Case Study of Phytoplankton Blooms in Serangoon Harbor of Singapore

Abstract

A recent algal bloom in the East Johor Strait has led to the damage of marine life in the water channel. This has lead to heavy economic losses to the fish farms located along the water channel. There is a desire to study and be able to predict the occurrences of algal blooms so that their effects on the fish industry can be reduced. Many factors such as weather patterns, tidal conditions and nutrient content in the water contribute to the extent of the eutrophication. This paper describes the design of experiments carried out in the East Johor Strait to study the dynamics of algal blooms. Physical and biogeochemical water column sampling were carried out using Acoustic Doppler Current Profilers (AD-CP) and a Conductivity, Temperature and Depth (CTD) probe that could measure various water quality parameters such as Turbidity, Salinity, pH level, Dissolved Oxygen (DO) and Chrolophyll-a concentration. Water samples from 1 m below the surface and 1 m above the channel floor were collected using Niskin Bottles. The water samples were sent to chemistry labs to test for the concentrations of various nutrients such as Ammonium, Nitrite, Nitrate and Phosphorus. Additional sampling was done using an Autonomous Underwater Vehicle (AUV) that was capable of measuring water quality parameters similiar to those measured by the CTD. The collection of the water sample data were meant to coincide with the spring and neap tides. The schedule is important to align with major phases of astronomic tide driving forces, such as flood tide, ebb tide and the transition between the two. Comparison can then be made to attempt to understand the various factors that contribute to algal blooms in the water body. Collected biogeochemical data can be used to improve water quality forecasts as well.