|SS4.09 Does Intentional Nutrient Fertilization (N,P And Fe) Foster C Sequestration and/or Increased Fish Fertilization?|
|Date: Tuesday, June 11, 2002|
|Time: 10:15:00 AM|
|Vrede, T, , Uppsala University, Dept. of Limnology, Uppsala, Sweden, firstname.lastname@example.org|
|Persson, J, , Uppsala University, Dept. of Limnology, Uppsala, Sweden, email@example.com|
|Sobek, S, , Uppsala University, Dept. of Limnology, Uppsala, Sweden, firstname.lastname@example.org|
|Blomqvist, P, , Uppsala University, Dept. of Limnology, Uppsala, Sweden, email@example.com|
|Jansson, M, , Umeå Univ., Dept. of Ecology and Environmental Science, Umeå, Sweden, firstname.lastname@example.org|
|Tranvik, L, , Uppsala University, Dept. of Limnology, Uppsala, Sweden, email@example.com|
|RESPONSE OF PLANKTON TO NUTRIENT ENRICHMENT|
|The response of plankton to N and P enrichment was studied in mesocosms in an ultra-oligotrophic sub-alpine reservoir. The experiment had an unreplicated factorial design with 4 levels of P addition (0-12 µg/l), and 3 levels of N addition (0-80 µg/l). The results will be used in the dimensioning of future fertilization of the reservoir to increase the production of salmonid fish.
P had a positive effect on phytoplankton (mainly edible mixotrophic flagellates) and protozoan biomass, particulate C, and bacterioplankton production. In contrast, N had no effect on these variables. CO2 was negatively correlated with chlorophyll a, indicating a shift towards net autotrophic conditions upon P enrichment. The response to P addition was non-linear, with only moderate or no increase in biomasses at P doses of 8 and 12 µgP/l compared with treatments with an P addition of 4 µgP /l. A possible explanation for this weak response is trace element deficiency at high P doses.