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Microevolution can have consequences at higher levels of ecological organization. Although divergence among populations can be rapid and driven by anthropogenic changes to the environment, the ecological relevance of evolution induced by human activities remains poorly understood.A frequent way in which human activities drive microevolution is the increase in supply of nutrients such as phosphorus (P) that are required for fitness‐relevant traits such as growth and reproduction. Because higher P concentrations decrease P‐use efficiency and feeding rate in heterotrophic consumers such as Daphnia, we hypothesized that such adjustments should alter consumer–resource dynamics.We examined how cultural eutrophication in temperate lakes causes trait variation in the grazer Daphnia pulicaria. We tested for variation in Daphnia traits and genetic variation in the metabolic enzyme phosphoglucose isomerase (Pgi) which are each known to respond to eutrophication. We then examined the impact of this variation on consumer–resource dynamics using a combination of experiments and a multi‐lake survey.We found that Daphnia from hypereutrophic lakes responded to experimental hypereutrophic conditions with increased growth rates and fecundity when raised on P‐fertilized seston, but had reduced performance on P‐poor seston relative to eutrophic source Daphnia. These results suggest that Daphnia may face a trade‐off in performance at low versus excess P that may be mediated in part by genetic variation at the Pgi locus.The variation observed in laboratory growth experiments scaled up to Daphnia populations in both mesocosm experiments and among lakes. In both the mesocosm experiment and in the lake survey, Daphnia from hypereutrophic source lakes reached high biomass while phytoplankton biomass also remained high.Given the prevalence and rapid eutrophication of freshwater ecosystems worldwide, these results indicate that considering the potential effects of evolutionary change in ecosystem models could be useful in forecasting the effects of anthropogenic environmental change on pivotal ecosystem services. [ABSTRACT FROM AUTHOR]

Algal blooms can have profound effects on the structure and function of aquatic ecosystems and have the potential to interrupt valuable ecosystem services. Despite the potential ecological and economic consequences of algal blooms, the spatial dynamics of bloom development in spatially complex ecosystems such as shallow lakes remain poorly characterised. Our goal was to evaluate the magnitude and drivers of spatial variability of algal biomass, dissolved oxygen, and pH over the course of a season, in a shallow lake in order to better understand the spatial dynamics of algal blooms in these ecosystems.We sampled 98 locations in a small eutrophic lake on a 65‐m grid for several parameters (chlorophyll a, phycocyanin, dissolved oxygen, pH, and temperature), weekly over 122 days. This was done to estimate the dynamics of variability and spatial autocorrelation during the course of multiple bloom events. We also compared the spatial measurements to a high frequency sensor deployed at a fixed station and estimated the optimal spatial sampling resolution by performing a rarefaction analysis.Spatial heterogeneity of algal pigments was high, particularly during bloom events, and this pattern and the overall severity of the bloom were not well captured with the fixed station monitoring. The pattern of algal pigments and other limnologically important variables (dissolved oxygen and pH) was related to the direction of prevailing winds 24 hr prior to sampling, the shallow northern basin where the main surface inlet is located, and heavy precipitation. Additionally, a dense bed of floating‐leaf macrophytes contributed to local patchiness in all variables. Finally, from the rarefaction analysis we found that minimal information about the mean state of the ecosystem was gained after c. 30 locations had been sampled.This study revealed how spatially heterogeneous shallow lakes are over the course of a single season, and that the magnitude of variability was highest during biologically intensive periods such as algal blooms. As such, continued research is needed across a range of trophic conditions to better understand the structure of horizontal variability in lakes. Overall, these data demonstrate the need for spatially explicit monitoring to better understand the dynamics and drivers of algal blooms in shallow lakes and to better manage ecosystem services. [ABSTRACT FROM AUTHOR]

Lakes provide significant ecosystem services that are compromised by human degradation. Watershed and in-lake restoration are used to improve the physical, chemical, and biological condition of lakes, but their success is rarely evaluated. Our objectives were to compare water quality and biological conditions following in-lake, watershed, or a combination of both restoration activities in 20 lakes throughout Iowa, USA compared to reference systems. Lake-specific responses to restoration were variable, making it challenging to detect systematic effects in water quality parameters. Secchi depth generally improved following restoration, particularly in natural in-lake restorations and following sediment removal, fishery renovation, and with the number of restoration practices implemented, but improvements were not sustained. Restoration also tended to reduce nutrient and plankton concentrations and relative abundance of some benthic fishes. Due to the prolonged degradation of eutrophic lakes, it may be unrealistic to expect immediate and long-lasting water quality improvements. In-lake restoration in natural lakes may be the most likely to have detectable effects, but our results also highlight the need for improved restoration documentation and additional research to identify factors associated with restoration success. Our results are useful for guiding lake restoration practices and educating lake users and stakeholders on expected restoration outcomes. [ABSTRACT FROM AUTHOR]