ISSN:
1573-5117
Keywords:
planktivorous carp
;
plankton community
;
microbial food web
;
carbon flow
;
picophytoplankton
;
ecological efficiency
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Biomass and production of plankton communities were investigated in two Chinese integrated fish culture ponds in August, Dianshanhu Pond (with high density of planktivorous carp) and Pingwang Pond (with low density of planktivorous carp). The plankton communities were composed of rotifers, protozoans, phytoplankton (〈40 µm) and bacteria. The large phytoplankton (〉40 µm), cladocerans and copepods were rare because of grazing pressure by the carp. The density or biomass of bacteria (1.93 × 107 and 2.20 × 107 cells ml−1 on average in Dianshanhu and Pingwang Ponds, respectively), picophytoplankton (24.6 and 18.5 mg m−3 Chla on average) and rotifers (5372 and 20733 ind. 1−1 on average) exceeded the maximum values reported for natural waters. The average [3H]thymidine uptake rates were 694 and 904 pmoles 1−1 h−1 (13.4 and 20.6 µgC 1−1) and the bacterial production by the 〉2 µm fraction amounted 21–28% of total [3H] thymidine uptake rate in both ponds. The mean chlorophylla concentrations were 59.1 and 183 mg m−3 in Dianshanhu and Pingwang Ponds, respectively. 82.4% and 65.3% of the total Chla was contributed by the 〈10 µm nano- and picophytoplankton in each pond, respectively. In particular, the picophytoplankton contribution amounted 41.2% of thtal Chla in Dianshanhu Pond. Primary production was 2.5 and 3.4 gC m−2 d−1 in each pond, respectively, and 〉50% of production was contributed by picophytoplankton. The mean biomasses of protozoa were 168 µg 1−1 and 445 µg 1−1 and those of rotifers were 763 µg 1−1 and 1186 µg 1−1 in Dianshanhu and Pingwang Ponds, respectively. The ecological efficiencies expressed in terms of the ratios of primary production to zooplankton production were 0.22 and 0.31, for the two ponds.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00051951
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