Distribution of phytoplankton in the southern Black Sea in summer 1996, spring and autumn 1998

The species composition, abundance, and biomass of micro- (>15 mum) and nano- (<15 mu m) phytoplankton were studied along the southern Black Sea during June-July 1996 and March-April and September 1998. A total of 150 species were identified, similar to 50% of them being dinoflagellates. The average total phytoplankton abundance changed from 77 x 10(3) Cells l(-1) in spring to 110 x 10(3) cells l(-1) in autumn and biomass from 250 mu g l(-1) in summer to 1370 mu g l(-1) in spring. Based on the extensive sampling grid from June-July 1996, phytoplankton seemed to have a rather homogeneous biomass distribution in the southern Black Sea. In all periods, the coccolithophorid Emiliania huxleyi was the most abundant species, its contribution to the total abundance ranging from 73% in autumn to 43% in spring. However, in terms of biomass, diatoms made up the bulk of phytoplankton in spring (97%, majority being Proboscia alata) and autumn (73%, majority being Pseudosolenia calcar-avis), and dinoflagellates in summer (74%, Gymnodinium sp.). There was a remarkable similarity in the dominant species between the western and eastern regions of the southern Black Sea, indicating transport of phytoplankton within the basin

Karadeniz' de birincil üretimi pompalayan Cyanobakterium Synechococcus' un su kolonundaki dağılımını etkileyen fiziko-kimyasal etmenlerin araştırılması

TÜBİTAK YDABÇAG Proje01.11.1997Bu rapor "Karadeniz'de Birincil Üretimi Pompalayan Cyanobakterium Synechococcus'un Su Kolonundaki Dağılımını Etkileyen Fiziko-Kimyasal Etmenlerin Araştırılması" projesi kapsamında yapılan çalışmaları, elde edilen bulguları, bunların analizlerini ve yorumlarını içermektedir. Adı geçen proje Türkiye Bilimsel ve Teknik Araştırma Kurumu'nun (TÜBİTAK) parasal katkısı ve Orta Doğu Teknik Üniversitesi-Erdemli Deniz Bilimleri Enstitüsü'nün gemi, personel, araç ve gereç katkısıyla gerçekleştirilmiştir. Proje kapsamında 24 Eylül-5 Ekim 1996 tarihleri arasında Karadeniz Münhasır Ekonomik Bölge'mizi kapsayacak şekilde, ODTÜ -Deniz Bilimleri Enstitüsü'ne ait R/V Bilim gemisi ile bir sefer gerçekleştirilmiştir. Proje çerçevesinde toplam 26 istasyon ziyaret edilmiş olup, her istasyonda yüzey ve farklı derinliklerden olmak üzere, toplam 121 örnek toplanmıştır. Ayrıca tüm istasyonlarda incelenen su kolonunda kesintisiz fiziksel ve belirli aralıklarda kimyasal parametrelerin ölçümleri yapılmıştır. Hücre sayımları, istasyonlar arası ve ayrıca derinlikle farklılıklar göstermektedir. Derinlikle gözlenen bu farklılıklar nedeni ile hücre yoğunlukları yüzey, klorofil maksimum ve klorofil minimum tabakaları olmak üzere 3 farklı tabaka için değerlendirilmiştir. Tüm istasyonlarda, yüzeyde, mililitrede ortalama hücre sayısı 109,256 olmuş ve en düşük değer 37,323 ve en yüksek değer 211,569 arasında değişmiştir: En düşük ve en yüksek değerler arasında yaklaşık 5.7 kat bir oran mevcuttur. Bu oran bize aynı zamanda taranan alanın ne derecede değişken özelliklere sahip olduğunu göstermektedir. Genelde, kıyısal kesimler hücre sayımları açısından açık, iç kesimlere oranla daha zengin olmuştur. Synechococcus sp hücre sıklığı fluoresans maksimum tabakasında yüzeye oranla istasyonlar arası fazla bir değişkenlik göstermemiştir. Tüm istasyonlarda fluoresans maksimum tabakasında mililitrede ortalama hücre sayısı 126,456 olmuştur ve yüzey ortalamasından daha yüksektir. Hücre sayımları fluoresans minimum tabakasında üst tabakalara oranla istasyonlar arası büyük değişkenlikler göstermiştir. Tüm istasyonlarda fluoresans minimum tabakasında mililitrede ortalama hücre sayısı 11,820 olmuştur ve üst tabakalar ortalamalarından çok düşüktür. Cyanobakteri Synechococcus sp hücreleri genelde gece yarısından başlayarak sabah süresince gün ortasına kadar otlanma baskısı altında olmakta ve öğleden sonra da yavaş yavaş başlayarak akşam süresince bölünerek çoğalmaktadır. Yüzeyde daha belirgin olarak oluşan bu durum fluoresans maksimum tabakasında bulunan hücreler için de geçerlidir. Synechococcus sp hücre sayısı dağılımı ve ortam fiziksel ve kimyasal parametreleri arasında çok kuvvetli $(r>P_{.01.})$ ilişkiler bulunmuştur. Hücre sayımları ile tuzluluk, derinlik, besin tuzları (fosfat, nitrat, silikat) parametreleri arasında çok kuvvetli negatif bir ilişki bulunmuştur. Bu durumu hücre sayımlarının genelde derinlikle azalımı ve diğerlerinin derinlikle artışı olarak özetleyebiliriz. Hücre sayımları ile sıcaklık, çözünmüş oksijen, fluoresans ve klorofil a arasındaki pozitif ilişkiyi de derinlikle birbirleri arasındaki uyumlu azalışa bağlayabiliriz. Kısaca Cyanobakteri Synechococcus'un Karadeniz'de su kolonunda dağılımının ortam fiziko-kimyasal faktörlerine çok bağımlı olarak geliştiğini söyleyebiliriz

