9 research outputs found

    Protandric hermaphroditism in the whale-fall bivalve mollusc Idas washingtonia

    No full text
    Whale falls provide abundant but relatively ephemeral, sulphide-rich habitat islands on the deep-sea floor. To explore life-history adaptations to whale-fall habitats, we examined the reproductive biology of Idas washingtonia, a bathymodiolin mussel occurring in abundance on sunken whale skeletons in the deep northeast Pacific Ocean. Analysis of the reproductive biology of I. washingtonia demonstrates strong evidence of protandric hermaphroditism. Developing males were recognised in individuals as small as 1.7 mm shell length and spermatogenesis continued until 7 mm length. At &gt;6.5 mm, males were generally spent and the first previtellogenic oocytes were observed. Although developing females were found as small as 4.5 mm shell length, most well-developed females were &gt;6 mm shell length. Overall, females only formed 12% of the population. As with other modiolid bivalves, fecundity was high and the egg size &lt;50 ?m, indicative of planktotrophic development. The occurrence of protandric hermaphroditism, high fecundity and planktotrophic dispersal may be an adaptation to the ephemeral nature of their habitat. The success of this adaptation is shown by the rapid colonisation of whale falls even though these may have been severely reduced in abundance since the peak of commercial whaling activity in the 20th century.<br/

    Global raster maps indicating the habitat suitability for 7 suborders of cold water octocorals (Octocorallia found deeper than 50m)

    No full text
    This dataset consists of global raster maps indicating the habitat suitability for 7 suborders of cold water octocorals (Octocorallia found deeper than 50m). Maps present a relative habitat suitability index ranging from 0 (unsuitable) to 100 (highly suitable). Two maps are provided for each suborder (Alcyoniina, Calcaxonia, Holaxonia, Scleraxonia, Sessiliflorae, Stolonifera, and Subselliflorae). A publicly accessable low resolution map (grid size 10x10 arc-minutes) and a restricted access high resolution map (grid size 30x30 arc-seconds). Maps are geotiff format incorporating LZW compression to reduce file size. Please contact the corresponding author (Chris Yesson) for access to the high resolution data

    Towards a scientific community consensus on designating Vulnerable Marine Ecosystems from imagery

    Get PDF
    Management of deep-sea fisheries in areas beyond national jurisdiction by Regional Fisheries Management Organizations/Arrangements (RFMO/As) requires identification of areas with Vulnerable Marine Ecosystems (VMEs). Currently, fisheries data, including trawl and longline bycatch data, are used by many RFMO/As to inform the identification of VMEs. However, the collection of such data creates impacts and there is a need to collect non-invasive data for VME identification and monitoring purposes. Imagery data from scientific surveys satisfies this requirement, but there currently is no established framework for identifying VMEs from images. Thus, the goal of this study was to bring together a large international team to determine current VME assessment protocols and establish preliminary global consensus guidelines for identifying VMEs from images. An initial assessment showed a lack of consistency among RFMO/A regions regarding what is considered a VME indicator taxon, and hence variability in how VMEs might be defined. In certain cases, experts agreed that a VME could be identified from a single image, most often in areas of scleractinian reefs, dense octocoral gardens, multiple VME species' co-occurrence, and chemosynthetic ecosystems. A decision flow chart is presented that gives practical interpretation of the FAO criteria for single images. To further evaluate steps of the flow chart related to density, data were compiled to assess whether scientists perceived similar density thresholds across regions. The range of observed densities and the density values considered to be VMEs varied considerably by taxon, but in many cases, there was a statistical difference in what experts considered to be a VME compared to images not considered a VME. Further work is required to develop an areal extent index, to include a measure of confidence, and to increase our understanding of what levels of density and diversity correspond to key ecosystem functions for VME indicator taxa. Based on our results, the following recommendations are made: 1. There is a need to establish a global consensus on which taxa are VME indicators. 2. RFMO/As should consider adopting guidelines that use imagery surveys as an alternative (or complement) to using bycatch and trawl surveys for designating VMEs. 3. Imagery surveys should also be included in Impact Assessments. And 4. All industries that impact the seafloor, not just fisheries, should use imagery surveys to detect and identify VMEs

    Antarctic Ecosystem Research following Ice Shelf Collapse and Iceberg Calving Events

    No full text
    The calving of A-68, the 5,800 km2 iceberg that separated from the Larsen C Ice Shelf in July 2017, presents a unique and time-sensitive research opportunity. This event and other ice-shelf losses (e.g., from Larsen A and B, Wilkins, Wordie) are harbingers of warming effects along the Antarctic Peninsula in particular, and ultimately around all of Antarctica. The scientific momentum and public interest created by this most recent event led to an NSF funded workshop in November 2017. A consortium of US and international researchers with a diversity of expertise in Antarctic glaciological, geological, biological, and ecological sciences shared and reviewed the latest research, identified important research priorities and knowlegde gaps, and outlined strategic plans for the research community to advance understanding of the continent-wide changes that Antarctic ice shelves and surrounding ecosystems will experience in response to warming. The workshop has leveraged an opportunity to synergize efforts in investigating Antarctic ecosystems under the direct and indirect effects of ice-shelf collapse, and climatic warming in general. Here we present a review on the known and unknown ecosystem processes that will occur in the wake of massive, abrupt ice-shelf break-off and how they will affect ice-associated, pelagic, hard-bottom and soft-sediment substrates. We also present a view on future research approaches to address gaps in our knowledge and advance our understanding of the widespread effects of ice-shelf break-off and collapse

    Antarctic ecosystem responses following iceā€shelf collapse and iceberg calving: Science review and future research

    Get PDF
    The calving of Aā€68, the 5,800ā€kmĀ², 1ā€trillionā€ton iceberg shed from the Larsen C Ice Shelf in July 2017, is one of over 10 significant iceā€shelf loss events in the past few decades resulting from rapid warming around the Antarctic Peninsula. The rapid thinning, retreat, and collapse of ice shelves along the Antarctic Peninsula are harbingers of warming effects around the entire continent. Ice shelves cover more than 1.5 million kmĀ² and fringe 75% of Antarctica's coastline, delineating the primary connections between the Antarctic continent, the continental ice, and the Southern Ocean. Changes in Antarctic ice shelves bring dramatic and largeā€scale modifications to Southern Ocean ecosystems and continental ice movements, with globalā€scale implications. The thinning and rate of future iceā€shelf demise is notoriously unpredictable, but models suggest increased shelfā€melt and calving will become more common. To date, little is known about subā€iceā€shelf ecosystems, and our understanding of ecosystem change following collapse and calving is predominantly based on responsive science once collapses have occurred. In this review, we outline what is known about (a) iceā€shelf melt, volume loss, retreat, and calving, (b) iceā€shelfā€associated ecosystems through subā€ice, sedimentā€core, and preā€collapse and postā€collapse studies, and (c) ecological responses in pelagic, sympagic, and benthic ecosystems. We then discuss major knowledge gaps and how science might address these gaps
    corecore