Light respiration by subtropical seaweeds.

Here, we report the first-ever measurements of light CO2 respiration rate (CRR) by seaweeds. We measured the influence of temperature (15-25°C) and light (irradiance from 60 to 670 μmol · m-2  · s-1 ) on the light CCR of two subtropical seaweed species, and measured the CRR of seven different seaweed species under the same light (150 μmol · m-2  · s-1 ) and temperature (25°C). There was little effect of irradiance on light CRR, but there was an effect of temperature. Across the seven species light CRR was similar to OCR (oxygen consumption rate in the dark), with the exception of a single species. The outlier species was a coralline alga, and the higher light CRR was probably driven by calcification. CRR could be estimated from OCR, as well as carbon photosynthetic rates from oxygen photosynthetic rates, which suggests that previous studies have probably provided good estimations of gross photosynthesis for seaweeds.