AQUATIC ECOSYSTEM MASTER PROJECT (AMP)

Comparative Assessment of Langaran and Layawan Rivers

The state of health of the Langaran and Layawan Rivers of Mt. Malindang was determined through an assessment of the riparian biodiversity and the river water quality and quantity. These were used to generate and establish benchmark information useful for the development of protocols for basic monitoring system and environmental management. In general, results indicated a relatively healthy state of the rivers being assessed. The physico-chemical parameters (e.g., total suspended solids, dissolved oxygen, and nutrients) were at levels that fall within the standards set by the Department of Environment and Natural Resources (DENR). The presence of macroinvertebrates that was classified as excellent, and the good water quality indicators were still dominant in the Langaran and Layawan Rivers. However, coliform were present in all sampling stations during the two seasons, which indicate that river water is contaminated.

As for the riparian fauna, 60 species were recorded for birds, 12 species for mammals, 17 for reptiles, and 13 for fishes in Layawan River. In Langaran River, 52 species were reported for birds, 11 for mammals, 11 for reptiles and 25 for fishes. For flora, the sampled riparian area of Layawan River recorded 105 morphospecies of trees and about 111 of shrubs, herbs, and weeds. The first generation data gathered in Langaran River revealed a total of 251 species of vascular plants. The relatively healthy conditions in Langaran and Layawan Rivers have to be sustained by designing a monitoring protocol that will be readily adopted by the community using macroinvertebrates as bioindicators in the aquatic zones while in the riparian areas, a community-based bird monitoring is recommended. The local community (barangay captains, council members, and residents) have suggested some management actions, during the validation meeting, such as tree planting and prohibition of quarrying activities within the rivers.

A Comprehensive Analysis of the Ecological Factors for the Development of Strategies to Sustain Coastal Biodiversity and to Improve Fish Stock Management

The landscape approach to understanding the relationship of the mountain, river and sea, focused on the two major watershed areas in the Mt. Malindang range flowing through the Layawan river in Oroquieta and Langaran river in Plaridel. This report covers only the coastal component within the mouth of the two rivers. Field activities, done in a participatory manner with local stakeholders, were conducted during the northeast and southwest monsoon season. Survey methods used standard techniques as follows: manta tow for wide area survey of coral reefs; line intercept transect and daytime fish visual census for coral benthos, fish and associates; stratified random point quadrat sampling and core sampling for seagrass and seaweeds; and predetermined sites for water quality monitoring and plankton towing. Coordinates of all stations established were recorded using the GPS and plotted in GIS.

Results of the study showed that most of the reefs surveyed, in both deep (10 m) and shallow areas (3 m), were generally in poor to fair conditions (<50% live coral cover), while only two shallow stations with good (50-75%) live coral cover at Plaridel were recorded more than a kilometer from the river mouth. Reef fish biomass was also low with average values ranging from 3.5 to 13.3 kg ha-1 in both areas, generally composed of small individuals dominated by the damsel fish. Seagrass vegetation was observed to occur about a kilometer from the river mouth in Oroquieta, while in Plaridel, seagrasses occurred a few meters from both sides of the river mouth. Average seagrass cover was generally higher in Plaridel (33%) than in Oroquieta (18%) with a total of six to seven seagrass species. The dugong grass, Thalassia hemprichii dominated the seagrass. Seaweed vegetation was also in patches and occurred along rocky areas and reef edges dominated largely by the brown seaweeds, Sargassum and Padina. A total of 59 seaweed species, 47 phytoplankton and 35 zooplankton have been recorded in both sites. Water quality measurements indicated values that are within the normal seawater range for pH, nutrients (NO3-N, PO4-P) and dissolved oxygen. While total suspended solids (TSS) and river discharge were higher in Layawan than in Langaran river. The extent of impact seems apparent between the two rivers, with the differences in extent of seagrass and coral reef distribution from the river mouth, as a possible consequence of differences in river discharges and characteristics. Management implication and recommendations towards biodiversity conservation and sustainable development of Mt Malindang and its natural resources are provided in the report.

Assessment of the Headwaters of Layawan River: Linkage Between the Terrestrial and Aquatic Ecosystems in the Oroquieta Watershed of Mt. Malindang

This study characterized the headwaters of Layawan River in terms of the physiography of the catchment area and the physicochemical and biological components of its major headwater streams. The biota of the riparian zones of the headwater streams was also identified, as this was believed to provide linkage between the terrestrial and the aquatic ecosystems in the Mt. Malindang landscape. Results of the study showed that headwater streams had low ion concentration. Total hardness ranged from 50-158 ppm, total alkalinity from 48-156 ppm and total dissolved solids (TDS) from 89-240 ppm. The pH was within normal range of 6-8. The presence/number of coliform in all sites made the river water unsafe for drinking, although the river water still meets the standards for recreational water. Aquatic macroinvertebrates found in the headwater streams were mostly indicators of good water quality, the number of morphospecies ranging from 14 to 29. The terrestrial invertebrate fauna were represented by eight orders of insects, two classes of arthropods and one phylum. There were 72 tree species in the nine plots totaling to an area of 3600 sq m. The fauna inventory included native and endemic species but these are continually being threatened by activities of the local human population. Although the barangay population only consists of 49-52 households with approximately 250 individuals, their land use, hunting and fishing activities, extraction of timber and non-timber forest products, if uncontrolled and unregulated, all present threats to the conservation of biodiversity in this area and their sustainable use.

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