• European Marine Science
• 2018-2022close
• Open Access close
• RO close

Climate and land-use change drive a suite of stressors that shape ecosystems and interact to yield complex ecological responses (that is, additive, antagonistic and synergistic effects). We know little about the spatial scales relevant for the outcomes of such interactions and little about effect sizes. These knowledge gaps need to be filled to underpin future land management decisions or climate mitigation interventions for protecting and restoring freshwater ecosystems. This study combines data across scales from 33 mesocosm experiments with those from 14 river basins and 22 cross-basin studies in Europe, producing 174 combinations of paired-stressor effects on a biological response variable. Generalized linear models showed that only one of the two stressors had a significant effect in 39% of the analysed cases, 28% of the paired-stressor combinations resulted in additive effects and 33% resulted in interactive (antagonistic, synergistic, opposing or reversal) effects. For lakes, the frequencies of additive and interactive effects were similar for all spatial scales addressed, while for rivers these frequencies increased with scale. Nutrient enrichment was the overriding stressor for lakes, with effects generally exceeding those of secondary stressors. For rivers, the effects of nutrient enrichment were dependent on the specific stressor combination and biological response variable. These results vindicate the traditional focus of lake restoration and management on nutrient stress, while highlighting that river management requires more bespoke management solutions.A cross-scale analysis of paired-stressor effects on biological variables of European freshwater ecosystems shows that in 39% of cases, significant effects were limited to single stressors, with nutrient enrichment being the most important of these in lakes. Additive and interactive effects were similarly frequent (ca. 30% each), this frequency being independent of the spatial scale of analysis for lakes but increasing with scale for rivers. International audience

The analysis of copepod behaviour gained an increasing impetus over the past decade thanks to the advent of computer-assisted video analysis tools. Since the automated tracking consists in detecting the animal’s position frame by frame and improving signals corrupted by strong background noise, a crucial role is played by the length of the video recording. The aim of this study is to: (i) assess whether the recording time influences the analysis of a suite of movement descriptive parameters; (ii) understand if the recording time influences the outcome of the statistical analyses when hypotheses on the effect of toxicants/chemicals on the freshwater invertebrate behaviour are tested. We investigated trajectory parameters commonly used in behavioural studies—swimming speed, percentage of activity and trajectory convex hull—derived from the trajectories described by the inbenthic–interstitial freshwater copepod Bryocamptus pygmaeus exposed to a sub-lethal concentration of diclofenac. The analyses presented in this work indicate that the recording time did not influence the outcome of the results for the swimming speed and the percentage of activity. For the trajectory convex hull area, our results showed that a recording session lasting at least 3 min provided robust results. However, further investigations are needed to disentangle the role of concurrent factors, such as the behavioural analysis of multiple individuals simultaneously, whether they are of the same or opposite sex and the implications on sexual behaviour, competition for resources and predation.

ABSTRACT The region situated between the mountain area and the lowlands in NE Romania (East-Central Europe) is experiencing increased competition for water resources triggered by a growing population, intensification of agriculture, and industrial development. To better understand hydrological cycling processes in the region, a study was conducted using stable isotopes of water and atmospheric trajectory data to characterize regional precipitation and vapour sources derived from the Atlantic Ocean, Mediterranean and Black Seas, as well as recycled continental moisture, and to assess and partition these contributions to recharge of surface and groundwater. Atmospheric moisture in the lowlands is found to be predominantly delivered along easterly trajectories, while mountainous areas appear to be dominated by North Atlantic Ocean sources, with moisture transported along mid-latitude, westerly storm tracks. Large-scale circulation patterns affect moisture delivery, the North Atlantic Oscillation being particularly influential in winter and the East Atlantic pattern in summer. Winter precipitation is the main contributor to river discharge and aquifer recharge. As winter precipitation amounts are projected to decrease over the next decades, and water abstraction is expected to steadily increase, a general reduction in water availability is projected for the region.

