Kiitricha minuta n. Sp., a peculiar hypotrichous ciliate (Ciliophora, Spirotrichea) from the Yellow Sea

The morphology and infraciliature of a new ciliate, Kiitricha minuta n. sp., isolated from the Yellow Sea, were investigated using live observation and protargol impregnation. Kiitricha minuta represents a third member of the rarely known order Kiitrichida. It is unique in the subclass Hypotrichia in having many rows of small uniform cirri along the right side of the body and the dorsal kineties composed of dikinetids, most of which bear two cilia. Kiitricha minuta n. sp. is ovoid and measures about 60 x 45 mu m in vivo. It has a huge buccal cavity occupying about 80% of the body length, numerous body extrusomes, one macronucleus and two micronuclei, 27-27 adoral membranelles, 9-12 frontoventral cirral rows, a submarginal row of 7-9 cirri, 6 or 7 transverse cirri, and roughly 7-9 dorsal kineties. This new species differs distinctly from its only congener Kiitricha marina by its smaller size (60 mu m vs. 80-150 mu m), the presence of body extrusomes (vs. absent), the different macronuclear pattern (one vs. two nodules), and the lower number of frontoventral cirral rows (9-12 vs. 21-26), which terminate at the anterior two-thirds of body (vs. extend to the posterior). The new term "submarginal cirral row" is introduced to distinguish from the marginal cirral row in typical hypotrichs sensu lato. Based on our new observations and the literature, an improved diagnosis for the genus Kiitricha is provided and its phylogenetic importance is discussed.

Trichodinid ectoparasites (Ciliophora, Peritrichia) from the tiger puffer Takifugu rubripes in the Yellow Sea, with revision of Trichodina jadranica Raabe,1958

Two ectoparasitic ciliates, Trichodina fugu Imai et al., 1997 and T. jadranica Raabe, 1958, found on the gills and skin of the maricultured tiger puffer Takifugu rubripes on the China coast of the Yellow Sea, were studied using the dry silver nitrate method. Trichodina fugu is distinguished by its almost rod-shaped denticle blades. Trichodina jadranica is usually described as a small trichodinid with a clear central circle in the adhesive disc and with a low number of denticles. However, the data available suggest that the species is highly variable in morphometry and the Chinese population represents the largest in body size and denticle dimensions found to date. Based on the revision of T. jadranica, two major morphotypes, each represented by several populations are classified, differing in the shape of the blades, viz., distinctly curved and sickle-shaped with pointed distal ends (as in the classical T. jadranica) vs. less curved and more or less rectangle-like with rounded distal ends (as in T. domerguei gobii). Trichodina domerguei gobii Raabe,.1959, which was synonymised with T. jadranica, is thus elevated to species rank. Furthermore, Trichodina jadranica noblei Lom, 1970 has straight and stout blades with broadly rounded distal ends and is raised to species rank: T noblei Lom, 1970. Trichodina jadranica sensu Xu et al., 1995 shows high similarities in denticle shape and dimensions as well as the central granule pattern with T chlamydis Xu et al., 1999. Thus, it is synonymised with the latter species.

On two species of euxanthine crabs from the South China Sea, including a description of a new species of Crosnierius (Crustacea : Decapoda : Brachyura : Xanthidae)

A new species of the previously monotypic xanthid genus Crosnierius Serene & Vadon, 1981 is described from the South China Sea. The species differs from Crosnierius carinatus Serene & Vadon, 1981 in the structure of the anterolateral teeth, ambulatory leg proportions and form of the male first pleopod. Paramedaeus planifrons (Sakai, 1965) is also reported from the South China Sea, the first record of the species outside its type locality of Japan.

On a new genus and new species of xanthid crab (Crustacea, Decapoda, Brachyura, Xanthinae) from the South China Sea, with notes on the genus Liagore De Haan, 1833

A new genus and new species of xanthid crab, Ovatis simplex, is described from the South China Sea. The genus is closest to Liagore but can be distinguished by a suite of carapace and male gonopod characters. The systematic position of Liagore is also considered, and both genera, Liagore and Ovatis, are here referred to the subfamily Xanthinae. Comparisons with the allied genera, Paratergatis and Pulcratis, are also provided.

