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Does salinization impact long-term Daphnia assemblage dynamics? Evidence from the sediment egg bank in a small hard-water lake

Citation

Wersebe, Matthew; Edlund, Mark; Weider, Lawrence (2022), Does salinization impact long-term Daphnia assemblage dynamics? Evidence from the sediment egg bank in a small hard-water lake, Dryad, Dataset, https://doi.org/10.5061/dryad.tqjq2bw0j

Abstract

Salinization of freshwater ecosystems threatens global aquatic biodiversity. There is a need for studies that follow populations in situ during salinization to understand the effects on species and ecosystems. We follow 170 years of Daphnia dynamics in the sediment ephippia archive of a small urban lake near St. Paul, Minnesota, to characterize effects of severe recent salinization on lake Daphnia. We found modest changes in the flux of ephippia in this lake; all three key Daphnia functional groups remained in the assemblage throughout the period of salinization. Reconstruction of the size distribution of D. pulicaria demonstrated that predation pressure by fish may not have increased for the largest and most susceptible member of the assemblage despite cultural meromixis. Our findings highlight that in hardwater lakes, the effects of salinization are nuanced and require further investigation to better understand overall impacts of salinization on lake Daphnia assemblages.

Methods

Ephippia were collected from sediments of Tanners lake. Counts of ephippia were made and converted to fluxes based on the sediment accumulation model. 

Ephippia were measured on their dorsal axis. 

Usage Notes

Analysis were conducted in R.