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Göksu nehri etki alanında fitoplankton yamaları (Kuzeydoğu Akdeniz)
Seasonal phytoplankton samplings were made onboard R/V Bilim-2 of the Institute of Marine Sciences of Middle East Technical University around the Göksu river estuary to reveal a possible patchy distribution of phytoplankton due to presence of contrasting water masses with varying trophicity. To achieve this, biological, physical and chemical parameters were collected from 51 stations representing nutrient-rich Göksu river estuary, productive coastal, mesotrophic shelf and oligotrophic offshore waters. Over the year, the total number of 246 phytoplankton species belonging to Bacillariophyceae (79), Pyrrophyceae (146), Prymnesiophyceae (16), Cryptophyceae, Chrysophycea, Euglenophycea, Ebriophyceae and Chlorophyceae (with single species each) were identified. The community was found most diverse during spring followed by winter, summer and autumn. Based on seasonal surface mean cell abundances, summer population abundances (2.3 x 105 cells/l) were exceeded much the winter (1.2 x 105 cells/l), spring (1.1 x 105 cells/l) and lastly autumn (2.6 x 104 cells/l) population densities. Diatoms were observed dominant over dinoflagellates and remaining other groups in all seasons. The population has always found most species diverse and abundant in shallow coastal areas fed by nutrient-rich Göksu River and Lamas creek waters. Taşucu Bay surface waters have retained maximal population densities in all seasons due to direct freshwater inputs from the nearby Göksu River. Based on the Spearman Rank Correlation analysis, highly significant positive correlation between surface phytoplankton abundance and ambient temperature (r = 0.675, P < 0.01) and negative correlation with surface salinity (r = -0.398, P < 0.01) whereas almost no correlation with any of nutrient species were observed in autumn. In contrast, highly significant positive correlations were only present with nutrients (nitrate, nitrite, silicate) in winter. Despite a highly significant negative correlation with salinity (r = -0.806, P < 0.01), highly significant positive correlations with phosphate, nitrate, nitrite were observed in spring. Lastly, in summer, a highly significant negative correlation between phytoplankton abundance and salinity & temperature and a significant positive relationship with phosphate (r = 0.283, P < 0.01) were observed. Similar to Pielous' index values, Shannon diversity index values were found maximal during spring followed in decreasing order by autumn, winter and summer. Multivariate analyses have shown the formation of several distinct phytoplankton assemblages in each season. The number of patches observed in autumn (10) and in winter (8) have exceeded greatly those observed in spring (2) and summer (3). Despite the very complex affinities observed within various minor patches observed in autumn and winter, surface flora has split into two major, namely coastal - offshore, and east - west subpopulations in spring and summer.
Kuzey-doğu Akdeniz'den iki botryllid asidiyan türünün mitokondriyel ve nükleer dna filocoğrafyasi
With approximately 3000 species, ascidians are the largest tunicate group in the world seas. Botrylloides belongs to the genera of the worldwide spread Botryllid ascidians. In the Eastern Mediterranean coasts, a total of six Botryllid ascidians have been observed up to date. However, there is no study considering the distribution and phylogeographic analysis of ascidian species along the Mediterranean Sea's Turkish coasts. Within this study's scope, specimens were collected from the coastal area of Hatay (Konacık), Mersin (Mezitli, Kızkalesi, Tisan) and Antalya (Alanya) regions comprising approximately 550 km of coastline between 2012 and 2019. Mitochondrial (COI, CytB) and nuclear (18s, H3) gene regions were amplified for the analysis. For COI, 100% amplification success was obtained for 62 samples; however, the success rate varied from zero to 100% for the other markers according to sampling location. The intra- and inter-specific distances were calculated between the haplotypes/locations. The Median-joining network analysis of haplotypes was done, and the phylogenetic trees were constructed for the samples. Neutrality tests and mismatch distribution analyses were applied to detect any demographic change. B. anceps, Botrylloides sp. and Botrylloides israeliense were recorded on the Turkish coasts of Levantine Sea for the first time. The phylogeographic analysis was done only for B. anceps and Botrylloides sp., which could be sampled at Konacık, Mezitli, Kızkalesi, and Alanya sampling stations, in contrast to B. israeliense, for which only one specimen could be encountered in Tisan during sampling. No genetic variation was detected for the COI and CytB regions of B. anceps and the 18S gene regions of Botrylloides israeliense. H3 gene showed low variation for B. anceps, thus resulted in an insignificant neutrality test and Raggedness statistics. Therefore, B. anceps was found to have low invasive capacity due to low genetic variation related to a single introduction event that happened via anthropogenic ways and colony age. For Botrylloides sp., both mitochondrial markers have shown variations; however, not enough for a significant P-value. Thus, population size change or population expansion could not be detected for B. anceps and Botrylloides sp. species. On the other hand, Mezitli and Kızkalesi samples of Botrylloides sp. have shown strong genetic differentiation; FST=0.556COI and 0.361CytB, is an outcome of the limited dispersal capacity of the larva. A chimera formation, a single colony, consisting of at least two colonies with distinct genotypes, recorded between B. israeliense and Botrylloides sp. The blastogenesis, weekly asexual reproduction, of the species was monitored for the first time in this study. In this study, the distribution of three ascidian species on Turkey's Mediterranean coasts was revealed, and their populations were compared for phylogeographic analysis. Populations were found to be in a constant size, and the need for the use of combined markers was emphasized.