Harrison, P. University of British Columbia, pharrison@eos.ubc.ca

Mesocosms provide a vital link between the simple small scale laboratory experiments and the complicated field studies. They eliminate the problem of advection, allow time series sampling of the same plankton population and simulate key environmental factors such as light intensity, photoperiod and temperature. Mesocosms have been useful to study phytoplankton bloom dynamics, sinking rates, aggregate formation, nutrient cycling, biogeochemical cycling, food web development with contrasting phytoplankton assemblages (diatoms vs flagellates) and bottom-up vs top-down control of primary producers. Smaller mesocosms allow a biological oceanographer to conduct replicated field experiments, like the terrestrial field ecologist who uses plots or quadrats. On short time scales, the mesocosm acts like a large batch culture and simulates a bloom which is terminated by nutrient exhaustion and sinking. If experiments are run for longer periods of time (e.g. 1 month), then the mesocosm may diverge significantly from any time series pattern ever observed in nature. Therefore, long term experiments are more challenging in terms of mesocosm management (mixing, nutrient additions, etc.). Mesocosms need long term funding to retain the practical knowledge gained over the years for proper mesocosm management.
Day: Thursday, Feb. 4
Time: 08:30 - 08:45am
Location: Eldorado Hotel
Code: SS51TH0830E