A novel in situ benthic photorespirometer for estimating photosynthesis rates of benthic primary producers

Abstract

We developed a novel benthic photorespirometer (BP) to overcome limitations of existing benthic incubation chambers for in situ photosynthesis-irradiance (P-I) curve analysis, including prolonged measurement times, uneven light distribution, and poor sealing. The BP integrates an artificial light source, an oxygen optode sensor, and a neoprene skirt to enable rapid P-I curve construction through 2-h incubations. Field tests at four coastal sites in Korea validated uniform light delivery and thermal stability during incubation, which are essential for reliable measurements. The compact and rigid design allowed single-operator deployment with minimal habitat disturbance, while the neoprene skirt ensured effective sealing across diverse substrates, including uneven rocky bottoms. Single deployments yielded reproducible oxygen responses and community-specific P-I curves under uniform light conditions, reflecting distinct photosynthetic characteristics among benthic algal communities and demonstrating the BP's capability to assess benthic photosynthesis. These results validate the BP as a reliable, field-deployable tool for high-resolution assessment of benthic primary production in coastal ecosystems.