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Analysis of the anthropogenic-based disturbances among the indigenous goby population in Mandulog River System, Northern Mindanao, Philippines
Dissertation Abstract:
The biology and ecology of indigenous freshwater gobies might be affected by water pollution resulting from human activities, which posed changes in the water quality of the river. Hence, a study was conducted in the upstream, midstream, and downstream parts of Mandulong River System, Iligan City, Northern Mindanao in quarterly basis for one year to determine the species composition, abundance, morphomeristic characteristics, sexual dimorphism, body proportionality, gonadosomatic index (GSI) estimates, water quality, climatic conditions, and human-related activities.
Total number of individuals of all goby species was 1590, with 895 (56.25%) and 695 (47.72%) gobies collected during dry and wet seasons, respectively. There were 141 (15.75%), 559 (62.45%), and 195 (21.78%) individuals of all goby species recorded in the upstream, midstream, and downstream parts of the river, respectively, during dry season, while 147 (21.15%), 372 (53.52%), and 176 (25.32%) were recorded during wet season.
The study found 10 goby species in three families, namely: Belobranchus belobranchus (4.78%), Giuris margaritacea (10.25%), Oxyeleotris lineolata (31.76%), Awaous melanocephalus (13.46%), A. ocellaris (12.14%), Glossogobius celebius (8.99%), G. giuris (8.68%), Periophthalmus barbarous (3.52%), Sicyopterus lagocephalus (5.28%), and Rhyacichthys aspro (1.13%). Generally, the morphometric and meristic attributes did not differ significantly for each goby species. Only four out of 10 species exhibited sexual dimorphism, namely: G. celebius, P. barbarous, O. lineolata, and G. margaritacea. Body proportionality measures were highly correlated to all species, which connote a well-proportioned body structure. A decreasing trend of gonadosomatic index was observed form species found in the upstream toward downstream, which in turn, may indicate a slight sensitivity to water pollution. R. aspro, which can only be found in the upstream and midstream, may be the only species that is sensitive to water pollution, although the water quality of Mandulog River is still within the Department of Environment and Natural Resources (DENR) standards that could support the goby population.
This study revealed that the current domestic (i.e., toilet use, kitchen wastes,
laundry, bathing), agricultural (application of pesticides and fertilizers), and quarry and small-scale mining activities done within the river and its periphery did not pose any serious treats to goby population in terms of the level of pollution generated. However, it is imperative that the river be protected from overexploitation and pollution impacts for the economic and ecological benefits, particularly in providing sustainable fishery resources for the present and future generations. The increasing level of awareness based on the knowledge, perception, and attitude of the residents toward the riverine and terrestrial resources might empower and mobilize them through a concerted and holistic effort on biodiversity conservation and sustainable development programs of the local government units and other institutions.