A Study on Water Quality and Trophic State of Akgöl Lagoon (Mersin, Turkey)
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Aquatic Ecosystem Health & Management ISSN: 1463-4988 (Print) 1539-4077 (Online) Journal homepage: http://www.tandfonline.com/loi/uaem20 A study on water quality and trophic state of Akgöl Lagoon (Mersin, Turkey) Mehmet Tahir Alp, Yunus Emre Fakioğlu, Özgur Özbay & Mehmet Ali Turan Koçer To cite this article: Mehmet Tahir Alp, Yunus Emre Fakioğlu, Özgur Özbay & Mehmet Ali Turan Koçer (2016) A study on water quality and trophic state of Akgöl Lagoon (Mersin, Turkey), Aquatic Ecosystem Health & Management, 19:1, 58-63 To link to this article: http://dx.doi.org/10.1080/14634988.2015.1132057 View supplementary material Accepted author version posted online: 21 Dec 2015. Submit your article to this journal Article views: 77 View related articles View Crossmark data Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=uaem20 Download by: [Mersin Universitesi] Date: 25 March 2016, At: 00:31 A study on water quality and trophic state of Akgol€ Lagoon (Mersin, Turkey) Mehmet Tahir Alp,1 Yunus Emre Fakioglu, 2 Ozgur€ Ozbay,€ 3 and Mehmet Ali Turan Kocer¸ 4 1Fisheries Faculty, Mersin University, Yeni¸sehir-Mersin 33169, Turkey 2Graduate School of Natural and Applied Sciences, Mersin University, Yeni¸sehir-Mersin 33169, Turkey 3Advanced Technology of Education, Research and Application Center, Mersin University, Ciftlikk¸ oy,€ Mersin, Turkey 4Mediterranean Fisheries Research, Production and Training Institute, Antalya, Turkey Corresponding author: [email protected] This study aimed to determine the physicochemical characteristics of the water quality and trophic state of Akgol€ Lagoon located in the eastern Mediterranean. Cluster analysis clearly revealed the spatial heterogeneity classifying sampling stations as saline and freshwater/brackish water sites. A multivariate analysis of variance followed by principal component analysis supported that salinity was major factor affecting physicochemical water quality variations in the lagoon. As salinity was mainly governed by freshwater inflows depending on agricultural irrigation, it can be proposed that water quality was significantly influenced from freshwater use by human activities. The parameters used as predictors (total nitrogen, total phosphorus, chlorophyll a and Secchi disk transparency) yielded different trophic states for the lagoon. However, as chlorophyll is a better predictor than the other indices, it was concluded that the Akgol€ Lagoon is at mesotrophic status. Keywords: Goksu€ Delta, Ramsar site, salinity Introduction and their ability to accumulate nutrients from the whole of their catchment. Various human activities Downloaded by [Mersin Universitesi] at 00:31 25 March 2016 Coastal lagoons, which represent less than 1% of such as hydrological transformations and terrestrial the earth’s surface but comprise 13% of the earth’s nutrient loading have had significant impacts on eco- coastline, are accepted as a transitional media system health of lagoons (Pereira et al., 2009; Roselli between terrestrial and marine ecosystems (Plus et al., 2009). et al., 2006). They have high spatial and temporal Mediterranean lagoons, which are characterized physicochemical variations produced by salinity and by shallow waters and limited circulation, are eco- temperature gradients, and limited volumes (Loureiro systems particularly sensitive to freshwater et al., 2006). Therefore, they are among the most inflows and human activity (Roselli et al., 2009). dynamic and complex aquatic environments charac- Among them, the Akgol€ Lagoon is the largest in terized by multiple interfaces and features that result the Goksu€ Delta, is one of the most significant from their limited exchanges with the adjacent sea wetland areas in the Eastern Mediterranean. The 58 Aquatic Ecosystem Health & Management, 19(1):58–63, 2016. Copyright Ó 2016 AEHMS. ISSN: 1463-4988 print / 1539-4077 online DOI: 10.1080/14634988.2015.1132057 Alp et al./Aquatic Ecosystem Health and Management 19 (2016) 58–63 59 Goksu€ Delta, which is included in the Ramsar List dissolved oxygen (DO) and chlorophyll a (Chl a) of Wetlands of International Importance, is located were measured in situ by using Hydrolab DS5 to the south of Mersin (Turkey), where the Goksu€ Multiparameter sonde (OTT Hydromet, Loveland, River, with a 10,000 km2 catchment area, reaches CO, USA). Secchi depth transparency (SD) was the Mediterranean Sea. The Delta, surrounded by measured by Secchi disc. Total suspended solids the Taurus Mountains on the north and northeast, (TSS), total hardness (TH), total alkalinity (TA), is split in two by the Goksu€ River. There are two soluble reactive phosphorus (SRP), total phospho- shallow lakes, Paradeniz and Akgol,€ on the east rus (TP), total nitrogen (TN), chlorophyll a (Chl a) and the west, respectively. The Akgol€ Lagoon and chemical oxygen demand (COD) were ana- (12 km2) is the largest lake of the delta. The lysed according