AUTHOR=Ye Bingcong , Gu Zhifeng , Zhang Xingzhi , Yang Yi , Wang Aimin , Liu Chunsheng 

TITLE=Comparative Effects of Microalgal Species on Growth, Feeding, and Metabolism of Pearl Oysters, Pinctada fucata martensii and Pinctada maxima

JOURNAL=Frontiers in Marine Science

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.895386

DOI=10.3389/fmars.2022.895386

ISSN=2296-7745

ABSTRACT=<p><italic>Pinctada fucata martensii</italic> and <italic>P. maxima</italic> are two main traditional pearl oyster species that can produce seawater pearls. Our previous study showed a higher clearance rate (CR) and growth performance in <italic>P. f. martensii</italic> than in <italic>P. maxima</italic> fed with <italic>Isochrysis galbana</italic>. In this study, the <italic>P. f. martensii</italic> and <italic>P. maxima</italic> juveniles of two sizes (large and small) were fed with six different microalgae diets [<italic>I. galbana</italic> (<italic>I</italic>), <italic>Platymonas subcordiformis</italic> (<italic>P</italic>), <italic>Chaetoceros muelleri</italic> I, I+P, I+C, and P+C] to evaluate the differences in growth, feeding, and metabolism between two pearl oyster species. After 60 d of the rearing period, <italic>P. f. martensii</italic> and <italic>P. maxima</italic> fed with mixed microalgae showed a significantly higher relative growth rate (RGR) than those fed with single microalgae (P&lt; 0.05). The RGRs were significantly higher in <italic>P. f. martensii</italic> than those in <italic>P. maxima</italic> fed with the same diets (P&lt; 0.05). The RGRs showed a decreasing tendency with the growth in both pearl oyster species. The CRs of pearl oysters fed with mixed microalgae were significantly higher than those fed with single microalgae (P&lt; 0.05), and the CRs of <italic>P. f. martensii</italic> were significantly higher than those of <italic>P. maxima</italic> fed with the same diets (P&lt; 0.05). Significantly lower respiration rates (RRs) were observed in small-size <italic>P. f. martensii</italic> groups fed with I, P, and I+P diets and all large <italic>P. f. martensii</italic> groups compared to <italic>P. maxima</italic> fed with the same diets (P&lt; 0.05). Higher activities of amylase, cellulase, lipase, and pepsin in <italic>P. f. martensii</italic>were observed compared to <italic>P. maxima</italic> fed with the same diets at two sizes. The pepsin activities in <italic>P. maxima</italic> decreased with the growth, while there were no consistent pepsin activities of <italic>P. f. martensii</italic> with the growth. The carbonic anhydrase activities in <italic>P. maxima</italic> were significantly higher than those in <italic>P. f. martensii</italic> fed with the same diets (P&lt; 0.05). The carbonic anhydrase activities were highest in the I+C diet group, followed by C+P and I+P, I, C, and P groups. Significant differences were observed among different diet groups in the same pearl oyster species (P&lt; 0.05). Our results suggest that the lower CR and activities of digestive enzymes and higher RRs and activities of carbonic anhydrase may cause a lower growth rate of <italic>P. maxima</italic> compared to <italic>P. f. martensii</italic>.</p>