Abstract:
This study was conducted at the Setiu Lagoon during Southwest Monsoon, Intermonsoon
and Northeast Monsoon. The temperature, salinity, pH, dissolved oxygen
and water current data were collected in situ while for the total alkalinity it was
determined by titration method in laboratory. All the data were then analyzed in order
to compare the effect of monsoons to each parameter recorded. Most of the
hydrological parameters were significantly different to the monsoons (p<0.05). The
mean for temperature during Southwest Monsoon, Inter-monsoon and Northeast
Monsoon were 31.65 ± 0.03°C, 28.97 ± O. l 6°C and 28.17 ± 0.11 °C respectively. For
the salinity, the mean were 26.94 ± 0.08 ppt, 22.79 ± 1.80 ppt and 14.79 ± 0.53 ppt
respectively. As for the pH, the mean recorded were 7.75 ± 0.00, 7.68 ± 0.07 and 6.28
± 0.08 respectively. The means for dissolved oxygen were 5.37 ± 0.07 mg/1, 3.85 ±
0.25 mg/1 and 3.74 ± 0.19 mg/1 respectively. As for total alkalinity, the means
recorded were 118.05 ± 1.34 mgCaC03/l, 35.29 ± 0.80 mgCaC03/l and 30.76 ± 0.61
mgCaC03 /l respectively. However, the current movement was not significantly
different to the sampling period (p>0.05), most probably because the current
movement was influenced by tide. The means for the current flow were 0.123 ± 0.17
mis (Southwest Monsoon), 0.199 ± 0.19 mis (Inter-monsoon) and 0.220 ± 0.24 mis
(Northeast Monsoon). For the stations at the Northwest part of the lagoon, the current
direction was towards the Southeast and for the stations at the Southeast; the current
direction was in the opposite direction. Since there is monsoon changes in the Setiu
Lagoon, it can reduce the effect of wastes accumulation from the aquaculture, culture
pond and river runoff.