Limnetica, 27 (2): x-xx (2008) Limnetica, 27 (2): 285-298 (2008). DOI: 10.23818/limn.27.23 c Asociacion´ Iberica´ de Limnolog´ıa, Madrid. Spain. ISSN: 0213-8409 Influence of iron and nitrate concentration in water on aquatic Coleoptera community structure: Application to the Avia River (Ourense, NW. Spain) Marta Fernandez-D´ ´ıaz, Cesar Joao Benetti ∗ and Josefina Garrido Department of Ecology and Animal Biology, Faculty of Biology. University of Vigo, Campus Lagoas- Marcosende, 36310, Vigo, Spain 2 ∗ Corresponding author: [email protected] 2 Received: 26/3/08 Accepted: 8/7/08 ABSTRACT Influence of iron and nitrate concentration in water on aquatic Coleoptera community structure: Application to the Avia river (Ourense, NW. Spain) In this work the influence of the concentration of dissolved iron and nitrate in the water on the structure of the community of aquatic Coleoptera of a river in northwest Spain is analyzed. A total of 45 species and subspecies of aquatic Coleoptera (Adephaga and Polyphaga) were collected between March and November 1999 from 10 sites distributed along the Avia river (Ourense, N.W. Spain). Also, 24 physical and chemical parameters of water were measured and a CCA was made to evaluate which of these factors had the greatest influence on the studied fauna. At the same time an ecological analysis was made using the distribution of species and subspecies in relation to two water parameters (concentration of nitrate and dissolved iron). The study of distribution in relation to these factors by means of elaborating their ecological profiles suggested indicator species for each of these parameters. Seventeen species were found to be indicators for at least one of the parameters analyzed. The species Deronectes costipennis gignouxi, Enichocerus legionensis, Hydraena testacea, Megasternum obscurum, Nebrioporus depressus elegans and Stenelmis canaliculata are the best indicators of these parameters, if we consider only taxa collected in class 4, that is, with high values of iron and nitrate. Key words: Aquatic Coleoptera, dissolved iron, nitrate, indicator species, fluvial ecosystem. RESUMEN Influencia de la concentracion´ de hierro y nitrato en el agua sobre la estructura de una comunidad de Coleoptera acuati-´ cos: Aplicacion´ al r´ıo Avia (Ourense, NO de Espana)˜ En este trabajo se analiza la influencia de la concentracion´ de hierro disuelto y nitrato en el agua sobre la estructura de la comunidad de coleopteros´ acuaticos´ de un r´ıo en el noroeste de Espana.˜ Un total de 45 especies y subespecies de Coleoptera acuaticos´ (Adephaga y Polyphaga) fueron recolectados entre marzo y noviembre de 1999 en 10 puntos distribuidos a lo largo del r´ıo Avia (Ourense, NW Espana).˜ Tambien´ se tomaron medidas de 24 de parametros´ f´ısicos y qu´ımicos del agua y se hizo un CCA para evaluar cual´ de estos factores fue el de mayor influencia en la fauna estudiada. A partir de eso, realizamos un analisis´ ecologico´ de la distribucion´ de la presencia de especies y subespecies en relacion´ con dos factores qu´ımicos del agua (concentracion´ de nitrato y hierro disuelto). El estudio de la distribucion´ en relacion´ con estos factores a traves´ de la elaboracion´ de sus perfiles ecologicos´ senal˜ o´ las especies indicadoras para cada uno de estos parametros,´ de acuerdo a su informacion´ rec´ıproca de especie-factor. Diecisiete especies demostraron ser indicadoras de por lo menos unos de los parametros´ analizados. Las especies Deronectes costipennis gignouxi, Enichocerus legionensis, Hydraena testacea, Megas- ternum obscurum, Nebrioporus depressus elegans y Stenelmis canaliculata son las mejores indicadoras de estos parametros´ si tenemos en cuenta solo los taxones recogidos en la clase 4, es decir, con altos valores de hierro y nitrato. Palabras clave: Coleoptera acuaticos,´ hierro disuelto, nitrato, especies indicadoras, ecosistema fluvial. 286 Fernandez-D´ ´ıaz et al. INTRODUCTION macroinvertebrate communities as a whole, and Heuss (1989) affirms that some Coleoptera can Fluvial ecosystems are of special interest be- denote as many degrees of contamination as levels cause of their high biological richness and di- of dissolved oxygen. In the Iberian Peninsula, versity. Communities of aquatic organisms have different studies on fluvial networks (Garc´ıa de developed adaptations that allow them to pros- Jalon´ & Gonzalez´ del Tanago,´ 1982; Gonzalez´ del per in these environments, which at the same ti- Tanago,´ 1986; Gonzalez´ et al., 1986a; Gonzalez´ me, make them very vulnerable to possible al- et al., 1986b; Prat et al., 1983; Prat et al., 1984; terations in streams. In this sense, human acti- Alba-Tercedor et al., 1986; Palau & Palomes, 1986; vity often causes severe ecological damage to ri- Alba-Tercedor & Jimenez,´ 1987; Cortes,´ 1989; ver systems. These disturbances produce altera- Ribera & Foster, 1992), point out Coleoptera within tions in the chemical composition of water, and in benthic communities as important bioindicators of the structure of the communities of organisms li- pollution