248 research outputs found

    Taxonomy and biogeography of macroalgal communities in the upwelling region off the coast of Dhofar, Oman

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    This study investigates the floristic composition and the ecological and biogeographical characteristics of macroalgal communities in three bays along the coastline of the southern province of Dhofar in the Sultanate of Oman. Dhofar is located in the north-western Arabian upwelling province. From June through September the south-west monsoon winds cause Ekman transport of surface waters away from the Arabian coastline. This brings cold nutrient-rich waters from deeper layers into the eufotic zone.At each study site nine 0.25 m2 quadrants were sampled, three in the intertidal zone, three at a depth of 5m and three at a depth of 10m. In the intertidal zone Ulva fasciata and Melanothamnus somalensis are the dominant species. At two of the study sites Nizamuddinia zanardinii and Sargassum oligocystum are the dominant species in the subtidal zone, at the third site Jania sp. and Codium duthieae are the most abundant.Multivariate analysis was carried out on the data collected in the present study and data from previous studies on the macroalgal assemblages of the Socotra Archipelago and Masirah Island (Schils & Coppejans, 2003). DCA at species level showed a strong gradient in floristic composition from upwelling sheltered sites (Gulf of Oman, west coast of Masirah, north coast of Socotra and seagrass beds of both Masirah Island and the Socotra Archipelago) to upwelling exposed sites (east coast of Masirah Island, south coast of Socotra and Dhofar). The bays of Dhofar clearly have high affinities with the other upwelling exposed sites, but nonetheless cluster analysis showed that they are very well separated from all the other study areas. This uniqueness is also illustrated by the large number of indicator species pointed out by the indicator species analysis, among which are many endemics and species with a disjunct distribution.Affinities with remote areas were assessed based on the data collected in this study and species inventories of 11 countries in the Indian Ocean. For all Arabian Sea locations the similarity with the tropical coasts of east Africa and Indonesia is much lower than the similarity with South Africa and Australia, where besides subtropical conditions also temperate conditions occur. The rbcL gene of a number of specimens of Codium and Portieria was sequenced in order to assess whether these specimens are related to morphologically similar Japanese specimens. This analysis has shown that the Japanese and Omani specimens of the supposedly disjunctly distributed species are not related

    OBIS 2.0: Real-time integration, quality control and analysis of rich marine data streams

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    For almost two decades, the Ocean Biogeographic Information System (OBIS) has played a key role in the mobilisation and sharing of marine biodiversity data. The increasing demand for near real-time rich datasets to support conservation, human health, and the blue economy, as well as rapidly increasing data volumes due to technological advancements in observing systems, have triggered improvements in the data model and a reengineering of the OBIS platform. The new data platform can now handle complex high-volume datasets and make them available to users with very little delay

    The role of macrofauna in the functioning of a sea floor: is there any seasonal, density or functional identity effect?

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    Macrobenthos influences rates and intensities of benthic processes. The way in which these processes are affected depends on their densities and functional characteristics in terms of sediment reworking (bioturbation and bio-irrigation). This study focuses on the importance of three different functional groups (FG) of macrobenthos in the ecosystem processes of the Western Coastal Banks area (Belgian Part of the North Sea). Macrobenthic activity depends on temperature and food availability. Therefore two lab experiments were performed: one before sedimentation of the phytoplankton bloom (spring: low food availability and temperature) and one when organic matter had been settled on the sea bottom (late summer: high food availability and higher temperatures). Single - species treatments of key-species belonging to three different functional groups were added to microcosms at three density levels (average natural, lower and very low) to account for possible density declines. These species are the bivalve Abra alba (FG: biodiffuser), the tube-building polychaete Lanice conchilega (FG: piston-pumper) andthe predatory polychaete Nephthy sp. (FG: regenerator/gallery-diffuser).In both winter - and summertime, L. conchilega had a more pronounced influence on oxygen consumption and release Nephtys sp.. Abra alba appeared to be a more effective sediment reworker than Nephtys sp. in both seasons. In addition, ecosystem functioning (as oxygen consumption by the sediment community and bioturbation) seems to be related to animal densities. As such, a decline of densities (due to anthropogenic or natural disturbances) most probably will decrease the rates of ecosystem functioning in theWestern Coastal Banks area

    Notorious places: image, reputation, stigma: the role of newspapers in area reputations for social housing estates

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    This paper reviews work in several disciplines to distinguish between image, reputation and stigma. It also shows that there has been little research on the process by which area reputations are established and sustained through transmission processes. This paper reports on research into the portrayal of two social housing estates in the printed media over an extended period of time (14 years). It was found that negative and mixed coverage of the estates dominated, with the amount of positive coverage being very small. By examining the way in which dominant themes were used by newspapers in respect of each estate, questions are raised about the mode of operation of the press and the communities' collective right to challenge this. By identifying the way regeneration stories are covered and the nature of the content of positive stories, lessons are drawn for programmes of area transformation. The need for social regeneration activities is identified as an important ingredient for changing deprived-area reputations

    How may beach nourishment affect the sandy beach ecosystem? The case of Belgian beaches

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    Though often regarded as biological deserts, sandy beaches provide a unique habitat for several species. Research was conducted by a consortium of experts with as a first objective to provide an integrated overview of the Belgian beach ecosystem and all its major components. A second objective comprised a review of available literature on the ecological impact of beach nourishment. To meet the first objective, an integrated overview of the Belgian sandy beach ecosystem based on spatial and temporal variation of fauna and flora of 11 sandy beaches is provided. The presented results corroborate the overlooked ecological significance of sandy beaches as a habitat. Besides sedimentology and hydrodynamics, five ecosystem components were taken into account: microphytobenthos, vascular plants, terrestrial arthropods, zoobenthos and avifauna. Nourishment of beaches is a large scale anthropogenic influence on sandy beach ecosystem. Sandy beaches are regarded as systems with a strong resilience towards such impacts. Nevertheless serious (short term) ecological effects can be expected. A review of prior studies indicates that the impact of nourishment is rather case-specific and that it is difficult to draw general conclusions. Short term impact is mostly large due to total mortality of benthic life. It seems very likely that potential recovery from the impact of nourishment will be limited to two essential, species specific pathways: (1) survival by resident organisms and (2) re-colonisation by immigrating individuals, the latter depending on both the dispersal capacities and habitat demands of the organisms. Further research is needed to explore possibilities for reducing detrimental ecological effects. Specific studies are needed towards the survival options, the dispersal capacities and habitat demands of the species present. These should allow for management guidelines to be drawn in terms of preferable nourishment sediment characteristics, timing and practice of the deposition of the sand
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