Consistent dispersion of toxic chemical pollutants are one of the serious environmental issues, nowadays. Most of the developing countries such as the Philippines are suffering from these problems due to rapid industrializations and increase in the number of populations (Gupta et al., 2009). There are several bodies of water in the Philippines that has already been contaminated with these toxic heavy metals.
According to the Environment for Tourism (Region III) Candaba Swamp are well known as one of the wetlands/freshwater in the Philippines, it is located l5”05’N, 120”53’E in Pampanga nearby to the town of San Ildefonso and San Miguel in Bulacan. The probability of the contaminations of heavy metals in Candaba Swamp are at high potency because it receives overflowed water from the mountain of Sierra Madre, Penaranda River and Pampanga River (DENR-PAWB, 2013), which is connected with Manila de Bay, one of the polluted marine water in the country (Sia Su et al., 2013).
Candaba Swamp has a rich diversity of different terrestrial and aquatic living organisms. Based on the data of the Wild Bird Club of the Philippines in Candaba Swamp, there are thousands of species of migratory birds from other countries migrated in Candaba Swamp and it serves as their temporary home during winter season in their natural habitat. Proper ecological balance of the aquatic ecosystem will be in a risky and hazard condition if the water bodies are continuously contaminated with these heavy metals (Farombi et al, 2007; Vosyliene and Jankiite, 2006; Ashraj, 2005). These will probably result to the unnatural phenomenon called the ‘fish kill’ which is commonly happened in the Philippines that would result to a great loss of investment in the economy.
A contamination of heavy metals threatened the populations of the plants, animal and other microorganism’s diversity present in terrestrial and aquatic ecosystem due to the anthropogenic activities. Depositions of heavy metals in water were primarily derived from the industrial site that releases toxic chemicals, domestic wastes products, activities in mining area that releases toxic substances and agricultural wastes products such as fertilizers and pesticides that would be penetrated into the soil and be possibly deposited and mixed into the underground water (Woodling et al 2001; Patra et al 2005 and Swarup et al 2006; Saxsena and Garg, 2011). The petroleum (gasoline) coming from the shipping vessels and the harmful substances from the dump sites near the water may also contribute to the water pollution (Nair et al., 2006). Contaminations of water may also be affected with the natural events such as the volcanic eruptions, interactions of water, atmosphere and sediments the entire ecosystem (Sankar et al., 2006). Heavy metals that are highly prevalent in the aquatic ecosystem are the copper (Cu), cadmium (Cd), mercury (Hg), nickel (Ni), and lead (Pb) (Mohammad et. al., 2010). These are the elements that are hazardous to the entire community of the ecosystem, to the organisms inhabited in the aquatic ecosystem as well as to the human health.
Nile Tilapia is one of the freshwater fishes in the Philippines that provide a primary source of food and employment to the people (BFAR, 2008). They are usually affected to these pollutants and having a high concentrations of these elements can be traced, and noticeable in the selected organ of Nile Tilapia such as their gills (Hosseini Alhashemi et al., 2012). These organs act as a good bio-indicator of different toxic chemical pollutants in the aquatic ecosystem (Lasheen et. al., 2013). The gills are the main entry point of water containing a dissolved oxyen and different heavy metals contaminants (Rashed, 2001). High exposures to heavy metals may cause unfavourable changes in the tissues of fishes, which include the gradual degradation of gills, degeneration of epithelial cells of the gill filaments, blood vessel dilation and the congestion of gill filaments (Chavan and Muley, 2014).
However, some of the heavy metals also called as trace elements, which include the copper, are very essentials to the human body for some metabolic mechanisms, which includes the enzymatic and metabolic activities (Yilden, 2003) whereas cadmium, lead and mercury are not needed by the body even in a minute amount (Tuzen, 2003). Having an excessive amount of heavy metals concentrated in the human body can cause severe damage in the organ and tissues that may result to death (Belitz and Grosch, 1999). Abnormalities in the tissue will be studied and investigated in Nile Tilapia collected from Candaba Swamp in Pampanga. This study also aims to determine the heavy metal existing in the water, gills and liver of Nile Tilapia in the swamp of Candaba.