cological connectivity is important for ef- fective marine planning and biodiversity conservation. Our aim was to identify factors important in influencing variation in benthic community structure on shallow rocky reefs in 2 regions of the Mediterranean Sea with contrasting oceanographic regimes. We assessed beta (β) diversity at 146 sites in the littoral and shallow sub- littoral from the Adriatic/Ionian Seas (eastern region) and Ligurian/Tyrrhenian Seas (western region) using a null modelling approach to account for variation in spe- cies richness. The distance decay relationship between species turnover within each region and geographic distance by sea was determined using generalised lin- ear models. Mantel tests were used to examine correla- tions between β diversity and connectivity by ocean currents, estimated from Lagrangian dispersal simula- tions. Variation in β diversity between sites was parti- tioned according to environmental and spatial compo- nents using a distance-based redundancy approach. Species turnover along a gradient of geographic dis- tance was greater by a factor of 3 to 5 in the western region than the eastern region, suggesting lower con- nectivity between sites. β diversity was correlated with connectivity by ocean currents at both depths in the eastern region but not in the western region. The influnce of spatial and environmental predictors of β diver- sity varied considerably between regions, but was simi- lar between depths. Our results highlight the interaction of oceanographic, spatial and environmental processes influencing benthic marine β diversity. Persistent cur- rents in the eastern region may be responsible for lower observed β diversity compared to the western region, where patterns of water circulation are more variable.

Effects of geographic distance, water circulation and environmental conditions in shaping the biodiversity of Mediterranean rocky coasts

Valentina Asnaghi;CHIANTORE, MARIACHIARA;
2016

Abstract

cological connectivity is important for ef- fective marine planning and biodiversity conservation. Our aim was to identify factors important in influencing variation in benthic community structure on shallow rocky reefs in 2 regions of the Mediterranean Sea with contrasting oceanographic regimes. We assessed beta (β) diversity at 146 sites in the littoral and shallow sub- littoral from the Adriatic/Ionian Seas (eastern region) and Ligurian/Tyrrhenian Seas (western region) using a null modelling approach to account for variation in spe- cies richness. The distance decay relationship between species turnover within each region and geographic distance by sea was determined using generalised lin- ear models. Mantel tests were used to examine correla- tions between β diversity and connectivity by ocean currents, estimated from Lagrangian dispersal simula- tions. Variation in β diversity between sites was parti- tioned according to environmental and spatial compo- nents using a distance-based redundancy approach. Species turnover along a gradient of geographic dis- tance was greater by a factor of 3 to 5 in the western region than the eastern region, suggesting lower con- nectivity between sites. β diversity was correlated with connectivity by ocean currents at both depths in the eastern region but not in the western region. The influnce of spatial and environmental predictors of β diver- sity varied considerably between regions, but was simi- lar between depths. Our results highlight the interaction of oceanographic, spatial and environmental processes influencing benthic marine β diversity. Persistent cur- rents in the eastern region may be responsible for lower observed β diversity compared to the western region, where patterns of water circulation are more variable.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11567/865216
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