Potential use of Fiji sea grapes, Caulerpa racemosa “nama”: ecophysiological and biochemical investigations

Abstract Caulerpa species are valued for their nutritional benefits and are commercially farmed as sea grapes in several Southeast Asian countries. In Fiji, sea grapes are locally known as Nama and are highly valued and harvested from the wild. Despite their importance, they are not cultivated yet. There is limited understanding of the ecophysiology, particularly regarding their natural growing conditions and how environmental factors, such as light irradiance, influence their physiological and biochemical responses. Conflicting information about taxonomy adds to the complexity of this issue. This study aimed to document environmental conditions at important harvest sites and identify species using DNA barcoding. Primarily, it investigated the effects of varying light irradiances (50, 100, 300, and 600 µmol photons m − 2 s − 1 ) on photosynthetic performance and recovery abilities of the test organisms. The species identified were C. racemosa and C. oligophylla . Photosynthetic efficiency remained stable under moderate light (50 µmol photons m − 2 s − 1 ; F v /F m 0.79 ± 0.02) but showed significant photoinhibition under high irradiance (600 µmol photons m − 2 s − 1 ; F v /F m 0.42 ± 0.04). However, full recovery under moderate light was observed (F v /F m 0.73 ± 0.03), indicating resilience to light stress. These findings provide important insights into the ecophysiology of Fiji’s sea grapes, laying the groundwork for future research on their aquaculture potential. This could reduce pressure on wild populations, ensure sustainability, and create economic opportunities for local and export markets, with special attention to the socio − economic role of sea grapes for local communities, particularly women.