Aim: For conservation purposes it is important to understand the forces that shape biodiversity in transitional waters (TWs) and to evaluate the effects of small scale latitudinal changes. To this end, we analyzed data on soft-sediment macroinvertebrates from nine Italian TWs in order (1) to investigate the structure and distribution of the benthic fauna and their relationships with environmental and geographical variables, and (2) to examine species richness and beta-diversity at different spatial scales. Location: European Transition Waters Ecoregion 6. Using a data set collected along a 7° latitudinal cline between 45°28’N and 39°56’N, we used Spearman’s rank correlation analysis to evaluate the relationships between species richness and both environmental and geographical variables, and linear regression analysis to show the relationships between alpha-, beta- and gamma-diversity. Three different measures were used to assess beta-diversity: Whittaker’s BetaW, and two similarity indices: the Bray-Curtis similarity index and Delta-s. Using multivariate analyses, we determined the similarity in composition of the benthic community between sites and compared the biotic ordination to abiotic (geographical and environmental) characteristics. Two hundred and sixty-eight species were recorded from 46 sites. Of these, 53.4% were restricted to one TW. Annelida were the dominant taxonomic group, followed by crustacea and mollusca. The alpha-diversity was highly variable (5–87 species) and was correlated with latitude. The gamma-diversity, measured at TW scale, was significantly correlated with alpha-diversity. The gamma-diversity increased with spatial scale and habitat heterogeneity. In the community pattern identified by multivariate analysis, TWs segregated by latitude and biogeography and this reflected different climatic conditions. We found that alpha-diversity increased when moving from higher to lower latitudes , and was dependent on both regional and local factors. Latitudinal variations in the extent of regional influence on local species richness were detected. The observed distribution pattern of TW faunas was mostly due to different climate types. We suggest that the distribution of annelidan species could be used as a proxy for assessing general community patterns for Italian TWs
Biodiversity of soft-sediment benthic communities from Italian transitional waters
MUNARI, Cristina;MISTRI, Michele
2008
Abstract
Aim: For conservation purposes it is important to understand the forces that shape biodiversity in transitional waters (TWs) and to evaluate the effects of small scale latitudinal changes. To this end, we analyzed data on soft-sediment macroinvertebrates from nine Italian TWs in order (1) to investigate the structure and distribution of the benthic fauna and their relationships with environmental and geographical variables, and (2) to examine species richness and beta-diversity at different spatial scales. Location: European Transition Waters Ecoregion 6. Using a data set collected along a 7° latitudinal cline between 45°28’N and 39°56’N, we used Spearman’s rank correlation analysis to evaluate the relationships between species richness and both environmental and geographical variables, and linear regression analysis to show the relationships between alpha-, beta- and gamma-diversity. Three different measures were used to assess beta-diversity: Whittaker’s BetaW, and two similarity indices: the Bray-Curtis similarity index and Delta-s. Using multivariate analyses, we determined the similarity in composition of the benthic community between sites and compared the biotic ordination to abiotic (geographical and environmental) characteristics. Two hundred and sixty-eight species were recorded from 46 sites. Of these, 53.4% were restricted to one TW. Annelida were the dominant taxonomic group, followed by crustacea and mollusca. The alpha-diversity was highly variable (5–87 species) and was correlated with latitude. The gamma-diversity, measured at TW scale, was significantly correlated with alpha-diversity. The gamma-diversity increased with spatial scale and habitat heterogeneity. In the community pattern identified by multivariate analysis, TWs segregated by latitude and biogeography and this reflected different climatic conditions. We found that alpha-diversity increased when moving from higher to lower latitudes , and was dependent on both regional and local factors. Latitudinal variations in the extent of regional influence on local species richness were detected. The observed distribution pattern of TW faunas was mostly due to different climate types. We suggest that the distribution of annelidan species could be used as a proxy for assessing general community patterns for Italian TWsI documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
