Comparison of temperature adaptation patterns of subtropical/tropical, subantarctic and antarctic phytoplankton communities
1998
Yamamoto, T. (Hiroshima Univ., Fukuyama (Japan). Faculty of Applied Biological Science)
Carbon incorporation rate of natural phytoplankton communities in the Southern Hemisphere was measured using 14C radioisotope under different temperature conditions including at in situ temperature. Photosynthetic activity of both the subtropical/tropical and the subantarctic regions decreased with raising and lowering of incubation temperature, i.e., the communities north of the Polar Front attained the maximum photosynthetic activity at in situ temperatures. However, the decreasing trend in the calculated assimilation number at raised and lowered temperature was different between the subtropical/tropical and the subantarctic communities; the former showed a sharp decrease than the latter. These results may reflect the difference in seasonal temperature variation of each latitudinal sea region; usually stable temperature condition is expected in the subtropical/tropical region, while there exist relatively a large seasonal temperature variation in the subantarctic region. On the other hand, the photosynthetic activity of antarctic phytoplankton community south of the Polar Front increased ca. 1.5 times with raising of incubation temperature up to ca. 10 degrees C compared to those at in situ temperature. This implies that photosynthesis of the antarctic phytoplankton is suppressed by the ambient sub-zero temperature. It can be concluded that phytoplankton communities in the respective regions in the Southern Hemisphere are considered to have been adapted to the respective environmental temperature conditions
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