Species composition and diversity of periphytic diatoms along Umalag River, Philippines

Rivers are one of the providers of both economic and ecosystem services. However, it has been gradually degraded by general public. One of which is Umalag River, considered to be as one of the heavily stressed rivers due to different anthropogenic activities nearby. Consequently, not only locals are affected to these changes, but also the aquatic life as well. Hence, this study was conducted to assess the current water quality status of the river. It involved species composition, abundance and diversity of periphytic diatoms. Two sites were established, Site A described as a rocky substrate while Site B is a combination of rocky and muddy substrate. Simpson’s Diversity Index was employed to attain the species diversity status in the two sites. Based on the results, fifteen (15) genera were found in two (2) sites, eleven (11) of which were identified in Site A, while eight (8) were found in Site B. Navicula sp. , Gomphonema sp. , and Nitzschia sp. dominated in Site A, while Pinnularia sp. , followed by Navicula sp. , and Nitzschia sp. were some of the species found in Site B. It was evident that both sites were dominated by Navicula sp. , and Nitzschia sp. which are known to be pollution tolerant species. Site B obtained the highest diversity index of 0.823. The existence of periphtyic diatoms can be associated to the type of substrate, habitat preferences as well as to the varying environmental factors which may possibly poses an important implication to the water quality and biological integrity. *Corresponding Author: Fatima F. Malaran  fatima.malaran@gmail.com Journal of Biodiversity and Environmental Sciences (JBES) ISSN: 2220-6663 (Print) 2222-3045 (Online) Vol. 14, No. 1, p. 121-130, 2019 http://www.innspub. net J. Bio. Env. Sci. 2019 122 | Malaran et al. Introduction Many rivers in the world are severely degraded or at risk, which undermines their ability to provide critical ecosystem services and related benefits. The general public have become increasingly concerned about maintaining the quality of aquatic resources. Rivers are complex systems of flowing waters draining a specific land surfaces or areas. As defined by Oates and Parker (2016), rivers are natural streams of water flowing in channels and emptying into larger bodies of water. One of the measurements that provide quantitative data on the presence and levels of aquatic pollution and degradation are physical and chemical,but these parameters do not reflect the extent of environmental stress reaching the living organisms or the subsequent effects of this stress (Omar, 2010). However, they are only representative of short-term conditions found at the instant of sampling and do not provide information about the effects of these changes on biological communities. In aquatic ecosystems, benthic algae are the main component. It is an important primary producers, chemical modulators, and important habitats for other organisms in those aquatic ecosystems (Stevenson et al., 1996). Periphyton comprises an assemblage of organisms growing on free-surfaces of any objects such as plants, old leaves, woods, stones, rocks and plastic sheets submerged in water (Khan and Firuza 2012). The use of periphyton, or attached benthic algae, as an indicator of stream water quality has provided an important source of information for the detection and assessment of environmental degradation in streams and rivers (Herbst and Blinn, 2007). According to Porter et al., (2008), the assessments of algalcommunity structure can reveal that eutrophication problems exist or that water-quality conditions are favorable for such problems to develop. Umalag River in Tablon is one of the major river in Cagayan de Oro City traversing many big industries and residential settlements. The river supports livelihood to local populace for irrigation, bathing, fishing, and washing as well as the supply of potable water. As can be observed, undesirable happenings like improper disposal of garbage, application of fertilizer by some farmers, on-going constructions, quarrying, and effluent coming from industry that may result to many consequences such as congestion of waterways, loss of clean water supply, damage of aquatic ecosystem and the possibility of flooding due to overflowing river. The local government of Tablon as well as the residents is alarmed to drastic happenings in the river. As reported by Arasga of Remate ang Diaryo ng Masa (2015), the river has been experiencing several fish kill incidents due to toxic liquid waste material coming from a particular industry. Moreover, Foreet al., (2010) stated that the index and metrics of periphyton derived in a particular water body is highly correlated with independent measures of human disturbance. Although there were recent studies conducted in the said river regarding physico-chemical properties of the water and species composition and distribution of phytoplankton, the study was the first to cover those benthic organisms particularly periphytic diatoms which can be a useful tool in biological monitoring. Fisher and Dunbar (2007) stated that diatoms, a relevant component of periphyton have long been used as a tool for monitoring surface water quality. Thus, the study determined the composition, abundance and diversity of periphytic diatoms as well as the present condition of water quality along the area of Umalag River. The study aims to assess the species composition, abundance and diversity of periphytic diatoms along Umalag River, Tablon, Cagayan de Oro City. Specifically, the study aims to identify the species composition up to genus level, abundance and diversity of periphytic diatoms present in each site and to determine the substrate type of the two established sites. Materials and methods Research design The research adopted the descriptive-comparative type of study. Descriptive since the study employed the water quality analysis in accordance to the parameters that were used. Meanwhile, it was comparative J. Bio. Env. Sci. 2019 123 | Malaran et al. because the researchers compared the differences of the composition, abundance and diversity of periphytic diatoms as well as the physico-chemical parameters in the two established sampling sites of Umalag River. Fig. 1. Map of the two (2) established sites in Umalag River. Research setting Umalag River is considered one of the heavily stressed rivers in Cagayan de Oro City because of its exposure to various anthropogenic activities such as bathing, cleaning, washing, quarrying and on-going construction that could be observed in the area (see Fig. 1). The area showed clear signs of industrialization where liquid and solid waste materials coming from households, small agricultural sector and industry may had emptied into the bodies of water. Site A has higher elevation surrounded with vegetation and lesser number of people was noted. In addition, the residents in the area depend on the river in terms of bathing, washing, irrigating plants/crops and watering farm animals. The area was observed to have a very rocky substrate with many large rocks. Whereas, Site B is considered to be the lower portion of the river. It was proximate to the sea and Umalag Bridge where there were many households, nearby industries and other urban settlements. A combination of muddy and rocky substrate was being noticed in the area. Collection of Periphytic Diatoms The collection of water samples for periphytic diatoms assessment was obtained in each site. This was done by composite sampling method on the established transect line in every site.Using a combination of scraping, brushing, and rinsing with stream water, all the algal materials from the known surface area of the rock were collected. It was then washed using minimal volume of distilled water. Preservation of Periphytic Diatoms The preservation of periphytic diatoms was done by preparing a concentrated formalin and it was then diluted with water sample. Composite samples were poured into a dark sample container and was transported and stored in a bucket filled with ice. It J. Bio. Env. Sci. 2019 124 | Malaran et al. was then brought to the laboratory for cleaning and for initial identification by the researchers. Identification of Samples A compound microscope with a magnification of 100x, microscope slide, cover slip and dropper were used to initially identify the species composition of periphytic diatoms. Confirmation and validation was done by a periphyton expert using Lackey drop-transect method. Species Richness and Diversity Index (a) Species richness is determined by the number of species present in a community. The relative abundance for each species is calculated as: Relative abundance = ( ai A ) 100% Where ai the number of individuals is collected in the ith species and A is the total number of species collected. (b) Simpson's Diversity Index is a measure of diversity which takes into account the number of species present, as well as the relative abundance of each species. As species richness and evenness increase, so diversity increases. Results and discussion Species Composition of Periphytic Diatoms along Umalag River Diatoms belong to the algal division of Bacillariophyta which is divided into three (3) classes namely Bacillariophyceae, Fragilariophyceae and Coscinodiscophyceae (Round et al., 1990). Fig. 2 shows the composition of periphytic diatoms along Umalag River. Table 1. Presence and absence of periphytic diatoms species along Umalag River. Genus Name Sites A B Class Bacillariophyceae Achnanthidium sp.  