Fatty acids of some algae from the Bohai Sea

The fatty acid compositions of 22 species of marine macrophytes, belonging to the Ceramiales, Cryptonemiales, Nemalionales, Laminariales, Chordariales, Scytosiphonales, Desmarestiales, Dictyosiphonales, Fucales, Dictyotales and Ulvales and collected from the Bohai Sea, were determined by capillary gas chromatography. The contents of polyunsaturated fatty acids (FAs) in the Bohai Sea algae, in comparison with the same species from the Yellow Sea were found to be lower. Red algae had relatively high levels of the acids 16:0, 18:1(n-7), 18:1(n-9), 20:5(n-3) and 20:4(n-6), and those examined were rich in C-20 PUFAs, these chiefly being arachidonic and eicosapentaenoic acids. The major FAs encountered in the Phaeophyta were 14:0, 16:0, 18:1(n-9), 18:2(n-6), 18:3(n-3), 18:4(n-3), 20:4(n-6) and 20:5(n-3). C18PUFAs are of greater abundance in the brown algae than in the red algae examined. All three green algae from the Ulvales had similar fatty acid patterns with major components, 16:0, 16:4(n-3), 18:1(n-7), 18:2(n-6), 18:3(n-3), and 18:4(n-3). They contained 16:3(n-3) and more 16:4(n-3), were rich in C18PUFAs, chiefly 18:3(n-3) and 18:4(n-3) and had 18:1(n-7)/18:1 (n-9) ratios higher than 1. (C) 2002 Elsevier Science Ltd. All rights reserved.

Necessity of dietary lecithin and eicosapentaenoic acid for growth, survival, stress resistance and lipoprotein formation in gilthead sea bream Sparus aurata

The substitution of dietary docosahexaenoic acid (DHA) with eicosapentaenoic acid (EPA) reduces larval growth in gilthead sea bream. However, the value of EPA when dietary DHA is able to meet the requirements of the larvae has not been sufficiently studied. Dietary phosphoacylgliceride levels also affect fish growth and it has been suggested that they enhance lipid transport in developing larvae. The present experiment was carried out to further study the effect of dietary lecithin and eicosapentaenoic acid on growth, survival, stress resistance,. larval fatty acid composition and lipid transport, when DHA is present in the microdiets of gilthead:sea bream. Eighteen thousand gilt-head sea bream larvae of 4.99+/-0.53 mm total length were fed three microdiets tested by triplicate: a control diet [2% soybean lecithin (SBL) and 2.89% EPA], a low EPA diet,(2% SBL and 1.63% EPA) and a no SBL diet (0% SBL and 2.71% EPA). Handling, temperature and salinity tests determined larval resistance to stress. The results show that when dietary DHA levels are high, but dietary arachidonic acid (ARA) levels are about 0.2%, EPA is necessary to improve larval growth, and survival. Larval EPA content, but not DHA or ARA, was affected by dietary EPA levels. Increased dietary EPA improved larval stress resistance to handling and temperature tests, which could be related to its possible role as a regulator of cortisol production whereas it did not affect stress resistance after salinity shock. Larvae fed the no SBL diet showed a lower lipid content characterized by a low proportion of saturated and monounsaturated fatty acids, together with a significant reduction in the appearance of lipoprotein particles in the lamina propria and in the size of such particles, denoting a critical reduction in dietary lipid transport and utilization, and lower larval growth and survival rates.

