The grooved carpet shell clam (Ruditapes decussatus) is one of the most economically essential mollusks in Mediterranean lagoons and sandy beaches, with fisheries and aquaculture both contributing to its abundance. The goal of this research is to see how varying amounts of acidity affect this calcifying organism. 420 ppm (ambient control), 550 ppm, 750 ppm, and 1050 ppm were used to incubate juvenile clams in CO₂  enriched saltwater. With increasing pCO₂ , the biological parameters evaluated revealed a small decline. Differences, however, were not substantial. In terms of overall weight, the reduction was greatest at 550 and 1050 ppm. Furthermore, clams kept at 550 parts per million had the lowest condition index and the greatest mortality rate of 8%. Both the 550 ppm and the control 420 ppm groups demonstrated an increase in metabolic rate and ammonia excretion in the physiological response testing. With increasing acidification, the algal feed clearance rate declined, with the highest average value in the control (420 ppm) group and the lowest average value in the extremely high pCO₂ (1050 ppm) group. Ocean acidification may put further strain on R. decussatus' health and economic value by the end of the century

low pH ,Ruditapes decussatus ,Mollusca