AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS Aquatic Conserv: Mar. Freshw. Ecosyst. 14: 465–479 (2004) Published online 28 June 2004 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/aqc.633 Selecting areas to protect the biodiversity of aquatic ecosystems in a semiarid Mediterranean region using water beetles D. SAANCHEZ-FERN! AANDEZ*,! P. ABELLAAN,! J. VELASCO and A. MILLAAN! Department of Ecology and Hydrology, University of Murcia, 30100 Espinardo, Murcia, Spain ABSTRACT 1. In this work, carried out in the province of Murcia, a representative semi-arid area of the Iberian Peninsula, water beetles were used as indicators to identify the aquatic ecosystems with the highest interest for conservation. For that purpose, an iterative algorithm of complementarity based on the richness of aquatic Coleoptera was applied. ‘Complementarity’ refers to the degree to which an area, or set of areas, contributes otherwise unrepresented attributes to a set of areas. This principle was used to maximize the number of species represented within a given number of areas. 2. Only the species subsets whose taxonomic status, presence and distribution in the study area are well known were used. In total, 146 species were included, of which 12 are Iberian endemics and 32 are rare species (found only in one grid cell in the study area). 3. The highest correlation was generally shown by species richness with endemic, rare and vulnerable species richness. Thus, basing conservation strategies on species richness appears to be an effective protocol. 4. To preserve the highest degree of biodiversity in the aquatic ecosystems of the study area, the following need to be protected: (a) headwater streams in the north west of the province; (b) the uppermost reaches of the Segura River; (c) hypersaline and coastal ramblas; (d) rock pools and coastal ponds. 5. The present network of Protected Natural Spaces in the study area does not include many of the aquatic ecosystems shown to have the highest biodiversity of beetles. However, the future European ‘Natura 2000’ network will protect the 10 grid cells of highest aquatic biodiverstity, or at least part of them. Copyright # 2004 John Wiley & Sons, Ltd. KEY WORDS: water beetles; biodiversity conservation; complementarity; Protected Natural Spaces; semi-arid Mediterranean region INTRODUCTION The Mediterranean basin is considered one of the most important hotspots of biodiversity in the world (Myers et al., 2000). The south east of the Iberian Peninsula is a Mediterranean region of special interest because, although it is located in the most arid zone of Europe, it comprises a wide range of aquatic ecosystems, from freshwater streams, ponds and wetlands to hypersaline ramblas (ephemeral streams; for *Correspondence to: D. Saanchez-Fern! aandez,! Department of Ecology and Hydrology, University of Murcia, 30100 Espinardo, Murcia, Spain. E-mail: [email protected] Copyright # 2004 John Wiley & Sons, Ltd. Received 27 October 2003 Accepted 8 March 2004 466 D. SA´NCHEZ-FERNA´NDEZ ET AL. details see Moreno et al. (1997)) or continental and coastal salt-pans. Many of these ecosystems are unique because of their ecological characteristics and because of the presence of rare and endemic species (Moreno et al., 1997; Millaan! et al., 2002; Saanchez-Fern! aandez! et al., in press). Nevertheless, for centuries the region has been subjected to the severe influence of human activities, leading to marked alterations, reduced area, and even the disappearance of some habitats, especially aquatic ones (Meedail! and Queezel,! 1999). Any remaining ecosystems, therefore, should be high on the list of conservation priorities. During the last decade, and following the ‘R!ııo Conference’, there has been a growing awareness of the need to conserve species and habitats in many parts of the world. In this context, the identification of areas of high biodiversity at all scales (world-wide, national or regional) has become an important element in assigning conservation priorities (Gaardenfors,. 2001). In approaching something so complex as the measurement of biological diversity, surrogates of biodiversity are commonly used. Among them, broad- scale biodiversity measures (such as climatic or vegetation data), habitat features (naturalness or typicality), higher taxonomic groups (genera or families) or indicator taxa are frequently used (Noss, 1990; Williams, 1996). In the last case, taxonomically well-known groups that have been sufficiently studied in the area are used, so their taxonomic richness, rarity and endemicity patterns are assumed to be indicative of similar patterns in lesser known groups (Reyers and Jaarsveld, 2000). Freshwater invertebrates have been used extensively as indicators to monitor the status of