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E-International Scientific Research JournalISSN: 2094-1749 Volume: 2 Issue: 4, 2010typhoons due to the El Niňo and La Niňa phenomena. The trend towards the “shallowing”process and the flooding of rivers due to climate variability can significantly alter theconditions of river systems in terms of biodiversity composition and physical condition.Extreme drought causes rivers to dry out and this would mean the extinction of some speciesthat are not resistant or adaptable to the absence of water (Juranilla-Sanchez et al., 2007). Flashflooding after heavy rains or during typhoons causes the river to swell or overflow anddestroys the river banks and the plants that grow there. Floods also erode the soil thatsubsequently contribute to the siltation process downstream.Research Method and DesignSeven stations were established as sampling sites along the Liboran River and weresampled in June 2006 and May 2010. Physico-chemical parameters such as pH, temperature,dissolved oxygen (DO), salinity, total suspended solids, phosphates and nitrates weremeasured, as well biological parameters such as total coliform, Escherichia coli and planktoncomposition.Determination of Dissolved Oxygen (DO), pH, Salinity and Temperature. In situmeasurements of dissolved oxygen, pH, temperature and salinity were conducted a portableDO meter, pH meter, thermometer and refractometer, respectively in three replications.Phosphates (PO 4 -P mg/L) Analysis. Water samples in three replicates (350 ml each)were taken from the three sampling sites and were placed in a glass bottle. (Sampling bottleswere soaked with muriatic acid and washed with a phosphate free detergent before use).Samples were then placed in a styropore box with ice and were brought to Silliman UniversityMarine Laboratory for analysis.Stocks solutions of Sulphuric Acid, Ascorbic Acid, and Mixed Reagent were firstprepared. Sulphuric Acid was prepared through adding 125 ml concentrated H 2 SO 4 to waterand was diluted to 500 ml, stored in a plastic bottle. Ascorbic Acid on the other hand, wasprepared through dissolving 5.0g ascorbic acid in an amber glass bottle with 25 ml water, andadded with 25 ml sulphuric acid solution and stored in the refrigerator. Mixed Reagent wasprepared through dissolving 6.25 g (NH 4 ) 6Mo 7 0 24 .4H 2 O in 62.5 ml water. Then 0.25gpotassium antimony tartrate (with or without 1/2H 2 O) was dissolved in 10.0 ml water. Themolybdate solution was then added to 175 ml of dilute sulphuric acid with the tartrate, andwas stored in a glass bottle. Then the following were added to a test tube or scintillation vial:10 ml filtered sample, 0.2 ml ascorbic acid reagent, and 0.2 ml mixed reagent. Absorbance at880 nm was measured between 5 and 30 minutes. The concentration of PO 4 -P in mg/L is givenby the formula of Spotte as quoted by Argente (2009):C u =C s V s A sV u AsWhere: C u = the concentration of the unknown in mg PO 4 -P/LC s = the concentration of the standard in mg PO 4 -P /LA u = the absorbance of the unknownA s = the absorbance of standard367