Djuradj Milošević

Spatio-temporal pattern of the Chironomidae community: toward the use of non-biting midges in bioassessment programs

We employed the self-organizing map (SOM) method to investigate the spatio-temporal pattern of the Chironomidae community in the Southern Morava River basin (Serbia) and to examine to what extent the Chironomidae community is affected by environmental factors. Additionally, this study explores the problems of utilizing chironomids in bioassessment programs. The SOM analysis of the chironomid community data produced 3 groups of sites. The indicator species analysis presented indicator taxa for two groups. Twenty taxa (at species, species group and genus level), according to the Kruskal–Wallis test, showed the most pronounced differences among the temporal units. Out of 15 measured environmental parameters, one-way ANOVA pointed out that 10 significantly differ between the groups. Elevation had the most important influence on the chironomid community, also affecting other environmental parameters. According to our findings, the winter season and the periods with high water level are the main sources of natural variability. To avoid such variability and to successfully incorporate Chironomidae in bioassessment programs, we suggest exclusion of the arguable months from monitoring programs.

Chironomid faunal composition represented by taxonomic distinctness index reveals environmental change in a lotic system over three decades

The widely distributed family of the Chironomidae represents the most diverse and abundant group of macroinvertebrate fauna and potentially provides information on stream water quality and the effect of anthropogenic disturbances. Change in the chironomid faunal composition in the Southern Morava River basin (Serbia) was examined by comparing data from 1981 and 2010. We tested the performance of the parameter “taxonomic distinctness” (delta+) as an indicator of water quality and examined the possible relationship between delta+ and water quality using PCA. The 2010 survey yielded 96 taxa in 28 localities over three seasons. In total, 10,179 specimens represented the five subfamilies. Chironomid diversity was captured with the index delta+ that is based upon taxonomic distinctiveness and purported to be independent of sampling effort. Delta+ was correlated to total species richness and is significantly higher now than it was in 1981. In keeping with PCA results, delta+ was increasing in accordance with water quality increase. We conclude that delta+ is a useful measure for estimating anthropogenic disturbance over time. The linear relationship between delta+ and the water quality gradient gives rise to a novel metric, independent of sampling effort, in the multimetric approaches of analyzing macroinvertebrate assemblage data for bioassessments.

Different aggregation approaches in the chironomid community and the threshold of acceptable information loss

Due to the problem of identification, Chironomidae larvae, although very abundant, are often avoided or not properly used in bioassessment programs. The aim of this work was to test how different aggregation processes—taxonomic resolution and the random aggregation approach (best practicable aggregation of species—BestAgg) affect the analysis of chironomid communities regarding any information loss. The self-organizing map method, together with classification strength analysis and Spearman’s rank correlation, revealed that the genus-level and BestAgg-abundance matrix most accurately approximated the species-level community pattern. The subfamily-level dataset was ineffective at presenting the chironomid community structure, with a substantially lower concordance with the species-level dataset. The biologic environmental gradients analyses presented the same set of important environmental variables for the species-level, genus-level, and BestAgg-abundance matrix. The indicator values analysis showed that indicator genera provide information very close to that gained from species indicators. According to our results, the numeric relationship between species and higher taxa influences taxonomic scaling, limiting Chironomidae family aggregation, with acceptable information loss only up to genus level. In addition, the BestAgg approach, with the maximum level of aggregation, properly assesses the community structure and consequently describes environmental conditions.

Using a Fish-Based Model to Assess the Ecological Status of Lotic Systems in Serbia

Fish biotic indices have become common tools for measuring and monitoring the ecological status of aquatic ecosystems. In this study, we aimed to develop the first fish-based model for stream quality assessment in Serbia taking into account the regional specificity of the country. Fish samples were collected between 2003 and 2011 at 131 sampling sites. We employed a self-organizing map (SOM) in order to group samples into river types depending on the character of the habitat they came from. Next, the k-means cluster analysis classified samples into four groups, each describing a particular ecological condition. The indicator species were presented for each group based on their constancy and dominance. Gradients over the SOM map were sought for 17 fish community metrics. On the basis of the core metrics and selected indicator species, we proposed a fish-based index for the assessment of the ecological status of running waters in Serbia.

The utility of two marine community indices to assess the environmental degradation of lotic systems using fish communities.

Multimetric approaches are commonly used to evaluate the ecological status of aquatic ecosystems. However, it has been recommended that the sensitivity of existing methods be improved through the investigation of the potential of new metrics to detect environmental disturbances. In this study we tested the effectiveness of two community indices (Taxonomic distinctness index (TDI) and Abundance biomass comparison (ABC) method), primarily proposed for marine ecosystems, to identify sites with different levels of environmental degradation in lotic systems using fish community data. Fish samples were collected over the period 2003-2011 at 131 sampling stations. To generate water and habitat quality classes, a self-organizing map (SOM) based on environmental data was applied. Gradients over the SOM map were investigated for the values of the TDI and ABC indices. The results of this study reveal that the values of both the TDI and ABC indices are highly correlated with water and habitat quality gradients. However, despite the observed correlation, the utility of TDI as a potential metric in bioassessment programs is rather limited, due to its lack of discriminatory power. In contrast, the ABC method could be proposed as a novel metric, but can only be applied in type-specific multimetric approaches.

The Alburnus benthopelagic fish species of the Western Balkan Peninsula: An assessment of their sustainable use.

In this study, we aimed to assess the population status of bleak (Alburnus spp.) over the Western Balkan Peninsula in terms of its sustainable use. A second objective was to determine key factors important for fishery management planning. Two different basins, continental (the Danube Basin and the Sava River sub-basin) and marine (the Adriatic and the Aegean Sea Basins) were examined. A sustainability assessment and factor analysis were conducted using the adjusted ESHIPPOfishing model, extended with additional socio-economic sub-elements, and the categorical principal components analysis (CATPCA), respectively. The results of the assessment revealed the bleak populations in the Danube Basin and the Sava River sub-basin to be highly sustainable. The population characteristics with abiotic and biotic factors were responsible for this status, while the influence of socio-economic factors was insignificant. The sustainability status of the bleak populations of the Mediterranean basin varied, with the populations from Ohrid and Skadar Lakes showing a high and those from Prespa and Dojran Lakes a medium status. Socio-economic factors with traditional fishing were the most important for the Mediterranean bleak populations.

The best data design for applying the taxonomic distinctness index in lotic systems: A case study of the Southern Morava River basin

The taxonomic distinctness (Δ+) index has been recognized as a robust measure to assess human impacts on marine biodiversity. However, its applicability in freshwater ecosystems has still not been confirmed. We aimed to propose the most suitable data design for calculating the Δ+ index for application in assessing anthropogenically caused degradation in lotic environments. We calculated the values of Δ+ based on different taxa groups and taxa resolutions, in order to examine its utility as a potential metric in bioassessment programs. We found that the exclusion of non-insect taxa and selected insect orders significantly increased the index sensitivity. Thus, we believe that an appropriate data design for Δ+ calculation based on macroinvertebrate assemblages is the main prerequisite for the effective estimation of degradation in lotic environments. In addition, we argue that a decrease in taxonomic resolution up to genus level is completely acceptable, as it results in only minor information loss. Bearing this in mind would significantly facilitate its application in rapid bioassessment programs. Despite the observed correlation, the utility of Δ+ as a potential bioassessment metric is rather limited, since its fails to detect fine differences in environmental stress, and instead only roughly distinguishes between two basic classes of degradation level, unimpacted and impacted.