Distribution patterns of freshwater molluscs along environmental gradients in the southern Guadiana River basin (SW Iberian Peninsula)

Abstract

The taxonomic status of the freshwater mollusc fauna of the Iberian Peninsula it is reasonably well known, but, unlike other benthic macroinvertebrate, its distribution and ecology has been poorly studied. In this article, I study the relationships between environmental characteristics and distribution and community structure of freshwater molluscs along climatic, hydrological, physicochemical, and heterogeneity gradients in the southwestern Iberian Peninsula. Ninety-four sampling points were analysed, in which, in addition to habitat features, the presence/ absence and abundance of species were evaluated. The environmental gradients were measured by use of principal-components analysis (PAC), which orders the variables along two gradients: headwaters-mouth gradient (PC1) and water availability (PC2). According to canonical correspondence analysis (CCA), the main environmental factors related to species distribution and community structure were conductivity, permanency, channel width, turbidity, slope, and distance to the main river axis. The relationship between biodiversity (measured as species richness and the Shannon-Weiner diversity index), the ratio of the number of introduced species to the total number of species (zoogeographic integrity coefficient), and environmental variables was best explained by a regression model incorporating, basically, the permanence of water in streams as the variable that accounted for most of the variance. This study demonstrates that the distribution of freshwater molluscs along a Mediterranean gradient highly stressed by drought depends, mainly, on the hydrological stability and environmental conditions of the headwaters and estuarine sites.

Diversidade de moluscos em riachos de uma região de encosta no extremo sul do Brasil

“…A introdução de espécies exóticas de moluscos também tem sido sugerida como causa importante para a extirpação de certas espécies nativas (Ricciardi et al 1998, Strayer 1999, Mansur et al 2012. Desta forma, estudar a biodiversidade dos moluscos límnicos, gerando informações sobre diversos aspectos da ecologia de espécies, populações e comunidades, é imprescindível para preservá-los (Lysne et al 2008, Downing et al 2010, Pérez-Quintero 2011.…”

The influence of the landscape structure within buffer zones, catchment land use and instream environmental variables on mollusc communities in a medium‐sized lowland river

“…2014). Although M. glutinosa is uncommon in most parts of Denmark, Ireland, England, Sweden and Finland; it has been recorded in ten of the 25 limnofaunistic regions of Europe (Økland 1990;Kerney 1999). Eutrophication, the regulation of rivers, the loss of marshy habitats and removing macrophytes are the main threats to these five gastropod species.…”

Caracterização Química E Avaliação Da Atividade Biológica Da Framboesa (Rubus Idaeus L.). Contribuição Para O Desenvolvimento De Uma Alegação De Saúde

“…Essas interferências antrópicas alteram fatores ambientais importantes para sobrevivência dos moluscos, como velocidade da água, conteúdo de oxigênio dissolvido, matéria orgânica em suspensão, etc. (PÉREZ-QUINTERO, 2012). A introdução de espécies exóticas de moluscos também tem sido sugerida como causa importante para a extirpação de certas espécies nativas (RICCIARDI et al, 1998;STRAYER, 1999;MANSUR et al, 2012).…”