| Summary |
In the Arctic, there are two main sources of primary production that are of significance to benthic organisms: phytoplankton, which blooms in the summertime in the absence of sea ice; and ice algae, which blooms prior to and potentially after the phytoplankton bloom, when sea ice is present. The current research investigates feeding rates and absorption efficiency for the two food sources using the tellinacn bivalve, Maconia balthica. I collected M. balthica from Kotzebue Sound, Alaska, and fed them either phytoplankton or ice algae in 100mL graduated cylinders in the lab. Feeding occurred at simulated summer (10 °C) and winter (0 °C) temperatures and at multiple food concentrations. M. balthica were shown to exhibit increased feeding lates with increased food concentrations that could be modeled by the type II functional response model described by Holling (1959), or by linear equations. M. balthica was found to increase its feeding rate on ice algae at 0°C relative to 10°C, in contrast to the accepted metabolic paradigm that low temperatures lower rates, as was shown for phytoplankton. As such, M. balthica's feeding behavior in the lab suggests an appropriate response to the annual large-magnitude deposition of ice algae to the benthos during ice breakup. Absorption efficiency was measured using the ash-ratio technique (Conover 1966). Within a food type, absorption eefficiencywas uniform across food concentration and temperature, however phytoplankton was always absorbed more efficiently than ice algae. Therefore, from an absorption perspective, a shift away from ice algae to phytoplankton could be beneficial. Under a scenario of reduced sea-ice coverage, M. balthica may be harmed overall by the lack of ice algae at near 0°C temperatures assuming phytoplankton is in low abundance; however increased phytoplankton at warmer temperatures may provide a significant benefit. |
