Morphology and molecules say: Tanytarsus latens, sp. nov. from Finland (Diptera: Chironomidae).

Tanytarsus latens sp. nov. is described from Finland (Ostrobothnia borealis, Satakunta). Both morphological and             molecular analyses indicate that T. latens belongs to the mendax species group. The adult male hypopygium of the new species resembles that of Tanytarsus occultus Brundin and of T. desertor Gilka et Paasivirta, while the molecular analysis based on the mitochondrial cytochrome oxidase (COI) gene fragment evidences that T. latens is a sister species to most of European Tanytarsus of the mendax group's core, for which the COI barcodes are known. Notes on biology of T. latens are also provided.

Groundwater contamination and land drainage induce divergent responses in boreal spring ecosystems.

Degradation of freshwater ecosystems has engendered legislative mandates for the protection and management of surface waters while groundwater-dependent ecosystems (GDEs) have received much less attention. This is so despite biodiversity and functioning of GDEs are currently threatened by several anthropogenic stressors, particularly intensified land use and groundwater contamination. We assessed the impacts of land drainage (increased input of dissolved organic carbon, DOC, from peatland drainage) and impaired groundwater chemical quality (NO3--N enrichment from agricultural or urban land use) on biodiversity and ecosystem functioning in 20 southern Finnish cold-water springs using several taxonomic and functional measures. Groundwater contamination decreased macroinvertebrate and bacterial diversity and altered their community composition. Changes in macroinvertebrate and bacterial communities along the gradient of water-quality impairment were caused by the replacement of native with new taxa rather than by mere disappearance of some of the original taxa. Also species richness of habitat specialist (but not headwater generalist) bryophytes decreased due to impaired groundwater quality. Periphyton accrual rate showed a subsidy-stress response to elevated nitrate concentrations, with peak values at around 2500 µg L-1, while drainage-induced spring water brownification (increased DOC) reduced both periphyton accrual and leaf decomposition rates already at very low concentrations. Our results highlight the underutilized potential of ecosystem-level functional measures in GDE bioassessment as they seem to respond to the first signs of spring ecosystem impairment, at least for the anthropogenic stressors studied by us.

Cladotanytarsus saetheri sp. nov. and C. gedanicus Gilka: Holarctic sibling species (Diptera: Chironomidae).

Cladotanytarsus saetheri, sp. nov., a widely distributed species (Fennoscandia; Russia: Far East; Canada: Manitoba; USA: Colorado, Michigan, South Carolina, Wisconsin) is described and compared with C. gedanicus Gilka, 2001 on the basis of new records (Fennoscandia; Canada: Manitoba, Nunavut; USA: Colorado, New Mexico). Intraspecific morphological variability of adult males is presented in order to delimit the two previously misidentified species.

Identifying taxonomic and functional surrogates for spring biodiversity conservation.

Surrogate approaches are widely used to estimate overall taxonomic diversity for conservation planning. Surrogate taxa are frequently selected based on rarity or charisma, whereas selection through statistical modeling has been applied rarely. We used boosted-regression-tree models (BRT) fitted to biological data from 165 springs to identify bryophyte and invertebrate surrogates for taxonomic and functional diversity of boreal springs. We focused on these 2 groups because they are well known and abundant in most boreal springs. The best indicators of taxonomic versus functional diversity differed. The bryophyte Bryum weigelii and the chironomid larva Paratrichocladius skirwithensis best indicated taxonomic diversity, whereas the isopod Asellus aquaticus and the chironomid Macropelopia spp. were the best surrogates of functional diversity. In a scoring algorithm for priority-site selection, taxonomic surrogates performed only slightly better than random selection for all spring-dwelling taxa, but they were very effective in representing spring specialists, providing a distinct improvement over random solutions. However, the surrogates for taxonomic diversity represented functional diversity poorly and vice versa. When combined with cross-taxon complementarity analyses, surrogate selection based on statistical modeling provides a promising approach for identifying groundwater-dependent ecosystems of special conservation value, a key requirement of the EU Water Framework Directive.

Why on the snow? Winter emergence strategies of snow-active Chironomidae (Diptera) in Poland.

A long-term study of adult non-biting midges (Chironomidae) active in winter on the snow in mountain areas and lowlands in Poland yielded 35 species. The lowland and mountain communities differed significantly in their specific composition. The mountain assemblage was found to be more diverse and abundant, with a substantial contribution from the subfamily Diamesinae, whereas Orthocladiinae predominated in the lowlands. Orthocladius wetterensis Brundin was the most characteristic and superdominant species in the winter-active chironomid communities in both areas. Only a few specimens and species of snow-active chironomids were recorded in late autumn and early winter. The abundance of chironomids peaked in late February in the mountain and lowland areas with an additional peak in the mountain areas in early April. However, this second peak of activity consisted mainly of Orthocladiinae, as Diamesinae emerged earliest in the season. Most snow-active species emerged in mid- and late winter, but their seasonal patterns differed between the 2 regions as a result of the different species composition and the duration of snow cover in these regions. Spearman's rank correlation coefficient tests yielded positive results between each season and the number of chironomid individuals recorded in the mountain area. A positive correlation between air temperature, rising to +3.5 °C, and the number of specimens recorded on the snow in the mountain community was statistically significant. The winter emergence and mate-searching strategies of chironomids are discussed in the light of global warming, and a brief compilation of most important published data on the phenomena studied is provided.