habitats in terms of nutrient enrichment or the presence of potential pollutants (Wright et al., 2000). To identify high-priority conservation areas, researchers have used plants and/or vertebrates, but only on a few occasions have invertebrates been taken into account for this purpose (Posadas et al., 2001; Serrano, 2002), despite the fact that they represent around 95% of all known animal species (Hull et al., 1998; Palmer, 1999; Sluys, 1999). Among invertebrates, beetles are the richest group, representing one-third of all species described (Ribera et al., 2002), and water beetles are one of the most useful for ranking sites in relation to their conservation value (Jeffries, 1988; Foster et al., 1990). They constitute an ideal indicator of freshwater ecosystem biodiversity and meet most of the criteria proposed in the literature for the selection of indicator taxa: taxonomically well- known and stable; biology and general life history well understood; populations easily surveyed and manipulated; groups and related species occupying a breadth of habitats and a broad geographical range; specialization of each population within a narrow habitat; patterns observed in the indicator taxon reflected in other related and unrelated taxa (Noss, 1990; Pearson and Cassola, 1992; Pearson, 1994). Water beetles include many species, they show high functional diversity, and they are capable of colonizing a wide variety of habitats (Ribera and Foster, 1993). Furthermore, there is ample knowledge of beetle taxonomy and ecology (Ribera et al., 1998; Ribera, 2000), and their importance as indicators of the spatial and temporal changes that take place in aquatic systems has been demonstrated (Bournaud et al., 1992; Richoux, 1994). However, a single taxonomic group cannot reflect the different components of an ecosystem, and the current trend is to choose little-related complementary taxa that may be considered representative of different parts of the system (Halffter et al., 2001). In this sense, the water beetles used in this study are presented as complementary to the establishment, management and conservation of the scarce aquatic ecosystems included in the Protected Natural Spaces (PNSs) of the study area (Saanchez-Fern! aandez! et al., 2003). The objectives of this study were to assess priority areas for biodiversity conservation in freshwater ecosystems in a semi-arid Mediterranean region using water beetles as indicators, and to detect gaps in the network of PNSs in the study area, through overlaying the high-priority conservation areas on the PNSs currently recognized or proposed in the province of Murcia. STUDY AREA The study is confined to a semi-arid region of south east Spain (region of Murcia) covering 11 137 km2 and with an annual average rainfall around 300 mm and an annual average temperature above 16 8C. The analyses used cells defined by Universal Transverse Mercatore (UTM) coordinates as analytical units. Copyright # 2004 John Wiley & Sons, Ltd. Aquatic Conserv: Mar. Freshw. Ecosyst. 14: 465–479 (2004) SELECTING AREAS TO PROTECT BIODIVERSITY 467 Figure 1. Location of the study area (province of Murcia) and sampled surface in UTM 10 Â 10 km grid cells. Sixty-six of the 144 UTM 10 Â 10 km grid cells of the region of Murcia were sampled, covering 45.8% of the total regional surface (Figure 1). They included most of the aquatic ecosystems of the study area. In these 66 grid cells, 227 sampling sites were selected and grouped into habitat types based on environmental and ecological parameters, according to Millaan! et al. (1996, 2002). Sixteen habitat types were distinguished: headwater streams; middle-reach streams; middle course of rivers; channelized river reaches; river reaches influenced by dams; eutrophic streams; ramblas (ephemeral streams); springs; irrigation channels; reservoirs; irrigation pools; pools, ponds and other wetlands; rice fields; continental salt-pans; coastal salt-pans and rock pools. METHODS The information on species occurrence (cumulative species richness) came from two sources: the literature and field samples collected between 1981 and 2002. Beetles were sampled with a D-frame net (500 mm mesh), with each collection generally taking 30 min per site. Samples were preserved in 70% ethanol and taken to the laboratory for processing, identification and enumeration. Although not visited regularly, each site was surveyed at least twice and most were sampled five times. A database was created to include Copyright # 2004 John Wiley & Sons, Ltd. Aquatic Conserv: Mar. Freshw. Ecosyst. 14: 465–479 (2004) 468 D. SA´NCHEZ-FERNA´NDEZ ET AL. information on species identity, number of specimens collected, location, date, and collector. More than 3000 records of aquatic beetles in the study area were included.