Global Advanced Research Journal of Agricultural Science (GARJAS) ISSN: 2315-5094

November 2013 Vol. 2(11): pp. 289-298

Copyright © 2015 Global Advanced Research Journals

 

Full Length Research Paper

Carrying Capacity of Net Primary Productivity of Laguna Lake, Philippines

Aurora S. Jose and Simplicia A. Pasicolan

 

Ecosystems Research and Development Bureau-Department of Environment and Natural Resources, College, Laguna, Philippines, 4030.

*Corresponding Author’s Email: aurora.jose@yahoo.com

Accepted 16 September, 2013

 

Abstract

A model was developed to determine  the carrying capacity of net primary productivity of Laguna Lake measured in terms of water quality variables, namely: (1)physicochemical properties such as pH, dissolved oxygen (DO), biochemical oxygen demand (BOD), chloride, ammonia (NH3), nitrate (N03), phosphate (PO4), total nitrogen (TN), total phosphate (TP), turbidity, alkalinity; (2) microbiological (total coliform); and (3) heavy metals (chromium (Cr), Cadmium (Cd), lead (Pb), copper (Cu), iron (Fe), nickel (Ni) and zinc (Zn)). A 10-year period (1999-2008) water data of the Laguna Lake Authority (LLDA) was used in the development of the carrying capacity model. Results of the Pearson correlation test showed that among the variables with significant correlation between net primary productivity and water quality were the parameters on pH (0.204), biological oxygen demand (0.304), chloride (0.376),  nitrate (-0.207), phosphate (-0.151), total phosphate (-0.112),  turbidity (-0.133),  alkalinity (0.113), total coliform (0.179), and iron (-0.140). It means that water quality has changed significantly over the past years that these parameters can cause harm to the fishes and other aquatic life of the lake. In the regression analysis using stepwise method showed that the significant predictors of net primary productivity were: (1) chloride with R value of 0.376; (2) chloride and nitrate with R values of 0.428; (3) chloride, nitrate and total coliform with R value of 0.478; and (4) chloride, nitrate, total coliform and biological oxygen demand with R value of 0.496.  The final model contained four (4) predictors which were found to have significant to NPP.  The R value means that the independent variables in the model can account for about 49.6 or 50 %t of the variance to NPP. However, this also indicates that another 50% of the variance to NPP can be explained by other limiting factors. Carrying capacity of net primary productivity of the lake water in 10-year period (1999-2008) was in decreasing trend. It implies that the four (4) parameters poses threat to the aquatic environment of the lake, particularly on the growth of the natural food (algae) used for fish production. The model of carrying capacity of net primary productivity was developed in which NPP could be a function of the water quality parameters expressed as chloride, nitrate, total coliform, and biological oxygen demand.  These parameters will also serve as one of the limiting factors that could affect the productivity of the water.

Keywords: Languna Lake, Productivity of Laguna Lake Philippines.

 


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