Cyanobacterial Diversity and the Presence of Microcystins in the Küçük Menderes River Basin, Turkiye

Although cyanobacteria are commonly associated with eutrophic lakes, they are the basic compo-nents of phytoplankton communities in lakes that have different trophic statuses. In inland waters, both nutrient loading from watersheds and warmer conditions promote phytoplankton growth and cause extensive cyanobacterial blooms. Certain bloom-forming cyanobacterial species can pose a healthrisktohumansandaquaticecosystemsthroughcyanotoxinproduction.Theaimofthisstudy was to evaluate the cyanobacterial composition and toxins in five reservoirs and two natural lakes in the Küçük Menderes River Basin, all with varying trophic statuses. Within this scope, sam-pleswerecollectedinautumn2017andspring2018.CyanobacterialspecieswereenumeratedaccordingtotheUtermöhlmethod.CyanotoxinsampleswereanalyzedusingHPLC.Tofindthetrophic status of the water bodies, the Trophic State Index (TSI) developed by Carlson (1977) was used and Total Phosphorus (TP), Secchi Depth (SD), and Chlorophyll-ɑ (chl-ɑ) measurements were performed. Cyanobacterial abundance, species composition, and cyanotoxin production differed significantly between the lakes and reservoirs. A total of 13 cyanobacteria species were identified including potential cyanotoxin producers such as Microcystis, Aphanizomenon, and Dolichospermum. According to the TSI, three reservoirs were mesotrophic and the other four waterbodies had eutro-phic-hypereutrophic conditions. Microcystis is the most common bloom-forming freshwater cyano-bacteria in the Küçük Menderes River Basin. However, microcystin concentrations were relatively low and the highest microcystin concentration was detected in the Tahtalı Reservoir at 9 μg/L. The Küçük Menderes River Basin is under water-stressed conditions and the cyanobacteria blooms in the region might pose another threat for wildlife and humans

Variation in Water Quality in an Impacted Coastal Lagoon over the Last Decade (Küçükçekmece Lagoon, Turkey)

Küçükçekmece Lagoon, located inside the Istanbul metropolitan area, is connected to the Marmara Sea by a small canal. Due to the construction of a dam on the Sazlıdere stream, which is the most important feeding source for the lagoon, there has been a decrease in freshwater inflow, so the amount of salinity in the lagoon has started to increase. While salinity was around 11 ppt in the surface water of the lagoon in the 2010s, the level of salinity concentration exceeds 17 ppt today which also has an impact on the ecosystem. The aim of this study is to evaluate the water quality changes in Kucukcekmece Lagoon in a decade. The water quality revealed a high spatial and temporal variation in the lagoon and the bottom (ca 18 m) waters were rich in H2S, of which the highest concentration was measured as 215 mg/L. Overall, from the large dataset of water quality for more than ten years, there is an obvious effect of anthropogenic activities and the closure of freshwater inlets on the trophic conditions of the lagoon

Water Quality and Risk Assessment in Rainwater Harvesting Ponds

The aim of this study was to investigate the water quality of rainwater harvesting ponds in Istanbul which are used for irrigation. For this purpose, samples were collected from 17 rainwater harvesting ponds during the summer of 2022 and selected physicochemical and biological characterization of these samples was carried out. Cyanobacterial bloom was observed in 2 ponds out of 17 and the dominant species were potentially cyanotoxin producers (Microcystis, Aphanizomenon, Dolichospermum, Planktothrix, and Cuspidothrix). It is found that one of these ponds was not proper for irrigation purposes due to microcystin presence. To increase the water quality in these reservoirs, onsite management strategies should be taken into consideration

Seçilen Antifauling Biyositlerin Sucul Ortamda Etkisi

Biofouling results from the accumulation of a wide variety of organisms including microorganisms, plants, algae, mollusks, and hydrozoans on submerged structures in the aquatic environment. Antifouling paint is used to prevent any structures placed in the aquatic environment such as oil rig supports, buoys, fish cages, and ship’s and boat’s hulls to reduce biofouling. Nevertheless, some of these biocides are also toxic to non-target organisms and may be highly persistent in the aquatic environment. For a long period, unsustainable biocides have been applied in paints including organotin compounds such as tributyltin (TBT), arsenic, mercury, and lead but then there were restrictions on the use of these biocides. To enhance the effectiveness of the paint, organic-booster biocides, Irgarol 1051®, DCOIT, dichlofluanid, chlorothalonil, zinc pyrithione, and Zineb are also added as an alternative to TBTs which also adverse effects on aquatic organisms. For instance, chlorothalonil causes behavior changes, and larval mortality in crustaceans, and Irgarol-1051 causes reduction in growth rate and decrease in the photosynthetic activity of algae. Copper-based compounds have become the most used antifouling paints. A microbicide, copper pyrithione, can result in inhibition/alteration of Na/K ATPase and Mg2+ ATPase enzyme activities of crustaceans and mollusks. It also leads to alterations in gill and osmoregulation in teleosts. Besides direct application of the antifouling paints, the spent paint particles which are released in the boatyards and marinas can cause the accumulation of biocidal metals in the tissue of mussels, periwinkles, and lugworms. To minimize the impacts of biocides, they need to be designed to have a large spectrum activity, with low mammalian toxicity, low bioaccumulation rate, and a high degradation rate in the marine environment

Driving factors affecting the phytoplankton functional groups in a deep alkaline lake

This study evaluated the phytoplankton communities based on functional groups to obtain information about the water quality of Lake İznik, Turkey. The phytoplankton consisted of 103 taxa, classified in 12 phytoplankton functional groups (PFGs), with dominancy of 5 species, Chrysosporum ovalisporum, Dolichospermum mendotae, Planktothrix rubescens, Fragilaria capucina, and Mougeotia sp. The Shannon–Wiener diversity index (H’) was calculated and results ranged between 0.41 and 2.47. The redundancy analysis (RDA) and Spearman’s correlation analysis were used to assess the relationships between the PFGs and environmental variables. According to the multiple comparisons of the data, the main efficient factors that determined the seasonal distribution of the PFGs were TP, DO, SiO2 , SD, and pH. The ecological requirements of the dominant PFGs (C, D, F, J, H1 , Lo, SN, N, P, R, T, and X2 ) indicated mainly meso-eutrophic waters. Similarly, Carlson’s trophic state index (TSI) stated mesotrophy conditions. As a result, the approach of PFGs can be successfully applied in a deep, alkaline lake to understand the water quality and trophic status

The Effects of Climate Change on Aquatic Ecosystems in Relation to Human Health

This review paper aimed to summarize the climate change impacts on water sources and their relation with human and ecosystem health and evaluate better management strategies. In aquatic environments, climate change causes alteration of biodiversity and species distribution, changes in the duration of biological functions, decreasing productivities, alteration in food web structures, as well as triggering the invasion of various species, and variation in the presence, abundance, and concentrations of various co-stressors. Since the beginning of the 20th century, the surface water temperature in the oceans has risen by about 1°C. Consequently, human well-being is directly and indirectly affected by these alterations. The World Health Organization (WHO) estimates that 3.5 million people die from water-related diseases each year. It is projected that the number of water-related diseases will increase due to the effects of climate change. To cope with these problems, alternative water management strategies should be developed to have resilient water systems in terms of both ecological and technological perspectives. Thus, water management requires the cooperation of many sectors including citizens, institutions, public and private sectors, etc. within a multi-stakeholder approach