Minimal diel vertical migration and consistent zooplankton capturability in low productivity reservoirs, Oregon
Abstract
Diel migrations of zooplanktons occur in marine and freshwater systems and can complicate inferences from studies. If populations perform vertical or horizontal diel migrations, daytime-only sampling can mischaracterize distributions and abundances. Zooplanktons also often display reduced capture avoidance at night and occupy areas easier to sample near the surface and away from littoral structure and the benthos. We examined zooplankton abundance, water column position and taxonomic composition during daytime and nighttime new moon periods using discrete depth sampling in oligo-mesotrophic reservoirs in Oregon, USA. These reservoirs have limited littoral structures, but support populations of zooplanktivorous fishes that we expected to drive diel vertical migrations. Contrary to our expectations, at night, most zooplankton taxa were within 2 m of their daytime distributional peak and did not display differences in abundance from day to night sampling. We consider factors that may help predict whether diel vertical migration occurs in a system. Where daytime sampling is sufficient to characterize zooplankton densities and distributions, costs and risks specific to nighttime sampling may be avoided. Improving our knowledge of zooplankton dynamics, particularly in ecosystems with limited diurnal variability, is an important part of understanding lake and reservoir food webs and can optimize the efforts of future studies.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Nov 21, 2022
- Source ID
- 10.1093/plankt/fbac060
Entities
People
- Amanda M. Pollock
- Angela Strecker
- Christina A Murphy
- Sherri L Johnson
Organizations
- Oregon State University
- Pacific Northwest Research Station
- United States Army Corps of Engineers
- United States Department of Agriculture
- University of Maine
- Western Washington University