Species composition and abundance of macrobenthic invertebrates at Pupot River, Brgy. Plaza Aldea, Sitio Balimbing, Tanay Rizal in relation to certain physico-chemical parameters

This thesis is a study of the species composition, abundance and distribution of macrobenthic invertebrates in Pupot River, Tanay, Rizal for the period from February to July, 1995.A total of 3,187 macrobenthos belonging to the following phyla: Anthropoda (Orders Ephemeroptera, Coleoptera, Plecoptera, Diptera, Trichoptera, Hemiptera, Araneida, Depapoda), Mollusca (Orders Bassomatrophorida and Eullamellibranchia), Platyhelminthes (Order Tricladida), Annelida (Order Gnathobdellida) and Nematoda (Class Aphasmidia) were collected. Six species of benthos, Chironomus sp. (dipteran larvae), Eubrianax sp. (coleopteran), Caenis sp., Baetis sp., Epeorus sp. (ephemeropteran) and Hydropsyche sp. (trichopteran) were found to be abundant. Result of the statistical analysis revealed that five orders (Ephemeropteram Coleoptera, Plecoptera, Diptera, and Trichoptera) were significantly correlated with factors such as: dissolved oxygen content, velocity of flow and substrate composition at P .05 level (.231). The nymph stage of mayflies (Order Ephemeroptera) showed a positive correlation (+.327) with dissolved oxygen content and negative correlation (-.238) with increasing velocity of flow. Likewise, dipterans also showed a positive correlation (+.336) with dissolved oxygen and substrate composition (+.270). The abundance of coleopterans (beetles) was significantly correlated with increasing substrate particle size (+.370). The larval stage of caddisfly (Order Trichoptera) also preferred gravel (+.242) rather than find sand. The abundance of plecopterans increased as velocity of flow increases (+.263). The presence of opportunistic species of annelids, Hirudo sp. during the months of April and May indicated the tolerance of these species to decreasing dissolved oxygen content