Size-related photosynthetic characteristics of phytoplankton during periods of seasonal mixing and stratification in an oligotrophic multibasin lake system
| Autor: | Serge Demers, Jean-Jacques Frenette, Michel Boulé, Louis Legendre |
|---|---|
| Rok vydání: | 1996 |
| Předmět: |
0106 biological sciences
010504 meteorology & atmospheric sciences Ecology 010604 marine biology & hydrobiology fungi Irradiance Stratification (water) Aquatic Science Plankton 01 natural sciences Oceanography Water column 13. Climate action Epilimnion Phytoplankton Environmental science Photic zone Picoplankton Ecology Evolution Behavior and Systematics 0105 earth and related environmental sciences |
| Zdroj: | Journal of Plankton Research. 18:45-61 |
| ISSN: | 1464-3774 0142-7873 |
| Popis: | Phytoplankton photosynthetic responses were studied in two basins of an oligotrophic lake (Quebec, Canada), which are characterized by the absence (shallow Basin 1) and presence (deeper Basin 2) of seasonal thermal stratification. Size-fractionated photosynthesis was used to characterize changes in phytoplankton characteristics during periods of seasonal mixing and stratification. Seasonal variations of /•" showed size-related differences, with maximum values in July for the picoplankton and in November for the nanoplankton. Similar patterns of variability in a and /k were observed for the two size fractions throughout the season. However, size-related differences in the magnitudes of /k indicate that the picoplankton have lower light requirements than the nanoplankton to saturate photo- synthesis and can sustain large variations of irradiance in the surface layer during their growth season. Tight inverse correlations between in situ irradiance and a, at the seasonal scale, indicate that the two size fractions respond to lower irradiance by increasing their photosynthetic efficiencies. />_, and a are strongly correlated for the two size fractions, which suggests that biochemical processes controlling these two parameters are closely coupled. Hydrodynamics may influence photosynthesis differently for pico- and nanoplankton. Picoplankton in Basin 1 are adapted to higher irradiance than those in the euphotic zone of Basin 2, as shown by their lower a and higher lk during most of the study period, which may be explained by more frequent exposure to high irradiance through mixing in the shallowest basin. Vertically changing photosynthetic parameters in Basin 2 show that both pico- and nanoplankton were photoadapted as a function of depth. The size-related pattern of residence in the water column coupled to the turbulence regime in the epilimnion may be responsible for size-related differences in photoadaptation. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|