The effect of methoxychlor on carbon assimilation by freshwater phytoplankton

The effect of the insecticide methoxychlor (2,2-bis(p-methoxyphenyl)-1,1,1-trichloroethane) on photosynthetic carbon assimilation by natural phytoplankton populations was determined by incubation of plankton samples in situ at a 1.0-metre depth with [14C]bicarbonate for 4-h periods with or without 100 parts per billion (ppb) (100 μg/l) pure or technical grade methoxychlor. The different algal populations occurring over a 5-week period in May and June in Lake Opinicon, Leeds County, Ontario, were found, in 19 experiments, to be seldom affected by the insecticide. In the few cases where carbon assimilation in methoxychlor-treated samples was found to be significantly lower than that of the controls, the inhibition ranged in extent from 9.7% to 67.4% and these effects could not be correlated unequivocally with cell number or with the presence of any particular algal species.

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Leaf and community photosynthetic carbon assimilation of alpine plants under in-situ warming

10.21203/rs.3.rs-132375/v1 ◽

2020 ◽

Author(s):

Zhou Zijuan ◽

Su Peixi ◽

Wu Xiukun ◽

Shi Rui ◽

Ding Xinjing

Keyword(s):

Net Photosynthetic Rate ◽

Photosynthetic Rate ◽

Climate Warming ◽

Alpine Meadow ◽

Carbon Assimilation ◽

Community Level ◽

Photosynthetic Carbon ◽

Leaf Level ◽

Photosynthetic Carbon Assimilation

Abstract Background: The Tibetan Plateau is highly sensitive to elevated temperatures and has experienced significant climate warming in the last decades. While climate warming is known to greatly impact alpine ecosystems, the gas exchange responses at the leaf and community levels to climate warming in alpine meadow ecosystems remain unclear.Results: In this study, the alpine grass, Elymus nutans, and forb, Potentilla anserina, were grown in open-top chambers (OTCs) for three consecutive years to evaluate their response to warming. Gas exchange measurements were used to assess the effects of in-situ warming on leaf- and community-level photosynthetic carbon assimilation based on leaf traits and photosynthetic physiological parameters. We introduced a means of up-scaling photosynthetic measurements from the leaf level to the community level based on six easily-measurable parameters, including leaf net photosynthetic rate, fresh leaf mass per unit leaf area, fresh weight of all plant leaves, the percentage of healthy leaves, the percentage of received effective light by leaves in the community, and community coverage. The community-level photosynthetic carbon assimilation and productivity all increased with warming, and the net photosynthetic rate at the leaf level was significantly higher than at the community level. Under elevated temperature, the net photosynthetic rate of E. nutans decreased, while that of P. anserina increased.Conclusions: These results indicated that climate warming may significantly influence plant carbon assimilation, which could alter alpine meadow community composition in the future.

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Leaf and Community Photosynthetic Carbon Assimilation of Alpine Plants Under in-situ Warming

Frontiers in Plant Science ◽

10.3389/fpls.2021.690077 ◽

2021 ◽

Vol 12 ◽

Author(s):

Zijuan Zhou ◽

Peixi Su ◽

Xiukun Wu ◽

Rui Shi ◽

Xinjing Ding

Keyword(s):

Net Photosynthetic Rate ◽

Photosynthetic Rate ◽

Climate Warming ◽

Alpine Meadow ◽

Carbon Assimilation ◽

Community Level ◽

Photosynthetic Carbon ◽

Leaf Level ◽

Photosynthetic Carbon Assimilation

The Tibetan Plateau is highly sensitive to elevated temperatures and has experienced significant climate warming in the last decades. While climate warming is known to greatly impact alpine ecosystems, the gas exchange responses at the leaf and community levels to climate warming in alpine meadow ecosystems remain unclear. In this study, the alpine grass, Elymus nutans, and forb, Potentilla anserina, were grown in open-top chambers (OTCs) for 3 consecutive years to evaluate their response to warming. Gas exchange measurements were used to assess the effects of in-situ warming on leaf- and community-level photosynthetic carbon assimilation based on leaf photosynthetic physiological parameters. We introduced a means of up-scaling photosynthetic measurements from the leaf level to the community level based on six easily measurable parameters, including leaf net photosynthetic rate, fresh leaf mass per unit leaf area, fresh weight of all plant leaves in the community, the percentage of healthy leaves, the percentage of received effective light by leaves in the community, and community coverage. The community-level photosynthetic carbon assimilation and productivity all increased with warming, and the net photosynthetic rate at the leaf level was significantly higher than at the community level. Under elevated temperature, the net photosynthetic rate of E. nutans decreased, while that of P. anserina increased. These results indicated that climate warming may significantly influence plant carbon assimilation, which could alter alpine meadow community composition in the future.

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