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  • AGU (American Geophysical Union)  (59)
  • MDPI  (50)
  • PANGAEA  (41)
  • EuroSea  (31)
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  • 11
    Publication Date: 2023-02-08
    Description: Ocean deoxygenation is a threat to marine ecosystems. We evaluated the potential of two ocean intervention technologies, i.e. “artificial downwelling (AD)” and “artificial upwelling (AU)”, for remedying the expansion of Oxygen Deficient Zones (ODZs). The model‐based assessment simulated AD and AU implementations for 80 years along the eastern Pacific ODZ. When AD was simulated by pumping surface seawater to the 178 ~ 457 m depth range of the ODZ, vertically integrated oxygen increased by up to 4.5% in the deployment region. Pumping water from 457 m depth to the surface (i.e. AU), where it can equilibrate with the atmosphere, increased the vertically integrated oxygen by 1.03%. However, both simulated AD and AU increased biological production via enhanced nutrient supply to the sea surface, resulting in enhanced export production and subsequent aerobic remineralization also outside of the actual implementation region, and an ultimate net decline of global oceanic oxygen.
    Type: Article , PeerReviewed
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  • 12
    Publication Date: 2024-02-07
    Description: Shallow, semi-enclosed coastal systems are particularly prone to eutrophication. Depending on local site conditions and historical nutrient legacies, sea-based measures might be necessary in addition to land-based nutrient removal. In this study, C:N:P ratios were combined with open-source bathymetric information and linked with the prevailing geomorphological and sedimentological regimes to gain insights into nutrient hotspots and understand their sources and fate in coastal waters. Land-based sediment samples were taken behind outlets at three sites in Eckernförde Bay (Baltic Sea), and complemented with ship-based sampling at locations approximately 8 m and 12 m water depth. The total carbon, nitrogen and phosphorus concentrations in surface sediments increased at deeper sites. This suggests that an increased downslope particle transport and deposition regime, based on local geomorphology, might influence nutrient hotspots to a larger extent than proximity to sources (e.g., outlets). Overall, the recorded C:N ratios (mean = 28.12) were closer to the ratio of terrestrial plants than those of marine phytoplankton, indicating allochthonous sources of organic matter.
    Type: Article , PeerReviewed
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  • 13
    Publication Date: 2022-01-31
    Description: Gelatinous zooplankton (Cnidaria, Ctenophora, and Urochordata, namely, Thaliacea) are ubiquitous members of plankton communities linking primary production to higher trophic levels and the deep ocean by serving as food and transferring “jelly‐carbon” (jelly‐C) upon bloom collapse. Global biomass within the upper 200 m reaches 0.038 Pg C, which, with a 2–12 months life span, serves as the lower limit for annual jelly‐C production. Using over 90,000 data points from 1934 to 2011 from the Jellyfish Database Initiative as an indication of global biomass (JeDI: http://jedi.nceas.ucsb.edu, http://www.bco‐dmo.org/dataset/526852), upper ocean jelly‐C biomass and production estimates, organism vertical migration, jelly‐C sinking rates, and water column temperature profiles from GLODAPv2, we quantitatively estimate jelly‐C transfer efficiency based on Longhurst Provinces. From the upper 200 m production estimate of 0.038 Pg C year−1, 59–72% reaches 500 m, 46–54% reaches 1,000 m, 43–48% reaches 2,000 m, 32–40% reaches 3,000 m, and 25–33% reaches 4,500 m. This translates into ~0.03, 0.02, 0.01, and 0.01 Pg C year−1, transferred down to 500, 1,000, 2,000, and 4,500 m, respectively. Jelly‐C fluxes and transfer efficiencies can occasionally exceed phytodetrital‐based sediment trap estimates in localized open ocean and continental shelves areas under large gelatinous blooms or jelly‐C mass deposition events, but this remains ephemeral and transient in nature. This transfer of fast and permanently exported carbon reaching the ocean interior via jelly‐C constitutes an important component of the global biological soft‐tissue pump, and should be addressed in ocean biogeochemical models, in particular, at the local and regional scale.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
