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    ABSTRACT: Huvadhoo Atoll is a little-known and generally uncontaminated atoll of the southern Maldives, although the human pressure is increasing. This study represents the first attempt to characterize the meiofaunal and nematode assemblages of its lagoon both from a taxonomic and functional point of view. The nematode assemblage was made up of a total of 131 genera in 33 families. Desmodoridae, Chromadoridae and Xyalidae represented the richest and most abundant families, followed in terms of abundance by Selachinematidae and Comesomatidae. The nematode richness was overall higher than that reported in the previous studies carried out in the Central part of the archipelago. The diversity patterns revealed higher values than those reported for the back-reefs platforms, so confirming the positive influence of the water depth on the biodiversity of the nematode assemblage. The statistical analysis highlighted a significant taxonomic difference of the assemblages between the stations characterized by fine and medium-coarse sands, respectively, in line with the auto-ecological preferences of the taxa detected. The use of some nematode descriptors for assessing the ecological quality status (EQS) of the lagoon has revealed a slight disturbance in the station close to Viligili, one of the most urbanized islands. However, the summarization of all the descriptors used allows the highlighting of the good EQS of the Huvadhoo lagoon. Thus, the results of this study may be taken as the starting point for the future monitoring of the potential and real impact of the anthropogenic activity on the area over time.
    Journal of the Marine Biological Association of the UK 05/2014; DOI:10.1017/S002531541400068X · 1.13 Impact Factor
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    ABSTRACT: This study investigated the distribution of Molgolaimus species (Nematoda) at different hierarchical spatial scales and observed the turnover of species along bathymetrical transects and among transects in two separate geographical regions. Samples from six transects (200–2000 m) from the Southern Oceans (SO) and four bathymetric transects (50–2000 m) from the Western Indian Ocean (WIO) were compared. Of the 30 species recorded, only one was common to both regions. WIO had higher local species richness than the SO. In both regions, the local scale was the greatest contributor to the total species richness. In the SO, there was no difference between species turnover at the different spatial scales, however, in the WIO, the turnover along bathymetrical transects was higher than among separated transects. For the particular genus studied, the evidence suggests that the study area in WIO has more widespread species and was better sampled, while the SO has many restricted species and it is most probably characterized by different biogeographical provinces. At the ocean scale (i.e. WIO versus SO), evolutionary histories may have strongly influenced nematodes species composition, while at local and regional scales, ecological processes are probably promoting species co-existence and speciation. The high co-existence of certain species at local scale is partially explained by species preference for different sediment layers.
    Marine Ecology 11/2007; 28(4):446 - 459. DOI:10.1111/j.1439-0485.2007.00202.x · 1.84 Impact Factor
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    ABSTRACT: There is little meiofauna data from the southwest Atlantic, and especially lacking are studies examining deep-sea communities. In this study, the structure of meiofauna communities, particularly nematodes, was analyzed from data derived from 101 samples (48 samples on the continental-slope and 53 samples at a deep-sea site) collected at Campos Basin, SE Brazil. Differences in the meiofauna densities and in the number of taxa between continental slope and deep-sea sites depended on the taxonomic level examined. While total meiofauna abundance did not differ significantly between sites, nematode densities were significantly higher in the deep sea (mean of 157 inds.10 cm−2) than on the slope (mean of 129 inds.10 cm−2). The number of meiofauna taxa was significantly higher at the continental slope site. Yet for the most abundant meiofaunal group, the nematodes, whilst the number of families did not differ between continental slope and deep sites, the number of genera was significantly higher in the deep sea. The remarkable resemblance between the dominant nematodes (Halalaimus, Acantholaimus, Daptonema, Theristus and Sabatieria) from SE Brazil and other deep sea studies confirmed earlier suggestions of a typical deep-sea nematode community with a broad geographical distribution. Multivariate analysis derived from meiofauna and nematode data showed that the structure of the fauna differed significantly between sites. Correlations detected between meiofauna and some sediment properties, such as grain size and sediment heterogeneity, although significant, were very low.
    Deep Sea Research Part I Oceanographic Research Papers 05/2005; DOI:10.1016/j.dsr.2004.11.009 · 2.83 Impact Factor