Studies on breeding of Sargassum vachellianum on artificial reefs in Gouqi Island, China

The breeding of Sargassum vachellianum on artificial reefs was firstly performed in the Gouqi Island coast, Zhejiang Province, China. A new algal reef with pedestal and breeding boards was designed and produced for breeding S. vachellianum. The adult male and female plants with receptacles were collected and cultured in a breeding room for 7 days for eggs releasing out of conceptacles and for fertilizing. Approximately 3.41 million fertilized eggs were collected, and then sprayed evenly onto 105 breeding boards in 3 tanks for breeding. Fertilized eggs then sank and were attached on the bottom breeding boards for germination. After 35 days of culture, the seedlings' average length reached approximately 5 mm. And then, one hundred and five breeding boards with seedlings were transported to the Houtou coast of Gouqi Island by boats, and 21 artificial algal reefs (five breeding boards to one pedestal) were installed underwater at both Site A (slow current) and Site B (rush current). After being cultivated for 45 days in the open sea, the average length and density of seedlings on artificial reefs at Site A and Site B were 31.85 ± 0.62 and 41.31 ± 1.39 mm, 4.70 ± 1.40 and 5.19 ± 2.65 seedlings dm− 2, respectively. One year later, the length of the plants on artificial algal reefs in the Gouqi Island coast reached up to 15.51 ± 3.42 cm. All the results indicated that large scale artificial breeding of S. vachellianum with artificial algal reefs was feasible.