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The emergence of DNA analyses of lake sediments has opened up many new areas of inquiry, including the study of taxa that were traditionally not considered in paleolimnology because they do not leave distinct morphological fossils. Here, we discuss the potential and challenges associated with the study of DNA in paleolimnology to address critical research questions in lacustrine ecology. We examine some recent applications by highlighting studies that have quantified centennial to millennial-scale dynamics, and that considered a diversity of planktonic groups, including bacteria, phytoplankton and zooplankton. We also summarize the main methodological precautions to be taken into account for implementing these types of DNA analyses. Based on our review of the literature focused on the analysis of DNA preserved in lake sediments, the emerging topics we have identified include: (1) the spread, establishment and effect of invasive species, (2) past fish population dynamics, (3) interactions within lacustrine communities, identified through network analyses, (4) potential application of metabarcoding for transfer functions. There are many new and exciting questions that could be addressed using DNA preserved in lake sediment and this will no doubt be an area of continued expansion in the field of paleolimnology for many years to come

As a model of communication and engagement, citizen science has the potential to promote individual and collective climate change action. This article systematically reviewed literature that jointly addressed climate change and nature-based citizen science and identified 23 reported learning outcomes. Overall, evidence related to learning outcomes was limited across reviewed studies, but documentation of outcomes that are directly relevant to collective climate action was particularly scarce. Findings suggest more research examining citizen science from a collective climate action perspective is needed. To support future research efforts, results link the 23 revealed learning outcomes to two potential evaluation frameworks.

Aim Understanding the magnitude and drivers of freshwater diversity over the last 150 years provides essential insights for developing scenarios of future change. Here, we quantify and identify drivers of spatial and temporal beta diversity in diatom assemblages between historical and modern times. Location United States of America. Major Taxa Studied Diatoms. Tim Period pre‐AD 1850 and c. 2007. Methods Using sedimentary genus‐level diatom data from 169 lakes and species‐level data for 52 lakes, we computed spatial beta diversity across all lakes and within ecoregions for 2007 and pre‐AD 1850 time points. We also computed local contributions to beta diversity (LCBD) and analysed them with respect to environmental variables. Total beta diversity was partitioned into replacement and abundance difference components to identify mechanisms possibly responsible for spatial beta at each time point. Temporal beta diversity indices (TBI) were also computed for each lake by comparing the diatom data of all lakes at the time points. TBIs were decomposed into taxon losses and gains to facilitate interpretation. TBIs and their components were related to contemporary land cover. Results Temporal beta diversity varied significantly as a function of forest cover, with higher temporal beta in lakes from watersheds with contemporary lower forest cover. Spatial beta diversity was similar between the historical and 2007 time points. Lakes with substantial local contributions to beta diversity were differentiated by water quality and land cover variables at a local scale, but showed no systematic regional pattern. Main conclusions Spatial beta diversity of diatoms across the U.S.A. does not appear to have changed between pre‐AD 1850 and 2007, suggesting that broad‐scale land use and hydrological alteration of the landscape has not homogenized these communities. Temporal beta diversity occurred through genus gains and losses and was significantly related to land cover in watersheds. These analyses, pairing spatial and temporal beta diversity, provide insight into the mechanisms maintaining diatom diversity.