Dinoflagellate cyst records in recent sediments from Daya Bay, South China Sea

Nine sediment cores of 8–26 cm in length were collected from two basins of Daya Bay, the South China Sea, by Tokyo University Fisheries Oceanography Laboratory core sampler in August 2001 to investigate the distribution of dinoflagellate resting cysts. In the present study, 51 different cyst morphotypes representing 22 genera were identified from 65 sediment samples. Among them, there were 21 autotrophic species and 30 heterotrophic ones. Cyst species richness in each sample varied from 12 to 29, while the values of Shannon‐Weaver diversity index (H′) were between 0.15 and 4.13. There were an obvious increase in both species richness and values of H′in 2–6 cm sediments. Cyst concentrations varied from 154 to 113 483 cysts per gram dry weight sediment, and were much higher in upper sediments. Scrippsiella trochoidea was the most dominant cyst type, which took up over 90% of cyst assemblages in the upper sediments. The abrupt increase of S. trochoidea cysts in the surface sediments reflected the bloom of this species in Daya Bay in 2000. The results from cyst assemblages showed some trend of changes in water quality in this area, and indicated a typical type of pollution caused by cultural eutrophication, which started in the 1980s and greatly accelerated in the middle of 1990s. Cysts of Alexandrium, mainly those of Alexandrium catenella and Alexandrium tamarense complex, occurred frequently and abundantly in this area, with the highest concentration and relative frequency of 503 cysts per gram dry weight sediment and 22.3%, respectively. The high abundance of Alexandrium cysts provided rich ‘seed bed’ for Alexandrium blooms and was also an important source of paralytic shellfish poisoning toxins, especially in winter.     

Abundance and distribution of toxic Alexandrium tamarense resting cysts in the sediments of the Chukchi Sea and the eastern Bering Sea

Abundance and distribution of the toxic dinoflagellate Alexandrium tamarense species complex resting cyst were investigated in the eastern Bering Sea and the Chukchi Sea for the first time. Sediment samples (top 0–3 cm depth) were collected from the continental shelf of the eastern Bering Sea (17 stations) and the Chukchi Sea (13 stations) together with a long core sample (top 0–21 cm depth) from one station in the Chukchi Sea during 2009–2012. The cysts were enumerated using the primuline staining method. Species identification of the cysts was carried out with multiplex PCR assay and the plate morphology of vegetative cells germinated from cysts in the both areas. Alexandrium cysts were widely detected in the both areas, ranging from not detected (<1 cysts cm⁻³) to 835 cysts cm⁻³ wet sediment in the eastern Bering Sea and from not detected (<1 cysts cm⁻³) to 10,600 cysts cm⁻³ in the Chukchi Sea, and all isolated cysts were genetically and morphologically identified as the North American clade A. tamarense. Their cysts were mainly distributed in the shallow continental shelf where the water depth was less than 100 m in both areas. The cysts were detected from the deep layer (18–21 cm depth of sediment core) of the long core sample. The present study confirmed the abundant existence of A. tamarense with wide range of distribution in these areas. This fact suggests that A. tamarense vegetative cells have appeared in the water column in the both areas. Furthermore, these abundant cyst depositions indicate that this species originally distributed in the Arctic and subarctic regions and well adapted to the environments in the marginal ice zone.     

Dinoflagellate resting cysts as factors in phytoplankton ecology of the North Sea

The occurrence and distribution of dinoflagellate resting cysts were investigated at 11 locations in the south-eastern part of the North Sea. Twenty-six known cyst species and 7 unknown cyst types, which may act as seed population for planktonic dinoflagellate blooms, have been recorded for the first time in the area. The most common cysts in recent sediments were those ofScrippsiella trochoidea, Zygabikodinium lenticulatum, Peridinium dalei, Scrippsiella lachrymosa, Protoceratium reticulatum, Protoperidinium denticulatum, andP. conicum. At all stations,S. trochoidea dominated the cyst assemblages with a maximal abundance of 1303 living cysts/cm³ in the uppermost half centimetre. Cysts of the potentially toxic dinoflagellatesAlexandrium cf.excavatum andA. cf.tamarense were scarce. In the upper 2-cm layer of sediment, dinoflagellate cysts were found in concentrations of 1.8 up to 682 living cysts/cm³. Empty cysts constituted 22–56% of total cyst abundance. The comparative distribution of the cysts showed a general increase in abundance from inshore sites to the offshore area, whereby sandy stations exhibited the lowest cyst abundance and diversity. The wide distribution of living and empty cysts ofScrippsiella lachrymosa suggests that its motile form, which has not been officially recorded in the area until now, is a common plankton organism in German coastal waters. The relatively high abundance of cysts in recent sediments demonstrates the potential importance of benthic resting stages for the initiation of dinoflagellate blooms in the study area.     

