocean acidification increased development, carbon growth, size and mortality under the warming scenario of 19°C. At 13°C mortality rates decreased, while carbon growth, size and condition increased with acidification. We conclude from our experimental approach that a single species shows a variety of responses depending on the focal functional trait. Trait-specific mesozooplankton responses need to be further investigated and compared between geographical regions, seasons and taxonomic groups.
    Type: Article , PeerReviewed
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  • 8
    Publication Date: 2022-01-31
    Description: Highlights: • A combination of methods is necessary to assess the foraging ecology of avocets. • Marine fish make up a higher proportion of the diet than previously assumed. • Telemetry data indicate that intertidal channels are important foraging grounds. • Avocet behaviour implies high fish densities in intertidal channels. • Protected areas are important habitats for breeding, resting and foraging avocets. Abstract: Pied avocets (Recurvirostra avosetta) breeding in the Wadden Sea typically forage in shallow water, using their characteristic upward-curved bill to feed on macrozooplankton in the water column and prey items in the uppermost centimetre of the sediment. Former studies on prey choice based on droppings and visual observations of feeding behaviour suggested that ragworms were the main prey items of avocets. The present study combined different methods to assess the foraging ecology of breeding avocets in the eastern Wadden Sea. Important foraging grounds were identified using GPS telemetry. Diet was analysed from droppings and stable isotope signatures of whole blood samples from breeding avocets at two different colonies in April–June 2014 and 2015. Analysis of droppings confirmed the former results, but stable isotope analysis suggested that marine fish comprised the highest proportion of the avocet diet by mass. Telemetry data indicated that intertidal channels close to the breeding areas were used as the main foraging grounds. Avocets performed short foraging trips (maximum distance: 0.3–5.9 km) mainly during the daytime. Logger data and diet analysis thus implied the existence of high fish densities in intertidal channels, underlining the importance of this saltmarsh habitat as foraging areas for breeding avocets.
    Type: Article , PeerReviewed
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  • 9
    Publication Date: 2022-01-31
    Description: We present the first study to examine the year-round distribution, activity patterns, and habitat use of one of New Zealand’s most common seabirds, the fluttering shearwater (Puffinus gavia). Seven adults from Burgess Island, in the Hauraki Gulf, and one individual from Long Island, in the Marlborough Sounds, were successfully tracked with combined light-saltwater immersion loggers for one to three years. Our tracking data confirms that fluttering shearwaters employ different overwintering dispersal strategies, where three out of eight individuals, for at least one of the three years when they were being tracked, crossed the Tasman Sea to forage over coastal waters along eastern Tasmania and southeastern Australia. Resident birds stayed confined to waters of northern and central New Zealand year-round. Although birds frequently foraged over pelagic shelf waters, the majority of tracking locations were found over shallow waters close to the coast. All birds foraged predominantly in daylight and frequently visited the colony at night throughout the year. We found no significant inter-seasonal differences in the activity patterns, or between migratory and resident individuals. Although further studies of inter-colony variation in different age groups will be necessary, this study presents novel insights into year-round distribution, activity patterns and habitat use of the fluttering shearwater, which provide valuable baseline information for conservation as well as for further ecological studies.
    Type: Article , PeerReviewed
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  • 10
    Publication Date: 2022-01-31
    Description: We present the first study to examine the year-round distribution, activity patterns, and habitat use of one of New Zealand's most common seabirds, the fluttering shearwater (Puffinus gavia). Seven adults from Burgess Island, in the Hauraki Gulf, and one individual from Long Island, in the Marlborough Sounds, were successfully tracked with combined light-saltwater immersion loggers for one to three years. Our tracking data confirms that fluttering shearwaters employ different overwintering dispersal strategies, where three out of eight individuals, for at least one of the three years when they were being tracked, crossed the Tasman Sea to forage over coastal waters along eastern Tasmania and southeastern Australia. Resident birds stayed confined to waters of northern and central New Zealand year-round. Although birds frequently foraged over pelagic shelf waters, the majority of tracking locations were found over shallow waters close to the coast. All birds foraged predominantly in daylight and frequently visited the colony at night throughout the year. We found no significant inter-seasonal differences in the activity patterns, or between migratory and resident individuals. Although further studies of inter-colony variation in different age groups will be necessary, this study presents novel insights into year-round distribution, activity patterns and habitat use of the fluttering shearwater, which provide valuable baseline information for conservation as well as for further ecological studies.
    Type: Article , PeerReviewed
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