| 1. |
- SHELDON, RW, et al.
(författare)
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NANOPLANKTON AND PICOPLANKTON GROWTH AND PRODUCTION IN THE BAY OF VILLEFRANCHE-SUR-MER (NW MEDITERRANEAN)
- 1992
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Ingår i: Hydrobiologia. - 0018-8158 .- 1573-5117. ; 241:2, s. 91-106
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Tidskriftsartikel (refereegranskat)abstract
- Plankton production in the Bay of Villefranche was relatively constant during March and April 1986 but the particle size at which the production occurred was more variable. At the beginning of the study, production was dominated by the larger (ca. 6 mum) flagellates but towards the end it was more or less equally divided between the nano- and picoplankton. There were considerable differences in the estimates of population growth rates, depending on the methods used, but on average the population doubling times were close to 12 hours for autotrophs and 24 hours for heterotrophs. As autotrophs do not grow during the night, each population was therefore doubling once per day. It seemed that each of the nano- or picoplankton populations could adversely affect the growth of the others. This could be either by simple predation or by some form of inhibition. Although nutrient levels in the bay were uniformly low, the addition of nutrients did not always stimulate algal growth. The plankton populations seemed to be both in a state of equilibrium and intense ecological competition.
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| 2. |
- Wikner, Johan, 1961-, et al.
(författare)
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Periodic bacterivore activity balances bacterial-growth in the marine-environment
- 1990
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Ingår i: Limnology and Oceanography. - : American Society of Limnology and Oceanography. - 0024-3590 .- 1939-5590. ; 35:2, s. 313-324
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Tidskriftsartikel (refereegranskat)abstract
- The grazing rate of pelagic bacteria was repeatedly determined during 36-h time-course experiments with the minicell recapture technique. Die1 variation in the rate of grazing occurred in all water masses investigated. Maximal rates reached 2 x lo5 cells ml-’ h-r, whereas minimal values were 20 times lower. Highest grazing rates were found during the day in most cases, but grazing could also dominate at night as found in one study. Die1 periodicity was mainly due to variation in the per-cell feeding rate of bacterivorous flagellates. Accumulation of the bacterial biomass into the l-3-pm size fraction was positively correlated with changes in bacterial grazing. The transfer efficiency to organisms z 10 pm was low. On average, the daily grazing rate equaled 60% of the bacterial standing stock, exceeding bacterial growth by a factor of 2.6, as estimated from [3H]thymidine incorporation.
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