Resting stages of microalgae in recent marine sediments of Peter the Great Bay,Sea of Japan

Data on the qualitative and quantitative composition of resting stages of planktonic microalgae in recent marine sediments of Peter the Great Bay (Sea of Japan) over the period 2000–2007 are presented. A total of sixty one morphological forms of resting stages represented by dinoflagellate and raphidophyte cysts and diatom spores and resting cells were recorded in the sediment samples. This study revealed cysts of the potentially toxic species Alexandrium tamarense, A. cf. minutum, Alexandrium sp., Gymnodinium catenatum (PSP toxin producers), and Protoceratium reticulatum (yessotoxin producer); resting cells of Pseudo-nitzschia sp. (potential producer of domoic acid); and cysts of bloom-forming species Cochlodinium cf. polykrikoides and Heterosigma cf. akashiwo.     

Length–weight relationships of deep-sea fishes from the western Bering Sea

Length–weight relationships are lacking for most deep-sea fishes. This study presents length–weight relationships for 42 species from the western Bering Sea. Results show significantly different relationships between females and males for 11 species and between juveniles and adults of four species. A plot of length–weight estimates, log a over b , showed the deep-sea fishes in this study to be more of the elongated shape compared with other marine fishes.     

黄海海域海洋沉积物细菌多样性分析

【背景】海洋独特的环境造就了海洋生物的多样性,海洋沉积物中细菌对海洋环境具有至关重要的作用。【目的】研究陆地土壤和海洋沉积物间细菌群落相似性和差异性,以便更好地认识海洋细菌多样性,深入了解沉积物细菌在海洋环境中的潜在作用。【方法】从中国黄海海域及大连市大黑山脚下分别采集样品,以陆地土壤为对照,采用16SrRNA基因高通量测序技术分析海洋沉积物的细菌群落结构。【结果】海洋沉积物样品中芽孢杆菌纲(Bacilli)、鞘氨醇单胞菌属(Sphingomonas)和芽孢杆菌属(Bacillus)丰度高于陆地土壤样品;海洋沉积物中亚硝化单胞菌(unculturedbacterium f. Nitrosomonadaceae)和厌氧绳菌(uncultured bacterium f. Anaerolineaceae)丰度虽低于陆地土壤,但丰度值也均高于1%;样品分类学统计显示酸杆菌门(Acidobacteria)在海洋沉积物和陆地土壤样品中的序列丰度比例都较大,鞘氨醇单胞菌属(Sphingomonas)在海洋沉积物样品中的序列丰度大于陆地土壤样品。【结论】海洋沉积物细菌多样性可作为海洋环境恢复情况的重...     

Seasonal variation in Arctic marine mammal acoustic detection in the northern Bering Sea

Declines in Arctic sea ice cover are influencing the distribution of protected endemic marine mammals, many of which are important for local Indigenous Peoples, and increasing the presence of potentially disruptive industrial activities. Due to increasing conservation concerns, we conducted the first year-round acoustic monitoring of waters off Gambell and Savoonga (St. Lawrence Island, Alaska), and in the Bering Strait to quantify vocalizing presence of bowhead whales, belugas, walruses, bearded seals, and ribbon seals. Bottom-mounted archival acoustic recorders collected data for up to 10 months per deployment between 2012 and 2016. Spectrograms were analyzed for species-typical vocalizations, and daily detection rates and presence/absence were calculated. Generalized additive models were used to model call presence as a function of time-of-year, sea surface temperature, and sea ice concentration. We identified seasonality in call presence for all species, corroborating previous acoustic and distribution studies, and identified finer-scale spatiotemporal distribution via occurrence of call presence between different monitoring sites. Time-of-year was the strongest significant effect on call presence for all species. These data provide important information on Arctic endemic species' spatiotemporal distributions in biologically and culturally important areas within a rapidly changing Arctic region.     

