The effects of monsoon on distribution of orthophosphate and total phosphorus in water at Setiu Lagoon, Terengganu, South China Sea

Abstract

This study focused on the distribution of orthophosphate and total phosphorus in Setiu Lagoon, Terengganu involving 14 sampling stations which occupied the area of lagoon, estuarine and river. Water sample was taken at every station except for stations 7, 8, 9 and 10 where two water samples were taken due to the depth of water level which was more than one meter. Three samplings had been done due to the monsoon. First sampling th was on 8 September 2007 during South West monsoon season while second sampling st was done on 21 October 2007 during inter-monsoon and the third sampling was done on th 29 December 2007 during North East monsoon. Statistic showed that there were a significant different of orthophosphate between the stations (p = 0.007) and also between the sampling periods (p = 0.000). For total phosphorus, there is no significant different between stations (p = 0.267) but there was a significant different between sampling periods (p = 0.000). The N:P ratio for samplings in Setiu Lagoon is 19: 1 indicated that phosphorus is the growth limiting factor that limits the primary productivity in aquatic system in Setiu Lagoon. For the first sampling, the average value of orthophosphate was 0.33 .±. 0.26 µM and 1.82 ± 0.70 µM for total phosphorus.