Although Mediterranean wetlands were recognized as biodiversity hotspots, most of them are nowadays threatened by human activities that have led to habitat loss and degradation. A total of 36 wetlands were monitored to assess species richness of branchiopods and copepods by using accumulation curves and non-parametric estimators. Three different types of wetlands were identified: i) temporary freshwaters-subsaline-hyposaline (TFSH); ii) permanent freshwaters-subsaline-hyposaline (PFSH); and iii) mesosaline-hypersaline (MH) wetlands (including temporary and permanent ones). A total of 60 species were recorded; they belong to seven different orders. A large number (37%) of rare species (present in only one wetland) were found while only 11% of the total species were common (i.e., present in more than 20% of wetlands). Species richness was related to wetland typology, with the largest number of species observed in TFSH, followed by MH and by PFSH wetlands. We have found that rare species are mainly present in temporary wetlands, the most vulnerable to hydrological changes; hence, these types of wetlands represent unique sites deserving conservation.Key words: Biodiversity, conservation, Mediterranean wetlands, non-parametric estimators, zooplankton.
METHODS
Study wetlandsIn the present study, we selected a total of 36 endorheic wetlands (Fig. 1) widely differing in their limnological characteristics (Tab. 1). The term endorheic reflects the closed nature (no outlet) of the drainage systems of wetlands (Dantín, 1929;1940;Allan et al., 1995). In particular the studied wetlands differ in altitude (265 to 1582 m asl) and in morphological characteristics: maximum area ranging from 0.2 to 46 ha and maximum depth from 10 to 456 cm (Ortega et al., 2003. All these wetlands are located in the Alto Guadalquivir, a representative region of the southern Iberian Peninsula (Spain), with a Mediterranean continental climate, a Mediterranean type of climate with continental tendencies (Capel Molina, 1981;Díaz de la Guardia et al., 2003). The three main morphologic and geologic units that exist in Andalusia are present in the study area: Sierra Morena siliceous mountains at the north, the Guadalquivir depression with olitostromics deposits and Triassic rocks in the centre and Baetic calcareous mountains in the south and east (Vera, 1994). The valley of the Guadalquivir River represents the most important geographical entity of this district, being a large proportion of this area which is characterized by a semiarid climate with a mean annual precipitation around 400 mm, although aridity decreases from the Guadalquivir valley to mountain areas located in the north, south and east of this valley (AEMET, 2011).
SamplingAccordingly to the high inter-annual variability that characterized Mediterranean wetlands, zooplankton samples (branchiopods and copepods) were collected seasonally during a multi-year sampling (1998-2002 and 2010, representing a great range of weather conditions that affect Mediterranean wetlands) to obtain c...