Acute peristome edema disease in juvenile and adult sea cucumbers Apostichopus japonicus (Selenka) reared in North China

Acute peristome edema disease (APED) is a new disease that broke out in cultured sea cucumber along the Shangdong and Liaoning province coasts in China, PR, and has caused a great deal of death in Apostichopus japonicus (Selenka) since 2004. Here we report virus-like particles found in intestine epithelium of sea cucumbers reared in North China. It is the first time that sea cucumbers are reported to be infected by virus. Histological examinations showed that the viral inclusion bodies existed in intestine epithelium cells. Electron microscopic examinations show that the virions were spherical, 80-100 nm in diameter, and composed of a helical nucleocapsid within an envelope with surface projections. Detailed studies on the morphogenesis of these viruses found many characteristics previously described for coronaviruses. Virus particles always congregated, and formed a virus vesicle with an encircling membrane. The most obvious cellular pathologic feature is large granular areas of cytoplasm, relatively devoid of organelles. Tubular structures within virus-containing vesicles, nucleocapsid inclusions, and double-membrane vesicles are also found in the cytopathic cells. No rickettsia, chlamydia, bacteria, or other parasitic organisms were found. (c) 2007 Elsevier Inc. All rights reserved.

Preliminary studies on the vitrification of red sea bream (Pagrus major) embryos

The objective was to identify an appropriate cryoprotectant and protocol for vitrification of red sea bream (Pagrus major) embryos. The toxicity of five single-agent cryoprotectants, dimethyl sulfoxide (DMSO), propylene glycol (PG), ethylene glycol (EG), glycerol (GLY), and methyl alcohol (MeOH), as well as nine cryoprotectant mixtures, were investigated by comparing post-thaw hatching rates. Two vitrifying protocols, a straw method and a solid surface vitrification method (copper floating over liquid nitrogen), were evaluated on the basis of post-thaw embryo morphology. Exposure to single-agent cryoprotectants (10% concentration for 15 min) was not toxic to embryos, whereas for higher concentrations (20 and 30%) and a longer duration of exposure (30 min), DMSO and PG were better tolerated than the other cryoprotectants. Among nine cryoprotectant mixtures, the combination of 20% DMSO + 10% PG + 10% MeOH had the lowest toxicity after exposure for 10 min or 15 min. High percentages of morphologically intact embryos, 50.6 +/- 16.7% (mean +/- S.D.) and 77.8 +/- 15.5%, were achieved by the straw vitrifying method (20.5% DMSO + 15.5% acetamide + 10% PG, thawing at 43 degrees C and washing in 0.5 M sucrose solution for 5 min) and by the solid surface vitrification method (40% GLY, thawing at 22 degrees C and washing in 0.5 M sucrose solution for 5 min). After thawing, morphological changes in the degenerated embryos included shrunken yolks and ruptured chorions. Furthermore, thawed embryos that were morphologically intact did not consistently survive incubation. (C) 2007 Elsevier Inc. All rights reserved.

Corrosion of steel structures in sea-bed sediment

Seabed sediment (SBS) is a special soil that is covered by seawater. With the developments in marine oil exploitation and engineering, more and more steel structures have been buried in SBS. SBS corrosion has now become a serious problem in marine environment and an important issue in corrosion science. In this paper, approach in the field of SBS corrosion is reviewed. Electrochemical and microbial corrosion factors, corrosion mechanism, measurement of metal corrosion rate, corrosion evaluation and prediction of corrosion are also discussed here.

Corrosion failure of marine steel in sea-mud containing sulfate reducing bacteria

The corrosion failure behavior of marine steel is affected by stress, which exists in offshore structures at sea-mud region. The sulfate reducing bacteria (SRB) in the sea-mud made the steel more sensitive to stress corrosion cracking (SCC) and weaken the corrosion fatigue endurance. In this paper, a kind of natural sea-mud containing SRB was collected. Both SCC tests by slow strain rate technique and corrosion fatigue tests were performed on a kind of selected steel in sea-mud with and without SRB at corrosion and cathodic potentials. After this, the electrochemical response of static and cyclic stress of the specimen with and without cracks in sea-mud was analyzed in order to explain the failure mechanism. Hydrogen permeation tests were also performed in the sea-mud at corrosion and cathodic potentials. It is concluded that the effect of SRB on environment sensitive fracture maybe explained as the consequences of the acceleration of SRB on corrosion rate and hydrogen entry into the metal.

