A B S T R A C TA multi-purpose epibenthic sledge, designed for sampling of small benthic macrofauna in marine habitats and at any navigable depth, is presented. The new epibenthic sledge operates reliably on soft sediments in shallow and in open oceanic deep water, as well as on steep slopes, between rocks and glacier moraines as frequently found in Antarctic waters, and on primary hard substrate. The construction is of high mechanical stability with fully protected nets. In case of damage, parts of the sledge can be replaced or repaired easily on board. A description of the gear with a detailed construction plan, as well as parameters for handling in diverse marine habitats, is given. Calculation of the towing distance and first results with possible sources of errors are discussed.
Heightened interest in the exploitation of deep seafloor minerals is raising questions on the consequences for the resident fauna. Assessing species ranges and determination of processes underlying current species distributions are prerequisites to conservation planning and predicting faunal responses to changing environmental conditions. The abyssal central Pacific nodule belt, located between the Clarion and Clipperton Fracture Zones (CCZ), is an area prospected for mining of polymetallic nodules. We examined variations in genetic diversity and broad-scale connectivity of isopods and polychaetes across the CCZ. Faunal assemblages were studied from two mining claims (the eastern German and French license areas) located 1300 km apart and influenced by different productivity regimes. Using a reverse taxonomy approach based on DNA barcoding, we tested to what extent distance and large-scale changes in environmental parameters lead to differentiation in two macrofaunal taxa exhibiting different functions and life-history patterns. A fragment of the mitochondrial gene Cytochrome Oxidase Subunit 1 (COI) was analyzed. At a 97% threshold the molecular operational taxonomic units (MOTUs) corresponded well to morphological species. Molecular analyses indicated high local and regional diversity mostly because of large numbers of singletons in the samples. Consequently, variation in composition of genotypic clusters between sites was exceedingly large partly due to paucity of deep-sea sampling and faunal patchiness. A higher proportion of wide-ranging species in polychaetes was contrasted with mostly restricted distributions in isopods. Remarkably, several cryptic lineages appeared to be sympatric and occurred in taxa with putatively good dispersal abilities, whereas some brooding lineages revealed broad distributions across the CCZ. Geographic distance could explain variation in faunal connectivity between regions and sites to some extent, while assumed dispersal capabilities were not as important.
In the Southern Ocean, that is areas south of the Polar Front, long-term oceanographic cooling, geographic separation, development of isolating current and wind systems, tectonic drift and fluctuation of ice sheets amongst others have resulted in a highly endemic benthic fauna,\ud which is generally adapted to the long-lasting, relatively stable environmental conditions. The Southern Ocean benthic ecosystem has been subject to minimal direct anthropogenic impact (compared to elsewhere) and thus presents unique opportunities to study biodiversity and its\ud responses to environmental change. Since the beginning of the century, research under the Census of Marine Life and International Polar Year initiatives, as well as Scientific Committee of Antarctic Research biology programmes, have considerably advanced our understanding of the Southern Ocean benthos. In this paper, we evaluate recent progress in Southern Ocean benthic research and identify priorities for future research. Intense efforts to sample and describe the benthic fauna, coupled with coordination of information in global databases, have greatly enhanced\ud understanding of the biodiversity and biogeography of the region. Some habitats, such as chemosynthetic systems, have been sampled for the first time, while application of new technologies and methods are yielding new insights into ecosystem structure and function. These advances have\ud also highlighted important research gaps, notably the likely consequences of climate change. In a time of potentially pivotal environmental change, one of the greatest challenges is to balance conservation with increasing demands on the Southern Ocean’s natural resources and services. In\ud this context, the characterization of Southern Ocean biodiversity is an urgent priority requiring timely and accurate species identifications, application of standardized sampling and reporting procedures, as well as cooperation between disciplines and nations
Field and laboratory protocols that originally led to the success of published stud− ies have previously been only briefly laid out in the methods sections of scientific publica− tions. For the sake of repeatability, we regard the details of the methodology that allowed broad−range DNA studies on deep−sea isopods too valuable to be neglected. Here, a com− prehensive summary of protocols for the retrieval of the samples, fixation on board research vessels, PCR amplification and cycle sequencing of altogether six loci (three mitochondrial and three nuclear) is provided. These were adapted from previous protocols and developed especially for asellote Isopoda from deep−sea samples but have been successfully used in some other peracarids as well. In total, about 2300 specimens of isopods, 100 amphipods and 300 tanaids were sequenced mainly for COI and 16S and partly for the other markers. Although we did not set up an experimental design, we were able to analyze amplification and sequencing success of different methods on 16S and compare success rates for COI and 16S. The primer pair 16S SF/SR was generally reliable and led to better results than univer− sal primers in all studied Janiroidea, except Munnopsidae and Dendrotionidae. The widely applied universal primers for the barcoding region of COI are problematic to use in deep−sea isopods with a success rate of 45-79% varying with family. To improve this, we recommend the development of taxon−specific primers.
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