Cylindrotheca Closterium Research Articles

Phytoplankton abundance in relation to the quality of the coastal water – Arabian Gulf, Saudi Arabia

Phytoplankton abundance in relation to some physicochemical characters of the costal water of Arabian Gulf (Saudi Arabia) was studied for one year. The sampling program included 15 locations in Dammam, Saihat, Al-Qatif, Al-Awamia and Safwa. Water samples were analyzed monthly for these parameters; temperature, pH, salinity, dissolved oxygen, nitrite, nitrate, ammonia, carbon dioxide, total chloride, reactive orthophosphate and total phosphorus and alkalinity, also phytoplankton communities were identified and Chlorophyll a was estimated. The results showed that, the high phytoplankton density attaining the maximum (190.3 × 104/m3) during May and June, and the minimum (10.4 × 104/m3) during November and December. Forty Five species belonging to 5 phytoplankton groups were recorded. Bacillariophyceae was the first dominant group forming 48% of the total phytoplankton communities (23 species). The dominant species of Bacillariophyceae were Pleurosigma strigosum, Pleurosigma elongatum, Lyrella clavata, Rhizosolenia shrubsolei, Cylindrotheca closterium, Nitzschia panduriform, Nitzschia longissimia, Amphora sp and Stephanopyxis. Dinophyceae was the second dominant group and formed 31% of the total phytoplankton communities (10 species); the dominant species were Ceratium fusus, Heterosigma sp, Ceratium furca, Prorocentrum triestium, Protoperidinium sp, Gyrodinium spirale, Noctiluca scintillans and Scrippsiella trochoidea. Cyanophyceae formed 13% (5 species) where Nostoc sp, Oscillatoria and Merismopedia sp were the dominant species. Chlorophyceae had 8% (6 species); Scendesmus sp., Chlorella sp., Chlamydomonas sp., Dunaliella salina and Nannochloropsis sp were the dominant species. The Euglinophyceae was rare only one species (Euglina sp). The relationship was positive between the phytoplankton, chlorophyll a and carbon dioxide while negative amongst dissolved oxygen and total nitrogen. This research indicated that the relation between water quality and phytoplankton organisms at the coast of Arabian Gulf (Saudi Arabia) was extremely overlapping and interdependent; any changes in the one component may significantly affect those of the other components.

Формирование биообрастания в структурированном пространстве искусственных рифовых конструкций

