Transylv. Rev. Syst. Ecol. Res. 7, (2009), "The Arieş River Basin" 77 AQUATIC AND SEMIAQUATIC HETEROPTERA FROM ARIEŞ RIVER BASIN (TRANSYLVANIA, ROMANIA) - METHODS IN ESTIMATING BIODIVERSITY Daniela Minodora ILIE * and Horea OLOŞUTEAN * * “Lucian Blaga” University of Sibiu, Faculty of Sciences, Department of Ecology and Environment Protection, Raţiu Street 5 - 7, Sibiu, Sibiu County, Romania, RO-550337, [email protected], [email protected] KEYWORDS: Romania, Transylvania, Heteroptera, α-biodiversity, β-biodiversity, γ- biodiversity, numeric equivalent. ABSTRACT This paper is part of a study made in order to establish the Arieş Basin water quality. The aim was to inventory the habitats of aquatic and semiaquatic Heteroptera (inventory that will regard the number and quality of those habitats, and also the human intervention in the area), and to establish the biodiversity degree, using two different methods that estimate both α-, β- and γ-biodiversity. In order to reach that, we took samples from 16 sampling stations along the hydrographic basin, the results showing the presence of at least 17 species, most of them eurivalent ones, but also with exceptions like Gerris gibbifer Schummel 1832, Hebrus pusillus (Fallén, 1807) or Hesperocorixa sahlbergi Fieber 1848, species with rare sightings in Romanian fauna. The α-biodiversity analysis reveals low values, counterbalanced by higher β- biodiversity values for most of the hydrographic basin, the gradient used in this case being the altitude. Both methods used for diversity estimation show more or less similar results. ZUSAMMENFASSUNG: Die aquatischen und semiaquatischen Heteropteren aus dem Einzugsgebiet des Arieş (Transylvanien, Rumänien) - Methoden zur Schätzung der Biodiversität. Die Arbeit ist Teil einer Untersuchung, die Bewertung der Wasserqualität im Einzugsgebiet des Arieş diente. Das Ziel war die Erfassung der von den aquatischen und semiaquatischen Heteropteren bevorzugten Habitate (berücksichtigt wurden Zahl und Qualität der Habitate sowie der menschliche Einfluss) und die Bestimmung der Biodiversitätswerte mit Hilfe von zwei Methoden zur Schätzung der α- und β-, oder γ-Diversität. Dafür wurden an 16 Punkten im Einzugsgebiet Proben entnommen. Die Auswertung der Proben ergab das Vorhandensein von mindestens 17, vorwiegend eurivalenten Arten, aber auch Ausnahmen wie Gerris gibbifer Schummel 1832, Hebrus pusillus (Fallén, 1807) oder Hesperocorixa sahlbergi Fieber 1848, die in Rumänien als selten gelten. Die Analyse der α-Biodiversität ergibt geringe Werte für jede Sammelstelle, denen jedoch hohe Werte der β-Biodiversität für den größeren Teil des Einzugsgebietes gegenüber stehen, wobei der verwendete Gradient die Höhenlage ist. Beide Schätzungsmethoden der Diversität haben mehr oder weniger ähnliche Ergebnisse erbracht. 78 I. Ilie and H. Oloşutean – Arieş Basin aquatic and semiaquatic Heteroptera - estimation methods (77 ~ 86) REZUMAT: Heteropterele acvatice şi semiacvatice din bazinul râului Arieş (Transilvania, România) - metode de estimare a biodiversităţii. Lucrarea face parte dintr-un studiu realizat cu scopul evaluării calităţii apei din Bazinul Arieşului. Ţinta a fost inventarierea habitatelor preferate de Heteropterele acvatice şi semiacvatice (inventarierea ţine cont de numărul şi calitatea habitatelor şi de impactul antropic), şi stabilirea valorilor biodiversităţii, cu ajutorul a două metode, ce vor estima biodiversitatea α, β şi γ. Au fost colectate probe din 16 puncte, de-a lungul bazinului, rezultatele aratând prezenţa a cel puţin 17 specii, majoritatea eurivalente, dar şi excepţii ca Gerris gibbifer Schummel 1832, Hebrus pusillus (Fallén, 1807) sau Hesperocorixa sahlbergi Fieber 1848, specii considerate rare în România. Analiza de biodiversitate α oferă valori reduse pentru fiecare punct de colectare, contrabalansate de valori mari ale biodiversităţii β pentru marea parte a bazinului, gradientul, folosit fiind altitudinea. Ambele metode au oferit rezultate mai mult sau mai puţin similare. INTRODUCTION Arieş River drains the central part of the Apuseni Mountains in western Romania, being one of the largest tributaries of Mureş River. The upper basin is formed from two separate rivers (Arieşul Mare and Arieşul Mic) wich unite near the city of Câmpeni to form the main river. In the upper basin, the two rivers run mostly trough crystalline rocks, while the lower basin is characterized by the presence of sedimentary rocks (especially limestone). Aquatic Heteroptera belong, according to the latest classifications, to Infrasuborder Nepomorpha Popov 1968, while the semiaquatic ones belong to Infrasuborder Gerromorpha Popov 1971 (Gaby Viskens, 2005, on www.earthlife.net). There are insects associated, more or less, to water surfaces, forming, along