PHYTOPLANKTON PRODUCTION IN SUB-ARCTIC LAKE AND RIVER ECOSYSTEMS - DEVELOPMENT OF A PHOTOSYNTHESIS-TEMPERATURE-IRRADIANCE MODEL

Authors
Citation
R. Rae et Wf. Vincent, PHYTOPLANKTON PRODUCTION IN SUB-ARCTIC LAKE AND RIVER ECOSYSTEMS - DEVELOPMENT OF A PHOTOSYNTHESIS-TEMPERATURE-IRRADIANCE MODEL, Journal of plankton research, 20(7), 1998, pp. 1293-1312
Citations number
48
Categorie Soggetti
Marine & Freshwater Biology
ISSN journal
01427873
Volume
20
Issue
7
Year of publication
1998
Pages
1293 - 1312
Database
ISI
SICI code
0142-7873(1998)20:7<1293:PPISLA>2.0.ZU;2-D
Abstract
We investigated the size-dependent temperature response of natural phy toplankton communities from a lake and a river in the Canadian subarct ic. Photosynthesis by total, <2 mu m and >2 mu m size fractions was de termined at 11 irradiances (1-109% of ambient solar radiation) and fiv e temperatures (5-25 degrees C) in outdoor solar incubators. Temperatu re had no effect on photosynthesis at low irradiance, but strongly reg ulated the photosynthetic response at saturating and inhibiting irradi ances. For the river phytoplankton, low temperatures lowered E-K value s (onset of light saturation) and shifted photosynthesis in the water column from light dependence to temperature dependence. A photosynthes is-temperature-irradiance (P-T-E) model was developed to describe the varied temperature response of photosynthesis across the full range of limiting, saturating and inhibiting irradiances. The P-T-E model expl ained 74-95% of the variation in photosynthesis for all size fractions (total community, >2 mu m fraction and <2 mu m fraction). Picoplankto n (<2 mu m) had greater photosynthetic rates (P-max) at all temperatur es than did the total and >2 mu m communities. The picoplankton fracti on was also more responsive to increasing temperature than larger cell s, implying a greater sensitivity to diurnal or longer term changes in lake water temperature.