Climate-induced warming imposes a threat to north European spring ecosystems.

Interest in climate change effects on groundwater has increased dramatically during the last decade. The mechanisms of climate-related groundwater depletion have been thoroughly reviewed, but the influence of global warming on groundwater-dependent ecosystems (GDEs) remains poorly known. Here we report long-term water temperature trends in 66 northern European cold-water springs. A vast majority of the springs (82%) exhibited a significant increase in water temperature during 1968-2012. Mean spring water temperatures were closely related to regional air temperature and global radiative forcing of the corresponding year. Based on three alternative climate scenarios representing low (RCP2.6), intermediate (RCP6) and high-emission scenarios (RCP8.5), we estimate that increase in mean spring water temperature in the region is likely to range from 0.67 °C (RCP2.6) to 5.94 °C (RCP8.5) by 2086. According to the worst-case scenario, water temperature of these originally cold-water ecosystems (regional mean in the late 1970s: 4.7 °C) may exceed 12 °C by the end of this century. We used bryophyte and macroinvertebrate species data from Finnish springs and spring-fed streams to assess ecological impacts of the predicted warming. An increase in spring water temperature by several degrees will likely have substantial biodiversity impacts, causing regional extinction of native, cold-stenothermal spring specialists, whereas species diversity of headwater generalists is likely to increase. Even a slight (by 1 °C) increase in water temperature may eliminate endemic spring species, thus altering bryophyte and macroinvertebrate assemblages of spring-fed streams. Climate change-induced warming of northern regions may thus alter species composition of the spring biota and cause regional homogenization of biodiversity in headwater ecosystems.

Inferring the effects of potential dispersal routes on the metacommunity structure of stream insects: as the crow flies, as the fish swims or as the fox runs?

1. Metacommunity research relies largely on proxies for inferring the effect of dispersal on local community structure. Overland and watercourse distances have been typically used as such proxies. A good proxy for dispersal should, however, take into account more complex landscape features that can affect an organism's movement and dispersal. The cost distance approach does just that, allowing determining the path of least resistance across a landscape. 2. Here, we examined the distance decay of assemblage similarity within a subarctic stream insect metacommunity. We tested whether overland, watercourse and cumulative cost distances performed differently as correlates of dissimilarity in assemblage composition between sites. We also investigated the effect of body size and dispersal mode on metacommunity organization. 3. We found that dissimilarities in assemblage composition correlated more strongly with environmental than physical distances between sites. Overland and watercourse distances showed similar correlations to assemblage dissimilarity between sites, being sometimes significantly correlated with biological variation of entire insect communities. In metacommunities deconstructed by body size or dispersal mode, contrary to our expectation, passive dispersers showed a slightly stronger correlation than active dispersers to environmental differences between sites, although passive dispersers also showed a stronger correlation than active dispersers to physical distances between sites. The strength of correlation between environmental distance and biological dissimilarity also varied slightly among the body size classes. 4. After controlling for environmental differences between sites, cumulative cost distances were slightly better correlates of biological dissimilarities than overland or watercourse distances between sites. However, quantitative differences in correlation coefficients were small between different physical distances. 5. Although environmental differences typically override physical distances as determinants of the composition of stream insect assemblages, correlations between environmental distances and biological dissimilarities are typically rather weak. This undetermined variation may be attributable to dispersal processes, which may be captured using better proxies for the process. We suggest that further modifying the measurement of cost distances may be a fruitful avenue, especially if complemented by more direct natural history information on insect dispersal behaviour and distances travelled by them.

Checklist of the familes Chaoboridae, Dixidae, Thaumaleidae, Psychodidae and Ptychopteridae (Diptera) of Finland.

A checklist of the families Chaoboridae, Dixidae, Thaumaleidae, Psychodidae and Ptychopteridae (Diptera) recorded from Finland is given. Four species, Dixelladyari Garret, 1924 (Dixidae), Threticustridactilis (Kincaid, 1899), Panimerusalbifacies (Tonnoir, 1919) and Panimerusprzhiboroi Wagner, 2005 (Psychodidae) are reported for the first time from Finland.

Checklist of the family Chironomidae (Diptera) of Finland.

A checklist of the family Chironomidae (Diptera) recorded from Finland is presented.