INFLUENCE OF RIVER FLOW ON OXYGEN DEPLETION IN INNER JOHOR STRAITS Maznah Ismail1, Noor Baharim Hashim2, a and Ziba Kazemi3 1 PhD Student, Universiti Teknologi Malaysia/Department of Hydraulic and Hydrology, Malaysia 2 Senior Lecturer, Universiti Teknologi Malaysia/Department of Hydraulic and Hydrology, Malaysia E-mail :
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[email protected] 3 PhD Student, Universiti Teknologi Malaysia/Department of Hydraulic and Hydrology, Malaysia E-mail:
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[email protected] The severity of dissolved oxygen (DO) depletion in the bottom waters of estuaries appears to range widely depending on a combination of factors, including morphometry, vertical density stratification, nutrient and organic matter inputs. Relationship among bottom water DO, vertical stratification and the factors responsible for stratification-destratification in inner Western Johor Strait were studied with vertical profiles and continuous monitoring data measurements on October 2009. The analysis data results indicate that stratification events and DO levels has a strong influence with estuarine circulation and variation in tidal amplitude. Keywords: oxygen depletion; tidal range; estuarine circulation Introduction The occurrence of severe oxygen depletion, either hypoxia (<2.0 mg/l, or <3.0 mg/l in some systems) or anoxia (0.0 mg/l), is a growing concern for estuarine and coastal areas around the world, leading to water quality problems (Kuo & Neilson, 1987; Diaz and Rosenberg, 2008; Kim et al., 2010; Zhang and Li, 2010; Brown & Power, 2011). Prolonged oxygen depletion not only can disrupt benthic and demersal communities but also can cause mass mortalities of aquatic life (Diaz and Rosenberg, 1995; Yin, 2004). The development of oxygen depletion involves the combination of several physical and biological processes.