Effect of nutrients on culture dynamics of marine phytoplankton

The effects of nitrate, ammonium and phosphate on the abundance, chlorophyll a content (chl a), in vivo fluorescence, particulate organic carbon, nitrogen, phosphorus and cell morphology of the diatom Skeletonema costatum, the dinoflagellate Prorocentrum micans and the coccolithophore Emiliania huxleyi were investigated in the laboratory. The carbon:chlorophyll a ratio (as weight), a parameter often used in productivity estimates, differed substantially among the three species as well as at different nutrient concentrations at the end of the exponential growth phase. The cell chl a content was higher in the earlier phases of growth in all three species in agreement with previous investigations. Average chl a content per cell during the experiments was higher in P. micans (8 pg) than in S. costatum (0.4 pg) and E. huxleyi (0.2 pg). However, chl a content per unit volume was higher in E. huxleyi (similar to 15 fg mu m(-3)) than in S. costatum (similar to 7 fg mu m(-3)) and P. micans (similar to 1 fg mu m(-3)). Prorocentrum micans cultures reached the highest total biovolume (74 mm(3) L(-1) and was 3 and 5 times higher than S. costatum and E. huxleyi cultures, respectively) under high nutrient concentrations. Nevertheless, total chl a concentration of S. costatum culture was almost twice higher (122 mu g L(-1)) than that of the other two species at the end of the exponential growth phase. Phosphate consumption by S. costatum occurred at higher rates compared to the other two species during the experimental period, probably showing that this nutrient was more favourable for this species. Our findings from these laboratory experiments emphasize that chl a values in the natural habitat may not accurately indicate actual phytoplankton biomass

Phytoplankton distribution in the western and eastern Black Sea in spring and autumn 1995

Species composition, abundance, and biomass of micro- (>15 mu m) and nano(50% were dinoflagellates. Abundance and biomass values were lower during the March-April period (average 129 +/- 28 thousand cells I(-1) and 330 +/- 124 mu g I(-1)) than during the October period (average 364 +/- 161 thousand cells I(-1) and 1794 +/- 515 mu g I(-1)) and compared with previous investigations. Values for the north-westerly region were higher than for the southerly areas, probably owing to effects of the Danube river, but were much lower than previously reported, possibly indicating improved ecological conditions. In March-April, dinoflagellates (mainly Heterocapsa triquetra and Scrippsiella trochoideum) were the most important groups, whereas, in October, diatoms (mainly Pseudosolenia calcar-avis) and coccolithophores (Emiliania huxleyi) were dominant. Nanophytoplankton constituted 57% and 84% of total abundance and 8% and 3% of total biomass in spring and autumn, respectively. Microphytoplankton were dominant in the western Black Sea, whilst nanophytoplankton were dominant in the eastern region in spring. (C) 1999 International Council for the Exploration of the Sea

New pelagic Gastropoda species encountered on the Turkish coast of the Levant Sea

In this work, 9 species of pelagic gastropods were studied during bottom trawling and net sampling for zooplankton of Akkuyu in Erdemli and in Iskenderun Bay (the northeastern Mediterranean). Among those, Pterotrachea hippocampus Phlippi, 1836, Cavolinia tridentate (Forsskal, 1775), Limacina (Munthea) trochiformis (D'Orbigny, 1836), and Corolla spectabilis (Dall, 1871) were first records for Turkish mollusk fauna, and the remaining, Atlanta peronii Lesuer, 1817, Firoloida desmarestia Lesuer, 1817, Clio pyramidata Linne, 1767, Creseis acicula Rang, 1828, and Creseis virgula Rang, 1828 were first records for the Mediterranean coast of Turkey

Trophic ecology and assessment of the predatory impact of the Moon jellyfish Aurelia aurita (Linnaeus, 1758) on zooplankton in the Black Sea

