Viscosity drives feeding behavior of E. norvegica

Temperature has been shown to affect the swimming performance of copepods, and this is typically attributed to changes in physiology, such as metabolic rate. However, the physical properties of water are also affected by temperature changes, particularly the kinematic viscosity of water is substantially higher at lower temperatures. In this study, we investigated the extent to which the thermal dependence of copepod prey capture reflects changes in the physical properties of water independent of physiological changes. Copepods are a key link in the marine food web, bringing energy from primary producers to higher trophic levels. While much is known about herbivorous copepods, less is understood about the role of carnivorous copepods in marine ecosystems. Euchaeta norvegica, a marine carnivorous copepod, was used to conduct feeding experiments that separate the effect of temperature and viscosity on ingestion rate. Based on data from functional response curves, we ran experiments in 4L jars at a concentration of 9 prey/L(Acartia hudsonica). Ingestion rates were measured at temperatures ranging from 4C-16C. Viscosity trials were conducted at 12C and mimicked viscosities from 12C-0C by adding a high weight molecular polymer (polyvinylpyrrolidone; MW 360 kD). Our study found E. norvegica eat less prey at lower temperatures and higher viscosities. When viscosity was altered independent of temperature, 64%-73% of the change in the ingestion rate was due to viscosity. These results support the hypothesis that viscosity has a greater impact on the ingestion rate than temperature.

Presentation Preference: Poster

Primary Presenter: Timothy Buckley, University of Connecticut/Bigelow Laboratory For Ocean Sciences (timothy.buckley@uconn.edu)

Authors:

Timothy Buckley, University of Connecticut/Bigelow Laboratory for Ocean Sciences  (timothy.buckley@uconn.edu)

Maura Niemisto, Bigelow Laboratory for Ocean Scienes  (mniemisto@bigelow.org)

Zachary Wagner, Bigelow Laboratory for Ocean Sciences  (zwagner@bigelow.org)

David Fields, Bigelow Laboratory for Ocean Sciences  (dfields@bigelow.org)