В статье обсуждаются вопросы, связанные с возможностью управления биообрастанием через структуру искусственных рифовых конструкций (ИРК), и вопросы пространственной организации растительных пологов, формируемых на ИРК, что является актуальным при решении задач культивирования гидробионтов на твёрдых субстратах. ИРК представляет собой частокол вертикальных структур цилиндрической формы (di = 0,33 см, li = 20 см) на горизонтально расположенной пластине So = a1 · a2 = 900 см2. Частокол охватывает пространство (Vг = 0,018 м³), одна часть которого занята вертикальными структурами (∑Vi = Vi · n, где n ― общее количество осевых структур на горизонтальной поверхности модуля), а другая свободна от них (Vf = Vг – ∑Vi). Задавались три варианта плотности расположения вертикальных структур (n/So): 544, 3956 и 10 678 экз·м-2 — и, соответственно, три варианта величины концентрации их площади поверхности в границах объёма ИРК (Cs = (∑Si) / Vг)): 0,056, 0,295 и 1,106 см-1. В течение 43 суток (c 27 мая по 9 июля 2014 г.) ИРК экспонировались в прибрежной акватории бухты Севастополя (Чёрное море) на глубине 2 м. Температура воды в море варьировала в пределах +23,3…+25,6 °C. Пробы отбирали каждые 6–8 суток. В составе биообрастания по массе преобладали диатомовые водоросли, присутствовали проростки многоклеточных водорослей, из животных встречались гидроиды, мшанки, спирорбисы, личинки балянусов. На 7-е сутки экспозиции на поверхности ИРК при «редком» (544 экз.·см-2) и «плотном» (10 678 экз.·см-2) расположении структур идентифицирован 51 вид диатомовых водорослей, из которых только 15 видов (каждый по отдельности) вносят заметный (> 5 %) вклад в общую численность (ni, %) и биомассу (Wi, %) сообщества на отдельно взятых участках вертикальных структур. К ним относятся: Achnanthes longipes, Amphora hyalina, Berkeleya rutilans, Cylindrotheca closterium, Entomoneis paludosa, Haslea ostrearia, Licmophora abbreviata, L. hastata, Neosynedra provincialis, Nitzschia sigma, N. tenuirostris, Parlibellus delognei, Pleurosigma elongatum, Proboscidea insecta, Trachyneis aspera. Значения коэффициентов Сёренсена — Чекановского (Ksc = 0,7) и Стугрена — Радулеску (Psr = -0,077) указывают на очень близкое сходство систематического состава сравниваемых сообществ. На рассматриваемом отрезке времени выделяются четыре характерных этапа в изменении величины плотности обрастания вертикальных структур (W/Si, где W — сухая биомасса обрастания, Si — площадь поверхности осевой структуры). Условно первый этап завершается седьмым днём наблюдения, и к этому моменту на верхушках структур, независимо от плотности их расположения, создаётся примерно одинаковая плотность обрастания (0,51–0,91 мг (сухой массы) · см-2), а в серединной части ИРК она сильно различается (0,03–0,57 мг (сухой массы) · см-2). Второй этап (7–21-е сутки) характеризуется низкими величинами скорости изменения биомассы на единицу обрастаемой поверхности и меняющимся вектором её направленности (0,003–0,08, 0,25, -0,17 мг (сухой массы) · сут-1 · см-2) и относительно невысокими значениями W/Si (0,36–2,23 мг (сухой массы) · см-2). Третий этап отличается быстрым увеличением плотности обрастания (0,30–0,75 мг (сухой массы) · сут-1 · см-2). Максимум W/Si (3,09–9,07 мг (сухой массы) · см-2) достигается на 29-е и 36-е сутки экспозиции. Четвёртый этап проявляется снижением W/Si и не может рассматриваться как закономерный: он является следствием действия внешних факторов среды (подвижности воды). Рассмотрено вертикальное распределение сухой биомассы биообрастаний (W/Si) вдоль осевых структур при разной плотности их расположения на 7, 14, 21, 29, 36-е и 43-и сутки эксперимента. Общая картина вертикального распределения W/Si на 29-е и 43-и сутки была сходной: с увеличением плотности размещения вертикальных структур максимум биомассы обрастателей смещается в сторону верхней границы ИРК. На конструкциях с редким расположением структур максимум биомассы отмечен в серединной части растительного полога, при «частом» (3956 экз.·м-2) расположении основная часть биомассы (83,5–73,8 %) сосредоточена в верхней половине растительного полога, а при плотном — в верхнем двухсантиметровом слое (63,9–79,3 %). Рассмотрена связь величин концентрации сухой массы биообрастания в объёме обитаемого пространства (Cw = (∑Wi) / Vf)) и концентрации физической поверхности ИРК (Cs) по отношению к верхнему двухсантиметровому слою ИРК (1) и по отношению ко всему объёму рифовой конструкции (2) при высоте вертикальных структур в 20 см, на 29-е сутки эксперимента ((1): Cw = -0,232 + 7,136Cs, R² = 0,99; (2): Cw = 0,084 + 2,652Cs, R² = 0,93). Показано, что при высоте вертикальных структур в 20 см с увеличением значений Cs усиливается экранирующее действие как со стороны структур конструкции, так и со стороны биообрастаний, что приводит к частичному световому и биогенному лимитированию роста биообрастателей и, следовательно, к «недобору» биомассы в соответствующем объёме пространства конструкции.

Diatom-driven recolonization of microbial mat-dominated siliciclastic tidal flat sediments.

