Macroinvertebrates as Indicators of Water Quality in Three Estuary Sites in Iligan City, Philippines

Macroinvertebrate assemblages were used as indicators to assess the water quality of the three estuary sites in Iligan City. A total of six orders (Decapoda, Diptera, Odonata, Archaeognatha, Gastropoda, and Oligochaeta) were collected in the three estuary sampling sites during the four sampling periods. Arthropoda was the most diverse group of all macroinvertebrates, and it was present in the three estuaries due to its high tolerance to some organic pollution. The overall diversity indices in the three estuaries obtained low values that imply that the estuaries were composed only of a small variety of macroinvertebrate assemblage. Tambacan area has the highest value of Field Biotic Index, between 5.30-5.40, which was influenced by anthropogenic disturbances. The highest rating of water quality was found in Timoga, and the lowest value was obtained in Tambacan. Associating dissolved oxygen with the macroinvertebrates in Timoga site signified that the macroinvertebrates in the area were sensitive since they were abundant in high oxygenated streams. The estuaries in Iligan City showed a poor abundance of macroinvertebrates due to the low water quality that could be caused by the disturbances arising from human activities.

 

Keywords: diversity, oxygen, pollution, streams, tolerance