Karlo Jose J. Calderon (March 2012)
Philippine Science High School Western Visayas Campus – Department of Science and Technology (DOST-PSHS WVC), Brgy. Bito-on, Jaro, Iloilo City 5000, Philippines
ABSTRACT
The Iloilo Flood Control Project was built to address the problems brought by annual flooding in Iloilo City. With its aim to reduce annual flood damage by providing a new outlet channel, the newly constructed project brings freshwater influx and sediments that expose the mangroves lining the coast of Balabago to salinity and sedimentation changes. According to Gilman and others (2008), mangroves may not survive changes in salinity and sedimentation. This study therefore evaluates the growth through internodal lengths of Rhizophora spp. seedlings before and after the opening of the Iloilo Flood Control Project (IFCP) in Balabago, Jaro, Iloilo City. Internodes after hypocotyl and before the topmost internode of 52 Rhizophora spp. seedlings were counted, measured, and tagged after sampling. Age reconstruction technique was used to evaluate the age and growth pattern of seedlings. An inconsistent growth pattern was observed before the opening of IFCP while a steadily decreasing pattern was observed after the opening. A growth rate of 0.085 cm day-1 was observed in the Rhizophora spp. seedlings after IFCP opening. In normal conditions, Rhizophora spp. grows at an optimal rate of 0.275 cm day-1 . This suggests that Rhizophora spp. seedlings exhibited only 30.97% growth. Salinity fluctuated from as low as 0 ppt and as high as 32 ppt. while sedimentation rates ranged from 0.003 to 0.364 g cm-1day-1. The fluctuating salinity of the area may present an additional burden of acclimatization to salinity while the sudden deposition of sediments altered the oxygen supply to the hypocotyls root system thereby interrupting root and soil gas exchange.