Modern microbial mats and biofilms play a paramount role in sediment biostabilization. When sporadic storms affect tidal flats of Bahía Blanca Estuary, the underlying siliciclastic sediment is exposed by physical disruption of the mat, and in a few weeks' lapse, a microbial community re-establishes. With the objective of studying colonization patterns and the ecological succession of microorganisms at the scale of these erosional structures, these were experimentally made and their biological recolonization followed for 8 weeks, with replication in winter and spring. Motile pennate diatoms led the initial colonization following two distinct patterns: a dominance by Cylindrotheca closterium in winter and by naviculoid and nitzschioid diatoms in spring. During the first 7 days, cell numbers increased 2- to 17-fold. Cell densities further increased exhibiting sigmoidal community growth, reaching 2.9-8.9×106 cells cm-3 maxima around day 30; centric diatoms maintained low densities throughout. In 56 days after removal of the original mat, filamentous cyanobacteria that dominate mature mats did not establish a significant biomass, leading to the rejection of the hypothesis that cyanobacteria would drive the colonization. The observed dominance of pennate diatoms is attributed to extrinsic factors determined by tidal flooding, and intrinsic ones, e.g. motility, nutrient affinity and high growth rate.

Differential environmental responses of tropical phytoplankton community in the southwest coast of India

Phytoplankton characteristics (biomass, primary productivity, species composition and community structure) were studied in a tropical estuary (Cochin estuary) and adjacent coastal marine region for understanding the factors controlling their productivity patterns and community dynamics. The Cochin estuary (CE) sustained a high level of inorganic nutrients supporting very high phytoplankton biomass, productivity, and abundance. Though the CE exhibited a 2–3 fold increase in the annual mean of chlorophyll a (14.6±8.5mgm−3) and primary production (1288±999mgCm−3d−1) than the coastal waters, both regions sustained a substantial dominance of small-sized phytoplankton, in particular nanoplankton (2–20 μm), which apparently contributed >70% of total chlorophyll a and primary production. Diatoms were the dominant phytoplankton functional group (>75% of total abundance) prevailed over both sampling locations almost throughout the year. However, the sporadic dominance of certain species of dinoflagellates (during premonsoon) and green and blue–green algae (during monsoon) were also encountered in the estuary. The SIMPER analysis, based on phytoplankton species abundance data, revealed the presence of certain characterizing species exclusive for both estuary and coastal waters, and most of them belonged to smaller diatoms e.g., Skeletonema costatum, Thalassiosira subtilis, Nitzschia longissima, Cylindrotheca closterium etc. The incessant proliferation of these small sized diatoms, especially in the CE, can be considered as a potential source of consistently higher phytoplankton biomass and primary productivity, and which can even survive in the recurring short-term (tides) and long-term (seasonal) hydrographic changes of the Cochin estuary.

Cell-mediated immune response of postmetamorphic sea urchin juveniles against infectious stages of diatom Cylindrotheca closterium (Bacillariophyceae).

In this study, successive infectious stages by diatom Cylindrotheca closterium (Bacillariophyceae) are described for the first time during the early development of sea urchin at low temperature (8°C). Diatom cell-types enclosed or not by typical theca were capable of infection. As an immune response, red spherulocytes and amoebocytes migrated towards infested areas and restrained the infection spreading over shells in 2- and 3-month old urchins. Only amoebocyte cells appeared to be involved in the immune reaction of 1-month old specimens which turned out to be a less effective fence to stop infestation. The effectiveness of the inflammatory process caused by diatoms within sea urchin spines seemed to vary as a function of urchin age, cohort's type and individual cell pool.

Analysis of sterols in selected bloom-forming algae in China

Sterols, a group of stable lipid compounds, are often used as biomarkers in marine biogeochemical studies to indicate sources of organic matter. In this study, sterols in 13 species of major bloom-forming algae in China, which belong to Dinophyceae, Bacillariophyceae, Ulvophyceae, and Pelagophyceae, were analyzed with gas chromatography-mass spectrometry (GC–MS) to test their feasibility in representing different types of harmful algal blooms (HABs). It was found that (24Z)-stigmasta-5,24-dien-3β-ol (28-isofucosterol) was a major sterol component in green-tide forming macroalga Ulva prolifera. In bloom-forming dinoflagellates Alexandrium spp., Prorocentrum micans and Scrippsiella trochoidea, (22E)-4α,23-dimethyl-5α-ergost-22-en-3β-ol (dinosterol) was detected in addition to cholest-5-en-3β-ol (cholesterol), (22E)-ergosta-5,22-dien-3β-ol, (22E)-stigmasta-5,22-dien-3β-ol and other minor sterol components. In brown-tide forming pelagophyte Aureococcus anophagefferens, (24E)-24-propylcholesta-5,24-dien-3β-ol ((24E)-24-propylidenecholesterol) and (24Z)-24-propylcholesta-5,24-dien-3β-ol ((24Z)-24-propylidenecholesterol) were detected together with cholesterol, (22E)-stigmasta-5,22-dien-3β-ol, stigmast-5-en-3β-ol and campest-5-en-3β-ol. Among the selected bloom-forming diatoms, Chaetoceros sp. and Pseudo-nitzschia spp. only produced cholesterol, while Cylindrotheca closterium produced solely (22E)-ergosta-5,22-dien-3β-ol. Sterol content in four bloom-forming algal species correlates well with their biomass or abundance. It's proposed that 28-isofucosterol could serve as a promising biomarker for green algae in green-tide studies. Dinosterol and (24Z)-24-propylidenecholesterol can be used as potential biomarkers to represent bloom-forming dinoflagellates and pelagophytes, while (22E)-ergosta-5,22-dien-3β-ol is not a good indicator for diatoms.

