The recovery of European freshwater biodiversity has come to a halt.

Owing to a long history of anthropogenic pressures, freshwater ecosystems are among the most vulnerable to biodiversity loss1. Mitigation measures, including wastewater treatment and hydromorphological restoration, have aimed to improve environmental quality and foster the recovery of freshwater biodiversity2. Here, using 1,816 time series of freshwater invertebrate communities collected across 22 European countries between 1968 and 2020, we quantified temporal trends in taxonomic and functional diversity and their responses to environmental pressures and gradients. We observed overall increases in taxon richness (0.73% per year), functional richness (2.4% per year) and abundance (1.17% per year). However, these increases primarily occurred before the 2010s, and have since plateaued. Freshwater communities downstream of dams, urban areas and cropland were less likely to experience recovery. Communities at sites with faster rates of warming had fewer gains in taxon richness, functional richness and abundance. Although biodiversity gains in the 1990s and 2000s probably reflect the effectiveness of water-quality improvements and restoration projects, the decelerating trajectory in the 2010s suggests that the current measures offer diminishing returns. Given new and persistent pressures on freshwater ecosystems, including emerging pollutants, climate change and the spread of invasive species, we call for additional mitigation to revive the recovery of freshwater biodiversity.

The recovery of crustacean zooplankton from acidification depends on lake type.

Acidification has harmed freshwater ecosystems in Northern Europe since the early 1900s. Stricter regulations aimed at decreasing acidic emissions have improved surface-water chemistry since the late 1980s but the recovery of biotic communities has not been consistent. Generally, the recovery of flora and fauna has been documented only for a few lakes or regions and large-scale assessments of long-term dynamics of biotic communities due to improved water quality are still lacking. This study investigates a large biomonitoring dataset of pelagic and littoral crustacean zooplankton (Cladocera and Copepoda) from 142 acid-sensitive lakes in Norway spanning 24 years (1997-2020). The aims were to assess the changes in zooplankton communities through time, compare patterns of changes across lake types (defined based on calcium and humic content), and identify correlations between abiotic and biological variables. Our results indicate chemical and biological recovery after acidification, as shown by a general increase in pH, acid neutralizing capacity, changes in community composition and increases in the total number of species, number of acid-sensitive species and functional richness through time. However, the zooplankton responses differ across lake types. This indicates that the concentration of calcium (or alkalinity) and total organic carbon (or humic substances) are important factors for the recovery. Therefore, assessment methods and management tools should be adapted to the diverse lake types. Long-term monitoring of freshwater ecosystems is needed to fully comprehend the recovery dynamics of biotic communities from acidification.

Sociodemographic characteristics of youth licensing at age 17 in the context of supervised driving in Denmark.

INTRODUCTION: Allowing young drivers to gain experience while being supervised by an experienced driver is a widely used measure to try to reduce crash risk. On 1 January 2017, the Danish licensing system was updated to allow licensing at age 17 with post-license supervised driving until solo driving at age 18. METHOD: Based on data from the Danish Driving License register and Statistics Denmark, including the entire population, the purpose of this study is to determine if sociodemographic characteristics and a history of violations and crash involvement among youth predict licensing at age 17. A second purpose is to estimate the time period from licensing until the driver turns 18 and to explore changes in license demand in the context of Denmark's updated licensing system. RESULTS: An increasing proportion choose to license at the age of 17, but the proportion below 19 with a driver's license is unchanged. On average, the license is obtained 5.3 months before turning 18. Living in rural areas, with both parents, and in a family with several cars and higher income increases the likelihood of licensing at age 17. Young people with a history of involvement in non-traffic-related accidents or violations are more likely to license at age 17. CONCLUSION: Lowering the license age to allow supervised driving increases early licensing. The average time period from licensing until the driver turns 18 is less than six months. Sociodemographic characteristics predict early licensing. PRACTICAL IMPLICATIONS: Minimum requirements for the time period from licensing until the driver turns 18 are needed to support a safety benefit. Follow-up studies mapping supervised driving, crash involvement, and possible changes in crash risk associated with the change in the Danish licensing system are needed to specify the requirements.

Meta-analysis of multidecadal biodiversity trends in Europe.