and evaluators of good water quality. In ving in this environment (Somolders et al., 1999; this sense the most abundant families in rivers are Smolders et al., 2003; Oller & Goitia, 2005). Hydraenidae and Elmidae, considered as the best According to Nummelin et al. (2007) diffe- indicators of environmental impacts (D´ıaz, 1991; rent groups of insects are excellent indicators of Garc´ıa-Criado, 1999; Garc´ıa-Criado & Fernandez-´ contamination by heavy metals. For Beasley & Alaez,´ 1995; Garc´ıa-Criado & Fernandez-Al´ aez,´ Kneale (2003) macroinvertebrates, among them 2001; Garc´ıa-Criado et al., 1999). different groups of Coleoptera, are good indica- Different studies have used ecological profi- tors of high iron concentrations. A detailed study les to designate indicator species (Petraglia & of the autoecology of different species of aqua- Tomaselli, 2003; Bonada et. al. 2004; Mitov & tic beetles shows that many of them have qui- Stoyanov, 2005). There are different studies on te narrow ecological requirements and are very the autoecology of several species of these Co- useful as bioindicators in determining the charac- leoptera (Puig 1983, Sainz-Cantero´ et al., 1987; teristics of aquatic environments (Castella et al., Sainz-Cantero´ et al., 1988; Gil et al., 1990; 1984; Flechtner, 1986; Davis et al., 1987; Foster D´ıaz ,1991; Garrido et al., 1994), and others et al., 1990; Foster et al., 1992; Eyre et al., 1992; that evaluate the sensitivity of many species to Eyre et al., 1993; Collinson et al., 1995; Ribera different ecological factors by ecological profi- et al. 1995a; Ribera et al. 1995b; Moreno et al., le analysis and calculation of reciprocal informa- 1997). Other authors (Eyre & Foster, 1989; Ey- tion (Valladares et al., 1990; Garrido et al., 1994; re & Rushton, 1989) consider them as the most Garc´ıa-Criado & Fernandez-Al´ aez,´ 1995). The useful group in assessing environmental quality study shows the preferences of several species of and change in static water. Brancucci (1980) and Coleoptera within the ranges of values found for Ribera & Foster (1992) state that beetles can be several chemical factors of water. considered good indicators of macro and micro environmental characteristics of the aquatic envi- ronment in which they live. METHODS Aquatic beetles are abundant in different fresh- water habitats and show a high species richness of The study area is the Avia river in the south around 600 species and subspecies in the Iberian of the Galician Community, in the north-north Peninsula (Ribera, 2000). In the first studies of west of Ourense Province, NW Spain (Fig. 1). water quality they remained very much in the It is surrounded by a set of massive mountain background, but have now become more important ranges forming the border with the provinces as indicators (Garc´ıa-Criado & Fernandez-Al´ aez,´ of Pontevedra and Lugo. Along its course it 2001), since most of their life cycle occurs in is fed by numerous streams forming a river aquatic environments. Jeffries (1988) shows that of 643 Km2 surface. The eastern part of the communities of aquatic beetles are a reflection of river flows on schistose substrate and mainly on Influence of iron and nitrate concentration in water on aquatic Coleoptera 287 Figure 1. Location of the study area: Avia river with the sampling sites, in the Minho river basin. Localizacion´ del area´ de estudio: r´ıo Avia, con los puntos de muestreo, en la cuenca del rio Mino.˜ granite substrate in the west. The river Avia is water were obtained. The determination of tra- located in the Mino˜ river basin. ce elements was made with ICP-MS technique. Samples were taken seasonally during an an- The measured ions were: calcium, magnesium, nual cycle (from March 1999 to November 1999) sodium, potassium, iron, manganese, copper, and were collected from ten sites (A1-A10) so we chromium, aluminium, lead, zinc and cadmium. initially had forty samples designated with a co- Some of the environmental variables did not sur- de indicating the site (Ax) and season (Wi, Sp, pass the detection limit, for example, chromium, Su, Au) when the sample was taken. The sam- cadmium, lead, zinc, phosphates and sulphates. ples were taken with an entomological water net These do not appear in the results (Table 1) and (0.5 μm mesh), along 10 m for ten minutes. This were not considered in this paper. is one of the more efficient methods of sampling Canonical correspondence analysis (CCA) to evaluate the specific diversity and structures of was used to analyse species-environment rela- the community (Garc´ıa-Criado & Trigal, 2005). tionships (see Ter Braak & Van Tongeren, 1995) Also, different physical and chemical parameters in order to identify environmental (abiotic) fac- were measured, of which pH, temperature, total tors potentially influencing aquatic Coleoptera dissolved salts (TDS), dissolved oxygen and con- assemblages. The factors analyzed were potas- ductivity were measured in situ. sium, sodium, aluminium, manganese, iron and Laboratory analysis of the water samples in- nitrate.