Comparison of antifouling properties of native and invasive Sargassum (Fucales, Phaeophyceae) species

The invasiveness of algal species can be facilitated by chemo-ecological traits that allow the establishment of invasive species in a highly competitive environment. Anti-bacterial, anti-quorum sensing, anti-diatom and anti-larval properties of the invasive brown macroalga Sargassum muticum and three native Sargassum species from Oman waters were compared in laboratory and field experiments to assess whether these traits have the potential to facilitate the invasion process. Only the extract of S. muticum inhibited bacterial growth of four marine bacterial strains and quorum sensing in the reporter strain Chromobacterium violaceum CV017. Settlement, growth and survival of the diatom Cylindrotheca closterium and larvae of the bryozoan Bugula neritina were significantly inhibited by all Sargassum extracts in laboratory experiments. However, crude extracts of S. muticum had the strongest antifouling effect. Natural tissue-level concentrations of S. muticum extract reduced diatom density to about 20% compared with the controls. Larval mortality increased by 80–90% compared with controls with S. muticum extract diluted to one-third natural levels. Significant anti-diatom activity of S. muticum was confirmed in the field experiments with Sargassum extracts embedded in a phytagel matrix. Comparison of non-polar compounds by gas chromatography–mass spectrometry demonstrated that S. muticum extracts had overall fewer secondary metabolites but more species-unique compounds than extracts of native Sargassum spp. The greater antifouling defence of invasive vs. native Sargassum species indicates a selective trait that may contribute to the invasion success of S. muticum.

Epiphytic Microalgal Dynamics and Species Composition on Brown Seaweeds (Phaeophyceae) on the Northern Coast of Jeddah, Saudi Arabia

Epiphytic microalgae grow on host seaweeds. Seaweeds are multicellular macro-algae, which are abundant in intertidal zones of coastal environments. The report on epiphytic microalgae is rare in the Red Sea. Thus, an investigation on epiphytic microalgae was carried on northern coast of Jeddah, the Red Sea, Saudi Arabia. The Red Sea is narrow oceanic basin which is lying between the African and the Asian continental shelves. During the study, 4 species of seaweeds were recorded in Phaeophyceae which were Laminaria sp., Padina fraseri, Sargassum muticum and Turbinaria ornata. A total of 83 epiphytic microalgae were identified, including 76 belong to Bacillariophyceae, 5 belong to Cyanophyceae, 1 belongs to Chlorophyceae and 1 belongs to Dinophyceae. On seaweeds of Laminaria sp., the dominant epiphytes were Leptocylindrus danicus, Licmophora flabellata and Navicula ramosissma. On seaweeds Padina fraseri, the dominant epiphytes were Cylindrotheca closterium, Navicula sp., Nitzschia sp. and Prorocentrum lima and Cocconeis lineatus. On seaweeds of Sargassum muticum, the dominant epiphytes were Navicula distans, Nitzschia socialis and Navicula vanhoeffeni. On seaweeds Turbinaria ornata, the dominant epiphytes were Leptocylindrus minimus, Bacillaria paxillifer, Leptocylindrus danicus, Nitzschia hungarica and Thalassionema frauenfeldii. The host seaweeds influenced the associated diatoms mainly through its morphology and surface texture and roughness to provide a point of attachment and shelter for host-adapted species. Most of the dominant epiphytes were in smaller cell size diatoms, except Cylindrotheca closterium. The findings of the study focused on individual species of benthic marine diatoms associated with specific seaweeds species even in different regions of the Red Sea in different seasons of Saudi Arabia. These findings could be the important source for future explanation of marine eco-biogeographical phenomena in the Red Sea.

