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Daphnia magna life history data for caged and uncaged individuals (lab and mesocosm)

Citation

O'Connor, Michael et al. (2022), Daphnia magna life history data for caged and uncaged individuals (lab and mesocosm), Dryad, Dataset, https://doi.org/10.5061/dryad.zgmsbcccq

Abstract

Life history studies are often conducted in a laboratory environment where it is easy to assay individual animals. However, factors such as temperature, photoperiod, and nutrition vary greatly between laboratory and field environments, making it difficult to compare results. Consequently, there is a need to study individual life histories in the field, but this is currently difficult in systems such as Daphnia where it is not possible to mark and track individual animals. Here, we present a proof of principle study showing that field cages are a reliable method for collecting individual-level life history data in Daphnia magna. As a first step, we compared the life history of paired animals reared outside and inside cages to test the hypothesis that cages allow free-flow of algal food resources. We then used a semi-natural mesocosm setting to compare the performance of individual field cages versus glass jars re-filled with mesocosm water each day. We found that cages did not inhibit food flow, and that differences in life histories between three clones detected in the jar assays were also detectable using the much less labour-intensive field cages. We conclude that field cages are a feasible approach for collecting individual-level life history data in systems such as Daphnia where individual animals cannot be marked and tracked.