Effects of stocking density on the productivity and nutrient removal of Agarophyton vermiculophyllum in Paralichthys oli
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23RD INTERNATIONAL SEAWEED SYMPOSIUM, JEJU
Effects of stocking density on the productivity and nutrient removal of Agarophyton vermiculophyllum in Paralichthys olivaceus biofloc effluent Sook Kyung Shin 1 & Su-Kyoung Kim 2 & Jun-Hwan Kim 2 & Taejun Han 1 & Charles Yarish 3 & Jang K. Kim 1 Received: 12 July 2019 / Revised and accepted: 3 December 2019 # Springer Nature B.V. 2020
Abstract Optimal stocking density of the marine red alga Agarophyton vermiculophyllum was determined to maximize the productivity and nitrogen removal in biofloc effluent. Agarophyton vermiculophyllum was cultured at 0.2, 2, 4 and 8 g L−1 (FW) stocking densities, 160 ± 10 μmol photons m −2 s −1 and 12:12 L:D photoperiod for 20 days. Agarophyton vermiculophyllum was cultured in effluent from a juvenile Paralichthys biofloc tank culture system and von Stosch– enriched (VSE) medium at 20 °C. The total nitrogen and phosphorus concentration of VSE medium was adjusted to the biofloc level, 1000 μmol L−1 and 33 μmol L−1, respectively. Specific growth rate was significantly higher at 0.2, 2, 4 and 8 g L−1 in both media. However, the productivity was significantly higher at 8 than 0.2 g L−1 in both media. Tissue carbon contents were not significantly influenced by the medium at 8 g L−1 (34.9% in VSE and 34.0% in biofloc). However, tissue nitrogen content was significantly higher at VSE medium than at biofloc medium at 8 g L−1 (3.7% in VSE and 3.4% in biofloc). The carbon removal rate was highest at the highest stocking density, 1.98 mgC g−1 DW day−1 (VSE) and 1.89 mgC g−1 DW day−1 (biofloc), respectively. Also, the nitrogen removal rate was highest at the highest stocking density, 0.21 mgN g−1 DW day−1 (VSE) and 0.19 mgN g−1 DW day−1 (biofloc), respectively. The nutrient removal was not significantly influenced by medium at 4 and 8 g L−1. These results show that A. vermiculophyllum can grow and have the potential to remove nutrients in the biofloc medium at high nitrogen concentrations. Keywords Agarophyton vermiculophyllum . Rhodophyta . Biofloc . Nitrogen . Stocking density
* Jang K. Kim [email protected] Sook Kyung Shin [email protected] Su-Kyoung Kim [email protected] Jun-Hwan Kim [email protected] Taejun Han [email protected] Charles Yarish [email protected] 1
Department of Marine Science, Research Institute of Basic Sciences, Incheon National University, Incheon 22012, Republic of Korea
2
Department of Aquaculture, National Institute of Fisheries Science, Incheon, South Korea
3
Department of Ecology & Evolutionary Biology, University of Connecticut, Stamford, CT, USA
Introduction The annual fish aquaculture production in Korea has increased about 13% in 2017 (86,387 t) compared with 2012 (76,308 t) (KOSIS 2018). The proportion of floating fish cages decreased to 63% in 2017 from 69% in 2012, whereas the proportion of land-based aquaculture has increased from 31 to 34% during the same time (KOSIS 2018). The floating fish cages and land-based aquaculture have faced many serious environmental issues. For example, fish escaping f
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