Phytoplankton community structure in the VAHINE mesocosm experiment

Abstract. The VAHINE mesocosm experiment was designed to trigger a diazotroph bloom and to follow the subsequent transfer of diazotroph-derived nitrogen (DDN) in the rest of the food web. Three mesocosms (50 m3) located inside the Nouméa lagoon (New Caledonia, southwestern Pacific) were enriched with dissolved inorganic phosphorus (DIP) in order to promote N2 fixation in these low-nutrient, low-chlorophyll (LNLC) waters. Initially, the diazotrophic community was dominated by diatom diazotroph associations (DDAs), mainly by Rhizosolenia/Richelia intracellularis, and by Trichodesmium, which fueled enough DDN to sustain the growth of other diverse diatom species and Synechococcus populations that were well adapted to limiting DIP levels. After DIP fertilization (1 µM) on day 4, an initial lag time of 10 days was necessary for the mesocosm ecosystems to start building up biomass. However, changes in community structure were already observed during this first period, with a significant drop of both Synechococcus and diatom populations, while Prochlorococcus benefited from DIP addition. At the end of this first period, corresponding to when most added DIP was consumed, the diazotroph community changed drastically and became dominated by Cyanothece-like (UCYN-C) populations, which were accompanied by a monospecific bloom of the diatom Cylindrotheca closterium. During the second period, biomass increased sharply together with primary production and N2-fixation fluxes near tripled. Diatom populations, as well as Synechococcus and nanophytoeukaryotes, showed a re-increase towards the end of the experiment, showing efficient transfer of DDN to non-diazotrophic phytoplankton.

Nitrogen isotopic evidence for a shift from nitrate- to diazotroph-fueled export production in the VAHINE mesocosm experiments

Abstract. In a coastal lagoon with a shallow, 25 m water column off the southwest coast of New Caledonia, large-volume ( ∼ 50 m3) mesocosm experiments were undertaken to track the fate of newly fixed nitrogen (N). The mesocosms were intentionally fertilized with 0.8 µM dissolved inorganic phosphorus to stimulate diazotrophy. N isotopic evidence indicates that the dominant source of N fueling export production shifted from subsurface nitrate (NO3−) assimilated prior to the start of the 23-day experiments to N2 fixation by the end of the experiments. While the δ15N of the sinking particulate N (PNsink) flux changed during the experiments, the δ15N of the suspended PN (PNsusp) and dissolved organic N (DON) pools did not. This is consistent with previous observations that the δ15N of surface ocean N pools is less responsive than that of PNsink to changes in the dominant source of new N to surface waters. In spite of the absence of detectable NO3− in the mesocosms, the δ15N of PNsink indicated that NO3− continued to fuel a significant fraction of export production (20 to 60 %) throughout the 23-day experiments, with N2 fixation dominating export after about 2 weeks. The low rates of organic N export during the first 14 days were largely supported by NO3−, and phytoplankton abundance data suggest that sinking material primarily comprised large diatoms. Concurrent molecular and taxonomic studies indicate that the diazotroph community was dominated by diatom–diazotroph assemblages (DDAs) at this time. However, these DDAs represented a minor fraction (< 5 %) of the total diatom community and contributed very little new N via N2 fixation; they were thus not important for driving export production, either directly or indirectly. The unicellular cyanobacterial diazotroph, a Cyanothece-like UCYN-C, proliferated during the last phase of the experiments when N2 fixation, primary production, and the flux of PNsink increased significantly, and δ15N budgets reflected a predominantly diazotrophic source of N fueling export. At this time, the export flux itself was likely dominated by the non-diazotrophic diatom, Cylindrotheca closterium, along with lesser contributions from other eukaryotic phytoplankton and aggregated UCYN-C cells, as well as fecal pellets from zooplankton. Despite comprising a small fraction of the total biomass, UCYN-C was largely responsible for driving export production during the last ∼ 10 days of the experiments both directly ( ∼ 5 to 22 % of PNsink) and through the rapid transfer of its newly fixed N to other phytoplankton; we infer that this newly fixed N was transferred rapidly through the dissolved N (including DON) and PNsusp pools. This inference reconciles previous observations of invariant oligotrophic surface ocean DON concentrations and δ15N with incubation studies showing that diazotrophs can release a significant fraction of their newly fixed N as some form of DON.

