Temperature Effects Explain Continental Scale Distribution of Cyanobacterial Toxins

Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains.Peer reviewe

Flood pulse influence on phytoplankton community of the Aksu Stream, Giresun, Turkey

Flood pulse influence on phytoplankton communities of the Aksu Stream, Giresun, Turkey were studied between December 2008 and December 2009. The phytoplankton communities consisted of 54 species. The number of species and diversity of phytoplankton showed seasonal variation, being high in rainy season. As a consequence of the flood which occurred twice in July 2009, phytoplankton environment changed physically and chemically, which resulted in an alteration in the composition of phytoplankton community. The phytoplankton community that existed previous to the flood event, had been dominated by Hantzschia amphioxys but was replaced by Nitzschia palea and a teratological form of Fragilaria sp. Presence of teratological form of diatom in the stream indicated unfavourable conditions in this region

Seasonal succession and diversity of phytoplankton in a eutrophic lagoon (Liman lake)

The seasonal succession, composition and diversity of phytoplankton in a eutrophic lagoon (Liman lake) were studied between January 2002 and November 2003. Samples were collected from surface water and deeper (1m depth) at stations and species diversity (Shannon-Weaver, H) and evenness were calculated. Shannon Diversty was similar at Station 1 and Station 2. Minimum and maximum diversity values (0.101 and 0.765 bits.mm-3) were recorded in June and July 2003 at Station 2. Cluster analysis and NMDS (Non metric multidimensial scaling) were applied to the phytoplankton community. The lagoon exhibits high conductivity (7211-10757 µScm-1), mean temperature of 17.7oC, varying concentrations of dissolved oxygen (3.3-8.4 mgl–l). Light, temperature, rainfall, turbidity and salinity were expected to be the main factors affecting the seasonal succession. The seasonal succession of phytoplankton were similar at surface water and 1m depth. A total of 130 taxa belonging to Bacillariophyta, Chlorophyta, Euglenophyta, Cyanophyta, Dinophyta, Xantophyta, Chrysophyta and Cryptophyta divisions were identified. Pseudanabaena limnetica, Kirchneriella obesa, Kirchneriella lunaris, Ankistrodesmus falcatus and Ankistrodesmus spiralis were highly represented

Relationship of Epilithic Diatom Communities to Environmental Variables in Yedikir Dam Lake (Amasya, Turkey)

WOS: 000422959000002In order to evaluate the composition and seasonal variations of the epilithic diatoms in Yedikir Dam Lake were studied using samples collected from the stones in the barrier area between November 2004 and April 2006. The diatom communities were diverse; 88 taxa were found, belonging to the Bacillariophyta. Cymbella minuta, Cyclotella ocellata and Encyonema silesiacum have become the most abundant organisms in the epilithon. Environmental variables together with biological data obtained during the monthly routine biomonitoring of epilithic samples in the dam were analysed to understand variability of epilithic diatom communities and their relationships with environmental variables. Moreover, cluster analysis was applied to the epilithic algal communities and the seasonal variations of the samples were classified according to their similarity levels. Speciess richness and shannon diversity of the samples which were counted were measured in monthly periods. The results of the diversity analysis and the counting did not exactly match up with each other. Multivariate analyses indicated that both the regional distribution and seasonal variation of some epilithic diatoms (e.g. Cymbella spp., Nitzschia spp., Amphora delicatissima) are mainly driven by nutrient concentrations. Furthermore, epilithic diatoms are predominantly affected by geochemical characteristics including pH and total alkalinity (CaCO3) levels

Morphological and 18S rRNA analysis of coccoid green algae isolated from lakes of Kizilirmak Delta

WOS: 000304071800002Molecular techniques are used today in many areas and have increased the confidence level of studies. The aim of the study was to compare the classical morphological characters of coccoid green algae under field and culture conditions by using modern molecular analysis. To achieve this aim, we first isolated the coccoid green algae from Liman and Cernek lakes. The morphological variations of green algae were observed under culture conditions and the phylogenetic relationships of these strains were defined according to the 18S rRNA gene sequences. According to sequence analysis, 2 of the isolated species had high similarity to Scenedesmus subspicatus (98%) and Desmodesmus sp. (100%).Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [2214]; Leibniz Institute of Freshwater Ecology and Inland Fisheries, Stechlin, GermanyWe are grateful to Lothar Krienitz for his kind help and useful guidance throughout the course of this study in Germany. This work was supported by the Scientific and Technological Research Council of Turkey (TUBITAK) under the International Research Fellowship Program (2214). Additional support was provided by the Leibniz Institute of Freshwater Ecology and Inland Fisheries, Stechlin, Germany

New Diatom Records for Turkish Freshwater Algal Flora from Lakes Ladik (Samsun, Turkey) and Hazar (Elazig, Turkey)

