No abstract

Until the E.U. Water Framework Directive listed benthic invertebrates as a biotic element to be used for ecological classification of lakes, techniques for the assessment of the response of littoral invertebrates to anthropogenic pressures were extremely limited compared with those of rivers and lake profundal zones. We describe here the development of an ecological classification model based on changes of littoral invertebrate assemblages across a gradient of eutrophication, which is the most widespread anthropogenic pressure on lakes across Europe. The model comprises three derived parameters, two of which were developed from taxonspecific optima along a total phosphorus gradient calculated using canonical correspondence analysis, and the third based on invertebrate abundance. Combining the parameter metrics, we can estimate the ecological quality ratio (EQR), relative to those from paleolimnologically-confirmed reference lakes. The model was tested using independent samples collected from both hard and soft substrata and across two seasons from 45 lakes, comprising three alkalinity groups (n = 15 in each), and across gradients in water column total phosphorus concentrations. For hard substrata, EQRs were related consistently and highly significantly to water column concentrations of total phosphorus, accounting for the majority of the variance in every alkalinity group. For samples taken from soft substrata, a significant relationship was found only for high alkalinity lakes, accounting for a moderate proportion of the variability in water column total phosphorus concentrations. Our results compare highly favourably with those from other aquatic ecological assessment methods, irrespective of the faunal or floral group upon which they are based, demonstrating that littoral invertebrate assemblages can provide a statistically robust prediction of nutrient status when samples are collected from hard substrata. While the method was developed specifically to assess nutrient pressures on littoral invertebrates, many lakes are subject to multiple pressures. The development of classification models that incorporate multiple pressures presents a particularly significant challenge for the implementation of the Water Framework Directive, requiring both reliable identification of minimally-impacted reference states and incorporation of pressures that are unlikely to interact in predictable ways.

No abstract

Seismic geophysical methods have rarely been used in precision agriculture, predominantly due to the perception that they are slow and results require a complex evaluation. This paper explores the possibility of using a recently developed surface wave seismic geophysical approach, the Multichannel Analysis of Surface Waves (MASW) method, for assessment of agricultural compaction. This approach has the advantage of being non-intrusive, rapid and is able to produce 2D ground models with a relatively high density of spatial sampling points. The method, which was tested on a research site in Oakpark, Ireland, detected a significant difference in shear wave velocity between a heavily compacted headland and an uncompacted location. The results from this approach compared favourably with those obtained from measurements of bulk densityand cone penetrometers and demonstrate that the MASW approach can distinguish between the extreme states of heavily compacted and uncompacted soil.

No abstract

This paper is a result of the project WISER (Water bodies in Europe: Integrative Systems to assess Ecological status and Recovery) funded by the European Union under the 7th Framework Programme, Theme 6 (Environment including Climate Change) (contract No. 226273), http://www.wiser.eu. We thank Daniel Graeber for help with the statistical analysis.

ABSTRACT1. Morphological degradation constitutes one of the most severe threats to the ecological integrity of lakes. The development of biotic assessment methods for human lake shore alterations using littoral macroinvertebrates requires quantification of the degree of degradation by a stressor index and is complicated through simultaneous physical pressures that alter natural habitat structure.2. The Lake Habitat Survey (LHS) method and macroinvertebrate sampling were used to produce a pan-European dataset of morphological lake shore degradation and macroinvertebrate densities covering 51 lakes in seven countries and across four geographical regions -northern, western, southern and central Europe.3. Lake Habitat Survey parameters that differed significantly among three categories of morphological pressure were combined to develop the stressor index components 'Number of habitats', 'Habitat diversity', 'Total percentage volume inhabited by macrophytes', 'Sum of macrophyte types', 'Sum of vegetation cover types', 'Sum of coarse woody debris/roots/overhanging vegetation', 'Pressure index' (number of human disturbance sources) and 'Natural/artificial dominant land cover type '. 4. Stressor index components were tested for cross-correlations and for differences among pressure levels. The final composition of the stressor index was optimized for the four studied geographical regions in Europe. The resulting stressor index correlated more strongly with macroinvertebrate metrics than simpler site-specific LHS parameters or the HabQA index developed previously in one lake in north-western Europe.5. The stressor index developed provides deeper insight into the morphological pressures that affect littoral invertebrate communities. The results also support the use of LHS to quantify morphological stressors at sampling site level, which can ease developing other multimetric bioassessment methods.6. The stressor index offers the possibility for wide and regional specific application to assess hydromorphological pressures on lakes to assist conservation planning and management and further global efforts to develop and test biotic assessment methods for lakes.

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.