Local biodiversity trends over time are likely to be decoupled from global trends, as local processes may compensate or counteract global change. We analyze 161 long-term biological time series (15-91 years) collected across Europe, using a comprehensive dataset comprising ~6,200 marine, freshwater and terrestrial taxa. We test whether (i) local long-term biodiversity trends are consistent among biogeoregions, realms and taxonomic groups, and (ii) changes in biodiversity correlate with regional climate and local conditions. Our results reveal that local trends of abundance, richness and diversity differ among biogeoregions, realms and taxonomic groups, demonstrating that biodiversity changes at local scale are often complex and cannot be easily generalized. However, we find increases in richness and abundance with increasing temperature and naturalness as well as a clear spatial pattern in changes in community composition (i.e. temporal taxonomic turnover) in most biogeoregions of Northern and Eastern Europe.

Regulation of atypical MAP kinases ERK3 and ERK4 by the phosphatase DUSP2.

The atypical MAP kinases ERK3 and ERK4 are activated by phosphorylation of a serine residue lying within the activation loop signature sequence S-E-G. However, the regulation of ERK3 and ERK4 phosphorylation and activity is poorly understood. Here we report that the inducible nuclear dual-specificity MAP kinase phosphatase (MKP) DUSP2, a known regulator of the ERK and p38 MAPKs, is unique amongst the MKP family in being able to bind to both ERK3 and ERK4. This interaction is mediated by a conserved common docking (CD) domain within the carboxyl-terminal domains of ERK3 and ERK4 and the conserved kinase interaction motif (KIM) located within the non-catalytic amino terminus of DUSP2. This interaction is direct and results in the dephosphorylation of ERK3 and ERK4 and the stabilization of DUSP2. In the case of ERK4 its ability to stabilize DUSP2 requires its kinase activity. Finally, we demonstrate that expression of DUSP2 inhibits ERK3 and ERK4-mediated activation of its downstream substrate MK5. We conclude that the activity of DUSP2 is not restricted to the classical MAPK pathways and that DUSP2 can also regulate the atypical ERK3/4-MK5 signalling pathway in mammalian cells.

Does excess dietary carbon affect respiration of Daphnia?

Like many invertebrate herbivores, Daphnia frequently face diets with excess carbon (C) relative to elements like phosphorus (P), and with limited ability to store C-rich compounds. To cope with this relative surplus of C they may either regulate the net uptake of C or dispose of excess assimilated C via increased release of dissolved organic carbon or CO(2). Here we investigate whether juvenile Daphnia magna use respiration as a means of stoichiometrically regulating excess C. Growth rate and respiration were measured under different algal food qualities (P-replete and P-depleted algae). Growth rate was strongly reduced by P-depleted food, implying a stoichiometric disposal of excess ingested C. Respiration rates of feeding animals were measured after short- (0.5 h), medium- (12 h) and long- (five days) term acclimation to P-limited food. The respiration rates of animals during active feeding were not affected by the acclimation period per se, whereas food quality had a significant effect; respiration rates of feeding animals increased slightly in individuals receiving low-P food under all acclimation regimes. Respiration was also measured on nonfeeding and fasting animals that had been acclimated for five days to P-limited food. Respiration rates of these animals were strongly affected by feeding conditions but not by food quality; feeding individuals had higher respiration rates than those deprived of food, which again had higher respiration than fasting animals. Although animals grown on low-P food had strongly reduced growth and thus were expected to have decreased respiration rates due to reduced growth-related costs, this seems to be canceled out by increased stoichiometric respiration under P-deficiency. These results indicate that D. magna partly releases excess C as CO(2), but other means of stoichiometric regulation most likely add to this.

Age-dependent shift in response to food element composition in Collembola: contrasting effects of dietary nitrogen.

We examined the effect of different food qualities, in terms of the C:N:P content, on the collembolan Hypogastrura viatica. We hypothesised that (faster growing) juveniles would have higher demands for P and N than adults; this, however, was rejected by our experiments. There was no difference between the elemental compositions of juveniles and adults. In food preference experiments, juveniles and adults were offered green algae Raphidocelis subcapitata with three different C:N:P ratios. There was a strong shift in dietary response with age; juveniles preferred algae with low or medium N contents over the most N-rich algae, whereas adults showed the opposite. No response was seen when the specific P content in the food was varied. Juveniles fed on algae with high N content showed lower growth rates and survival than those fed on algae with other food qualities. In contrast, adults had lowest growth rates when fed on algae with a low N content. The negative effect on juveniles of the most N-rich diet appeared to be a toxic response that was directly or indirectly related to the algal N content. Adults had higher tolerance for N-rich diets, but were also more likely to face dietary N-limitation. These animals face a stoichiometric trade-off scenario in the sense that adaptation to maximise retention of a limiting element may result in reduced physiological ability to cope with excessive elements when feeding on "richer" diets, and vice versa. This problem is partly solved in H. viatica by contrasting selective feeding and ontogenetic dietary shifts between juveniles and adults.