Comparative study on breeding density of Lutraria sieboldii in nursery culture and adult culture in Beibu Gulf beaches of Guangxi Province, China

In order to investigate the efficient nursery culture mode and reasonable breeding density of Lutraria sieboldii, we had carried out an experiment at three different beaches in Beibu Gulf, Guangxi Province (Beihai, Qinzhou and Fangchenggang) using the same density gradient from February 2021 to April 2022. Two nursery culture modes, box and basket, were employed, followed by adult culture in baskets to compare the growth performance and survival rate of L. sieboldii at each stage. The results indicate that the box culture mode was more effective than the basket culture mode in Beihai and Fangchenggang, while the basket culture mode was more suitable for Qinzhou. The appropriate densities in Beihai, Fangchenggang and Qinzhou were 1 500, 1 000 grains·box⁻¹ and 500 grains·basket⁻¹, respectively. At the adult culture stage, the appropriate density in Beihai was 40 grains·basket⁻¹, and the survival rates at the end of the culture period in Qinzhou and Fangchenggang were 0. The results show that the changes of water temperature, beach temperature, salinity, pH and dissolved oxygen (DO) in Beihai are the smallest and the water quality environment is the most stable. Besides, the water quality environment in Qinzhou and Fangchenggang changes greatly and is unstable. The sediment particle size of Beihai beach is dominated by coarse sand and medium sand, whereas Fangchenggang and Qinzhou beaches is dominated by medium sand and fine sand, and Qinzhou beach is dominated by fine sand. The results of phytoplankton survey indicate that Beihai has the highest quantity and diversity of algae, followed by Fangchenggang and Qinzhou. Thus, it is showed that L. sieboldii is suitable for nursery culture in both Beihai and Fangchenggang sea areas, and for adult culture in Beihai sea area.