Efficient sampling methodologies for lake littoral invertebrates in compliance with the European Water Framework Directive

Lake shores are characterised by a high natural variability, which is increasingly threatened by a multitude of anthropogenic disturbances including morphological alterations to the littoral zone. The European Water Framework Directive (EU WFD) calls for the assessment of lake ecological status by monitoring biological quality elements including benthic macroinvertebrates. To identify cost- and time-efficient sampling strategies for routine lake monitoring, we sampled littoral invertebrates in 32 lakes located in different geographical regions in Europe. We compared the efficiency of two sampling methodologies, defined as habitat-specific and pooled composite sampling protocols. Benthic samples were collected from unmodified and morphologically altered shorelines. Variability within macroinvertebrate communities did not differ significantly between sampling protocols across alteration types, lake types and geographical regions. Community composition showed no significant differences between field composite samples and artificially generated composite samples, and correlation coefficients between macroinvertebrate metrics calculated with both methods and a predefined morphological stressor index were similar. We conclude that proportional composite sampling represents a time- and cost-efficient method for routine lake monitoring as requested under the EU WFD, and may be applied across various European geographical regions

Functional groups of hoverflies in Southeast Europe across different vegetation types

To better understand the relationship between biodiversity and ecosystem functioning, it is increasingly accepted that the focus of study needs to shift from taxonomic identity to the diversity of functional traits displayed by species within a community. Such an approach allows species to be grouped according to particular functional characteristics. Increasingly viewed as an extremely important group of model organisms, hoverflies have been the focus of a variety of ecological studies. Based on data regarding selected functional traits of hoverflies registered in Southeast Europe, the main aims of our study were to define hoverfly functional groups according to the similarity of these traits, as well as to compare the representation of delineated hoverfly functional groups among these vegetation types. We used fuzzy clustering to classify 568 SE European hoverfly species into five functional groups. The principle trait separating these functional groups was larval feeding type, followed by size of species range, flight ability, number of generations, inundation tolerance, and tolerance to human impact. For 9 of 11 vegetation types, the dominant functional group was characterized by species with good flight ability, having high human impact tolerance and more annual generations. The remaining two vegetation types, South-west Balkan sub-Mediterranean mixed oak forests and Mediterranean mixed forests, showed disparate dominance patterns, indicating that richness of functional groups is dependent on vegetation. Further investigation of whether and how established conservation measures enable recovery of the functional richness affected by habitat disturbance would help elucidate the importance of functional diversity in preserving biodiversity.Peer reviewe

Effects of shoreline modification on lake littoral macroinvertebrate assemblages

THESIS 9888The general aim of this study was to explore the effects of shoreline modifications on the structure of littoral macroinvertebrate assemblages in lakes, across the gradients of nutrients and alkalinity concentrations. Following this general aim, several aspects of the topic were investigated. The first aim was to establish whether shoreline habitat characteristics influence the composition of littoral macroinvertebrate assemblages. For this purpose, characteristics of shoreline habitats were recorded using the Lake Habitat Survey and associated with the assemblages at each site across six studied lakes. The relevance of specific shoreline features in structuring the macroinvertebrate composition was estimated

RECAP project, BLOCDUST hypothesis and SYNERGOSIS concept

Over 40% of terrestrial ecosystems worldwide suffer from land degradation, a natural or human-influenced process that affects the functionality of the land. Cyanobacterial biocrust carpet engineering has been proposed to fight land degradation. However, the rehabilitation takes a long time due to the lack of moisture during the initial phase. To solve this problem, our new project Integrated Strategy for Rehabilitation of Disturbed Land Surfaces and Control of Air Pollution (RECAP) will introduce different types of polysaccharide supports with improved sorption properties. Such supports will increase the availability of water as the main limiting factor. The viability of the cyanobacterial inoculum will be improved, the development of the biocrust accelerated and finally the efficiency of the biocrust carpet significantly increased. The theoretical background for RECAP novelty is based on two scientific concepts developed by the RECAP team: the BLOCDUST hypothesis and the SYNERGOSIS concept. The BLOCDUST hypothesis describes the role of cyanobacteria in the process of loessification. A new definition of loess emerged from it: loess is not eolian sediment only but also biogenic. The dual origin of loess and some other sediments has been described under concept of synergosis, a new term we introduced into sciences emphasizing the physical and functional relation between biotic and abiotic components where both benefit from each other. Analyses of cyanobacterial biomass, polysaccharide and cyanotoxin production were performed. The presence of toxin genes in the selected strains was also checked and found to be negative in order to guarantee environmental and human safety

