37 research outputs found

    DeZoZoo Cruise Data

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    Dataset: DeZoZoo Cruise DataThese data represent the gelatinous zooplankton counts and abundance from the samples collected with Tucker Trawl tows from the DeZoZoo project. For a complete list of measurements, refer to the supplemental document 'Field_names.pdf', and a full dataset description is included in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: http://www.bco-dmo.org/dataset/521596NSF Division of Ocean Sciences (NSF OCE) OCE-096192

    Hydrographic Features, Cetaceans and the Foraging of Thick-billed Murres and Other Marine Birds in the Northwestern Barents Sea

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    The at-sea distribution of thick-billed murres (Uria lomvia) in southeastern Svalbard waters was studied during the summers of 1992, 1993, and 1996. The Storfjordrenna region south of Svalbard was confirmed as an important foraging area for thick-billed murres; murre aggregations were located at distances of 85 to 126 km from the closest breeding colonies. Fish, mainly polar cod (Boreogadus saida), but also capelin (Mallotus villosus), were the main prey found in 16 murres and 3 black-legged kittiwakes (Rissa tridactyla) collected from these aggregations. Murres were seen flying with fish in their beaks at four locations 78 to 102 km away from the colonies. Murre aggregations were associated with frontal zones between cold Arctic waters and warmer Atlantic water, and in areas with strong stratification in salinity at 15-30 m. A positive association was found between the abundance of murres and the occurrence of cetaceans. Murres and other marine birds were often seen near surfacing cetaceans. The most common cetaceans were minke whales (Balaenoptera acutorostrata) and white-beaked dolphins (Lagenorhynchus albirostris).Durant les étés de 1992, 1993 et 1996, on a étudié la distribution en mer de la marmette de Brünnich (Uria lomvia) dans les eaux du sud-est du Svalbard. La région Storfjordrenna au sud du Svalbard a été confirmée comme une zone importante de collecte pour la marmette de Brünnich; des concentrations de marmettes étaient situées à des distances allant de 85 à 126 km des colonies nicheuses les plus proches. Le poisson, en particulier la morue polaire (Boreogadus saida), mais aussi le capelan (Mallotus villosus), était la proie principale trouvée chez 16 marmettes et 3 mouettes tridactyles (Rissa tridactyla) prélevées dans ces concentrations. On a vu les marmettes voler avec du poisson dans leur bec à quatre endroits éloignés de 78 à 102 km des colonies. Les concentrations de marmettes étaient associées à des zones frontales entre les eaux froides de l'Arctique et l'eau plus chaude de l'Atlantique, et dans des régions ayant une forte stratification dans la salinité à une profondeur de 15 à 30 m. On a trouvé qu'il existait une association positive entre l'abondance des marmettes et la présence des cétacés. On voyait souvent les marmettes et d'autres oiseaux marins près des cétacés qui faisaient surface. Les cétacés les plus communs étaient les petits rorquals (Balaenoptera acutorostrata) et les dauphins à nez blanc (Lagenorhynchus albirostris)

    Jellyfish, Forage Fish, and the World\u27s Major Fisheries

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    A majority of the world’s largest net-based fisheries target planktivorous forage fish that serve as a critical trophic link between the plankton and upper-level consumers such as large predatory fishes, seabirds, and marine mammals. Because the plankton production that drives forage fish also drives jellyfish production, these taxa often overlap in space, time, and diet in coastal ecosystems. This overlap likely leads to predatory and competitive interactions, as jellyfish are effective predators of fish early life stages and zooplankton. The trophic interplay between these groups is made more complex by the harvest of forage fish, which presumably releases jellyfish from competition and is hypothesized to lead to an increase in their production. To understand the role forage fish and jellyfish play as alternate energy transfer pathways in coastal ecosystems, we explore how functional group productivity is altered in three oceanographically distinct ecosystems when jellyfish are abundant and when fish harvest rates are reduced using ecosystem modeling. We propose that ecosystem-based fishery management approaches to forage fish stocks include the use of jellyfish as an independent, empirical “ecosystem health” indicator

    Jellyfish, Forage Fish, and the World\u27s Major Fisheries

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    A majority of the world’s largest net-based fisheries target planktivorous forage fish that serve as a critical trophic link between the plankton and upper-level consumers such as large predatory fishes, seabirds, and marine mammals. Because the plankton production that drives forage fish also drives jellyfish production, these taxa often overlap in space, time, and diet in coastal ecosystems. This overlap likely leads to predatory and competitive interactions, as jellyfish are effective predators of fish early life stages and zooplankton. The trophic interplay between these groups is made more complex by the harvest of forage fish, which presumably releases jellyfish from competition and is hypothesized to lead to an increase in their production. To understand the role forage fish and jellyfish play as alternate energy transfer pathways in coastal ecosystems, we explore how functional group productivity is altered in three oceanographically distinct ecosystems when jellyfish are abundant and when fish harvest rates are reduced using ecosystem modeling. We propose that ecosystem-based fishery management approaches to forage fish stocks include the use of jellyfish as an independent, empirical “ecosystem health” indicator

    Questioning the rise of gelatinous zooplankton in the World's oceans

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    During the past several decades, high numbers of gelatinous zooplankton species have been reported in many estuarine and coastal ecosystems. Coupled with media-driven public perception, a paradigm has evolved in which the global ocean ecosystems are thought to be heading toward being dominated by “nuisance” jellyfish. We question this current paradigm by presenting a broad overview of gelatinous zooplankton in a historicalcontext to develop the hypothesis that population changes reflect the human-mediated alteration of global ocean ecosystems. To this end, we synthesize information related to the evolutionary context of contemporary gelatinous zooplankton blooms, the human frame of reference forchanges in gelatinous zooplankton populations, and whether sufficient data are available to have established the paradigm. We conclude that the current paradigm in which it is believed that there has been a global increase in gelatinous zooplankton is unsubstantiated, and we develop a strategy for addressing the critical questions about long-term, human-related changes in the sea as they relate to gelatinous zooplankton blooms
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