Ann. Limnol. - Int. J. Lim. 52 (2016) 13–26 Available online at: Ó EDP Sciences, 2016 www.limnology-journal.org DOI: 10.1051/limn/2015036 Distribution, ecology and conservation status of two endemic amphipods, Echinogammarus acarinatus and Fontogammarus dalmatinus, from the Dinaric karst rivers, Balkan Peninsula Kresˇ imir Zˇ ganec1*, Petra Lunko2, Andrej Stroj3, Tomasz Mamos4 and Michal Grabowski4 1 Department of Teacher Education Studies in Gospic´ , University of Zadar, dr. Ante Starcˇ evic´ a 12, 53000 Gospic´ , Croatia 2 Croatian Agency for Environment and Nature, Radnicˇ ka cesta 80/7, 10000 Zagreb, Croatia 3 Croatian Geological Survey, Sachsova 2, 10000 Zagreb, Croatia 4 Department of Invertebrate Zoology and Hydrobiology, Laboratory of Biogeography and Invertebrate Ecology, University of Lodz, St. Banacha 12/16, 90-237 Lodz, Poland Received 21 July 2015; Accepted 07 December 2015 Abstract – The Balkan Peninsula is recognized to be one of the most important biodiversity hotspots world- wide. However, biogeographic patterns of its freshwater fauna are poorly understood due to the lack of basic data on distribution and ecology, particularly for endemic taxa. We studied the distribution, habitats and conservation status of two endemics, Echinogammarus acarinatus and Fontogammarus dalmatinus, in the Dinaric karst rivers. Altogether, 711 sites were sampled from 2000 to 2014 and supplemented by literature data. Although previously known only from rivers of the Adriatic Sea (AS) basin, both species were also found in the Black Sea (BS) basin. E. acarinatus has a mosaic distribution extending from the Una River to the delta of the Neretva River, particularly in the rivers Vrbas and Bosna (BS). Its presence in the AS basin rivers, Krka and Neretva, could result from river capture events by which former tributaries of the Una and Bosna (BS) were directed to the AS basin. Two subspecies of F. dalmatinus are distributed in the Una, Zrmanja and Krka Rivers. F. dalmatinus dalmatinus occurs in upper and middle parts of the Zrmanja (AS), and in the upper part of the Una (BS), while F. dalmatinus krkensis was found exclusively in springs and upper parts of the Krka (AS). Distribution of both subspecies in the Zrmanja and Krka indicates former connection between these rivers. The ecology and conservation status of all the studied taxa are presented and discussed. This study illustrates the importance of including ecological and historical interpretations of spe- cies’ distributions for managing conservational issues in the case of freshwater endemics with narrow ranges. Key words: Freshwater / biogeography / endemic gammarids / microdistribution Introduction with nearly half being local endemics (Tierno de Figueroa et al., 2013). Species that have restricted geographical Due to its complex geological history and unique distributions are particularly vulnerable to habitat de- combination of geological and climatic factors, the widely struction, giving freshwaters a high degree of irreplace- defined Mediterranean Region, including the Balkan ability (Dudgeon et al., 2006). In fact, the extinction rate Peninsula, is recognized as one of the most important of freshwater invertebrates is higher than in terrestrial hot-spots of biodiversity and endemism globally (Griffiths groups, mostly due to the heavy anthropogenic degrada- et al., 2004; Woodward, 2009; Blondel et al., 2010). tion of aquatic ecosystems. Adding to that, no more than Particularly, freshwater habitats are characterized by high 1% of invertebrates have been assessed with regards to levels of endemism resulting from isolation and allopatric their conservation status by the International Union for speciation combined with specific habitat requirements Conservation of Nature (IUCN) (Borrell, 2012). This and limited dispersal abilities of many freshwater organ- leads to a situation in which the rate of extinctions will isms (Strayer, 2001, 2006). The Mediterranean Region exceed the rate of identification and description of bio- houses at least 35% of the Palearctic freshwater species, diversity. What is even worse, the biogeographic patterns of freshwater invertebrate fauna remain poorly known and *Corresponding author: [email protected] understood due to the lack of basic data on distribution Article published by EDP Sciences 14 K. Zˇ ganec et al.: Ann. Limnol. - Int. J. Lim. 52 (2016) 13–26 and ecology, particularly of endemic taxa. Without such and conservation status of two gammarid species, i.e., knowledge, it is difficult to plan reasonable and effective E. acarinatus (S. Karaman, 1931) and F. dalmatinus strategies preventing or at least minimizing the loss of S. Karaman, 1931, with its two subspecies F. dalmatinus biodiversity. It must also be remembered that planning