Genotoxic potential of marine sediments from the North Sea

The alkaline comet assay is a method for detecting DNA strand breaks and alkali labile sites in individual cells. An in vitro system was used to investigate the genotoxic potential of complex mixtures such as organic extracts of marine sediments. DNA damage was induced in leukocytes isolated from carp (Cyprius carpio) by exposure to organic sediment extracts from the North Sea or hydrogen peroxide as positive control, respectively. The minimum concentration for significant effects ranged from 1 to 40 mg sediment dry weight per milliliter assay volume. The sensitivity of the method was enhanced by using the DNA repair inhibitor, 1-beta-D-arabinofuranosylcytosine (ara C). From the results, it can be suggested that total organic carbon (TOC) as well as the different compositions of contaminants present in the sediment extracts may contribute to the genotoxic effects observed. The comet assay can be applied successfully as an in vitro bioassay for investigations on genotoxicity of marine sediment extracts.     

Bio-availability of phosphorus in sediments of the western Dutch Wadden Sea

The purpose of this study was to make a prognosis of the effects of extended purification of terrestrial waste water, reaching the Wadden Sea by the River Rhine and Lake IJssel, on the phosphate concentration in the western Wadden Sea.The quantities of different phosphorus fractions in intertidal and subtidal sediments of the Marsdiep tidal basin (western Dutch Wadden Sea) were measured. Different methods are applied to determine the amount of phosphorus that can be released from these sediments. The direct bioavailability is determined by inoculating sediment suspensions with a natural mixture of precultured micro-organisms from the sampling area. A second approach is the measurement of the phosphate release under different redox conditions. Sequential extraction of sediment samples with different solvents is also applied. Under the present conditions and compared to the nutrient loads from fresh water (Lake IJssel) and from the North Sea, the phosphorus stored in the sediments of the western Dutch Wadden Sea plays a minor role in the total supply to micro-algae and bacteria. The bulk of the biologically available phosphorus in the sediments originates from the metal-associated fraction. Releasable phosphate may contribute to the local annual primary production to an extent of ca 45 to ca 150 g C m^–2 a^–1. The total amount of phosphorus in the sediment (mainly calcite associated) is twice to 6 times the biologically available amount.     

楚科奇海及白令海大型底栖生物初步研究

1999年夏季在楚科奇海、白令海采用30 cm×30 cm箱式取样器,取得16个站位大型底栖生物定量样品。经分析研究有大型底栖生物92科164种,其中多毛类、软体动物和甲壳动物种数最多,占总种数的88.41％,三者构成北极楚科奇海和白令海大型底栖生物的主要类群。优势种有独毛虫属一种(Tharyx sp.) 、齿吻沙蚕属一种(Nephtys sp.)、囊叶齿吻沙蚕(Nephtys caeca)、平滑胡桃蛤(Ennucula tenuis)、短吻状蛤(Nuculana pernula pernuloides)、拟猛钩虾属一种( sp.)、日本沙钩虾(Byblis japonicus)和萨氏真蛇尾(Ophiura sarsii)等。楚科奇海和白令海大型底栖生物平均生物量为111.83 g/m²,平均栖息密度为2538个/m²。生物量和栖息密度均以多毛类和软体动物占多数。楚科奇海和白令海大型底栖生物有5个群落类型：Ⅰ. 梯额虫(Scalibregma inflatum)-紫轮参(Polycheira rufescens)-结栉盖蛇尾(Stegophiura nodosa)群落, Ⅱ. 拟单指虫(Cossurella sp.)-平滑胡桃蛤-鳞甲钩虾(Lepidepecreum sp.)群落, Ⅲ. 缩头竹节虫(Maldane sarai)-葛氏希泊钩虾(Hippomedon gorbunovi)-萨氏真蛇尾群落, Ⅳ.齿吻沙蚕(Nephtys sp.)-平滑胡桃蛤-日本沙钩虾-戈芬星虫(Golfingia sp.)群落和白令海群落, 即索沙蚕(Lumbrineris fragilis)-户枢蛤(Asthenothaerus sp.)-太平洋方甲涟虫(Eudorella pacifica)-革囊星虫(Phascolion sp.)群落。楚科奇海的群落Ⅰ、群落Ⅱ和白令海各群落结构相对稳定;楚科奇海群落Ⅲ和群落Ⅳ出现一定扰动。     

