Limnetica, 28 (1): 139-148 (2009) Limnetica, 28 (1): x-xx (2008) c Asociacion´ Iberica´ de Limnolog´a, Madrid. Spain. ISSN: 0213-8409 Jarabugo (Anaecypris hispanica) and freshwater blenny (Salaria uviatilis): habitat preferences and relationship with exotic sh species in the middle Guadiana basin Francisco Blanco-Garrido 1,2,∗, Miguel Clavero 3,4 and Jose´ Prenda 1 1 Departamento de Biolog´a Ambiental y Salud Publica,´ Universidad de Huelva, Campus Universitario de El Car- men, 21007 Huelva, Espana.˜ 2 MEDIODES, Consultor´a Ambiental y Paisajismo S. L. C/ Bulevar Louis Pasteur, 1 Bloque 2 1o 1. 29010 Mala-´ ga, Espana.˜ 3 Grup d’Ecologia del Paisatge, Area` de Biodiversitat, Centre Tecnologic` Forestal de Catalunya. Pujada del Se- minari s/n, 25280 Solsona, Espana.˜ 4 Departament de Ciencies` Ambientals, Universitat de Girona. Campus de Montilivi, 17071 Girona, Espana.˜ 2 ∗ Corresponding author: [email protected] 2 Received: 9/7/08 Accepted: 15/1/09 ABSTRACT Jarabugo (Anaecypris hispanica) and freshwater blenny (Salaria uviatilis): habitat preferences and relationship with exotic sh species in the middle stretch of the Guadiana basin In this work the habitat preferences of two endangered freshwater sh species, jarabugo (Anaecypris hispanica) and freshwater blenny (Salaria uviatilis) are analysed, and the distribution of both species in relation to the presence of exotic sh species in the middle stretch of the Guadiana basin is assessed (28 sampling sites). The jarabugo as well as the blenny showed a very restricted distribution, mainly jarabugo (only present in 14.3 % of the sites) which in comparison with previous studies suffered a strong reduction on its distribution area (86 %). This species preferred small streams (generally less than 10 m channel width) and with submerged aquatic vegetation, while the blenny appeared mostly in large downstream stretches (> 10 m channel width), a higher water ow, and water availability (permanent water ow) . Based on a randomisation test (Monte Carlo simulation), blenny distribution was random with respect to exotic species. However, the jarabugo and the centrarchidae (Lepomis gibbosus and Micropterus salmoides) never coexisted in the same locations, despite a high probability of co-occurrence expected by chance (Monte Carlo simulation P = 0.965). The spatial segregation between the jarabugo and centrarchids, together with the decline of the former in areas which experienced an increase in centrarchid abundance, suggest these exotics are a threat for the conservation of jarabugo. Key words: Iberian endemism, biotic interactions, large dams, Mediterranean streams, conservation. RESUMEN El jarabugo (Anaecypris hispanica) y el blenio de r´o (Salaria uviailis): preferencias de habitat´ y relacion´ con los peces exoticos´ en el tramo medio de la cuenca del Guadiana En este trabajo se analizan las preferencias de habitat´ de dos peces continentales amenazados, el jarabugo (Anaecypris his- panica) y el blenio de r´o (Salaria uviatilis), as´b como la distribucion´ de ambas especies en relacion´ a la presencia de especies exoticas´ en el tramo medio de la cuenca del Guadiana (28 localidades de muestreo). Tanto el jarabugo como el blenio mos- traron una distribucion´ muy restringida, especialmente el primero (solo´ presente en el 14.3 % de los sitios muestreados) que, en comparacion´ con estudios previos, vio reducida enormemente su area´ de distribucion´ (86 %). Esta especie prerio´ arroyos pequenos˜ (generalmente de menos de 10 m de anchura de cauce) y con vegetacion´ acuatica´ sumergida, mientras que el blenio ocupo´ principalmente los tramos bajos, con cauces amplios (> 10 m) y un mayor caudal y disponibilidad de agua (caudal permanente). Segun´ la aplicacion´ de un test de aleatorizacion´ (simulacion´ de Monte Carlo) la distribucion´ del blenio fue aleatoria respecto a la presencia de especies exoticas.´ Sin embargo, el jarabugo y los centrarquidos´ (Lepomis gibbosus y 140 Blanco-Garrido et al. Micropterus salmoides) nunca coexistieron en las mismas localidades, a pesar de existir una elevada probabilidad de coexis- tencia esperable por azar (P = 0.965, test de Monte Carlo). La segregacion´ espacial entre el jarabugo y los centrarquidos,´ junto con el declive del primero en zonas que han experimentado un aumento en la abundancia de centrarquidos,´ apunta a estas especies exoticas´ como una amenaza para su conservacion.´ Palabras clave: Endemismos ibericos,´ interacciones bioticas,´ infraestructuras hidraulicas,´ r´os mediterraaneos,´ conserva- cion.