Manasi is investigating whether clay minerals are ingested by zooplankton species such as copepods and are transported to deeper waters via fecal pellets. Copepods are the most abundant mesozooplankton taxa in the marine environment and represent a vital link in the marine food web between algae and higher predators such as fish, whales etc. Fecal pellets produced by copepods are an important nutrient source for deep water ecosystems and can rapidly transport organic matter to the ocean floor. Fecal pellet production rates of actively feeding copepods may exceed 10 pellets per hour.
Five ingestion experiments were set up with a control treatment- copepods feeding on algae (mixture of Rhodomonas salina and Thalassisosira weisflogii) only and an experimental treatment – copepods feeding on algae + clay minerals. Fecal pellets were then quantitively collected from each treatment and analyzed. We found that the dimensions of fecal pellets produced in the control and experimental treatment were not significantly different. However, the pellets produced per copepod per hour in the experimental treatment were significantly higher than those of the control treatment. Manasi is currently conducting fecal pellet sinking rate experiments. 10-15 fecal pellets from each treatment will be individually dropped into a cuvette and recorded to determine and compare their sinking rate.