|
In the Taiwan, net cage cultivation must consider the natural background of the sea area to avoid deterioration of the surrounding environment and the possible occurrence of red tide that may seriously jeopardize the sustainability of the industry. Recent trend of requiring of high quality seafoods by international consumers further warrant that the environmental quality is an important issue in net cage cultivation. Establishing factor analyses to analyze sea water quality data and investigate the importance of sea water environment to net cage cultivation is an indispensable task. In his study, nine batches of seasonable samples were collected at the middle and bottom layers of 8 locations in 4 net cage cultivation farms (Zhu-Wan, Tong-Liang, Tsai-Yuan, and Er-Kan) in Nei Wan, Penghu Hsien (Taiwan) from November, 2005 to September, 2007. The samples were analyzed for 12 water quality parameters including salinity, turbidity, conductivity, suspended solid, DO, BOD, COD, NH3-N, sulfide, TP, NO2-N, and NO3-N.. After classification of the results, factor analyses were implemented to investigate the factors that mostly impact the water quality of the cultivation farm and correlations of various water parameter in each factor. The results reveal that three main factors, i.e. the“salinity factor”,“alimentary pollution factor”, and“hygiene-apparel factor” influence water quality of the sampling stations. The“salinity factor”consists of salinity, conductility, NO2—N, and suspended solid; the“alimentary pollution factor”consists of TP, BOD, COD, and DO whereas the“hygiene-apparel factor”consists of NO3—N, turbidity, and NH3-N. As the salinity factor is concerned, all 4 water quality parameters are positively correlated; the sea water suspended solid and nitrate nitrogen are closely correlated to salinity and conductivity, and High salinity and suspended solids will lead to high nitrite nitrogen, Additionally, the sea water salinity will influence the fate of the other three parameters. As the alimentary pollution factor is concerned, DO is negatively correlated with BOD and COD; higher dissolved oxygen indicates lower alimentary substances such that the water quality is better due to low BOD and COD. An increasing total phosphate concentration is also noted to adversely influence the DO level. When the hygiene-apparel factor is considered, ammonia nitrogen is closely correlated to nitrate nitrogen because the former is oxidized to form nitrate nitrogen. Higher initial ammonia nitrogen concentration will eventually lead to higher nitrate nitrogen concentration after most ammonia is oxidized into nitrate nitrogen. The study results can be valuable referenced for regulator agencies to develop the most appropriate strategy for managing net cage cultivation
|