Effects of anaerobe in sea bottom sediment on the corrosion of carbon steel

The in-situ study of steel corrosion in sea bottom sediment (SBS) was carried out by Transplanting Burying Plate method (TBP method). It was found that the corrosion rate of steel in the sea bottom sediment with sulfate reducing bacteria (SRB) could be as high as ten times of that in sea bottom sediment without SRB. The experiments in simulated sea bottom sediments with different SRB contents by artificial culturing showed that the electrochemical behavior of steel in the sea bottom sediment with SRB was different from that without SRB. SRB altered the polarization behavior of steel significantly. The environment was acidified due to the activity of SRB and the corrosion of steel was accelerated. The corrosion of carbon steel in sea bottom sediment is anaerobic corrosion, and the main factor is anaerobe. There are SRB commonly in SBS, and the amount of SRB decreases along with the depth of sediment. Because of the asymmetry and variation of sea bottom sediment, the most dangerous corrosion breakage of steel in SBS is local corrosion caused by SRB. So the main countermeasure of corrosion protection of sea bottom steel facilities should be controlling of the corrosion caused by anaerobe.

Alloy elements' effect on anti-corrosion performance of low alloy steels in different sea zones

The corrosion rate of low alloy steel in different sea zones has close correlation with the content of the alloy element. From the field data of steel corrosion rates in atmospheric zone, splash zone and immersion zone, regression analysis was used to study the correlation between the corrosion rate of steels and the amount of added alloy elements. Three regression equations were obtained in different sea zones. Based on the equations, the anti-corrosion performance of the alloy elements can be deduced which can be used to screen out low alloy steel with good anti-corrosion performance. (C) 2007 Elsevier B.V. All rights reserved.

Effect of sulfate-reducing bacteria on corrosion behavior of mild steel in sea mud

Microbiologically influenced corrosion (MIC) is very severe corrosion for constructions buried under sea mud environment. Therefore it is of great importance to carry out the investigation of the corrosion behavior of marine steel in sea mud. In this paper, the effect of sulfate-reducing bacteria (SRB) on corrosion behavior of mild steel in sea mud was studied by weight loss, dual-compartment cell, electronic probe microanalysis (EPMA), transmission electron microscopy (TEM).combined with energy dispersive X-ray analysis (EDX) and electrochemical impedance spectroscopy (EIS). The results showed that corrosion rate and galvanic current were influenced by the metabolic activity of SRB. In the environment of sea mud containing SRB, the original corrosion products, ferric (oxyhydr) oxide, transformed to iron sulfide. With the excess of the dissolved H2S, the composition of the protective layer formed of FeS transformed to FeS2 or other non-stoichiometric polysulphide, which changed the state of the former layer and accelerated the corrosion process.

The hydrogen permeation investigation of API X56 steel in sea mud

It was found that the corrosion rate of steel in the sea mud with sulfate-reducing bacteria (SRB) could be as high as 10 times of that in the sea mud without SRB. And the hydrogen permeation reaction would occur when metals were corroded. So it is necessary to investigate the effect of living SRB on hydrogen permeation in the sea mud. Cathodic potential was often added to metals in order to protect them. But hydrogen permeation could be affected by the cathodic potential. So it is also necessary to study the effect of cathodic potential on hydrogen permeation. In this paper, the hydrogen permeation actions of APT X56 steel in the sea mud with and without SRB at corrosion and cathodic potential were studied with an improved Devanathan-Stachurski's electrolytic cell. Experimental results showed that during the growth of SRB, the current density curve of hydrogen permeation was accordant with the growth curve of SRB. But the hydrogen permeation current density of APT X56 steel hardly changed in the sterilized sea mud. Compared with the hydrogen permeation current density of APT X56 steel in the sterilized sea mud, the hydrogen permeation of APT X56 steel in the sea mud could be accelerated by living SRB. Experimental results also showed that the hydrogen permeation current density increased rapidly when the cathodic potential was added to the three-electrode system of the cathodic cell, and then the hydrogen permeation current density could obtain a stable value slowly. So the cathodic potential added to the cathodic cell could accelerate hydrogen permeation.