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  • 14
    Publication Date: 2024-01-16
    Description: Data on infauna and sediment characteristics were collected as part of an extensive research program on the effects of offshore wind turbines on the marine environment funded by the German Federal Maritime and Hydrographic Agency. The investigations were performed in the first German offshore wind farm alpha ventus in the German Bight (North Sea). The overall aim of the program was to evaluate the German national standard concept for environmental impact assessments for offshore wind farms. Specifically, our study addressed the potential changes of the infauna communities in different distances from single turbines in an early stage of the operational phase of the wind farm. The data were collected during the cruises HE296 (2008), HE313 (2009), HE340 (2010) and HE369 (2000) of the German research vessel RV Heincke. Infauna samples were taken with van Veen grab samples (sampling area: 0.1 m2, weight: 95 kg) inside the wind farm and in two reference sites outside the wind farm. Three replicate samples were taken at each station. The samples were sieved through a 1 mm mesh and species of the macro-infauna were determined to the lowest taxonomic level possible. Sub-samples of the sediments were fractionated in a cascade of sieves of different mesh sizes to determine the grain size distributions. The organic contents of the sediments were determined as weight loss on ignition. The dataset comprises 11,400 count and biomass records for 103 infaunal taxa (89 % on species level, 11 % others) from 528 samples. Sediments were characterised for 176 van Veen grabs.
    Type: Dataset
    Format: application/zip, 2 datasets
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  • 15
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    PANGAEA
    In:  EPIC3ANDRILL contribution 4., Bremerhaven, PANGAEA
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: PANGAEA Documentation , notRev
    Format: application/pdf
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  • 16
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    PANGAEA
    In:  Supplement to: Hiller, Anna E; Koo, Michelle S; Goodman, Kari R; Shaw, Kerry L; O'Grady, Patrick M; Gillespie, Rosemary G (2019): Niche conservatism predominates in adaptive radiation: comparing the diversification of Hawaiian arthropods using ecological niche modelling. Biological Journal of the Linnean Society, https://doi.org/10.1093/biolinnean/blz023
    Publication Date: 2024-02-17
    Description: Focal Taxa: Laupala, AMC Clade Drosophila, Tetragnatha, and Nesosydne. We assembled comprehensive occurrence datasets of all known records for each of the four lineages (included here), modeled their distributions using Maxent across the entire archipelago, and quantified niche overlap. Final base layers Mean Annual Air Temperature (°C), Mean Annual Rainfall (mm), Vegetation Height (m), and Normalized Difference Vegetation Index (NDVI) were selected based on optimum AUC values of trial models run. Rasters were obtained for the Rainfall Atlas of Hawaii, Climate of Hawaii, and USGS and resampled to a ~1km by ~1km resolution using smoothing for quantitative variables and nearest neighbor resampling for categorical variables (Giambelluca et al. 2013, Giambelluca et al. 2014, Hawaii Soil Survey 2000). Data presented here are the full set of georeferenced occurrence records, the filtered model inputs, and the final SDM models in ASCII format for each species. See the supplementary material in the corresponding publication (Hiller et al. 2017) for details on the georeferencing protocols used and a list of museum specimen numbers. Note that not all models were included in subsequent analyses due to poor quality (〈3 records as model input or low AUC score).
