ISSN:
1574-6941
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
As part of an investigation of the relationship between diversity and productivity, measurements were made in a solar saltern of carbon fixation, nitrate and ammonium uptake and microzooplankton grazing at salt concentrations ranging from 4 to 37%. Elevated photosynthetic pigment concentrations were present in ponds of intermediate (5–11%) and high (〉32%) salinity but rates of primary production and nutrient uptake were generally reduced at the highest salinity. Maximum primary production was measured at 8% salinity and chlorophyll-specific carbon fixation also maximised at this salinity. Ammonium was the dominant nitrogen source throughout the salinity gradient; turnover times of ammonium were from 2 to 14 days. Nitrate turnover times were very long (∼100 days) at salinities 〈22% but at 37% salinity, nitrate was taken up rapidly by the microbial assemblage in the light and turnover times for the ambient nitrate concentrations in the 37%-salinity pond were between 6 and 12 days. There were large changes in C:N uptake ratio. At salinities 〈11%, the C:N uptake ratio was higher than the Redfield ratio. However, at 〉22% salinity, the C:N uptake ratio was ∼1. That is, much more nitrate and ammonium were taken up than would be expected from the observed carbon-fixation rates. Although primary production declined with decreasing phytoplankton diversity along the salinity gradient, there was no clear relationship between heterotrophic activity and microbial biodiversity.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1574-6941.2002.tb00927.x
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