Ocean acidification impact on the grooved carpet shell clam (Ruditapes decussatus)

The grooved carpet shell clam (Ruditapes decussatus) is one of the most economically important mollusks inhabiting Mediterranean lagoons and sandy beaches both from fisheries and aquaculture. The present study aims to study the impact of different levels of acidification on this calcifying organism. Juvenile clams (avg. Shell Length, SL= 23.22 ± 0.84 mm) were incubated in CO2 enriched seawater at four different CO2 concentrations [420 ppm (ambient control), 550 ppm, 750 ppm and 1050 ppm] representing projected atmospheric CO2 concentration scenarios for the year 2100 by IPCC. The studied biological parameters showed slight decrease with increasing pCO2. However, differences were not significant. Standard length decreased as pCO2 concentration increased, with a maximum average decrease of (-0.12) recorded at 750 ppm as compared to the control group. Regarding total weight, the decrease was highest (-0.10) in both 550 and 1050 ppm. Moreover, clams kept at 550 ppm showed the lowest condition index (11.40 ± 1.49) and highest mortality rate of 8%. The study of physiological response showed increase in metabolic rate and ammonia excretion in both 550 ppm and the control 420 ppm groups. Algal feed clearance rate decreased with increasing acidification with highest value in the control (420 ppm) group and lowest average value of 3.34 l/h-1 in the extremely high pCO2 (1050 ppm) group. By the end of century, ocean acidification may exert additional stress on the health of R. decussatus and its economic value.

Awad M. E., Shaltout N. A., Madkour F. F., El-Regal M. A. A. , El-Sayed H. S. & El-Wazzan E., 2019. Ocean acidification impact on the grooved carpet shell clam (Ruditapes decussatus). Egyptian Journal of Aquatic Biology & Fisheries 23 (5): 169 – 182. Article.

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