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Comparison of measured growth rates with those calculated from rates of photosynthesis in Planktothrix spp. isolated from Blelham Tarn, English Lake District
Author(s) -
Davis P. A.,
Walsby A. E.
Publication year - 2002
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1046/j.1469-8137.2002.00495.x
Subject(s) - photosynthesis , irradiance , biology , cyanobacteria , growth rate , phytoplankton , biomass (ecology) , botany , horticulture , ecology , nutrient , physics , bacteria , genetics , geometry , mathematics , quantum mechanics
Summary• Differences in photosynthetic production and conversion to biomass of the red‐coloured cyanobacterium Planktothrix rubescensand the green‐colouredPlanktothrix agardhii , were investigated in relation to their growth in Blelham Tarn, UK, using clonal isolates from the lake. • Growth rates (µ) were measured in cultures under 12 h : 12 h light : dark cycles at 15 irradiances ( E) in temperatures (Θ) of 10–25°C. Photosynthetic rates (P ) were measured under the same conditions. • For P. rubescens, µ reached a maximum of 0.33 d−1at 25°C in photon irradiances > 40 µmol m−2 s−1and exceeded µ forP. agardhiiover the range of temperatures in Blelham Tarn (< 21°C), although not at temperatures > 25°C. InP. rubescens, the dif ference (Δµ) between the growth rate of cell carbon (µC), calculated fromP, and µ was only 3% at 10°C but increased with temperature to 30% at 25°C; inP. agardhii , Δµ values were higher at low temperatures and lower at the higher temperatures. • Using algorithms describing the irradiance‐ and temperature‐dependent growth rates and measured values of Eand Θ at different depths in Blelham Tarn, it was demonstrated thatP. rubescenswould outgrowP. agardhii, though the latter might grow better in warmer and shallower lakes. We discuss the problems of modelling phytoplankton growth from measurements ofin situ photosynthesis.