Svensen, C. C. Norwegian College of Fishery Science,
Wassmann, P. C. Norwegian College of Fishery Science,

In order to study the influence from turbulence and nutrients on sedimentation-rates from phytoplankton communities, four separate marine mesocosm experiments were conducted outside western-Norway at different times of the year. A common goal for all four experiments was to generate two distinct phytoplankton communities by manipulation with macronutrients (nitrogen, phosphate and silicate). Two of the experiments were also manipulated with different levels of turbulence. The possibility of obtaining a certain control of the physical environment, like excludation of large-scale advection, should make mesocosm enclosures a well-suited medium for investigation of mechanisms controlling the vertical flux of biogenic matter. Nevertheless, although the same treatments were given in these experiments, different results were achieved both between replicates and experiments. Thus, there are reasons to believe that enclosing a large amount of water can lead to unpredicted results and artefacts, probably caused by both biotic and abiotic factors. The importance of replicates and paying attention to the timing of the experiments is demonstrated. Some particular problems related to the study of vertical flux in mesocosm experiments are discussed.
Day: Thursday, Feb. 4
Time: 11:15 - 11:30am
Location: Eldorado Hotel
Code: SS51TH1115E