Authors

Wilfredo H. Uy

Author

Asuncion B. De Guzman

Co-author

Rodrigo E. Acuña

Co-author

Rey L. Roa

Co-author

College of Science and Environment, Mindanao State University at Naawan, 9023 Naawan, Misamis Oriental, Philippines
School of Marine Fisheries and Technology, Mindanao State University at Naawan, 9023 Naawan, Misamis Oriental, Philippines

*Corresponding author: [email protected]

ABSTRACT

Lake Mainit is the deepest and fourth largest lake in the Philippines. The productivity and biodiversity of this oligotrophic lake have become vulnerable to various environmental and human pressures resulting from rapid economic development in the region. An inventory of fish, invertebrates and aquatic vegetation occurring within Lake Mainit and its single outlet Kalinawan river was conducted to generate a comprehensive profile and status of the lake’s biodiversity that will be useful in updating the Lake Mainit Development Plan towards the sustainable use of the lake resources. A total of 41 species of fish, 5 crustaceans, 8 mollusks and 14 species of aquatic plants were identified in the lake. The most popular fish resources are the gobies pijanga (Glossogobius giuris) and bugwan (Hypseleotris agilis) although their populations have declined through the years. Several exotic species of fish have been introduced in the lake, such as tilapia, carp and catfish. The most abundant crustaceans are two species of freshwater shrimp: the tiny shrimp Caridina mindanao locally known as isik and the freshwater prawn Macrobrachium lanceifrons locally known as ulang. The most abundant freshwater mollusks found in Lake Mainit are the bivalve Corbicula sp. locally known as bibe, and the snails Viviparia angularis (ige) and the golden apple snail Pomacea canaliculate (kuhol). Lake vegetation is dominated by submersed plants such as Hydrilla vertilicillata and Vallisneria sp., forming extensive underwater meadows. Floating plants such as the common water hyacinth Echornia crassipes are the dominant vegetation along Kalinawan river. Among the most conspicuous plants fringing Lake Mainit is the Indian or sacred lotus, Nelumbo nucifera, locally called paguse. Declining water quality, open access fisheries and exotic species introductions are among the most urgent environmental concerns that threaten the sustainability of Lake Mainit’s biodiversity.