Cálculo del contenido celular de carbono de cuatro taxones de diatomeas: biovolumen y espectrofotometría

Background. Phytoplankton biomass is an essential parameter in aquatic ecosystems; two of the most widely used indicators for estimating phytoplankton biomass are chlorophyll-a (Chl-a) by spectrophotometry and biovolume (BV). Goals. To show how different results are when estimating phytoplankton biomass by means of the spectrophotometric and BV methods. Methods. Biomass by Chl-a and BV were estimated in four cultures of marine diatoms. For estimating BV, we used live cells and acid Lugol’s solution fixed cells. Results. Biomass values were noticeably different: the BV for Thalassiosira hispida and Skeletonema costatum underestimates ≈41% of the biomass with respect to values obtained by spectrophotometry. In contrast, the BV for Pseudo-nitzschia sp. and Cylindrotheca closterium overestimates the biomass by 4% and 25%, respectively. In the case of estimated biovolume, the results indicate that fixer acid Lugol’s solution modified the size of the cell significantly in C. closterium and Pseudo-nitzschia sp. (p 0.05). Two equations are provided for biomass calculation when studying live (pgC/cell = -1.5567 + 0.1428 (BV)) or acid Lugol’s solution fixed (pgC/cell = -5.0126 + 0.1644 (BV)) diatom cells. Conclusions. Although BV is useful, it can have drawbacks because it produces values above and below those estimated by spectrophotometry, in addition to the fact that acid Lugol´s solution modifies cell size. We would advise considering the available information based in Chl-a or carbon of different species.

Ecological provinces of spring phytoplankton in the Yellow Sea: species composition

Phytoplanktonic ecological provinces of the Yellow Sea (31.20°–39.23°N, 121.00°–125.16°E) is derived in terms of species composition and hydrological factors (temperature and salinity). 173 samples were collected from 40 stations from April 28 to May 18, 2014, and a total of 185 phytoplanktonic algal species belonging to 81 genera of 7 phyla were identified by Utermohl method. Phytoplankton abundance in surface waters is concentrated in the west coast of Korean Peninsula and Korea Bay, and communities in those areas are mainly composed of diatoms and cyanobacteria with dominant species of Cylindrotheca closterium, Synechocystis pevalekii, Chroomonas acuta, Paralia sulcata, Thalassiosira pacifica and Karenia mikimotoi, etc. The first ten dominant species of the investigation area are analyzed by multidimensional scaling (MDS) and cluster analysis, then the Yellow Sea is divided into five provinces from Province I (P-I) to Province V (P-V). P-I includes the coastal areas near southern Liaodong Peninsula, with phytoplankton abundance of 35 420×103–36 163×103 cells/L and an average of 35 791×103 cells/L, and 99.84% of biomass is contributed by cyanobacteria. P-II is from Shandong Peninsula to Subei coastal area. Phytoplankton abundance is in a range of 2×103–48×103 cells/L with an average of 24×103 cells/L, and 63.69% of biomass is contributed by diatoms. P-III represents the Changjiang (Yangtze River) Diluted Water. Phytoplankton abundance is 10×103–37×103 cells/L with an average of 24×103 cells/L, and 73.14% of biomass is contributed by diatoms. P-IV represents the area affected by the Yellow Sea Warm Current. Phytoplankton abundance ranges from 6×103 to 82×103 cells/L with an average of 28×103 cells/L, and 64.17% of biomass is contributed by diatoms. P-V represents the cold water mass of northern Yellow Sea. Phytoplankton abundance is in a range of 41×103–8 912×103 cells/L with an average of 1 763×103 cells/L, and 89.96% of biomass is contributed by diatoms. Overall, structures of phytoplankton community in spring are quite heterogeneous in different provinces. Canonical correspondence analysis (CCA) result illustrates the relationship between dominant species and environmental factors, and demonstrates that the main environmental factors that affect phytoplankton distribution are nitrate, temperature and salinity.

