The potential of local sea grapes from Fiji: ecophysiological, biochemical and socioeconomic investigations of „Nama“ (Caulerpa racemosa)

Sea grapes (Caulerpa spp.) are valued for their nutritional benefits and are commercially farmed in several Southeast Asian countries. In many South Pacific nations, such as Fiji, sea grapes are highly valued and harvested from the wild, though not yet cultivated. Despite their importance, there is limited understanding of the ecophysiology of Fiji’s sea grapes, 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; Fv/Fm 0.79 ± 0.02), but showed significant photoinhibition under high irradiance (600 µmol photons m−2 s−1; Fv/Fm 0.42 ± 0.04). However, full recovery under moderate light was observed (Fv/Fm 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.