Ja. Furgal et al., ENVIRONMENTAL-CONTROL OF PHOTOSYNTHATE ALLOCATION IN THE PHYTOPLANKTON OF GEORGIAN BAY (LAKE HURON), Canadian journal of fisheries and aquatic sciences, 55(3), 1998, pp. 726-736
Allocation of photosynthate by phytoplankton in Georgian Bay was measu
red from spring through fall of 1993 to test previous models for envir
onmental control of allocation and to assess for the first time the ef
fects on allocation of solar ultraviolet radiation. Ultraviolet-B radi
ation (UV-B, 280-320 nm) at near-surface levels significantly inhibite
d photosynthesis (by up to 82%) under both natural and artificial ligh
t. UV-B effects on allocation to protein, polysaccharide, low molecula
r weight materials, and total lipids were rarely significant, but the
sensitivity of photosynthesis to UV-B increased directly with allocati
on to protein. UV-B exposure had more influence on allocation among li
pid classes, but the effects were still statistically marginal. Alloca
tion to protein and glycolipids varied directly with silicon availabil
ity, while allocation to total lipids and glycolipids varied inversely
with phosphorus availability. Previously published models for predict
ing protein, polysaccharide, and total lipid allocation from temperatu
re and daylength were unsuccessful. Lipid classes showed distinctive s
easonal patterns and environmental correlates, consistent with differi
ng functional roles and (or) taxonomic associations among the major li
pid classes. The allocation of photosynthate, and thus the food qualit
y and nutrient stoichiometry of the primary producers, appeared to be
under complex control that could not be precisely predicted from any s
imple combination of environmental variables.