82 research outputs found

    Effects of hypoxia on benthic macrofauna and bioturbation in the Estuary and Gulf of St. Lawrence, Canada

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    The bottom water in the 4300 m deep Lower St. Lawrence Estuary (LSLE) is persistently hypoxic in contrast to the normoxic bottom waters in the Gulf of St. Lawrence (GSL). We photographed the seabed at 11 stations in the Estuary and Gulf of St. Lawrence (EGSL) during the summers 2006 and 2007 and analysed the images to identify bioturbation traces (lebensspuren) and benthic macrofauna. The objective was to identify the environmental variables that influence the density and diversity of benthic macrofauna and bioturbation traces, and the differences that exist among regions with high, medium and low oxygen levels in the bottom water. The bottom water oxygen concentration is the variable that best explains the densities of total-traces as well as surface-traces. However, the density of these traces was higher in hypoxic regions than in well-oxygenated regions. The higher density of traces in the hypoxic region of the LSLE is mainly due to the activities of the surface deposit feeder Ophiura sp., which occurs in large numbers in this region. Possible explanations explored are stress behaviour of the organisms in response to hypoxia and different benthic macrofauna community structures between the hypoxic regions of the LSLE and the normoxic regions of the GSL. In the former, surface deposit feeders and low-oxygen tolerant species dominate over suspension feeders and low-oxygen intolerant species

    First in situ observations of soft bottom megafauna from the Cascais Canyon head

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    We report the first in situ observations of soft bottom megafauna from the Cascais Canyon head. Observations were collected opportunistically during three technical dives with the ROV Luso between 460-805 m at two locations distanced 1,230 m. The habitats were clas-sified as upper bathyal fine mud. The soft bottom fauna was dominated by burrows of Nephrops norvegicus reaching up to 2.9 burrows/m2, a common habitat along the Portu-guese continental margin. To our knowledge, densities are the highest ever reported for depths below 300 m. The ichthyofauna at the upper Cascais Canyon is a mixture of lower shelf and upper bathyal species, including Phycis blennoides, Scyliorhynus canicula, Coe-lorhynchus labiatus/occa and Chimaera monstrosa. Bait release attracted Myxine glutinosa. Surveys in other geological settings of the Cascays Canyon are required to understand more comprehensively the diversity of its sessile and vagile biodiversity

    Ten invertebrates new for the marine fauna of Madeira.

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    The nemertine Drepanogigas albolineatus, the gastropods Coralliophila kaofitorum, Haminoea orteai, Discodoris rosi and Janolus n sp, the decapod Palaemonella atlantica, the phoronids Phoronis australis and Phoronopsis californica, the starfish Chaetaster longipes and the tunicate Distaplia corolla are recorded from Madeira archipelago for the first time

    SQUID EGGS ATTACHMENT AND FISH ASSOCIATION ON THE SQUID ATTRACTOR AGGREGATING DEVICE

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    Indonesia reveals incommensurate movement between fishing and reproduction as well as growth of sea fishery commodities. This point can lead to overfishing problem so in order to solve it the enrichment program is required significantly, for instance, through aggregating device program. Research was done on October 2012 by drowning two shapes of aggregating device: quadrangular and cylindrical into Bangka Island’s waters. The monitoring result after nine months shows that cylindrical aggregating device is more effective to attach the squid eggs than quadrangular one because it is covered and protected well. The other sea creatures found in the same location with the squid aggregating device are lutjanus lutjanus (kind of fish), softcoral, gastropoda dan krustace. Keywords : Aggregating device, squid, squid egg, fish, macrobenthic

    Carbonate mounds and aphotic corals in the NE-Atlantic ; Reykjavik-Lissabon 03.08. - 17.08.04

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