Biophysico- chemical and Socioeconomic Study of two Major Manila Esteros [Philippines]

Two major Manila esteros namely Estero de San Miguel and Estero de Quiapo, were studied to determine their ecological status. Physicochemical parameters of the esteros investigated were: turbidity, temperature, salinity, EC [electrical conductivity], pH, DO [dissolved oxygen], BOD [biological oxygen demand], COD [chemical oxygen demand], TKN [total kjeldahl nitrogen], TP [total phophorous], chl-a and oil and grease. The results of analyses indicated that the recommended safe limits for the Class D water resources were all met. The TKN and TP values indicated hypertrophic conditions in all stations. Low ch1-a values were indicative of stressful conditions to the primary producers. Pearson Correlation analysis showed highly significant positive correlation between the following pairs of parameters, namely: salinity, conductivity, COD, depth, TP, TN; velocity, clarity; and BOD, TP, TN, ch1-a. Highly significant negative correlation were observed between: salinity, velocity, ch1-a; TP, TKN, BOD, and DO, turbidity, oil and grease. Statistical analyses showed significant mean differences of most of the parameters per station and sampling season. Four species of fishes were found in the esteros, namely, Rasbora maculata (Kataba), Gambusia affinis (Mosquito Fish), Anabas testudineus (Climbing perch or Gurami) and Hypostomus plecostomus (Janitor fish), with Rosbora and Gambusia which exhibits resiliency and dominance in the two esteros. On the other hand, a total of phytoplankton genera belonging to three algal groups were found thriving in the esteros, namely: Cyanophyta (3 spp.), Chlorophyta (9 spp.) and Bacillariophyta (7 spp.). Community indices of fishes and plankton showed high dominance in the plankton communities but low in evenness. Fish community exhibited high evenness but low dominance and diversity. Socioeconomic study revealed that attitude and actions of stakeholders to their esteros were influenced primarily by their economic status, educational and cultural background. Survey also showed that awareness of the communities on the problems of esteros and their willingness to cooperate in the rehabilitation of their polluted canals. Institutional initiatives such as environmental education and community-based programs were looked into as possible key for the effective rehabilitation and attainment of sustainability of Manila esteros.