to the selected methods of Stan- lagoon is fed by a few freshwater resources and is dard Methods (APHA et al., 1998). unconnected with surface flow of the Goksu€ River. Trophic State Index (TSI) developed by These inflows are used for irrigation, and over- Carlson (1977) was used for characterising tro- flows drain by concrete channels into the lagoon. phic state of the lagoon. TSI uses total phos- Therefore, water level is the highest during irriga- phorus, Secchi disc transparency and tion period, while average water level in the Akgol€ chlorophyll a to define the status at a numerical Lagoon fluctuated between 0.4 and 1.2 m during value from 0 to approximately 100. winter depending on precipitation. The Akgol€ Lagoon drains into the Paradeniz Lagoon and is TSIðÞ SD D 10 Ã ðÞ6 ¡ lnSD/ln2 not directly connected to the sea. Saline water reaches to the Akgol€ Lagoon via the Paradeniz TSIðÞ CHL D 10 Ã ðÞ6 ¡ ðÞ2:04 ¡ 0:68 Ã lnCHL /ln2 Lagoon (Kecer¸ and Duman, 2007). There is still limited data on the trophic state TSIðÞ TP D 10 Ã ðÞ6 ¡ lnðÞ 48/TP /ln2 of the Lagoon, although there are studies related to heavy metal and pesticide pollution Minimum and/or maximum extreme values, in surface waters and groundwater of the Delta which were possible outliers, were removed from (Ayas¸ et al., 1997; Barlas, 2002; Ergene et al., the data set. The normality of data was tested using 2007; Demirel et al., 2011) as well as phyto- the Shapiro-Wilk test. Normally and non-normally plankton diversity in the Lagoon (Roselli et al., 2013). This study aims to overcome the lack of information and to gain a better understanding of physicochemical water quality and trophic state of Akgol€ Lagoon by using monitoring data between April 2013 and March 2014. Downloaded by [Mersin Universitesi] at 00:31 25 March 2016 Methods This study was conducted between April 2013 and March 2014 in order to determine seasonal variations of water quality in the lagoon. Monthly water samples were collected from six stations. Station 1 represents the sea connection of the lagoon while Stations 5 and 6 were close to fresh- water inflows. The other stations were chosen from the central area to reflect the general charac- teristics of the lagoon. While Stations 2 and 3 Figure 1. Akgol€ Lagoon and sampling stations and coordinates were located near the southern coast, station 4 was (Silifke/Mersin/Turkey) (Geographical coordinates for the sta- selected from the middle part of the lagoon tions, respectively: 3618021.200N-3358026.0100E; (Figure 1). 361703.4200N-335708.2800E; 361703.4400N-3356023.8600E; Temperature (T), pH, electrical conductivity 361703.5300N-3357012.4000E; 3618014.800N-3355054.9100E; (EC), salinity (S), total dissolved solids (TDS), 3618041.1000N-335701.0500E). 60 Alp et al./Aquatic Ecosystem Health and Management 19 (2016) 58–63 distributed parameters were compared using a one- than those of other stations. EC and S varia- way analysis of variance (ANOVA) and Kruskal- tions in the lagoon were related to concentra- Wallis signed rank test, respectively. Tukey’s hon- tions of TDS (Appendix 2 in the SI). estly significant difference test (HSD) was used to Statistically significant differences were not discriminate significant differences. Heterogeneity observed between the sampling stations (p > of sampling stations was determined using cluster 0.05), while clear temporal variations were analysis (CA) which was performed on the trans- detected for EC and TDS (x2(11) D 51.41 and formed data set by means of the Ward’s method. x2(11) D 57.66, p < 0.001, respectively) which The linkage distance is reported as Dlink/Dmax were significantly higher in January and Febru- (Simeonov et al., 2003). ary than those in summer months (May, June, In the first step of another multivariate analy- July, August and September), indicating sea sis, detrended correspondence analysis (DCA) influence during winter (Tukey-Kramer HSD, p was calculated to select a linear or unimodal < 0.05). However, spatial variation in salinity method. Since DCA showed short gradient (average 4.5%)wasthecase(x2(5) D 11.68, p lengths (<1.2 SD), a linear model was appropri- < 0.05); Salinity in station 1 near the sea con- ate for the data. Therefore, principal component nection, was the significantly higher than those analysis (PCA) was used to accentuate variation in stations 5 and 6, near freshwater inlet and reduce the dimensionality in the dataset. For (Tukey-Kramer HSD, p < 0.05). Salinity was PCA, inter-variable relationships were scaled and also significantly different in January (x2(11) D scores divided by standard deviations. Data were 44.20, p < 0.001) with a similar tendency as transformed logarithmically (log (a £ y C b); a TDS. The mean DO was between 7.5 and D 1 and b D 1) for DCA and PCA (Leps and 8.2 mg L¡1 and it was affected by temperature. Smilauer, 2003). A multivariate analysis of vari- Differences in DO values were insignificant ance (MANOVA) on the scores of principal com- between the sampling stations (P > 0.05).