Mateusz Płóciennik

Spatial scale effects on Chironomidae diversity and distribution in a Mediterranean River Basin

Chironomidae are a very common insect group in running waters of Greece; however, they have been rarely studied. The aim of this work was to investigate Chironomidae distribution and abundance in a Mediterranean intermittent river basin, identify the environmental factors that are linked to variation in their assemblages and to partition the influence of environmental and spatial components, alone and in combination, on Chironomidae community composition. Multivariate ordination techniques were used to assess the association between environmental variables and species abundance, while variation partitioning was performed using partial canonical correspondence analysis to understand the importance of different explanatory variables in Chironomidae variation. Chironomidae variation was divided into independent and joint effects of micro-scale (physical and chemical variables, microhabitat composition, etc.), meso-scale (land use/cover) and macro-scale (altitude and distance to source, etc.) variables. Stream width and depth, water discharge, land uses, pH, and ecological quality were the most important factors structuring Chironomidae assemblages. Micro-scale variables accounted for 55.6% of the total explained variation followed by meso-scale (10.7%) and macro-scale (10.4%) variables. The results of partial constraint analyses suggest that micro-scale variables play a major role in Chironomidae assemblages.

Kohonen Artificial Neural Networks and the IndVal Index as Supplementary Tools for the Quantitative Analysis of Palaeoecological Data

Abstract We applied two widely-used methods for data partitioning - constrained incremental sum-of-squares (CONISS) and Optimal Partitioning (OP) along with two supplementary methods, a Kohonen artificial neural network (self-organising map, SOM) and the indicator value (IndVal) index, for the quantitative analysis of subfossil chironomid assemblages from a palaeolake in Central Poland. The samples, taken from 79 core depths, were divided into 5-11 groups (five by SOM, seven by CONISS, 11 by OP), for which different numbers of indicator taxa were determined with the use of the IndVal index (18 for CONISS, 15 for SOM, 11 for OP). Only six indicator taxa were common to all three methods. The number of highly specific (p < 0.001) taxa was highest for SOM. Only the SOM analysis clearly reflected the rate of the changes in chironomid assemblages, which occurred rapidly in the Late Glacial (as a result of greater climate variability) and slowly in the Holocene (as a reflection of slow long-term changes in the local habitat, such as paludification). In summary, we recommend using SOM and the IndVal index in combination with CONISS and/or OP in order to detect different aspects of temporal variability in complex multivariate palaeoecological data.

Pleistocene phylogeography and cryptic diversity of a tiger beetle, Calomera littoralis, in North-Eastern Mediterranean and Pontic regions inferred from mitochondrial COI gene sequences

Background. Calomera littoralis is a Palearctic species, widely distributed in Europe; inhabiting predominantly its Atlantic, Mediterranean and Black Sea coastlines. Methods. Its phylogeography on the Balkan Peninsula and on the north-western Black Sea coast was inferred using a 697 bp long portion of the mitochondrial COI gene, amplified from 169 individuals collected on 43 localities. Results. The results revealed two genetically divergent groups/lineages, the southern one inhabiting both the Balkan Peninsula and the Pontic Region and the northern one found exclusively in the Pontic Region. Species delimitation based on DNA barcoding gap suggested an interspecific level of divergence between these groups. Multivariate analysis of eight male and female morphometric traits detected no difference between the groups, implying they may represent cryptic species. The Bayesian time-calibrated reconstruction of phylogeny suggested that the lineages diverged ca. 2.3 Ma, in early Pleistocene. Discussion. The presence of the two genetically divergent groups results most likely from contemporary isolation of the Pontic basin from the Mediterranean that broke the continuous strip of coastal habitats inhabited by C. littoralis. Demographic analyses indicated that both lineages have been in demographic and spatial expansion since ca. 0.15 Ma. It coincides with the terminal stage of MIS-6, i.e., Wartanian/Saalian glaciation, and beginning of MIS-5e, i.e., Eemian interglacial, during which, due to eustatic sea level rise, a wide connection between Mediterranean and the Pontic basin was re-established. This, along with re-appearance of coastal habitats could initiate north-east expansion of the southern lineage and its secondary contact with the northern one. The isolation of the Pontic basin from the Mediterranean during the Weichselian glaciation most likely did not have any effect on their phylogeography.

The Diversity of the Zoobenthos Communities of the Lake Skadar/Shkodra Basin

Zoobenthos is an important component of the aquatic ecosystems of the Lake Skadar basin and represents a reliable bioindicator of environmental degradation. In Lake Skadar, the zoobenthos communities exhibit different patterns with regard to abundance and community composition in the nearshore and the open lake zones. The greatest diversity of benthic invertebrates was generally found in the nearshore environment. Oligochaeta, Chironomidae, and mollusks dominated in the macrozoobenthos of Lake Skadar. The lake meiobenthos is less studied and is dominated by ostracods, copepod, and cladoceran species. The current knowledge of the diversity of the 22 zoobenthic groups from Lake Skadar and its basin are summed up here. Lake Skadar has experienced gradual eutrophication and the impact of nonnative species over the past several decades that have affected the zoobenthos communities. Continuous monitoring of the zoobenthos communities is recommended for inclusion in the ongoing national and transboundary Lake Skadar assessment projects.