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Biogeosciences An interactive open-access journal of the European Geosciences Union
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Volume 14, issue 3 | Copyright
Biogeosciences, 14, 651-669, 2017
https://doi.org/10.5194/bg-14-651-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 09 Feb 2017

Research article | 09 Feb 2017

Evaluating environmental drivers of spatial variability in free-living nematode assemblages along the Portuguese margin

Lidia Lins1,2, Frederik Leliaert1, Torben Riehl3, Sofia Pinto Ramalho1,4, Eliana Alfaro Cordova5, André Morgado Esteves2, and Ann Vanreusel1 Lidia Lins et al.
  • 1Marine Biology research group, Ghent University, Krijgslaan 281 S8, 9000 Ghent, Belgium
  • 2Meiofauna Laboratory, Federal University of Pernambuco, Av. Prof Moraes Rego 1235, 50670-901, Cidade Universitária, Brazil
  • 3CeNak, Center of Natural History, University of Hamburg – Zoological Museum, Martin-Luther-King-Platz 3, 20146 Hamburg, Germany
  • 4Departamento de Biologia & CESAM, Universidade de Aveiro, Campus de Santiago, 3810-193, Aveiro, Portugal
  • 5Prodelphinus, Jose Galvez 780-E, Lima 18, Peru

Abstract. Understanding processes responsible for shaping biodiversity patterns on continental margins is an important requirement for comprehending anthropogenic impacts in these environments and further management of biodiversity. Continental margins perform crucial functions linked to key ecological processes which are mainly structured by surface primary productivity and particulate organic matter flux to the seafloor, but also by heterogeneity in seafloor characteristics. However, to what extent these processes control local and regional biodiversity remains unclear. In this study, two isobathic parallel transects located at the shelf break (300–400m) and upper slope (1000m) of the western Iberian margin were used to test how food input and sediment heterogeneity affect nematode diversity independently from the spatial factors geographical distance and water depth. We also examined the potential role of connectedness between both depth transects through molecular phylogenetic analyses. Regional generic diversity and turnover were investigated at three levels: within a station, between stations from the same depth transect, and between transects. High variability in food availability and high sediment heterogeneity at the shelf-break transect were directly linked to high diversity within stations and higher variation in community structure across stations compared to the upper slope transect. Contrastingly, environmental factors (food availability and sediment) did not vary significantly between stations located at the upper slope, and this lack of differences were also reflected in a low community turnover between these deeper stations. Finally, differences in nematode communities between both transects were more pronounced than differences within each of the isobathic transects, but these changes were paralleled by the previously mentioned environmental changes. These results suggest that changes in community structure are mainly dictated by environmental factors rather than spatial differences at the western Iberian margin. Furthermore, phylogenetic relationships revealed no evidence for depth-endemic lineages, indicating regular species interchanges across different depths.

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Anthropogenic impacts in the deep sea are regarded as high disturbers of the deep-sea bottom. This study focus in trying to understand the impact of disturbance in the ecosystem and how important functions, such as hydrodynamics and surface primary productivity, affect benthic organisms. Our results showed that high sediment variability due to hydrodynamics, and consequently disturbance, combined with high resource availability are probably the main factors promoting deep-sea species coexistence
Anthropogenic impacts in the deep sea are regarded as high disturbers of the deep-sea bottom....
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