WOS: 000422952500012The majority of phycological studies in Turkey focus on seasonal changes of phytoplankton and phytobenthos in lentic and lotic systems, while very few studies related to counting diatoms in sediment cores obtained as a result of paleolimnological work have been published. In this paleolimlogical study, seventeen (14+3) new diatom records for freshwater algal flora of Turkey were determined on sediment core samples at five different locations collected in July 2006 from Lakes Ladik (Samsun) and Hazar (Elazig). We recorded seventeen diatom taxa belonging to Naviculales (8), Cymbellales (2), Eunotiales (2), Bacillariales (2), Fragilariales (1), Tabellariales (1) and Aulacoseirales (1) orders from Lakes Ladik (Samsun) and Hazar (Elazig). All of the reported taxa are new records for freshwater algal flora of Turkey. General information on the morphology and taxonomy of the species are briefly described in this paper, with their illustrations

Kızılırmak Deltası’ndaki göllerden izole edilen küresel yeşil alglerin morfolojik ve 18S rRNA analizi

Molecular techniques are used today in many areas and have increased the confi dence level of studies. Th e aim of the study was to compare the classical morphological characters of coccoid green algae under fi eld and culture conditions by using modern molecular analysis. To achieve this aim, we fi rst isolated the coccoid green algae from Liman and Cernek lakes. Th e morphological variations of green algae were observed under culture conditions and the phylogenetic relationships of these strains were defi ned according to the 18S rRNA gene sequences. According to sequence analysis, 2 of the isolated species had high similarity to Scenedesmus subspicatus (98%) and Desmodesmus sp. (100%).Günümüzde moleküler teknikler pek çok alanda kullanılmakta ve yapılan çalışmaların güvenilirliğini artırmaktadır. Araştırmanın genel amacı, küresel yeşil alglerin klasik morfolojik karakterlerini arazi ve kültür şartları altında modern moleküler analizleri kullanarak karşılaştırmaktır. Bu amacı gerçekleştirebilmek için öncelikle Liman ve Cernek göllerinden (Samsun, Türkiye) alınan küresel yeşil alglerin farklı klon kültürlerinin izolasyonu gerçekleştirilmiştir. Kültür şartları altında yeşil alglerin morfolojik çeşitliliği gözlemlenerek, bu suşların 18S rRNA gen dizilerine göre fi logenetik ilişkileri belirlenmiştir. DNA dizi analizine göre 2 izolatın Scenedesmus subspicatus (98%) ve Desmodesmus sp. (100%) türlerine çok benzeklik gösterdikleri tespit edilmiştir

Functional Classification and Composition of Phytoplankton in Liman Lake

WOS: 000278236200008Functional classification and composition of phytoplankton of Liman Lake were studied between January 2002 and December 2003. A total of 109 taxa belonging to Bacillariophyta, Chlorophyta, Cyanophyta, Dinophyta, Xantophyta, Chrysophyta and Cryptophyta were identified. The succession during 2002 began with R-Strategists (with a high surface to volume ratio, including blue-green algae with filaments like Pseudanabaena limmetica Lemmermann). This group was followed by C-Strategists (small green algae characterised with fast nutrient absorption, assimilation and replication ratios). This group was again followed by R-Strategists and at last C-Strategists became dominant

Chlorococcal chlorophyte composition, community structure, and seasonal variations in the shallow lakes of the Kizilirmak Delta, Turkey

WOS: 000288187800014The chlorococcal chlorophyte community structure and seasonal variations in terms of species composition and abundance of dominant species in Tatli, Gici, Liman, and Cernek lakes (Samsun, Turkey) were investigated between 1996 and 2003. Species richness and diversity (Shannon-Weaver, H') were measured monthly from stations at the surface of each lake. Changes in the Chlorococcales community structure were examined with nonmetric multidimensional scaling (NMDS) ordinations. A total of 36 Chlorococcales species were identified in these lakes located in the Kizilirmak Delta. While the Chlorococcales composition was similar in Tatli, Gici, and Liman lakes, Cernek Lake showed different seasonal trends, indicating high species richness. Ankistrodesmus falcatus and Kirchneriella obesa were important in terms of their contribution to the total Chlorococcales present in Tatli, Gici, and Liman lakes, and Monoraphidium irregulare had high concentrations among the Chlorococcales in Cernek Lake. There were clear increases in the species richness of Monoraphidium and Ankistrodesmus in all lakes during winter compared with other seasons.Scientific Research Foundation of Ondokuz Mayis UniversityOndokuz Mayis University [F212]This study was supported by the Scientific Research Foundation of Ondokuz Mayis University (Project No: F212). The authors would like to thank Beyhan TAS for sharing the data from Cernek Lake and for contributions to the manuscript