´ INTRODUCTION Pereira et al., 1999; Doadrio, 2002). The jara- bugo is considered “Endangered” in Spain and The jarabugo (Anaecypris hispanica), an Iberian “Critically Endangered” in Portugal, while the sh species endemic to the Guadiana basin, and blenny is considered “Endangered” both in Spain the freshwater blenny (Salaria uviatilis,sim- and Portugal (Doadrio, 2002; ICN, 2005). ply blenny hereafter) are both among the most Both species exist in highly fragmented and threatened sh in Iberian freshwaters (Collares- localized populations (Changeux & Pont, 1995; Iberian Peninsula N SPAIN PORTUGAL r Olivenza e # iv r # Táliga Friegamuñoz a # n # ia # # # d # Alcarrache a # ## # u # # # # Ardila UTM grid 10x10 Km G # # Alqueva dam # # # # # # # Presence of jarabugo # Chanza # # # Presence of blenny Múrtigas # # Both species ## Chanza and Andévalo dams 60 Km ATLANTIC OCEAN Figure 1. Map of the middle-lower stretch of the Guadiana river basin showing the location of the sampling points. Field work was carried out before the construction of Alqueva and Andevalo´ dams. Mapa del tramo medio de la Cuenca del Guadiana y localizacion´ de los puntos de muestreo. El trabajo de campo se realizo´ antes de la construccion´ de las presas de Alqueva y Chanza-Andevalo.´ Jarabugo and freshwater blenny in the middle Guadiana basin 141 Corbacho & Sanchez,´ 2001; Salgueiro et al., METHODS 2003), and little is known about their specic ecological requirements, such as habitat prefe- The study area is located in the middle stretch rences (see Ribeiro et al., 2000; Vinyoles, 1993). of the Guadiana basin (Fig. 1). The climate is ty- The expansion of exotic sh species and habitat pically Mediterranean, with rainfall being con- disturbance are supposed to be important threats centrated between autumn and spring and featu- for both endangered species (Collares-Pereira et ring a severe summer drought (Gasith & Resh, al., 2000; Collares-Pereira & Cowx, 2001; Doa- 1999). These climatic characteristics generate a drio, 2002); however, there has been insufficient high intra- and inter-annual variability in ow re- analytical effort to clarify factors that threaten gime. In summer, most tributaries become a suc- them. Understanding the factors that influence the cession of pools of variable dimensions with little distribution and conservation of these endangered or no water ow. More permanent and stable hy- species is essential in order to identify the problems drological conditions exist in downstream stret- and to propose strategies for their conservation. ches and in the main river. This work addresses three main objectives: The eldwork was carried out from April to (i) to determine the distribution range of jara- June 2001, before the construction of the Alqueva bugo and blenny in the middle stretch of the and Chanza-Andevalo´ dams, two large reservoirs Guadiana basin, (ii) to describe the habitat pre- located in the study area (Alqueva: 3150 Hm3; ferences of both species, and (iii) to examine Chanza-Andevalo:´ 973 Hm3). A total of 28 lo- the spatial relationships between these endange- cations (Fig. 1) were sampled by electroshing red species and exotic sh. (230 V, 1-5 A). Sampling was conducted once in Table 1. Environmental variables used to characterise the 28 sampling locations. Variables ambientales utilizadas para caracterizar las 28 localidades de muestreo. Macrohabitat variables Method Drainage area in each sampling site (km2) Extracted from maps (1:100 000) Stream order (Strahler, 1964) Extracted from maps (1:100 000) Distance to the main river (km) Extracted from maps (1:100 000) Altitude (m) Extracted from maps (1:100 000) Mesohabitat variables Method Physico-chemical parameters Temperature (◦C) Portable probes Conductivity (μS/cm) Portable probes Turbidity (FTU) Portable probes Dissolved oxygen (mg/l and %) Portable probes pH Portable probes Stream structure parameters Current velocity Floating object, 3 replicates Depth (cm) Rigid meter Channel width (m) Flexible meter Substrate coarseness Wentworth scale Submerged vegetation cover ( %) Visual estimate, 2-3 observers Emergent vegetation cover ( %) Visual estimate, 2-3 observers Herbaceous cover ( %) Visual estimate, 2-3 observers Shrub cover ( %) Visual estimate, 2-3 observers Tree cover Visual estimate, 2-3 observers Fish shelter (submerged stones and branches, cavities between rocks...) Visual estimate, 2-3 observers 142 Blanco-Garrido et al. each site, over a length of between 100 and 250 m A probability analysis (Monte Carlo simulation and during a period of 1-1.5 hours. test) was performed to assess the relationship bet- Fifteen habitat variables at a mesohabitat sca- ween the presence of exotic species and the ob- le were measured or estimated in each of the sam- served distribution of jarabugo and blenny, tes- pled locations, including both physico-chemical ting the null hypothesis of random sh distribu- and stream structure parameters (Table 1). In tion in reference to exotic species. This analy-