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Primary production studies in two linked but contrasting Welsh lakes
Author(s) -
PENTECOST ALLAN,
HAPPEYWOOD CHRISTINE M.
Publication year - 1978
Publication title -
freshwater biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.297
H-Index - 156
eISSN - 1365-2427
pISSN - 0046-5070
DOI - 10.1111/j.1365-2427.1978.tb01421.x
Subject(s) - chlorophyll a , environmental science , shading , standing crop , photosynthesis , effluent , phosphorus , carbon dioxide , phytoplankton , light intensity , chlorophyll , algae , ecology , nutrient , chemistry , biology , biomass (ecology) , botany , environmental engineering , art , physics , organic chemistry , optics , visual arts
SUMMARY. Llyn Padarn and Llyn Peris have distinct phytoplankton populations. During 1975–76, the standing crop measured as chlorophyll‐ a was 5.5 times greater in Padarn than in Peris and the production rate, determined by the 14 CO 2 method, was faster by 3.4 times. These differences were attributed to the higher concentrations of phosphorus in the lower lake caused by treated sewage effluent. Incident light intensity, which was slightly lower in Peris due to mountain shading, and temperature, which was 1–4°C higher in Padarn, made little significant contribution to these differences during the summer. The reduced transparency of Padarn water, compared with that of Peris, resulted from denser phytopiankton crops in Padarn. During the summer, Padarn exhibited carbon dioxide depletion which correlated with the chlorophyll concentration. Light inhibition at the surfaces of both lakes correlated with solar radiation intensity. However, the relationship between pigment content and maximum photosynthetic rate was poor. Extracellular products accounted for about 16% of the total production in the lakes. Uptake of 14 C‐labelled acetate was low compared with that of 14 CO 2 uptake.