Bacterial utilization of algal extracellular products in a southwestern reservoir |
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Authors: | Thomas H. Chrzanowski James G. Hubbard |
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Affiliation: | (1) Department of Biology, The University of Texas at Arlington, 76019 Arlington, TX, USA |
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Abstract: | Rates of carbon flow from phytoplankton to bacteria were estimated for Lake Arlington, Texas. The lake is a warm (annual temperature range 7 to 35 °C), shallow, monomictic reservoir with limited macrophyte development in the littoral zone. Samples were collected from 6 depths within the photic zone from a site located over the deepest portion of the lake. Primary production and exudate production were calculated from NaH14CO3 incorporation. Bacterial production was calculated from [methyl-3H]-thymidine incorporation. Depth averaged primary production ranged from a seasonal low of 9.0 μg C l−1 h−1 in January to a seasonal maximum of 153 μg C l−1 h−1 during holomixis in September. Annual depth-averaged production was 67.8 ± 7.3 μg C l−1 h−1. Exudate production ranged between 21.9 and 54.2% of primary production and annually averaged 30.8%. Bacterial production ranged between 1.7 and 46.0 μg C l−1 h−1 and annually averaged 16.0 ± 1.9 μg C l−1 h−1. Bacteria processed approximately 70% of exudate and incorporated 35% into biomass. Bacterial production was positively correlated with total primary production (r = 0.38, p < 0.003, n = 6), particulate primary production (r = 0.34, p < 0.004, n = 70) and bacterial uptake of exudate (r = 0.43, p < 0.001, n = 68). While exudate was readily utilized by bacteria it dit not appear to be produced in sufficient quantity or at a sufficient rate to serve as the sole or a major source of carbon supporting bacterial growth. |
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Keywords: | bacteria phytoplankton carbon cycle reservoirs thymidine exudate |
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