AbstractThin fossil eggshell from Upper Cretaceous deposits of Europe, characterized by nodular ornamentation similar to modern gekkotan eggshell, has mostly been interpreted as gekkotan (=‘geckoid’) in origin. However, in some cases, as for the oogenus Pseudogeckoolithus, a theropod affinity has also been suggested. The true affinity of these fossil ‘geckoid’ eggshells has remained controversial due to the absence of analytical methods for identifying genuine gecko eggshell in the fossil record. In this study, we apply electron backscatter diffraction (EBSD) analysis to latest Cretaceous European ‘geckoid’ (including Pseudogeckoolithus) eggshell, in comparison with modern gekkotan and theropod (avian) eggshell. We found that Pseudogeckoolithus has a definite theropod eggshell‐like crystallographic configuration, in clear contrast to that seen in modern ‘gecko eggshells’. Furthermore, the crystallography of the nodular ornamentation in Pseudogeckoolithus is similar to that seen in megapode eggshell, but different from that of gecko eggshell, despite superficial morphological similarity. The remarkable morphological similarities between Pseudogeckoolithus and modern gecko eggshells are thus convergent, and the ‘gekkotan affinity’ hypothesis can be dismissed for Pseudogeckoolithus. This study provides a template for differentiating true gekkotan from dinosaurian eggshells in the fossil record. The potential functional significance of eggshell ornamentation, lost in most modern birds, requires further study, and experimental zoological approach may shed light on this issue. Finally, the present results suggest caution about the dangers of using potentially homoplastic eggshell characters in eggshell parataxonomy.

AbstractWe investigated the population dynamics of a highly clonal marine angiosperm, Cymodocea nodosa, in the eastern Mediterranean Sea, to identify the historical dynamics, demography, and connectivity of the species in the area. Eighteen microsatellite loci were used in conjunction with coalescent methods to investigate the genetic structure and demographic history of C. nodosa meadows. Approximate Bayesian computation (ABC) modeling was used to examine the pattern of divergence over time in the context of environmental change over the course of the Quaternary period. ABC analysis revealed an initial split of the C. nodosa populations between the north‐western, northern, and north‐eastern Aegean Sea during the Pleistocene epoch, followed by a more recent divergence of the north‐western population and the central‐western part of the Aegean Sea. According to the results, the most parsimonious historical scenario is that of a pervasive genetic signature of the effects of the drop in sea level during the Pleistocene epoch. This scenario supports the isolation of the north‐western, north, and north‐eastern area, and the subsequent recolonization after post‐glaciation sea level rise that may explain the north‐western differentiation as well present‐day detected dispersion of C. nodosa.

AbstractBackgroundGene and genome duplication play important roles in the evolution of gene function. Compared to individual duplicated genes, gene clusters attract particular attentions considering their frequent associations with innovation and adaptation. Here, we report for the first time the expansion of the ligand (e.g., pheromone and hormone)-transporter genes,apolipoprotein D(ApoD) genes in a cluster, specific to teleost fishes.ResultsThe singleApoDgene in the ancestor expands in two clusters with a dynamic evolutionary pattern in teleost fishes. Based on comparative genomic and transcriptomic analyses, protein 3D structure comparison, evolutionary rate detection and breakpoint detection, orthologous genes show conserved expression patterns. Lineage-specific duplicated genes that are under positive selection evolved specific and even new expression profiles. Different duplicates show high tissue-specific expression patterns (e.g., skin, eye, anal fin pigmentation patterns, gonads, gills, spleen and lower pharyngeal jaw). Cluster analyses based on protein 3D structure comparisons, especially the four loops at the opening side, show segregation patterns with different duplicates. DuplicatedApoDgenes are predicted to be associated with forkhead transcription factors and MAPK genes, and they are located next to the breakpoints of genome rearrangements.ConclusionsHere, we report the expansion ofApoDgenes specific to teleost fishes in a cluster manner for the first time. Neofunctionalization and subfunctionalization were observed at both protein and expression levels after duplication. Evidence from different aspects, i.e. abnormal expression induced disease in human, fish-specific expansion, predicted associations with forkhead transcription factors and MAPK genes, highly specific expression patterns in tissues related to sexual selection and adaptation, duplicated genes that are under positive selection, and their locations next to breakpoints of genome rearrangement, suggests the potential advantageous roles ofApoDgenes in teleost fishes. Cluster expansion ofApoDgenes specific to teleost fishes thus provides an ideal evo-devo model for studying gene duplication, cluster maintenance and new gene function emergence.