Ocean Acidification

Highlights

• Clam addition rapidly altered nitrogen, oxygen and dissolved-carbon dynamics.
• All chamber treatments maintained negative CO₂ fluxes during incubation.
• Algal monoculture showed stronger 6-h CO₂ uptake than co-culture.
• Hydrochemical variables and cardiac activity were recorded concurrently.

Abstract

Global warming and ocean acidification threaten marine aquaculture. Bivalve-microalgae co-culture is considered a promising approach for low-carbon aquaculture, but its effects on water quality, carbon dynamics and bivalve physiology are not fully understood. This study tested Ruditapes philippinarum and Chlorella vulgaris in sealed static chambers with three treatments: sterile seawater (NP-C), Chlorella monoculture (WP-C) and clam-Chlorella co-culture (WP). Water-quality variables, dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), air-water CO₂ flux and clam heart rate were measured in separate 3-h and 6-h incubations. At the end of incubation, WP had higher ammonium concentrations and lower dissolved oxygen than WP-C, indicating that clam addition changed nitrogen and oxygen conditions. DOC and DIC also changed differently in the two biological treatments. All treatments showed negative air-water CO₂ fluxes. In the 6-h experiment, CO₂ uptake was strongest in WP-C and intermediate in WP. Heartbeats were recorded continuously in four clams for 7.07 h. Overall, the co-culture rapidly altered water-quality and dissolved-carbon dynamics but did not result in greater short-term CO₂ uptake than the algal monoculture under the present chamber conditions.

Liu Y., Li F., Li H., Liu H., Zhou Z., Wang X., Liang J., Chen C., Guo Y. & Liang S., 2026. Carbon dynamics and water quality regulation in Ruditapes philippinarum-Chlorella vulgaris co-culture with cardiac monitoring. Aquaculture Reports 51: 103835. doi: 10.1016/j.aqrep.2026.103835. Article.