    Keywords: File content; File format; File size; Hawaii; Hawaiian Islands, North Central Pacific; Species; Uniform resource locator/link to file
    Type: Dataset
    Format: text/tab-separated-values, 659 data points
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  • 17
    Publication Date: 2023-02-08
    Description: Plastic pollution is a major global issue and its impacts on ecosystems and socioeconomic sectors lack comprehensive understanding. The integration of plastics issues into the educational system of both primary and secondary schools has often been overlooked, especially in Africa, presenting a major challenge to environmental awareness. Owing to the importance of early age awareness, this study aims to investigate whether plastic pollution issues are being integrated into South African primary and secondary education school curriculums. Using face-to-face interviews with senior educators, we address this research problem by investigating (i) the extent to which teachers cover components of plastic pollution, and (ii) educator understandings of plastic pollution within terrestrial and aquatic environments. The results indicate that plastic pollution has been integrated into the school curriculum in technology, natural science, geography, life science, life skills and life orientation subjects. However, there was a lack of integration of management practices for plastics littering, especially in secondary schools, and understanding of dangers among different habitat types. This highlights the need for better educational awareness on the plastic pollution problem at both primary and secondary school level, with increased environmental programs needed to educate schools on management practices and impacts
    Type: Article , PeerReviewed
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  • 18
    Publication Date: 2022-10-16
    Description: Numerous potentially toxic plankton species commonly occur in the Black Sea, and phycotoxins have been reported. However, the taxonomy, phycotoxin profiles, and distribution of harmful microalgae in the basin are still understudied. An integrated microscopic (light microscopy) and molecular (18S rRNA gene metabarcoding and qPCR) approach complemented with toxin analysis was applied at 41 stations in the northwestern part of the Black Sea for better taxonomic coverage and toxin profiling in natural populations. The combined dataset included 20 potentially toxic species, some of which (Dinophysis acuminata, Dinophysis acuta, Gonyaulax spinifera, and Karlodinium veneficum) were detected in over 95% of the stations. In parallel, pectenotoxins (PTX-2 as a major toxin) were registered in all samples, and yessotoxins were present at most of the sampling points. PTX-1 and PTX-13, as well as some YTX variants, were recorded for the first time in the basin. A positive correlation was found between the cell abundance of Dinophysis acuta and pectenotoxins, and between Lingulodinium polyedra and Protoceratium reticulatum and yessotoxins. Toxic microalgae and toxin variant abundance and spatial distribution was associated with environmental parameters. Despite the low levels of the identified phycotoxins and their low oral toxicity, chronic toxic exposure could represent an ecosystem and human health hazard.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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  • 19
    Publication Date: 2024-02-07
    Description: Global change has led to manifold changes of marine ecosystems and biodiversity world-wide. While it has been shown that certain jellyfish and comb jelly species have increased regionally, it remains to be investigated if this is a general trend or localized phenomenon. Especially for the economically important Baltic Sea, which is characterized by an extreme physical environmental gradient, this question has not been addressed to date. Here we present a detailed account of the gelatinous macro-zooplankton community including their physiological tolerance towards abiotic conditions and resulting distribution ranges in the Baltic. We show that the arrival and establishment of non-indigenous species has led to a rising importance of jellyfish and comb jellies in the Baltic. This accounts for the comb jelly Mnemiopsis leidyi, which was first observed in Northern Europe in 2005, as well as for the hydromedusae Blackfordia virginica, first sighted in 2014. Both species have been shown to attain high population densities with pronounced grazing impact in other invasive regions. Given the current and anticipated changes of the physical environment of the Baltic Sea, especially ongoing warming, amplification of their impact can be expected.
    Type: Article , PeerReviewed
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  • 20
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    PANGAEA
    In:  EPIC3Bremerhaven, PANGAEA
    Publication Date: 2019-07-17
    Description: In the last 20 years directed shark and ray fishery has increased alarmingly everywhere in the world. For most species though, no data on growth rate, mortality, fecundity and other life history aspects exist as of now and management of the fishery is therefore insufficient. Also there still exist methodological difficulties in the age determination of elasmobranchs fishes, a fact which complicates the investigation of growth parameters. This study tried to identify the best ageing methods and estimate growth parameters for ten skate species of the genus Bathyraja, all occurring in the southwest Atlantic in depths of 50m and more. 720 samples were collected on board of argentine research vessels in between 2003 and 2005. Crystal violet and a new staining method using potassium permanganate, both applied on sagittal sections of vertebral centra, proved to be most effective in enhancing the banding pattern in most of the species. Thorns were also tested and readings were consistent with the ones made on vertebral sections. Growth parameters could be derived for six species and for the other four estimates could be made. Growth rate as well as infinite length varied between species, with those attaining bigger sizes having lower growth rates. No latitudinal differences in growth rate could be detected but a comparison with samples from other studies showed that total lengths were always reported to be higher around the Malvinas Islands.
    Repository Name: EPIC Alfred Wegener Institut
    Type: PANGAEA Documentation , notRev
    Format: application/pdf
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