dalmatinus and F. dalmatinus krkensis, endemic to water- and implementing such strategies is one of the top courses of the Dinaric karst in Croatia and Bosnia and priorities of many EU and global agendas for conservation Herzegovina; (2) to interpret their distribution in the of natural resources (European Commission, 2011). context of local paleogeography and past connections Amphipod crustaceans are known to have restricted between now isolated drainage basins; (3) to provide basic distributions and many are narrow-ranged endemics ecological data for the species and subspecies and finally; (Va¨ ino¨ la¨ et al., 2008). For example, more than half (4) to propose and discuss the conservation status for the of freshwater species of the family Gammaridae have studied taxa. Finally, we aim to illustrate the importance restricted distributions with centers of endemism in the of thorough faunistic surveys including habitat informa- Iberian, Apennine and Balkan Peninsulas. The karst tion and historical interpretation of species’ distributions rivers of the Balkan Peninsula are well known for their for managing conservational issues in the case of fresh- endemic gammarid fauna. There are 17 endemic fresh- water endemics. water morphospecies of the genus Gammarus (Karaman and Pinkster 1977a, 1977b, 1987) and seven species in the genus Echinogammarus in the Balkan Peninsula Methods (Pinkster, 1993), with three endemic Balkan Echinogammarus species, Echinogammarus cari The data on the distribution of E. acarinatus and (S. Karaman, 1931), Echinogammarus acarinatus F. dalmatinus were gathered from our own field surveys (S. Karaman, 1931), Echinogammarus thoni (Scha¨ ferna, and from the literature (Scha¨ ferna 1920, 1922; Karaman, 1922), occurring in Croatia (Zˇ ganec, 2009). 1931a, 1931b, 1934, 1935; Karaman, 1965, 1970; Pljakic´ , Fontogammarus and Jugogammarus are two endemic 1962; Pinkster, 1993; Gottstein et al., 2008). The literature Balkan monotypic genera of epigean gammarids with records not overlapping with our sampling sites are shown Fontogammarus dalmatinus S. Karaman, 1931 in Croatia in Figure 1. Altogether, samples from 711 sites were (Karaman, 1965; Zˇ ganec, 2009; Zˇ ganec et al., 2010a) and included in this study (Fig. 1). Sampling was done with Jugogammarus kusceri S. Karaman, 1931 in Slovenia various methods (both qualitative and quantitative) using 2 (Karaman, 1931). However, based on recent molecular rectangular kick sample nets (25r25 cm with 0.5 or studies that focus on cryptic diversity of Gammaridae 0.2 mm mesh size), between 2000 and 2014. A great variety in Europe, these numbers are probably largely under- of lotic and lentic habitats were sampled, ranging estimated (Mamos et al., 2014, 2015; Weiss et al., 2014). from springs through small and medium streams and A case study of endemic Croatian E. cari, now large rivers to different types of lakes. The samples were endangered due to damming (Zˇ ganec et al., 2013), clearly instantly fixed in 75% ethanol. Temperature, dissolved showed deterioration of its population due to the adverse oxygen, conductivity, salinity and pH were measured with human impact. This provides a strong argument for a WTW probe. All the sampled localities were geocoded studies on the distribution and conservation status of the with a GPS receiver, while the geographic coordinates endemic Balkan amphipods. Moreover, distributional for literature data were based on locality description, patterns of such obligate freshwater organisms with using 1:25.000 topographic maps and GoogleEarth. Some limited dispersal abilities may provide interesting and literature sources (e.g., Pljakic´ , 1962) did not mention important evidence of former connections between now the locality but only streams in which the material was isolated river systems – particularly useful in the Balkan collected. In such cases, sites in the middle part of Peninsula where dynamic geology has often reshaped identified streams were chosen. Gauss–Kru¨ ger coordinates local hydrological networks (Fritz, 1972; Vlahovic´ et al., were determined for each site and the data were mapped 2012). using ArcMap in the ArcGIS 9.2 program package Except for the well-studied E. cari (Zˇ ganec and (1999–2006 ESRI Inc.). The samples were sorted in the Gottstein, 2009; Zˇ ganec et al., 2011, 2013) and E. thoni laboratory to separate gammarids from the substrate. (Zˇ ganec et al., 2010b) with relatively well-mapped dis- The gammarids were identified according to the keys by tribution, very little is known about other gammarids Karaman and Pinkster (1977a, 1977b, 1987) and Pinkster endemic to the Balkans. Only Laurogammarus scutarensis (1993). (Scha¨ ferna, 1922) from the Skadar Lake basin was re- Density of gammarids in two dominant microhabitats,