Primary study on the reasons for the rotten thallus of Porphyra haitanensis from Fuding Minzao Bay

In this paper we took samples of rotten thallus of Porphyra haitanensis from Fuding Minzao Bay in October, 2012. The investigation on the reasons for the rotten thallus were conducted. In our research the main symptoms included that the color of front-end thallus turned red into white, and finally rotten. The main cause of rotten thallus of Porphyra haitanensis were due to several reasons below: (1) In the low tide period with high temperature, the vertical exchange formed by the sea wind and wave has became weaker, and the carbon dioxide and nutrients exchange in seawater also became weaker, so the physiological function of thallu cells has declined.(2) The high densities of culture and low nitrogen in seawater has restricted the massive growth of Porphyra haitanensis; (3) the south offshore current was slow, and the suspended matter and other pollutants were accumulated and stuck on the thallus, affecting the growth of Porphyra haitanensis. In conclusion, the author of this paper proposed several countermeasures as some reference to the healthy and sustainable development of Porphyra haitanensis culturing of Fujian in future.