Variations in abundance and diversity of phytoplankton in the surface waters of the Golden Horn Estuary (Sea of Marmara)

Abstract

The abundance pattern and species diversity of phytoplankton in the surface waters of the Golden Horn Estuary were investigated between August 2011 and July 2012 in relation to environmental factors. Seventy-eight phytoplankton taxa (38 diatoms, 30 dinoflagellates and 10 phytoflagellates) belonging to eight taxonomic classes were identified in bottle and net samples. Phytoplankton abundance increased in spring and summer (from March to August) and reached its highest (10,429 × 103 cells L−1) during the bloom of Heterosigma akashiwo (Raphidophyceae) in the middle and upper estuary in late May. In general, phytoplankton abundance was higher in the middle estuary indicating more suitable conditions for phytoplankton growth, while species richness and diversity was higher in the lower estuary. The most abundant species were Skeletonema marinoi and Thalassiosira sp. among diatoms; Scrippsiella trochoidea among dinoflagellates; Plagioselmis prolonga and Heterosigma akashiwo among phytoflagellates. Diatoms were more abundant in the lower and middle estuary, while dinoflagellates and phytoflagellates in the upper estuary. The main factors causing the spatio-temporal variation of phytoplankton in the study area were temperature, salinity, water transparency and nutrients. Water transparency in the upper estuary is mostly influenced by organic and inorganic matter carried by two streams. As a result, this area should be considered a potential risk area for future algal blooms.

A new recorded of red tide forming species; Heterocapsa triquetra, Gymnodinium impudicum, Heterosigma akashiwo and Thalassiosira rotula in Alexandria Waters, Egypt

“…Heterosigma akashiwo seems to vary among different ecotypes and is environmental conditions dependent (Rensel, 2007;Rensel et al, 2010). This cosmopolitan alga exhibits a wide geographical distribution in the eutrophic waters of the Mediterranean Sea (Bizsel and Bizsel, 2002;Tas and Yilmaz, 2015;Dursun and Tas, 2019), first reported as a few scattered cells in Alexandria waters (Mikhail, 2001). During the present monitoring, H. akashiwo presented throughout most of the year and detected in 75.4% of the collected samples.…”

Assessment of phytoplankton group composition in the Golden Horn Estuary (Sea of Marmara, Turkey) determined with pigments measured by HPLC-CHEMTAX analyses and microscopy

“…The validity of using pigment signatures detected by HPLC to estimate phytoplankton group composition was tested for the Mediterranean Sea (Thyssen et al ., 2011; Yücel, 2017) and Black Sea (Ediger et al ., 2006; Eker-Develi et al ., 2012; Agirbas et al ., 2015, 2017). Although there have been many studies on phytoplankton in the Golden Horn Estuary (Tas et al ., 2009; Tas & Okus, 2011; Tas & Yilmaz, 2015; Dursun & Tas, 2019; Tas, 2019) based on microscopic examination, the phytoplankton group composition had not yet been evaluated by HPLC pigment analysis in this region.…”

“…In this study, the highest abundances in total phytoplankton were observed between April and September, as shown by microscopic analysis. The abundance pattern displayed seasonal variations in this study that are similar to previous studies (Tas et al ., 2009; Tas & Yilmaz, 2015; Dursun & Tas, 2019). Phytoplankton studies performed in estuaries show that environmental factors such as salinity, temperature, Secchi depth and adaptation to the environmental conditions play a major role in seasonal variations of phytoplankton in terms of diversity and abundance (Burić et al ., 2007; Barbosa et al ., 2010; Jasprica et al ., 2012).…”

“…Many studies of phytoplankton composition have been performed in estuaries around the Mediterranean Sea (Trigueros & Orive, 2001; Burić et al ., 2007; Barbosa et al ., 2010). Recently, studies have focused on phytoplankton communities of the Golden Horn Estuary (GHE) by microscopic analysis including the variations in phytoplankton composition (Tas et al ., 2009; Dursun & Tas, 2019), planktonic diatom composition (Tas, 2017; Tas & Hernández-Becerril, 2017), and algal blooms and potentially harmful species (Tas & Okus, 2011; Tas, 2015, 2019; Tas & Yilmaz, 2015; Dursun et al ., 2016; Tas & Lundholm, 2017). However, no study has been performed in the GHE using HPLC, despite HPLC pigment signatures being widely used in Turkish seas (Ediger et al ., 2006; Eker-Develi et al ., 2012; Agirbas et al ., 2017; Yücel, 2017).…”

An assesment of domoic acid levels as a function of salinity-temperature variations in the Sea of Marmara

“…The last reported total number of identified Pseudo-nitzschia species is 52 of which 26 are thought to be capable of producing DA (Bates et al, 2018). Moreover, many studies have reported that the toxic species of the genus Pseudo-nitzschia are frequent members of the phytoplankton community in the Golden Horn Estuary and Sea of Marmara in recent years (Dursun and Tas, 2019;Tas et al, 2016;Tas and Lundholm, 2017;Tas and Yilmaz, 2015). Furthermore, many studies have shown the importance of a variety of factors such as temperature (Lewis et al, 1993), salinity (Thessen et al, 2005), pH (Lundholm et al, 2004) and nutrients (Bates et al, 1991).…”