Non-toxic, anti-fouling silicones with variable PEO–silane amphiphile content

Non-toxic silicone coatings with improved resistance to diatom slime formation were prepared by simple blending and curing with a poly(ethylene oxide) (PEO)–silane amphiphile: α-(ethylene oxide)3Si-(CH2)2-oligodimethylsiloxane13-block-poly(ethylene oxide)8-OCH3. Coatings were formed by blending varying levels (1, 5 and 10 wt%) into a room-temperature vulcanization (RTV), silica-reinforced silicone. The coatings were subjected to a series of biofouling tests, including exposure to Bacillus and Pseudoalteromonas bacteria and Cylindrotheca closterium diatoms, both individually and as a mixed community of Bacillus and C. closterium. Additionally, microfouling was evaluated upon exposure of the silicone coatings to natural seawater by submersion in the Atlantic Ocean for extended periods. Biofouling was assessed in terms of percentage of coverage, biomass and average thickness based on confocal laser scanning microscopy images. For all tests, silicones modified with 5 and 10 wt% PEO–silane amphiphile exhibited similarly high anti-biofouling behavior. In addition, silicone coatings modified with just 1 wt% PEO–silane amphiphile displayed a marked improvement on resistance to C. closterium diatom settlement compared to the unmodified silicone.

Proliferation of Falcula hyalina and Cylindrotheca closterium (Bacillariophyceae) on copepods in Bahía de La Paz, Gulf of California, Mexico

A proliferation of the epizoic diatoms Falcula hyalina and Cylindrotheca closterium occurred, respectively, on the exoskeleton of marine copepods Acartia tonsa and Paracalanus sp. Samples were collected in February and in October 2013 in Bahia de La Paz. Both represent the first proliferations of this epizoic microalgae reported in the Gulf of California. Seawater temperature was 19°C in February and 28°C in October. A short morphological description, cell measurements and distribution of both species are provided.

Effects of geometrical configurations of photobioreactors on the growth of marine benthic diatom Cylindrotheca closterium / Fotobiyoreaktörlerin geometrik konfigürasyonlarının sucul bentik diatom Cylindrotheca closterium üremesi üzerine etkisi

Abstract Objective: For algal biotechnology, the primary barrier is the developing of cost effective photobioreactor operating in a high-efficiency. In this study, the effects of three different types of photobioreactors (bag, flat plate and bubble column) on the growth and sugar production of the diatom Cylindrotheca closterium were simultaneously investigated for 7 days of batch cultivation period. Methods: The photobioreactors were incubated at 21±2°C under the light intensity of 50 μmol photons m-2s-1 with a 12: 12 h light: dark cycle photoperiod at the air flow rate of 2 L min-1 for 7 days of batch productions. The turbidity (optical density), chlorophyll-a, exopolysaccharide (EPS) content and reducing sugar concentration were measured. Results: The maximum specific growth rate of 0.29 day−1, which corresponded to the doubling time of 2.40 day, was obtained in the bag photobioreactor cultivation of C. closterium. It was found that the polyethylene bag photobioreactors are suitable for the production of diatoms as a closed photobioreactor. Conclusion: The key is not only the selection of geometrical configuration of photobioreactor, but also the determination of the light penetration path for cost effective photobioreactor design operating in high efficiency related to the algal productions.

