AUTHOR=Xu Xian , Dong Shipeng , Zhang Dongxu , Yu Liye , Pu Weijia , Xie Yicheng , Shan Hongwei , Wang Fang 

TITLE=Filter-Feeding Bivalve Weakens Food Competition Between Crustaceans (Portunus trituberculatus, Marsupenaeus japonicus) in Integrated Culture Ponds: Evidence From 18S rDNA Barcoding and Stable Isotope Analysis

JOURNAL=Frontiers in Marine Science

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.884968

DOI=10.3389/fmars.2022.884968

ISSN=2296-7745

ABSTRACT=<p>In order to investigate the effects of razor clams (<italic>Sinonovacula constricta</italic>) on the food composition and isotopic niches of swimming crabs (<italic>Portunus trituberculatus</italic>) and kuruma shrimp (<italic>Marsupenaeus japonicus</italic>) in polyculture systems, this study analyzed 60 P<italic>. trituberculatus</italic>, 60 <italic>M. japonicus</italic> and 30 <italic>S. constricta</italic> to quantify the food sources, food source contributions, and isotopic niches of cultured organisms using 18S rDNA barcoding and stable isotope techniques. The results were as follows: (1) In the <italic>P. trituberculatus</italic>-<italic>M. japonicus</italic> (PM) polyculture system, the Sobs and Shannon-Wiener indices of the stomach contents of <italic>P. trituberculatus</italic> and <italic>M. japonicus</italic> were not significantly different (<italic>P</italic> &gt; 0.05). In the <italic>P. trituberculatus</italic>-<italic>M. japonicus</italic>-<italic>S. constricta</italic> polyculture (PMS) system, the Sobs and Shannon-Wiener indices of the stomach contents of <italic>P. trituberculatus</italic> and <italic>M. japonicus</italic> were also not significantly different (<italic>P</italic> &gt; 0.05), but the Sobs indices of <italic>P. trituberculatus</italic> in the PMS system were significantly higher than those in the PM system (<italic>P</italic> &lt; 0.05), <italic>M. japonicus</italic> shows a similar pattern. (2) 18S rDNA barcoding analysis showed the dominant taxa in the stomach contents of both <italic>P. trituberculatus</italic> and <italic>M. japonicus</italic> in the PM system were Trebouxiophyceae, Embryophyta and Rotifera, and the food overlap between them was 0.8992, which was significant (Q &gt; 0.6). In the PMS system, the dominant taxa in the stomach contents of <italic>P. trituberculatus</italic> were Chrysophyceae, Intramacronucleata, and Embryophyta, and in <italic>M. japonicus</italic> were Chrysophyceae, Embryophyta, and Bacillariophyceae, in this system the food overlap was 0.2061, which was not significant (Q &lt; 0.6). (3) Stable isotope analysis suggested, in both systems, the main food sources of <italic>P. trituberculatus</italic> and <italic>M. japonicus</italic> were iced trash fish, zooplankton, phytoplankton, and organic particulate matter (POM). Iced trash fish accounted 77.67% of food sources for <italic>P. trituberculatus</italic> and 69.42% for <italic>M. japonicus</italic> in the PM system, and 60.82% and 57.60% in the PMS system. (4) The isotopic niche overlap between <italic>P. trituberculatus</italic> and <italic>M. japonicus</italic> was 5.69% in the PM system and 1.21% in the PMS system. These results suggested food competition between <italic>P. trituberculatus</italic> and <italic>M. japonicus</italic>, and <italic>S. constricta</italic> can reduce the competition and isotopic niche overlap, improve the contribution of food sources such as phytoplankton. Razor clams also serve to purify the water and improve the utilization of iced trash fish by filtering phytoplankton (51.10%), POM (32.25%), SOM (7.47%), and iced trash fish (9.18%). Thus, <italic>P. trituberculatus</italic>-<italic>M. japonicus</italic>-<italic>S. constricta</italic> is a healthy and sustainable culture model.</p>