Experiments on the feeding of the Moon jellyfish Aurelia aurita have shown that digestion time of zooplankton typically varies between 2.2 and 5.1 h depending on the body weight of the predator, diet composition, amount of food, and seawater temperature. The daily ration of a Moon jellyfish with a wet body mass of 1 g reached 0.025-2.845 mg zooplankton.ind(-1).day(-1) corresponding to a carbon-specific food uptake of 0.2-9.1% C day(-1) with a mean value around 0.5% C day(-1). Such mesozooplankton consumption rates are consistent with the ration values (around 0.9% C day(-1)) calculated from the feeding rate experiments of jellyfish at natural food concentrations. However, in both cases the amount of mesozooplankton was insufficient to compensate for the minimum food requirements, calculated from oxygen consumption (6.7 +/- 0.6% C day(-1)) of the jellyfish. On average, the metabolic expenses of A. aurita were about one order of magnitude greater than its ration supplied by mesozooplankton, indicating the important role of visually overlooked food components in the jellyfish diet

Phytoplankton distribution in the Caspian Sea during March 2001

Phytoplankton abundance, biomass and species composition of the Caspian Sea were evaluated by using samples collected from the Iranian (southern Caspian Sea) and southern Kazakhstan (eastern Caspian Sea) surface waters in March 2001. A total of 45 taxa were found in the samples (20 diatoms, 17 dinoflagellates and 8 others). Abundance and biomass of diatoms were high at the eastern stations, while dinoflagellates were dominant in terms of both biomass and abundance in the southern region. Average abundance and biomass were 40 000 +/- 35 000 cell l(-1) and 580 +/- 690 mu g l(-1). The mean biomass value found here for the Middle and southern Caspian Sea in March are difficult to compare with the past due to limited information, but seems higher than previously registered values. Higher chlorophyll values were also apparent from the Sea WIFS images in 2001 compared to those in 1998. This is suggested to be due to decreased grazing of phytoplankton by zooplankton which is voraciously preyed by the recent invasive ctenophore Mnemiopsis leidyi

Population dynamics and morphological variability of Calanus euxinus in the Black and Marmara Seas

Temporal and spatial changes in abundance, prosome length, oil sac volume, molting patterns and morphometric parameters were studied in Calanus euxinus from the Black and Marmara Seas. In the south-western part of the Black Sea and deep shelf zone near Sinop the abundance of C. euxinus was high during the whole studied period (2000-2005), with a maximum 23,400 ind m-2 in March 2004. In the Marmara Sea near the Prince Islands in the deep zone the mean annual abundance of C. euxinus was 47 times lower than in the deep zone of the Black Sea (during 2000-2007). However, this parameter reached a significant magnitude of 12,264 ind m-2 in spring in Izmit Bay. During the warm season, C. euxinus are rare in the Marmara Sea. The high temperature and salinity accelerate development in this species; therefore, preadults and adults possess reduced prosome length and oil sac volume. In the cold period in the Marmara Sea the size and lipid content in late copepodite stages increase, especially in Izmit Bay. Similar size of eggs, prosome length of early copepodite stages in the Black and Marmara Seas indicate that the C. euxinus population in the Marmara Sea originates from the individuals penetrating from the Black Sea through the Bosphorus

Microplastic consumption and physiological response in Acartia clausi and Centropages typicus: Possible roles of feeding mechanisms

Multi-day experiments were carried out with two Marmara Sea calanoid copepod species: Acartia clausi and Centropages typicus, to assess the possible role of the type of feeding on the consumption of microplastics and its influence on the rate of energy metabolism of these species. In a mixture of microplastic beads (6 mu m diameter) and algae Rhodomonas salina (5-10 mu m size range) with equal concentrations of about 5000 cells/beads mL(-1) the ambush feeder A. clausi consumed almost 5 times less microplastic 858.8 +/- 294.1 beads ind(-1) day(-1) than the cruising feeder C. typicus and halved its consumption of microplastics alone, while C. typicus, on the contrary, increased its consumption rate of pure microplastics to 20237.4 +/- 7020.41 beads ind(-1) day(-1). Both types of reaction to microplastics lead to a decrease in the respiratory rates of the copepods. During the 5 days of maintenance on a solely microplastic diet, the respiration rates of A. clausi and C. typicus decreased 2.2 and 3.4 times, respectively, due to a decrease in the energy spent on motor activity, whilst maintaining basal metabolic energy. It has been shown that in A. clausi, consuming microplastics, a decrease in respiration rate occurs in the same way as in individuals starving in filtered water. A more rapid respiration rate decrease in Centropages typicus consuming microplastics may be due to the greater energy expenditure on microplastic beads capture and egestion via fecal pellets. Acartia clausi seems to exhibit a better strategy in dealing with the adverse consequences of microplastics consumption in comparison to Centropages typicus. (C) 2021 Elsevier B.V. All rights reserved