Short-term changes in a microplankton community in the Chukchi Sea during autumn: consequences of a strong wind event

Abstract. Recent studies indicate an increase in atmospheric turbulence in the Chukchi Sea due to the recent drastic sea-ice reduction during summer months. The importance of the effects of this atmospheric turbulence on the marine ecosystem in this region, however, is not fully understood. To evaluate the effects of atmospheric turbulence on the marine ecosystem, high-frequency sampling (daily) from five layers of the microplankton community between 0 and 30 m at a fixed station in the Chukchi Sea from 10 through 25 September 2013 was conducted. During the study period, a strong wind event (SWE) was observed on 18 and 19 September. The abundance of microplankton was 2.6 to 17.6 cells mL−1, with a maximum abundance being reported at 20 m on 22 September, while diatoms were the most dominant taxa throughout the study period. The abundance of diatoms, dinoflagellates and ciliates ranged between 1.6 and 14.1, 0.5 and 2.4 and 0.1 and 2.8 cells mL−1, respectively. Diatoms belonging to 7 genera consisting of 35 species (Cylindrotheca closterium and Leptocylindrus danicus were dominant), dinoflagellates belonging to 7 genera consisting of 25 species (Prorocentrum balticum and Gymnodinium spp. were dominant) and ciliates belonging to 7 genera consisting of 8 species (Strobilidium spp. and Strombidium spp. were dominant) were identified. Within the microplankton species, there were 11 species with abundances that increased after the SWE, while there was no species with an abundance that decreased following the SWE. It is conjectured that atmospheric turbulences, such as that of an SWE, may supply sufficient nutrients to the surface layer that subsequently enhance the small bloom under the weak stratification of the Chukchi Sea Shelf during the autumn months. After the bloom, the dominant diatom community then shifts from centric-dominated to one where centric/pennate are more equal in abundance.

Live diatoms facing Ag nanoparticles: surface enhanced Raman scattering of bulk cylindrotheca closterium pennate diatoms and of the single cells

Live diatoms exposed to AgNPs revealed SERS mechanism dependent on the nanoparticles type while the SERS output allowed detection of extracellular substances.

Fucoxanthin content of Cylindrotheca Closterium and its oxidative stress mediated enhancement

Fucoxanthin content of Cylindrotheca Closterium and its oxidative stress mediated enhancement

ECOLOGICAL AND BIOLOGICAL CHARACTERISTICS FORMICROALGAE OF SAND SUBSTRATES OF THE ODESA BAY (THE BLACK SEA)

The studies revealed 74 taxa of microalgae that live on sandy substrate in the Odesa Bay. The most common representatives of phytopsammon are Navicula salinarum Grunow , Diploneis chersonensis (Grunow) Cleve , Cylindrotheca closterium (Ehrenb.) Reimann et J. C. Lewin , Plagiotropis lepidoptera (W. Greg.) Kuntze , Attheya decora T. West , Pleurosigma elongatum (W. Sm.) van Heurk, Entomoneis paludosa (W. Sm.) Reimer. The most species (39 %) that are presented move freely over the substrate. However 27 % of the species are attached to sand grains. With respect to the salinity there are three groups which are the most abundant: oligogalobes (40 %), mezogalobes (31 %) and poligalobes (29 %). Most microalgae are alkaliphilic and cosmopolitans. The presence of oligosaprobes and xenosaprobes testifies the ongoing processes of self-purification on the coast of the Odesa Bay.

Effect of surface topological structure and chemical modification of flame sprayed aluminum coatings on the colonization of Cylindrotheca closterium on their surfaces

Biofouling is one of the major problems for the coatings used for protecting marine infrastructures during their long-term services. Regulation in surface structure and local chemistry is usually the key for adjusting antifouling performances of the coatings. In this study, flame sprayed multi-layered aluminum coatings with micropatterned surfaces were constructed and the effects of their surface structure and chemistry on the settlement of typical marine diatoms were investigated. Micropatterned topographical morphology of the coatings was constructed by employing steel mesh as a shielding plate during the coating deposition. A silicone elastomer layer for sealing and interconnection was further brush-coated on the micropatterned coatings. Additional surface modification was made using zwitterionic molecules via DOPA linkage. The surface-modified coatings resist effectively colonization of Cylindrotheca closterium. This is explained by the quantitative examination of a simplified conditioning layer that deteriorated adsorption of bovine calf serum proteins on the zwitterionic molecule-treated samples is revealed. The colonization behaviors of the marine diatoms are markedly influenced by the micropatterned topographical morphology. Either the surface micropatterning or the surface modification by zwitterionic molecules enhances antimicrobial ability of the coatings. However, the combined micropatterned structure and zwitterionic modification do not show synergistic effect. The results give insight into anti-corrosion/fouling applications of the modified aluminum coatings in the marine environment.