nasc 5 exer 2 inc.

INTRODUCTION Being situated in the Coral Triangle and having an archipelagic geography, Philippines has one of the most diverse marine ecosystems. Water resources play a vital role in the survival of all living organisms. The country is rich in freshwater resources having about 80 lakes and 400 rivers. In addition, the country has about 330 freshwater fish, including nine endemic genera and more than 65 endemic species. Laguna de Bay is the largest lake in the country, situated at the heart of CALABARZON. It has a lake surface area of 900 km2, bigger than the whole of Singapore, and an average depth of 2.5 m. There are approximately 14,618,353 people inhabiting around the region, benefiting directly and indirectly. Fishing is the main livelihood around the area and it has an estimated Php 7.3 million of fisheries production per year. The lake is also a source of power in the area. The Kalayan Hydroelectic Power Station in Laguna could generate 600 megawatts. It also provides irrigation for 102, 456 hectares of farmlands. Laguna de Bay can be used for transportation too. There are about 5,000 motorized and non-motorized watercrafts in the lake. There are as well 208,000 large, medium and small business establishments. It also serves as a floodwater reservoir through Manggahan Floodway and Napindan Hydraulic Control System, which reduce floodwater in Metro Manila. Despite the many benefits that can be derived from freshwater lakes in the Philippines, many of our lakes and rivers are gradually degrading. Our freshwater resources have been overused. The degrading situation of the lakes and rivers has affected the livelihood and health of the people relying on it. Protecting our environment should be valued by every Filipino. This exercise will provide the students of Nasc5 understanding on how human activities affect lake ecosystems, specifically the Laguna Lake. It also helps the students to realize ways and strategies to minimize the negative effects of human