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Aquaculture Environment Interactions

    AEI prepress abstract   -  DOI:

    Dissolved organic carbon from cultured kelp Saccharina japonica: production, bioavailability, and bacterial degradation rates

    Yaping Gao, Yitao Zhang, Meirong Du, Fan Lin, Weiwei Jiang, Wenhao Li, Fengxue Li, Xuning Lv, Jinghui Fang, Zengjie Jiang*

    *Corresponding author:

    ABSTRACT: Seaweed farming is widely perceived as one of the most environmentally benign types of aquaculture activity. In the past 10 yr, global seaweed production has doubled and reached 31.8 million t. Farmed seaweed also has important functions in local ecosystems. We focus on the production, bioavailability, and bacterial degradation rates of dissolved organic carbon (DOC) from cultured kelp Saccharina japonica. Semi in situ incubations in 2 growing seasons were conducted to estimate DOC production, and laboratory incubations were used to determine bioavailability and decay rates of DOC from cultured kelp. Results showed that DOC production was 6.2−7.0 mg C (g dry wt)−1 day−1 in the growing seasons and the proportion of DOC to net primary productivity was 23.7–39.1%. The decomposition rate of DOC was 4 ± 1% d−1and 9 ± 1% d−1 in January and April, respectively. About 37.8% remained as refractory DOC after the 150 d incubation. It was calculated that the total DOC from kelp in Sanggou Bay was approximately 11.3 times of that from phytoplankton for the whole bay (144 km−2). Our results suggest that more than a half of the bioavailable DOC will be exported out of the bay to potentially support the wider food chain through bacterial uptake. Cultured kelp is therefore an important source of DOC in the embayment, contributes to the coastal DOM pool and provides a potential way in carbon dioxide sequestration.