1.A study on the distribution pattern and conservation of freshwater molluscs of the south Guadiana River (SW Iberian Peninsula) was carried out between the Alqueva dam and the Atlantic Ocean.2. The knowledge of the distribution and abundance of molluscs before the closure of the Alqueva dam is an important tool for evaluating the potential reduction in diversity and the changes in species conservation status that may occur later.3. Twenty-three species (15 gastropods and 8 bivalves) were found in the study area. The presence of Unio crassus and Potomida littoralis indicates the importance of this basin for the conservation of endangered mussels (Unionidae) in the south Iberian Peninsula.4. Drainage area above the sampling site explained almost 58% of the variation in species richness. Larger drainage areas had a higher number of species, including those endemic to the basin.5. Patterns of habitat use were examined to identify species preferences with respect to the erosional-depositional gradient. Islamia minuta, Pisidium casertanum and Pisidium personatum find their optimum habitat in headwaters, whereas Theodoxus fluviatilis, Mercuria emiliana, Radix auricularia and all unionid species inhabit large and stable habitats downstream without marine influence.6. Populations of invasive Corbicula fluminea were found in the Guadiana River basin, both in rivers with large drainage areas and in brackish waters near the mouths of rivers.

We report on the reproductive cycle and reproductive characteristics of three oviparous lizard species: Psammodromus algirus, Psammodromus hispanicus and Acanthodactylus erythrurus from a sandy coastal area in SW-Spain. Maximum testicle activity in P. algirus is research between March-May. Oviposition occurs along the activity cycle until September, clutch size average 4.8 eggs (2-10) and larger females tend to produce larger clutches. In P. hispanicus testicle reaches maximal volume during February-May. Oviposition occurs throughout April-September, and two clutches, averaging 3.6 eggs (2-5), are produced annually. In A. erythrurus mean testicle volume reaches its maximum in March, oviposition occurs in two cycles: spring and summer, clutch size averages 4.4 eggs (3-6) and increases with female snout-vent length.

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a b s t r a c tThis paper reviews the environmental factors that influence biodiversity of freshwater mollusc communities and conservation status of watercourses in two Mediterranean acid mine drainage-impacted basins of the southern Iberian Peninsula. We found 17 mollusc species: 14 gastropods (10 native and 4 introduced) and 3 bivalves. We found five distribution patterns: native headwater (Arganiella wolfi, Stagnicola palustris, Unio delphinus, Pisidium casertanum and Pisidium personatum) and mouth (Hydrobia acuta, Peringia ulvae and Myosotella myosotis) sensitive-stenochoric species, intermediate sensitive-widely distributed species (Planorbarius metidjensis and Radix balthica), insensitive-eurychoric species (Ancylus fluviatilis), and erratic-distribution pattern species (Galba truncatula and Planorbis carinatus). The highest biodiversity indices have been found in non-impacted headwaters and, to a lesser extent, in tidal streams. The biodiversity of the middle reaches, with varying degrees of impact by acid mine drainage and high water deficit, was scarce and dominated by introduced species. Over 30% of the variation in native and introduced species richness is explained by environmental gradients related to heterogeneity (instream macrophytes cover and Fhi and Qbr indices) and acid runoffs (pH, conductivity, turbidity and concentration of sulphides). Severely impacted sites have no mollusc species. The conservation status of watercourses is also very remarkably influenced by the heterogeneity and contamination of the environment. Conservation values are higher in water bodies located in protected northern and southern sites in both basins.

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