Marko Ćaleta

A global assessment of freshwater fish introductions in mediterranean-climate regions

Mediterranean-climate regions (med-regions) are global hotspots of endemism facing mounting environmental threats associated with human-related activities, including the ecological impacts associated with non-native species introductions. We review freshwater fish introductions across med-regions to evaluate the influences of non-native fishes on the biogeography of taxonomic and functional diversity. Our synthesis revealed that 136 freshwater fish species (26 families, 13 orders) have been introduced into med-regions globally. These introductions, and local extirpations, have increased taxonomic and functional faunal similarity among regions by an average of 7.5% (4.6–11.4%; Jaccard) and 7.2% (1.4–14.0%; Bray–Curtis), respectively. Faunal homogenisation was highest in Chile and the western Med Basin, whereas sw Cape and the Aegean Sea drainages showed slight differentiation (decrease in faunal similarity) over time. At present, fish faunas of different med-regions have widespread species in common (e.g. Gambusia holbrooki, Cyprinus carpio, Oncorhynchus mykiss, Carassius auratus, and Micropterus salmoides) which are typically large-bodied, non-migratory, have higher physiological tolerance, and display fast population growth rates. Our findings suggest that intentional and accidental introductions of freshwater fish have dissolved dispersal barriers and significantly changed the present-day biogeography of med-regions across the globe. Conservation challenges in med-regions include understanding the ecosystem consequences of non-native species introductions at macro-ecological scales.

Combining Morphology and Genetics in Resolving Taxonomy - A Systematic Revision of Spined Loaches (Genus Cobitis ; Cypriniformes, Actinopterygii) in the Adriatic Watershed

Taxonomic investigation of spined loaches from Dalmatia and Herzegovina was conducted on specimens from 14 localities. The results of the detailed morphological investigations were combined with genetic data (based on one mitochondrial and two nuclear genes) in order to resolve the taxonomic status of each Cobitis population. Among the investigated features of external morphology, the appearance of spots on the caudal fin base turned out to have the greatest diagnostic value. Furthermore, the number of branched fin rays enabled the discrimination of several species. No morphometric character alone could ensure determination of any Cobitis species. Nevertheless, groups of populations that are more similar in their body shapes correspond to mitochondrial phylogenetic lineages. Based on molecular genetic markers, Dalmatian and Herzegovinian spined loaches form independent lineages inside the Adriatic phylogenetic group. Mitochondrial DNA phylogenetic reconstruction revealed six monophyletic lineages, corresponding to six species distributed in the investigated area. The population distributed in Mostarsko blato karstic field in Bosnia and Herzegovina is described as a new species based on a unique combination of morphological characters: a single triangular Canestrini scale; usually 51/2 branched anal fin rays, 61/2 branched dorsal fin rays, 14 branched caudal fin rays; no spots in the surface pigmentation layer on the caudal fin base; scales on the body very small.

Morphological comparison of bleaks (Alburnus, Cyprinidae) from the Adriatic Basin with the description of a new species

Abstract. The morphometric, meristic and phenotypical characters of the members of the genus Alburnus from the Adriatic Basin were analyzed on specimens from 11 localities, representing eight watersheds. The number of gill rakers, the number of lateral line scales, the number of branched anal fin rays and the coverage of the ventral keel by scales have the greatest significance in differentiating between species. Significant morphological differences exist between the Alburnus population from Lake Lugano (type locality for Alborella maxima Fatio, 1882) and all the remaining investigated populations. Alburnus from the Neretva River drainage is described as a new species and it is distinguished from other species of the genus Alburnus by the following combination of characters: 13½-15½ branched anal fin rays; 17–26 gill rakers; 40–48 lateral line scales; first anal fin ray below branched dorsal rays 6–10 or located up to one scale after the last dorsal fin ray; ventral keel exposed for at least ⅔ of a distance between the pelvic fin base and the anal aperture. The status of the Neretva River basin populations as a separate species was corroborated by genetic analyses, with p-distance between newly described species and A. arborella from the Zrmanja River 1.8–2.2%.

Different Histories, Different Destinies‒Impact of Evolutionary History and Population Genetic Structure on Extinction Risk of the Adriatic Spined Loaches (Genus Cobitis; Cypriniformes, Actinopterygii).

The region of Balkans is often considered as an ichthyologic “hot spot”, with a great number of species and high portion of endemics living in fresh waters in a relatively small area. The Adriatic watershed in Croatia and Herzegovina is inhabited by six spined loach species (genus Cobitis) whose extinction risk estimations were based solely on their extent of occurrence (and/or area of occupancy) and its fragmentation, and conservation proposals do not consider diversity below species level. In this investigation we employed molecular genetic methods to describe present genetic structure of the Adriatic spined loaches and reveal their demographic history. The divergence of the Adriatic lineages inside the genus Cobitis started in Miocene and lasted until Pleistocene epoch. Geological events responsible for shaping recent diversity of spined loaches in the Adriatic basin are: the Dinarid Mountains upwelling, the evolution of Dinaric Lake system, local tectonic activity, river connections during glaciations and differences in sea level. Even though all the investigated species inhabit karstic rivers located in the same geographic area and that were subject of similar geological events, the results obtained reveal great differences in their genetic diversity and structure and point out the necessity of different conservation measures to ensure their future viability. High level of genetic polymorphism is characteristic for species located more to the south. Two species comprised of more than one population have completely different intraspecific structure; populations of C. illyrica are genetically distinct and represent separate evolutionary significant units, whereas intraspecific structure of C. narentana corresponds to metapopulational pattern. Without population genetic data, evolutionary significant units could be easily misidentified. Furthermore, the obtained results affirm that population genetic measurements are able to detect differences among closely located and related species and estimate extinction risk even more accurately than currently applied IUCN criteria.

