Epilithic diatom assemblages and their relationships with environmental variables in the Nilüfer Stream Basin, Bursa, Turkey

Abstract

Patterns of epilithic diatom species distribution in relation to environmental variables from 12 sampling sites on the main stream and some of its tributaries in the Nilüfer Stream Basin were determined using multivariate statistical techniques. The stream basin has been heavily influenced by anthropogenic effects. The upper part of the basin that is distant from pollution sources mostly has a spring water quality, while the lower part where the stream flows through the urban area and receives domestic and industrial wastewater has a quite low quality. Ordination techniques using both diatom taxa and 21 environmental variables revealed non- to slightly polluted upper basin sites and highly polluted lower basin sites along the stream. The results showed that the stream catchment is polluted gradually from upstream to downstream and that most of the downstream sites have very low water quality especially in summer months. A total of 134 epilithic diatom taxa belonging to 50 genera were recorded for 12 sample sites. Partial CCA results indicated that water temperature (T), discharge (Q), and total phosphorus (TP) were the most important variables affecting the distribution of diatom species. Unpolluted or slightly polluted upper basin sites were dominated by Achnanthidium minutissimum, Cocconeis placentula var. euglypta, Gomphonema olivaceum, and Navicula tripunctata. Highly polluted lower basin sites were characterized by high levels of organic and inorganic matters and low dissolved oxygen (DO) values. Species widespread in the highly polluted lower basin sites such as Nitzschia umbonata, Nitzschia amphibia, Nitzschia capitellata, Nitzschia palea, Nitzschia paleacea, Luticola mutica, and Stephanodiscus niagarae were mostly related to pollution indicator variables such as ammonium nitrogen (NH-N), sodium (Na), total phosphorus (TP), and total organic matter (TOM).

Seasonal Variation of Some Trace Element and Heavy Metal Concentrations in a Turkish Stream

“…Karaca and Tasdemir [14] also reported pollution in Nilüfer Stream due to the illegally discharged industrial wastewater, municipal sewage discharges, solid waste disposals in stream beds, drainage water, erosion and atmospheric pollutants. Contamination of surface and groundwater resources with heavy metals leads to soil pollution, causes accumulation in plants grown on it and affects negatively all living things, including animals and humans that are fed with these plants [2,8,23]. Plant nutrients that are poorly soluble in the soil lead to deficiencies in the plant, and in contrast high soluble may lead accumulation and pollution in the soil [12,23].…”

“…A considerable increase in the population of Bursa Province has occurred in recent years due to migration, resulting in an increase of residential areas against fertile agricultural lands, and this has also resulted in the increase of various wastes [2,12]. Nilüfer Stream, with its several tributaries, reaches to an extent of approximately 168 km and is an important water resource of Bursa, which supplies water to irrigation of agricultural sites and for drinking [2][3][4][5][6][7][8][9][10][11][12]. The stream basin covers 1540 km 2 , and over 53.8% of the basin is used for agricultural purposes [2,[12][13].…”

“…Nilüfer Stream, with its several tributaries, reaches to an extent of approximately 168 km and is an important water resource of Bursa, which supplies water to irrigation of agricultural sites and for drinking [2][3][4][5][6][7][8][9][10][11][12]. The stream basin covers 1540 km 2 , and over 53.8% of the basin is used for agricultural purposes [2,[12][13]. The stream is not only significant for irrigating the agricultural lands but also is important as being the discharge point for many industries [2,14].…”

“…The stream basin covers 1540 km 2 , and over 53.8% of the basin is used for agricultural purposes [2,[12][13]. The stream is not only significant for irrigating the agricultural lands but also is important as being the discharge point for many industries [2,14]. In recent years, it has been contaminated by the industrial and domestic wastewater discharges.…”

Streams Under Urban Pressure: Blue-Green Infrastructure Planning and Design Approaches for Bursa Ayvali Creek Corridor

“…The water of Ayvali Creek is decreasing as a result of the activities of the Western Treatment Plant and the seasonally changing precipitation graph. Especially in the summer season, since the precipitation decreases, the water of the stream, which cannot be fed with rainwater, is completely wastewater (Karacaoğlu & Dalkıran, 2017).…”