Distribution of recent planktonic foraminifera in surface sediments of the Mediterranean Sea

The Mediterranean Sea is a partillay isolated ocean where excess evaporation over precipitation results in large east to west gradients in temperature and salinity. Recent planktonic foraminiferal distributions have been examined in 66 surface sediment samples from the Mediterranean Sea. In addition to mapping the frequency distribution of 16 species, the faunal data has been subjected to cluster analysis, factor analysis and species diversity analysis. The clustering of species yields assemblages that are clearly temperature related. A warm assemblage contains both tropical and subtropical elements, while the cool assemblage can be subdivided into cool-subtropical, transitional and polar-subpolar groupings. Factor analysis is used to delineate the geographic distribution of four faunal assemblages. Factor 1 is a tropical-subtropical assemblage dominated by Globigerinoiden ruber. It has its highest values in the warmer eastern basin. Transitional species (Globorotalia inflata and Globigerina bulloides) dominate factor 2 with highest values occurring in the cooler western basin. Factor 3 reflects the distribution of Neogloboquadrina dutertrei and is considered to be salinity dependent. Subpolar species dominate factor 4 (Neoglobuquadrina pachyderma and G. bulloides), with highest values occurring in the northern part of the western basin where cold bottom water is presently being formed. The Shannon-Weiner index of species diversity shows that high diversity exists over much of the western basin and immediately east of the Strait of Sicily. This region is marked by equitable environmental conditions and relatively even distribution of individuals among the species. Conversely, in areas where temperature and salinity values are more extreme, diversity values are lower and the assemblages are dominated by one or two species.     

Zoogeographical subdivision of the pelagic zone of the western Bering Sea based on nekton species ranges

The subdivision of the western Bering Sea into zoogeographical regions for nekton fauna was carried out using data from 40 pelagic trawl surveys made by the Pacific Fisheries Research Center. The selected approach involves computer methods for plotting a map that describes the spatial distribution of the index of latitudinal zoning in the form of continuous fields. This index is a digital designation of verbally formulated types of latitudinal species areas. Computer mapping of the region was performed based on generalized data; intraday, seasonal, and interannual time aspects; and trawling depths. According to generalized data, almost the entire western part of the Bering Sea belongs to the high-boreal latitudinal subzone. A small area of the low-boreal subzone occurs only in the southeast of the open part of the sea. The average value of the latitudinal zoning index and its variation significantly decreased with increasing depth. From the upper epipelagic to the mesopelagic layer, the degree of subdivision decreased and the results of zoning of the mesopelagic layer were substantially different from all other zoning results.     

Low nekton abundance in the western Bering Sea according to trawl survey data and model estimates

Complex trawl surveys were conducted in the upper epipelagic zone of the western Bering Sea and adjacent Pacific waters in the summer and fall seasons of 2002–2006. The abundance of small nekton (micronekton) was estimated using two independent methods: traditional trawling and a mathematical model of selective feeding by fish. According to the trawl data, total micronekton density varied from 1 to 158 (average 40) mg/m³ on the northwestern Bering Sea shelf and from 6 to 151 (37) mg/m³ in deep-water areas of the southwestern Bering Sea and adjacent Pacific waters. According to model calculations, micronekton density was higher—72–193 (141) mg/m³ on the shelf and 78–507 (228) mg/m³ in the deep-water part of the studied area. Both trawl and model data showed that small nekton on the northwestern shelf mostly consisted of larval and juvenile walleye pollock, as well as small fish species, such as capelin and Pacific sand lance. In the deepwater areas, mesopelagic fish and squid (northern lampfish, northern smoothtongue, and boreopacific gonate squid), which migrate to the surface at night, juvenile Atka mackerel, and shortarm gonate squid dominated among micronekton. The advantages and disadvantages of both the trawl and model methods for calculating the abundance of small fish and squid were considered. Comparison of abundance estimates for mass fish species, obtained through trawl and model methods, enabled us to analyze trawl catchability coefficients and propose a more differentiated division of micronekton into size classes than had been done earlier. A function that characterizes the dependence of the catchability coefficient (CC) on body length was offered for juvenile Atka mackerel. This equation can be also used for evaluation of CC for other fishes that have similar size and behavior.     

