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    • Article

      Diversity and distribution of freshwater fish assemblages in Tayabas River, Quezon (Philippines) 

      VGV Paller, MNC Corpuz & PP Ocampo - Philippine Journal of Science, 2013 - Science and Technology Information Institute
      Three stream sections (upstream, midstream, and downstream) of Tayabas River, Philippines were surveyed during the wet and dry seasons of 2010 to evaluate the poorly known status of freshwater fish assemblages. The study collected a total of 1,070 individuals comprising 15 species, 13 genera, and 8 families. The three most abundant groups were poeciliids (61.85%), gobiids (26.16%), and cichlid (5.51%). Shannon-Weiner’s diversity indices ranged from 1.270 to 2.171. Relatively high Shannon evenness indices (0.653–0.846) and low Simpson’s dominance values (0.142–0.322) were calculated implying a fairly equitable distribution of niche space for dominant and non-dominant fishes. Significant change on fish assemblage in longitudinal gradient was observed (p<0.05), being the most diverse fish assemblage registered in the upstream. Species richness is mostly composed of native fish species (10 species) and mainly represented by stream gobiids (six species). The downstream, however, had the highest cumulative abundance, in which the larger proportion was from introduced species. Also, wet season had considerably more fish species and individuals relative to dry season (p<0.05). This significant spatio-temporal differences in fish assemblage data were evaluated by multivariate analyses (p<0.05). Canonical correspondence analysis identified the depth (seasonal water level fluctuations), vegetation growth, and dissolved oxygen concentrations (in order of importance) as the most influential environmental parameters affecting fish assemblage structure. Also, climatic stress (prolonged drought) and anthropogenically-induced habitat alteration could negatively affect the integrity of freshwater fishes within the river. The study suggests extensive management programs of the river for the protection of native fish species.
    • Article

      Morphometric and morphomeristic variations in five populations of indigenous Celebes goby Glossogobius celebius (Perciformes: Gobiidae) from Southern Luzon, Philippines 

      MNC Corpuz, MVC Camacho & PP Ocampo - Philippine Agricultural Scientist, 2013 - College of Agriculture, University of the Philippines Los Baños
      To elucidate the population structure and pattern of morphological divergence of the indigenous Celebes goby Glossogobius celebius (Valenciennes, 1837), morphometric and morphomeristic characters of this species were compared among populations collected from five study sites in Southern Luzon, Philippines. Univariate analysis of variance confirmed significant differences among populations for 20 out of 23 allometrically-transformed metric characters (P<0.05), while nine meristic traits of five populations were comparatively homogeneous (P>0.05). Intrapopulation variability was very low (6.81-7.21%) for each location. Multivariate analysis of variance determined a very high significant group variability (P<0.05). Also, principal component analysis (PC1=36.60%; PC2=18.34%) and canonical variate analysis (CV1=44.59%; CV2=37.30%) identified the 2 super(nd) dorsal fin length, anal fin length, and the 2 super(nd) dorsal fin origin as the main significant contributors of population differentiation. Derived classification functions correctly classified an average of 68% individuals into their original groups. The canonical variate analysis plot exhibited high isolation of lacustrine populations (Lake Taal and Laguna de Bay) from riverine populations (Dampalit River, Alitaaw River and Pansipit River), with the latter having longer metric characters. Likewise, squared Euclidean distance similarity using metric data clearly produced two clusters representing both river and lake populations. This morphological divergence is suggested to be environmentally-induced (phenotypic plasticity) primarily by the differences in flow rate and temperature of the study sites.