Unravelling the effect of multiple stressors on ecological structure of littoral lake macroinvertebrates

Morphological alteration of shorelines and eutrophication both affect the biological integrity of European lakes. These pressures, often acting simultaneously, are difficult to tease apart. In this study, we related the number of taxa with specific habitat preference to habitat complexity across lakes of varying nutrient state. Habitat complexity at morphologically altered shorelines was significantly lower than at unaltered sites across trophic categories. A generalised linear mixed-effects model showed decreased number of taxa with specific mesohabitat preference at morphologically simplified sites in oligotrophic and mesotrophic, but not eutrophic lakes. These results suggest: (1) an antagonistic interaction between the effect of nutrient enrichment and morphological alterations on lake littoral communities and (2) the number of macroinvertebrate habitat specialists could potentially be used to assess the effects of structural simplifications of shorelines in lakes of low to medium nutrient status. We conclude that the use of functional traits approach in aquatic ecology should foster better understanding of stressor–response relationships for combined effect of multiple stressors.</p

Lake Macrophyte Nutrient Index of Standing Waters in Serbia (LIMNIS)

The aim of this study was to derive a Macrophyte Nutrient Index for standing waters in Serbia, based on the LEAFPACS method and to correlate it against existing Lake Typology. A single data matrix of 46 species and 1463 sample quadrats was compiled from two datasets: a revised phytocenological database given according to Braun-Blanquet Cover Abundance Scale and a database of sample quadrats collected during the summer months of 2009, 2010 and 2011 at 31 lakes in Serbia. The nutrient indices (MSI) for 46 lake hydrophytes were calculated using the Reprediction Algorithm on N-Ellenberg\u27s values. A Macrophyte Nutrient Index (LIMNIS) was calculated as the weighted average of MSI values for Serbian lakes. Correlation between rescaled MSI and original N-values was strong (0.82), and the same applies to the root-mean-square error value (0.75). Moderate LIMNIS values were derived for meso-oligotrophic lakes, as well as for eutrophic swamps and fens of the Danube floodplain. In the same manner, lakes classified as eutrophic showed the relatively higher LIMNIS values, and those recognised as potential conservation resources were characterised by moderate or low LIMNIS scores. Median LIMNIS values of six Lake Groups differed by less than one unit, which confirmed the similarity of the previously given Lake Types

Does lake habitat alteration and land-use pressure homogenize European littoral macroinvertebrate communities?