other groups, the nekton and the epineuston. They inhabit a large variety of micro biotopes, from those lacking in vegetation, to those completely covered (Andersen, 1982; Davideanu, 1999). The typical habitats for the group are ponds, lakes, slow flowing creeks or little bays formed at the shore of rivers. Most species are not sensible to moderate human impact in the habitat, as well to the presence of vegetation. The measurement of biodiversity is possible with the use of different techniques, the most common one technique involving indices that will reflect the particular aspects of the group in study. Using several measurement techniques can be revealed with greater precision the way in which the group has adapted to the habitats present in the specific area of the study. MATERIALS AND METHODS The study took place in June 2009, and the goal was to take qualitative samples. 16 sampling stations were taken in concern, covering the upper and lower basin of Arieş River (Fig. 1). There was taken one sample from each station, of 8 to 15 meters, covering the entire habitat (water surface and interior, aquatic vegetation if present, bottom); the samples were collected with an entomological net with 60 square centimeters opening. Transylv. Rev. Syst. Ecol. Res. 7, (2009), "The Arieş River Basin" 79 The identification of the species was made by their morphological features, studying the insects at the stereo binocular, or, in some of the cases, by genitalia, using data from other specialists (Jansson, 1986; Davideanu, 1999). The insect larvae found were not identified at the species' level, due to difficulties regarding this specific operation, and they will not be considered in the biodiversity analysis; the exception is the larvae of Nepa cinerea Lineé 1758, identifiable up to species' level, but the larvae of the species will not take part in the biodiversity analysis, because of the unitary approach we want for this study; from that point of view, two of the sampling stations, S2 and S8, will not take part in the analysis, since only larvae was sampled there. In station S10, one female Dichaetonecta sp. Hutchinson, 1940 was found, impossible to identify at species' level in the absence of the male (Poisson, 1986), but, since is the only Dichaetonecta found in the entire studied area, it will be considered as a different species in the biodiversity analysis. Figure 1: The location of the sampling points from Arieş River basin: stars represent sampling stations, rectangles represent cities and villages, and lines, creeks and rivers (personal representation). The results obtained from the sampling points will be analyzed from the biodiversity point of view, using two different approaches: the classical one, with specific α and β indices, and a more unconventional one. The classic approach in biodiversity states that biodiversity of an area (γ biodiversity) is obtained by adding or multiplying medium α values to β values. In our case, indices used will be Menhinick, for α biodiversity, calculated for each sampling station, and Whittaker Index, for β biodiversity, using altitude as a gradient. α values obtained will be used in calculating average α, which will be multiplied to Whittaker value, giving the value for γ biodiversity. 80 I. Ilie and H. Oloşutean – Arieş Basin aquatic and semiaquatic Heteroptera - estimation methods (77 ~ 86) A total different point of view is provided by Jost (2006, 2007). This author is proposing a new type of measurement, using the entropy like indices (Shannon, Renyi, Gini-Simpson etc.), with modified formulas as is the so called number equivalent. This number equivalent is used for calculation of the α and γ (total) biodiversity, the value of β being deduced from the other two. For our case study, in which community weights are different, Jost is suggesting the use of the Shannon Entropy (-Σpi*ln(pi)), with the number equivalent of exp(-Σpi*ln(pi)), for which the β value is obtained by dividing γ to α (Jost, 2007). RESULTS AND DISCUSSION The specific habitats for the group are scarcely present in the area, especially in the middle Arieş Basin and in the middle basin of Arieşul Mare River, due to intense human impact, represented by territorial improvement (terrain levelling, water banking) which leads to absence of specific habitats to the group (still waters, puddles, low flow sectors). Physico- geographical conditions take their part in the Arieş upper basin, where crystalline rock present in most areas, leads to rapid meteoric water infiltration, and the rapid flows of the local rivers and springs, concurs to the absence of a category of habitats that are preferred by Heteroptera. The 16 sampling stations from the studied area were selected to cover the entire diversity of habitats