Summary 1. This study examines phylogeography and phylogeny of the threatened stone crayfish, Austropotamobius torrentium, in order to elucidate the role of the Dinaric Karst geology in shaping the evolutionary history and genetic diversity of aquatic fauna in the western Balkans. Mitochondrial 16S rRNA and COI genes were partially sequenced from 188 and 159 crayfish, respectively, sampled from 70 localities. Phylogenetic relationships were reconstructed using four methods of phylogenetic inference. Divergence times between phylogroups were estimated in a Bayesian framework, and their demographic history was examined using neutrality tests and mismatch distribution analysis. 2. Seven geographically localised phylogroups separated by pronounced genetic gaps were found. Five of them have a distribution range within the northern‐central Dinaric (NCD) region, while the remaining two include populations from the southern Balkans (SB) and central and south‐eastern Europe (CSE). The oldest divergence event separated two NCD lineages from the rest of populations in the Late Miocene or Early Pliocene. Divergences amongst the five NCD phylogroups and SB + CSE occurred in the Pliocene. The most recent split separated SB and CSE phylogroups during the Late Pliocene. For both genes, uncorrected pairwise divergences between most of the phylogroups (4.1–8.7% for COI and 1.6–4.8% for 16S rRNA) were of the same range as, or higher than, some of the interspecific distances previously reported for the genus Austropotamobius. 3. Geographically isolated and deeply divergent cryptic monophyletic phylogroups within A. torrentium in the NCD region arose in the course of intensification of Neotectonic movements during the Pliocene and the beginning of the Pleistocene and the development of karstification that has heavily fragmented the palaeohydrography of the area. The results confirm a gradual north–south expansion of stone crayfish during the pre‐Pleistocene that preceded the rapid northward post‐glacial re/colonisation of central Europe (CSE phylogroup) through the Danube drainage. 4. Austropotamobius torrentium comprises morphologically cryptic but molecularly distinct taxa. Considering the relatively small geographical areas they inhabit, the NCD phylogroups of stone crayfish should be given the highest conservation priority.

Recent studies have revealed high local diversity and endemism in groundwaters, and showed that species with large ranges are extremely rare. One of such species is the cave shrimp Troglocaris anophthalmus from the Dinaric Karst on the western Balkan Peninsula, apparently uniform across a range of more than 500 kilometers. As such it contradicts the paradigm that subterranean organisms form localized, long-term stable populations that cannot disperse over long distances. We tested it for possible cryptic diversity and/or unexpected evolutionary processes, analysing mitochondrial (COI, 16S rRNA) and nuclear (ITS2) genes of 232 specimens from the entire range. The results of an array of phylogeographical procedures congruently suggested that the picture of a widespread, continuously distributed and homogenous T. anophthalmus was wrong. The taxon is composed of four or possibly five monophyletic, geographically defined phylogroups that meet several species delimitation criteria, two of them showing evidence of biological reproductive isolation in sympatry. COI genetic distances between phylogroups turned out to be a poor predictor, as they were much lower than the sometimes suggested crustacean threshold value of 0.16 substitutions per site. Most results confirmed the nondispersal hypothesis of subterranean fauna, but the southern Adriatic phylogroup displayed a paradoxical pattern of recent dispersal across 300 kilometers of hydrographically fragmented karst terrain. We suggest a model of migration under extreme water-level conditions, when flooded poljes could act as stepping-stones. In the north of the range (Slovenia), the results confirmed the existence of a zone of unique biogeographical conflict, where surface fauna is concordant with the current watershed, and subterranean fauna is not.

A description of the hitherto unknown larvae of Drusus radovanovici septentrionis Marinković-Gospodnetić, 1976 and Drusus croaticus Marinković-Gospodnetić, 1971 is given. The most important diagnostic features enabling separation from larvae of the other Drusinae are listed and illustrated. Larvae of D. croaticus are distinguished by the combination of specific morphological features (e.g. shape of head and pronotum, the absence of mandible teeth, the absence of prominent, black median setae on frontal margin of pronotum etc.). Besides the above mentioned, larvae of D. radovanovici septentrionis are primarily distinguished by distinct spinules on the head capsule. Some ecological notes are given and the life cycle of both species is discussed. Regarding the feeding behaviour, both analyzed species seem to be predominantly grazers. Both species were recorded in different spring types in the Dinarides. D. radovanovici septentrionis is known only from three springs in Bosnia and Herzegovina (springs of the Rivers Pliva, Bistrica and Sturba), while D. croaticus was recorded in 19 different springs in Croatia. Additionally, all Trichopteran species recorded from the sampled springs are listed.

Grouting is a procedure in which grout is injected into different kinds of spaces. This procedure has had broad applications in modern civil engineering, especially in karst terrains, for nearly 200 years. Ingredients for the preparation of mortars and grouting suspensions include cement, clay and fillers, bentonite, asphalt, additives for stability and water. The building of dams in karst areas is always accompanied by the construction of large grout curtains. During their construction, thousands of tons of materials are injected into the karst underground. Some ingredients and chemicals used in the preparation of mortars and grouting suspensions may be toxic, neurotoxic or carcinogenic, and may be irritants or corrosives. Their use is dangerous to both humans and the environment. The toxic components can pollute karst aquifers and cause long-lasting hazardous consequences on karst underground species. Both physically and chemically, this material voraciously and quickly destroys underground habitats and kills an enormous number of rare, endangered and endemic species. This is an extremely expensive procedure although, in many cases, it is not very successful from the engineering perspective. When the construction of a grout curtain is completed, the hydrostatic pressure upgradients of the curtain are increased to higher levels than ever. These high hydraulic gradients accelerate the dissolutional expansion of fractures and bedding planes beneath the dam by several orders of magnitudes. As a result, intolerable leakage of karst reservoirs can occur over the lifetime of a dam site. This paper provides several examples of varying negative impacts of grouting on the hydrological and ecological regimes of the karst environment in the Dinaric karst.

Many studies emphasized the role that water mites play within the invertebrate communities of spring ecosystems, regarding species diversity and its significance within the crenal food web, as well as the specific preferences water mites exhibit towards spring typology. In pristine natural springs with permanent flow, water mites are nearly always present and usually display high diversity. This study aimed to determine whether significant differences in water mite assemblages between rheocrene (river-forming springs with dominant riffle habitats) and limnocrene (lake-forming springs with dominant pool habitats) karst springs could be detected in terms of species richness, diversity and abundance, but also in different ratios of specific synecological groups: crenobiont (exclusively found in springs), crenophilous (associated with springs) and stygophilous (associated with groundwater) water mite taxa. Our research was carried out on four limnocrenes and four rheocrenes in the Dinaric karst region of Croatia. Seasonal samples (20 sub-samples per sampling) were taken at each spring with a 200-µm net, taking into consideration all microhabitat types with coverage of at least 5%. Water mite abundance was found not to differ between morphological spring types. Significantly higher values of species richness and diversity indices were found in rheocrenes compared to limnocrenes, like those usually reported for this type of springs. However, unlike the studies previously reported, in this case, the higher shares of crenophilous and crenobiont water mite individuals were found in limnocrenes. The differences between stygophilous water mite taxa ratios among spring morphotypes were not statistically significant, indicating that the degree of the groundwater/surface water interaction (and water mite interaction therein) does not seem to be directly influenced by spring morphotype. Within this research, 40% of identified water mite species (eight out of twenty) were recorded for the first time in Croatia, thus highlighting again a huge gap in water mite knowledge of karst springs.