Ecological status estimation of eight creeks in the Lake Sapanca Basin (Sakarya, Turkey) using diatom indices

Abstract

It is important to determine the water quality of the creeks in the Lake Sapanca basin since it is used for drinking water supply. For this purpose, environmental parameters and diatom assemblages as biological quality components were investigated to determine the ecological status of eight creeks with monthly intervals between March 2015 and February 2016. During the studied period, 19 taxa increased their relative abundance higher than 30% in at least one sample and showed a different seasonal pattern. Main nutrients [(nitrate-nitrogen, orthophosphate, total phosphorus (TP)] and some other parameters (specific conductance, temperature, pH, and dissolved oxygen) had strong impacts on the distribution of diatom assemblages. The ecological status of the creeks was characterized by using four different diatom indices, however, only Trophic Index Turkey (TIT) represented significant positive correlations with log (TP) gradient and separated the creeks as good and moderate ecological status. According to TIT, the 4th and 6th stations had a good ecological condition and were characterized by pollution-sensitive species such as Cymbella affinis, Reimeria sinuata, and Nitzschia dissipata. On the other hand, TIT resulted in the other stations having moderate ecological conditions, which had high nutrient levels and EC. Moreover, the occurrence of pollution-tolerant taxa such as Gomphonema angustatum, Ulnaria ulna, and Achnanthidium affine endorsed the moderate ecological conditions in these creeks. Based on the results, the TIT as a biological metric could be a useful tool for the assessment of running waters in the Sakarya river basin.

Using diatom indices to estimate the ecological status of minimally disturbed rivers of the Sakarya River Basin (Türkiye)

“…Except for E. turgida var. granulata, all of these species were found in lowland rivers of the Sakarya Basin (Çetin & Demir, 2019;Sevindik et al, 2021;Solak et al, 2020;Tokatlı & Dayıo glu, 2011;Yüce & Gönülol, 2016) Tokatlı & Dayıo glu, 2011). The following species were identified as dominant: U. ulna in Murat Stream (Tokatlı & Dayıo glu, 2011) and in Kurtköy Creek (Sevindik et al, 2021), M. varians, M. circulare, N. radiosa and U. ulna in Felent Creek , N. radiosa in lower Sakarya River (Yüce & Gönülol, 2016) and M. varians, M. circulare and U. ulna in the upper Sakarya River (Çetin & Demir, 2019).…”

“…In fact, many studies have reported that pH and ALK are the predominant factors controlling diatom assemblage structure (DeNicola, 2000; Soininen, 2007), making diatoms effective indicators for assessing the effects of ALK due to geological formation (Bennion & Simpson, 2011; Cantonati et al, 2012). In Turkey, the pH values of streams are generally between 7 and 9, and all of the above species have been detected in the Sakarya Basin (Çetin & Demir, 2019; Sevindik et al, 2021; Solak et al, 2012; Solak et al, 2020; Solak & Wojtal, 2012; Tokatlı & Dayıoğlu, 2011; Yüce & Gönülol, 2016) and other basins in Türkiye (e.g., Çelekli et al, 2022; Çelekli & Bilgi, 2019; Kıvrak & Uygun, 2012). Moreover, A. minutissimum , C. affinis , C. neocistula and G. angustatum have also been detected in the highly alkaline lakes Hazar, Tödürge and Hafik (Kılınç & Sıvacı, 2001; Sonmez et al, 2018).…”

“…granulata , all of these species were found in lowland rivers of the Sakarya Basin (Çetin & Demir, 2019; Sevindik et al, 2021; Solak et al, 2012; Solak et al, 2020; Tokatlı & Dayıoğlu, 2011; Yüce & Gönülol, 2016) and were described as mesotrophic or eutrophic (Solak et al, 2012; Tokatlı & Dayıoğlu, 2011). The following species were identified as dominant: U. ulna in Murat Stream (Tokatlı & Dayıoğlu, 2011) and in Kurtköy Creek (Sevindik et al, 2021), M. varians , M. circulare , N. radiosa and U. ulna in Felent Creek (Solak et al, 2012), N. radiosa in lower Sakarya River (Yüce & Gönülol, 2016) and M. varians , M. circulare and U. ulna in the upper Sakarya River (Çetin & Demir, 2019). However, the aforementioned taxa were not recorded as the dominant species in the study, which included 46 lowland river sites throughout the whole Sakarya Basin (Solak et al, 2020).…”

“…Numerous studies have been conducted using diatoms in Sakarya Basin rivers (e.g., Solak et al, 2012; Solak & Wojtal, 2012; Tokatlı & Dayıoğlu, 2011), and in recent years, the use of diatom indices to assess the ecological status of rivers in the Sakarya Basin has increased (e.g., Çetin & Demir, 2019; Sevindik & Kucuk, 2016). In addition to these various indices, TIT (Çelekli et al, 2017; Çelekli, Toudjani, et al, 2019) has also been used in studies of rivers in this basin (e.g., Sevindik et al, 2021; Solak et al, 2020). Although many studies have been conducted to determine river water quality using diatoms, the minimally disturbed rivers in the basin have not been studied before.…”