Changes in soft coral Sarcophyton sp. abundance and cytotoxicity at volcanic CO2 seeps in Indonesia

• Published in: AIMS Environmental Science
• Main Authors: Hedi Indra Januar, Neviaty Putri Zamani, Dedi Soedarma, Ekowati Chasanah
• Format: Article in Journal/Newspaper
• Language: English
• Published: AIMS Press 2016
• Subjects: Soft coral; Sarcophyton sp; cytotoxic metabolites; ocean acidification; geo; envir; Ocean acidification
• Online Access: https://doi.org/10.3934/environsci.2016.2.239; https://doaj.org/article/bebd6abc0ae3475ba125b8e3705e2e05

This study presents the relationship between benthic cover of Sarcophyton sp. living on coral reefs and their cytotoxicity (an assumption of soft coral allelochemical levels) along acidification gradients caused by shallow water volcanic vent systems. Stations with moderate acidification (pH 7.87 ± 0.04), low acidification (pH 8.01 ± 0.04), and reference conditions (pH 8.2 ± 0.02) were selected near an Indonesian CO2 seep (Minahasa, Gunung Api Island, and Mahengetang Island). Cover of the dominant soft coral species (Sarcophyton sp.) was assessed and tissue samples were collected at each site. The cytotoxicity tissue extracts were analyzed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolinon bromide (MTT) method. Levels of cytotoxicity were strongly correlated with Sarcophyton sp. cover (p < 0.05; R2 = 0.60 at 30 ppm and 0.56 at 100 ppm), being highest at mean pH 8.01 where the soft corals were most abundant. This finding suggests that Sarcophyton sp. can be expected to survive ocean acidification near Indonesia in the coming decades. How the species might be adversely affected by further ocean acidification later in the century unless CO2 emissions are reduced remains a concern.