A new endemic cyprinid species from the Danube drainage.

Populations of endemic Croatian dace were found to belong to two different species, one of which is first described in this study. Telestes karsticus sp. nov. differed morphologically from Telestes polylepis in the total count of lateral line scales, number of gill rakers and the shape of the posterior margin of the anal fin. Morphological differences were corroborated with mtDNA analyses (with p-distance between T. polylepis and T. karsticus sp. nov. ranging between 3·2 and 4·1%; and the number of substitutions between 37 and 47). The newly described species is geographically very localized. It has been recorded from only four localities around Velika Kapela and Mala Kapela mountains in Croatia.

First observation of Posthodiplostomum cuticola (Nordmann, 1832) metacercariae in cypriniformes from Croatia

SummaryDuring an ichthyological study of the Ilova River, rudd (Scardinius erythrophthalmus) infected with Posthodiplostomum cuticola was observed for the first time in Croatia. Later, a more detailed study was made at the same sampling point and the distribution of P. cuticola in the fish species present was examined. The condition of the hosts and parasitological indices such as prevalence, mean abundance and mean intensity of all hosts examined were investigated. Metacercariae of P. cuticola were most prevalent (100 %) in Rutilus rutilus, Pseudorasbora parva, Leuciscus leuciscus and Alburnus alburnus, slightly lower (93.94 %) in Leuciscus cephalus, substantially lower in Rhodeus amarus (66.67 %) and Barbatula barbatula (50 %) while the lowest prevalence was found in Gobio gobio (47.83 %). The correlation coefficient between number of parasites and total and standard length, weight and Fulton’s condition index of sampled specimen was significant only for L. cephalus.

Fauna of the Riparian Ecosystems: Amphibians, Reptiles, Birds, and Mammals

In pristine environments, riparian ecosystems are continuously distributed along large river flows. As ecotones, they harbor more species diversity than ecosystems bordering them from both sides. Along the Sava River flow, riparian ecosystems are discontinuously distributed, being preserved mainly in protected areas of Slovenia, Croatia, Bosnia and Herzegovina, and Serbia. Nine riparian ecosystem types could be listed, harboring in total 17 amphibian, 13 reptile, more than 280 bird, and 80 mammal species. Looking at global species conservation status (global IUCN status: 2009, amphibians and reptiles; 2012, birds; 2008, mammals), the highest concerns should be focused on Triturus dobrogicus (NT), Emys orbicularis (NT), Falco cherrug (EN), Aythya nyroca (NT), Rhinolophus euryale (VU), R. ferrumequinum (NT), R. hipposideros (NT), Barbastella barbastellus (VU), Miniopterus schreibersii (NT), Myotis bechsteinii (VU), M. blythii (NT), M. dasycneme (NT), Plecotus macrobullaris (NT), Lutra lutra (NT), and Eliomys quercinus (NT). Most of the vertebrate species occurring along the Sava River are also protected by national legislations. However, it seems that both their populations and native habitats need more appropriate treatment at place.

Occurrence of four-spined Gasterosteus aculeatus in an isolated Croatian river population

An isolated population of the three-spined stickleback Gasterosteus aculeatus in Croatia was found to have a high incidence of specimens either having a fourth dorsal spine or showing remnants of a fourth spine. Juvenile individuals showed a 9.4% incidence of a fourth spine. The population was examined for asymmetry of the skeletal defensive complex in order to determine whether the additional spine could be the result of developmental instability, a response to predation or environmental conditions.

Sexual dimorphism of five Cobitis species (Cypriniformes, Actinopterygii) in the Adriatic watershed

Abstract. Morphological differences between female and male spined loaches belonging to five species from the Adriatic basin were examined. Besides the presence of the Canestrini scale and the length of the pectoral fins, sexual dimorphism is also visible in the position of the pectoral fins, as well as in the length of the pelvic fins. Both pectoral and pelvic fins are significantly longer in males than in females, whereas pectoral fins of females are located more anteriorly then in males. Differences in the length of pectoral and pelvic fins among species are also revealed. The role of the secondary sexual characters in males is probably connected with their special mating behaviour. Furthermore, a hypothesis that habitat conditions have greater impact on body dimensions of females than males is proposed.

FIRST RECORD OF THREE-SPINED STICKLEBACK (Gasterosteus aculeatus Linnaeus, 1758) IN THE DANUBE BASIN OF CROATIA

The three-spined stickleback (Gasterosteus aculeatus Linaeus, 1758) is a small teleost fish considered to be one of the most widely distributed freshwater fishes in the world (Morrow, 2008). In the northern hemisphere, sticklebacks are absent only along the Arctic coasts of Siberia and North America (Mrakovcic et al., 2006). In Europe they often form highly abundant populations, and in some ecosystems are dominant (Clavero et al., 2009). Three-spined sticklebacks are listed as a species of Least Concern (LC) in the European IUCN Red List (Freyhof et al., 2008). However, freshwater populations in the Mediterranean region have experienced a sharp decline or even local extinction events (Clavero et al., 2009). Despite their wide global distribution, stickleback populations in Croatia are present in a fragmented distribution in isolated rivers of the Adriatic Basin: the Krka River (Visovac Lake), Neretva River catchment and Mirna River catchment on the Istrian peninsula (Mrakovcic et al., 2006; Zanella, 2009; Zanella et FIRST RECORD OF THREE-SPINED STICKLEBACK (Gasterosteus aculeatus Linnaeus, 1758) IN THE DANUBE BASIN OF CROATIA