DNA-based methods in paleolimnology: new opportunities for investigating long-term dynamics of lacustrine biodiversity

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

A role for nature-based citizen science in promoting individual and collective climate change action? A systematic review of learning outcomes

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

Insights into biodiversity sampling strategies for freshwater microinvertebrate faunas through bioblitz campaigns and DNA barcoding

Background: Biodiversity surveys have long depended on traditional methods of taxonomy to inform sampling protocols and to determine when a representative sample of a given species pool of interest has been obtained. Questions remain as to how to design appropriate sampling efforts to accurately estimate total biodiversity. Here we consider the biodiversity of freshwater ostracods (crustacean class Ostracoda) from the region of Churchill, Manitoba, Canada. Through an analysis of observed species richness and complementarity, accumulation curves, and richness estimators, we conduct an a posteriori analysis of five bioblitz-style collection strategies that differed in terms of total duration, number of sites, protocol flexibility to heterogeneous habitats, sorting of specimens for analysis, and primary purpose of collection. We used DNA barcoding to group specimens into molecular operational taxonomic units for comparison.Results: Forty-eight provisional species were identified through genetic divergences, up from the 30 species previously known and documented in literature from the Churchill region. We found differential sampling efficiency among the five strategies, with liberal sorting of specimens for molecular analysis, protocol flexibility (and particularly a focus on covering diverse microhabitats), and a taxon-specific focus to collection having strong influences on garnering more accurate species richness estimates.Conclusions: Our findings have implications for the successful design of future biodiversity surveys and citizen-science collection projects, which are becoming increasingly popular and have been shown to produce reliable results for a variety of taxa despite relying on largely untrained collectors. We propose that efficiency of biodiversity surveys can be increased by non-experts deliberately selecting diverse microhabitats; by conducting two rounds of molecular analysis, with the numbers of samples processed during round two informed by the singleton prevalence during round one; and by having sub-teams (even if all non-experts) focus on select taxa. Our study also provides new insights into subarctic diversity of freshwater Ostracoda and contributes to the broader “Barcoding Biotas” campaign at Churchill. Finally, we comment on the associated implications and future research directions for community ecology analyses and biodiversity surveys through DNA barcoding, which we show here to be an efficient technique enabling rapid biodiversity quantification in understudied taxa

Cladoceran diversity dynamics in lakes from a northern mining region: responses to multiple stressors characterized by alpha and beta diversity

The lakes surrounding the iron-ore mining region of Schefferville, QuĂŠbec, Canada sit within a landscape of historical disturbances, two of which have been relatively well documented over time: metal contamination and nutrient loading. Based on the analysis of sediment cores, we used cladoceran zooplankton subfossil assemblages from two lakes located in Schefferville to track both alpha and beta diversity over the last 100+ years. We showed that high metal concentrations were correlated with decreased cladoceran diversity and that the site that experienced both direct wastewater input and atmospheric metal loading (Lake Dauriat) had the greatest declines in cladoceran richness. In both lakes, turnover in cladoceran assemblages was highest in the mining period. During the period of mine closures and improvement of wastewater treatment, some decreases in metal enrichment in the sediments and increases in cladoceran richness were observed in Lake Dauriat. Overall, a combined use of species richness and beta diversity metrics showed alpha and beta diversity are not always congruent and that there are various ways to interpret scenarios of temporal beta diversity in northern freshwater systems.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Do local unemployment rates modify the effect of individual labour market status on psychological distress?

This study investigates whether the unemployment rate of the area in which an individual lives affects their level of psychological distress, and the extent to which this is dependent on their own labour market status. Data were taken from the British Household Panel Survey (1991-2008) and longitudinal multiple membership multilevel modelling was carried out in order to account for the complex hierarchical structure of the data. The results suggest that living in an area with a high unemployment rate, defined by the claimant count, confers a degree of protection against the negative psychological effects of unemployment. However, psychological distress levels among unemployed people were still significantly and substantially higher than among their securely employed counterparts

Calanoid copepod zooplankton density is positively associated with water residence time across the continental United States

Inherent differences between naturally-formed lakes and human-made reservoirs may play an important role in shaping zooplankton community structure. For example, because many reservoirs are created by impounding and managing lotic systems for specific human purposes, zooplankton communities may be affected by factors that are unique to reservoirs, such as shorter water residence times and a reservoir's management regime, compared to natural lakes. However, the environmental factors that structure zooplankton communities in natural lakes vs. reservoirs may vary at the continental scale and remain largely unknown. We analyzed data from the 2007 U.S. Environmental Protection Agency's National Lakes Assessment and the U.S. Army Corps of Engineers' National Inventory of Dams to compare large-bodied crustacean zooplankton communities (defined here as individuals retained by 0.243 mm mesh size) in natural lakes and reservoirs across the continental U.S. using multiple linear regressions and regression tree analyses. We found that large-bodied crustacean zooplankton density was overall higher in natural lakes compared to reservoirs when the effect of latitude was controlled. The difference between waterbody types was driven by calanoid copepods, which were also more likely to be dominant in the >0.243 mm zooplankton community in natural lakes than in reservoirs. Regression tree analyses revealed that water residence time was not a major driver of calanoid copepod density in natural lakes but was one of the most important drivers of calanoid copepod density in reservoirs, which had on average 0.5-year shorter water residence times than natural lakes. Reservoirs managed for purposes that resulted in shorter residence times (e.g., hydroelectric power) had lower zooplankton densities than reservoirs managed for purposes that resulted in longer residence times (e.g., irrigation). Consequently, our results indicate that water residence time may be an important characteristic driving differing large-bodied zooplankton dynamics between reservoirs and natural lakes.publishe

On the alarming state of freshwater biodiversity in Canada

Little is known about the current state of freshwater biodiversity in Canada, one of the countries with the greatest amount of surface waters in the world. To address this knowledge gap, we compiled a list of all available assessments of conservation status for freshwater species (over 3,000 taxa) and further evaluated the overall status of six distinct taxonomic groups, focusing on organisms reliant on freshwaters [i.e., aquatic plants, invertebrates (with a focus on freshwater mussels), fishes, herpetofauna (reptiles and amphibians), birds, and mammals]. Overall, 11.7% of all freshwater species of plants and animals assessed were found to be ‘at risk’ (i.e., listed as ‘Threatened’, ‘Endangered’, or ‘Extirpated’) and 17.9% identified as ‘Special Concern’. We found that 37.9% of species lacked sufficient data to enable their status to be assessed. Data gaps in Canada’s assessment of its freshwater species were most prevalent in invertebrates (excluding freshwater mussels). Given the alarming state of freshwater biodiversity in Canada, we conclude by providing recommendations that focus on evaluating temporal trends and informing conservation actions.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author