甲藻孢囊在长山群岛海域表层沉积物中的分布

2007年10月,在大连长山群岛海域采集了25个站点的表层沉积物,研究了甲藻孢囊的水平分布。在沉积物样品中共检测出甲藻孢囊46种,其中Pentaphasodinium dalei和Warowia rosea,在我国是首次报道。各站位孢囊种类数在7-20之间,平均14种;丰度在182-2960 个/g干重之间,平均为1201 个/g干重。香农-威纳指数(H')的变化范围为2.4-3.4。麻痹性贝毒藻--亚历山大藻的孢囊在调查海域分布广泛,最高密度达829个/g干重,可能是造成该海域虾夷扇贝贝毒超标的原因之一。     

"Dinoflagellate Sterols" in marine diatoms

Sterol compositions for three diatom species, recently shown to contain sterols with side chains typically found in dinoflagellates, were determined by HPLC and ¹H NMR spectroscopic analyses. The centric diatom Triceratium dubium (= Biddulphia sp., CCMP 147) contained the highest percentage of 23-methylated sterols (37.2% (24R)-23-methylergosta-5,22-dienol), whereas the pennate diatom Delphineis sp. (CCMP 1095) contained the cyclopropyl sterol gorgosterol, as well as the 27-norsterol occelasterol. The sterol composition of Ditylum brightwellii (CCMP 358) was the most complex, containing Δ⁰- and Δ⁷-sterols, in addition to the predominant Δ⁵-sterols. A pair of previously unknown sterols, stigmasta-5,24,28-trienol and stigmasta-24,28-dienol, were detected in D. brightwellii and their structures were determined by NMR spectroscopic analysis and by synthesis of the former sterol from saringosterol. Also detected in D. brightwellii was the previously unknown 23-methylcholesta-7,22-dienol.     

Pelagic Food Chain of the Bering Sea

Journal of Ichthyology - The order of magnitude of biomass and production at various trophic levels in the epipelagic community has been calculated, and the main pathways for the transformation of...     

Geochemistry of recent marine sediments in the Bardawil lagoon,northern Sinai,Egypt

The concentrations of major (Al, Fe, Mg, Ti, K and Na) and minor (Ba, Sr, V, Cu, Mn, Cr, Ni, Zn, Pb and Mo) elements as well as carbonate, organic carbon and total nitrogen have been determined in surface sediments collected at 12 stations from the Bardawil lagoon. The aim of the study was to characterize the geochemistry of the sediments in three different environments, the lagoon, the salt pans and the inlet between the lagoon and the Mediterranean Sea. Higher CaCO₃ percentage (53.5–70.5%) were found in the salt pans where biogenic calcareous components and carbonate rock fragments were found in sufficient quantities in the sediment fractions. Based on high C/N ratios, the organic carbon fraction of the Bardawil lagoon surface sediments is clearly dominated by terrigenous material. The distribution of Al, Fe, Mg and Ti are essentially controlled by the mineralogy of the sediments. The ratios of Ba, Sr, Cu, Mn, Pb and Mo to Al are all high in the salt pans and reflect changes in mineralogy and sediment texture.     

PCB contamination in marine sediments from Golfo Dulce, Pacific coast of Costa Rica

Twenty-nine marine sediment samples collected from 1996 through 2002 from the Golfo Dulce embayment of Costa Rica were analyzed for PCB concentrations. The Esquinas River and Rincon Bay in the northern and western part of the gulf had relatively low overall concentrations of PCBs, with no samples having greater than 2.1 microg/g dw sediment. The Port of Golfito had the highest overall concentrations, ranging up to 15.7 microg/g dw sediment. These samples were also dominated by higher chlorinated congeners. Samples from the deeper (> 100 m) waters in the northern part of the gulf, as well as within the sediment plume from the Rio Coto Colorado had intermediate values. Within the Rio Coto Colorado sediment plume the concentrations did decrease with increasing depth and the congeners showed a shift towards less chlorinated congeners with depth. However, the deep northern basin had some of the highest PCB concentrations and the shift towards less chlorinated congeners was not apparent or significant. Whether the anoxic conditions that exist in the deep waters are capable of initiating dechlorination is still unknown. Overall, the data from Golfo Dulce show moderate PCB contamination, despite the pristine nature of the gulf and surrounding lands.