|CS29 Phytoplankton & Primary Production|
|Date: Monday, June 10, 2002|
|Time: 3:00:00 PM|
|Location: Oak Bay|
|Yacobi, Y, Z, IOLR, Kinneret Limnological Laboratory, Migdal, Israel, firstname.lastname@example.org|
|Luz, B, , The Hebrew University, Jerusalem, Israel, email@example.com|
|Barkan, E, , The Hebrew University, Jerusalem, Israel, firstname.lastname@example.org|
|COMPARISON OF PRIMARY PRODUCTION USING 14C AND TRIPLE OXYGEN ISOTOPES |
|In the period from October 2000 to June 2001 gross primary production was estimated in Lake Kinneret, Israel, using a novel approach. It is based on the determination of the triple-isotopic composition of dissolved oxygen and the oxygen exchange rate between the atmosphere and the water body. The gross primary production ranged from 217 to 759 mM C m-2d-1and was 2.6 times higher than the estimate resulting from the 14C radio-tracer method. Exceptional was the estimate in January 2001 (1333 mM C/m2/d and >10 times higher than primary production determined by the 14C method ), when a dense crop of the diatom Aulecoseira granulata dominated the phytoplankton.
In a previous set of experiments (February 1998-February 1999) the average ratio between the 14C and oxygen isotope method was also about 2, but a ratio of >7 was found during the bloom of the dinoflagellate Peridinium gatunense. The similarity of the findings indicates that during periods of high crop of phytoplankton the possible mechanisms for recycling and /or loss of the freshly assimilated carbon tracer intensify.