1. Beta diversity is the compositional heterogeneity of biotic assemblages among sites, and biotic homogenization is the decrease in beta diversity, facilitated by an increase in similarity of biotic communities over time. Environmental harshness decreases the importance of stochastic processes in structuring assemblages, resulting in a homogenization of the biota. 2. We investigated if increasing nutrient enrichment, land-use pressure, and within-lake habitat alteration would decrease the beta diversity of macroinvertebrates in 46 lakes across Europe. Beta diversity was calculated using global multivariate dispersion. We utilized a structural equation modelling approach to account for hierarchical interdependence between potential impacts, that is the direct effects and correlations among the different impacts. 3. We found clear indications that European macroinvertebrate communities are being homogenized by ongoing lake shore development. Increasing land-use pressure in the form of residential and commercial development had a direct negative effect on beta diversity (standardized coefficient=-040), as did roadways, albeit indirectly through an increase in engineering structures (standardized coefficient=-031). Increasing within-lake silt levels also homogenized macroinvertebrate communities (standardized coefficient=-018), independent of near shore land use. Our results indicate the negative effect of both the near shore land-use pressure and the within-lake habitat alteration on macroinvertebrate beta diversity, with significant interactions between these pressures. 4. Habitat protection should take a more holistic approach to assessing lake development pressure, over a range of scales, as a solely site specific approach is not always biologically meaningful. Thus, future management plans should carefully control and mitigate ongoing development pressure if lake ecosystem health and resilience is to be maintained. 5. Synthesis and applications. This study is the first of its kind to demonstrate European-wide homogenization of littoral macroinvertebrate lake communities with increasing habitat alteration and land-use pressure. Significant interactions occur between different habitat scales, with no one scale entirely accounting for the homogenization effect. To avoid further biotic homogenization, development pressure must be carefully managed at multiple scales, and where possible, minimized. This presents a challenge, as globally there is an increasing expansion of the human population and a consequent increase in anthropogenic pressure across all habitats

A contribution towards improving the applicability of the Myriophyllum aquaticum sediment contact test

Abstract Background Whole sediment contact tests provide realistic exposure scenarios, but the inherent properties of sediments may play a significant role in organism’s response and interfere with result interpretation. Recently, a sediment contact test with a rooted aquatic macrophyte Myriophyllum aquaticum has been standardized. The present study aims to distinguish between effects of basic sediment properties and sediment-bound pollutants on M. aquaticum growth and evaluate the method as a tool in sediment quality assessment. Tests with artificial sediments with different organic matter, sand and clay content, as well as freshwater sediments with different levels of contamination were conducted. Results Results were based on comparison to the standard artificial control sediment. Organic matter content and grain size distribution in different variants of artificial sediments significantly affected M. aquaticum growth. Growth was impaired in formulations with low (1%) and high (10%) organic matter content, while better growth of plants compared to control was recorded in artificial samples with higher fine particles content. Because of the presence of unmeasured pollutants in freshwater sediments and inherent sediment properties, results of the M. aquaticum sediment contact tests were not always in accordance with the results of chemical analysis. Whorl, shoot and root parameters had different variability and showed a particular growth pattern in natural sediments. If the threshold of 20% for sediment toxicity is applied, then about 60% of tested natural sediments may be considered as toxic. As sediment structure may influence plant growth, this interpretation may be false as the physico–chemical properties of the control sediment used for comparison are considerably different from the properties of natural sediments. Conclusions Since inherent properties showed a significant effect on plant growth, the use of suitable controls more similar to tested natural sediments is advisable. To avoid over-, but also under-estimations, the use of the strict toxicity threshold of 20% or even higher inhibition for this test can be recommended, provided the statistical power of the test is high. The results of this study might contribute to the ongoing process of including effect-based methods in water quality monitoring under the Water Framework Directive

An insight into antimicrobial activity of the freshwater bryozoan Pectinatella magnifica

The antimicrobial activity of five crude extracts of the freshwater bryozoan Pectinatella magnifica (Leidy, 1851) was evaluated in vitro for the first time. P. magnifica acetone extract exhibited the highest antibacterial activity (minimum inhibitory concentrations (MIC) 0.004-0.350mg/mL and MBC 0.007-0.500mg/mL), while its methanol extract showed the most promising antifungal activity (MIC 0.03-0.12mg/mL and MFC 0.06-0.25mg/mL). Furthermore, at a concentration of 0.25 MIC, the methanol extract reduced biofilm formation of the bacterial strain Pseudomonas aeruginosa PAO1 in a considerable extent (59.14%). FTIR spectra of the most active extracts indicate the presence of carbonyl compounds, long-chain alcohols and/or sterols. According to the experimental data obtained, P. magnifica methanol extract may be considered as a good resource of novel natural products with potent antibiofilm activity against the bacterium well known for its resistance. [GRAPHCIS]