A new species of Allocreadium (Trematoda : Allocreadiidae) from freshwater fishes in the Danjiangkou Reservoir in China

A new species of Allocreadium, Allocreadium danjiangensis n. sp., is described from the intestine of several species of freshwater fish, including Abbottina rivularis (Basilewsky, 1855), Sarcocheilichthys nigripinnis nigripinns (Gunther, 1873), Gnathopogon argentatus (Sauvage et Dabry 1874), Opsariichthys uncirostris bidens (Gunther, 1873), and Erythroculter mongolicus mongolicus (Basilewsky, 1855) (Cyprinidae) from the Danjiangkou Reservoir in central China. The main morphological characters of the new species are as follows: vitelline follicles numerous, extending from the level of acetabulum to posterior extremity, distributed over both sides around the ceca; cirrus sac relatively large, developed, lying obliquely anterior to the acetabulum, extending from the level of the intestinal bifurcation to the central level of acetabulum, and overlapping left or right cecal; and ovary much smaller than testes, generally close to or even overlapping the anterior border of anterior testis. Observation by scanning electron microscopy shows only 2 kinds of tegumental formations, i.e., papillae and tubercles, instead of 3 types of tegumental formations, i.e., papillae, bosses, and minute sensor receptors observed on other species of the Allocreadiidae. The tegumental striations of the present species vary on the different parts of the body. In addition, a new structure, identified as the "groove" with a tonguelike tubercle, was observed on the inner wall of acetabulum.

Monitoring bioaccumulation and toxic effects of hexachlorobenzene using the polyurethane foam unit method in the microbial communities of the Fuhe River, Wuhan

Hexachlorobenzene (HCB) is a chlorinated aromatic hydrocarbon that was widely used for seed dressing in prevention of fungal growth on crops, and also as a component of fireworks, ammunition, and synthetic rubbers. Because of its resistance to degradation and mobility, HCB is widely distributed throughout the environment and is accumulated through food chains in different ecosystems. In this study, a preliminary investigation was carried out on the bioaccumulation and the toxic effects of HCB in the microbial (protozoan in particular) communities in the Fuhe River, Wuhan, a water body receiving industrial wastewaters containing HCB and other pollutants, using the standardized polyurethane foam units (PFU) method. Field samples were taken from eight stations established along the Fuhe River in January and August 2006. The concentration ratios of HCB in microbial communities and in water were 9.66-18.64, and the microbial communities accumulated 13.29-56.88 mu g/L of HCB in January and 0.82-10.25 mu g/L HCB in August. Correlation analysis showed a negative correlation between the HCB contents in the microbial assemblage, and the number of species and the diversity index of the protozoan communities. This study demonstrated the applicability of the PFU method in monitoring the effects of HCB on the level of microbial communities.

Biodiversity changes in the lakes of the Central Yangtze

The Central Yangtze ecoregion in China includes a number of lakes, but these have been greatly affected by human activities over the past several decades, resulting in severe loss of biodiversity. In this paper, we document the present distribution of the major lakes and the changes in size that have taken place over the past 50 years, using remote sensing data and historical observations of land cover in the region. We also provide an overview of the changes in species richness, community composition, population size and age structure, and individual body size of aquatic plants, fishes, and waterfowl in these lakes. The overall species richness of aquatic plants found in eight major lakes has decreased substantially during the study period. Community composition has also been greatly altered, as have population size and age and individual body size in some species. These changes are largely attributed to the integrated effects of lake degradation, the construction of large hydroelectric dams, the establishment of nature reserves, and lake restoration practices.

The toxicities of single-celled Microcystis aeruginosa PCC7820 and liberated M-aeruginosa to Daphnia carinata in the absence and presence of the green alga Scenedesmus obliquus

We evaluated the toxic effect of Microcystis aeruginosa on Daphnia carinata King using survival rate, population growth rate, and body length. When fed Microcystis aerugionsa PCC7820 and liberated colonial Microcystis spp., all D. carinata died within five days. When fed a mixture of M. aeruginosa PCC7820 and the green alga Scenedesmus obliquus, the survival rate, population growth rate, and body length of D. carinata generally increased. The survival rates were all above 80% after ten days. However, with liberated colonial M. aeruginosa, the toxic effect on D. carinata was more pronounced, and only at higher concentration of S. obliquus did that toxic effect abate. Our results indicated that green algae could greatly weaken the toxic effect of cyanobacteria.

The Yangtze River dolphin or baiji (Lipotes vexillifer): population status and conservation issues in the Yangtze River, China

1. Baiji were sighted 17 times during three recent simultaneous multi-vessel surveys in the Yangtze River, China (November 4-10, 1997; December 4-9, 1998; October 31-November 5, 1999). There were 11 sightings in 1997 (consisting of 17 animals), five in 1998 (seven animals), and two in 1999 (four animals). It was concluded that 13 individuals Could be considered as a minimum number of the baiji currently in the Yangtze River. 2. An annual rate of population decrease was roughly estimated as 10%. From the body sizes observed, the proportions of old, adult and immature individuals were approximately estimated at 57, 26, and 17% respectively. 3. Baiji showed a significant attraction to confluences and sand bars with large eddies. The present distribution range of the baiji is less than 1400 km in length in the Yangtze main river. Distances between the two nearest groups of baiji appear to be increasing. 4. Two typical sightings are described, in which surfacing and movements of baiji were recorded. Baiji were often found swimming together with finless porpoise. In the surveys they occurred in the same group in 63% of occurrences. Interactions between baiji and finless porpoise are described and discussed. 5. Human activities are the main threats to the baiji. Illegal electrical fishing accounted for 40% of known mortalities during the 1990s. Engineering explosions for maintaining navigation channels have become another main cause of baiji deaths. The last hope of saving the species may be to translocate the remaining baiji into a semi-captive reserve. known as the 'Baiji Semi-natural Reserve'. Copyright (C) 2003 John Wiley Sons, Ltd.

Bioaccumulation of polychlorinated dibenzo-p-dioxins and dibenzofurans in the foodweb of Ya-Er Lake area, China

Bioaccumulation of PCDD/F in the foodweb was investigated in the Ya-Er Lake area, which was heavily polluted by PCDD/F. The high concentrations of PCDD/F in sediment can be transferred and bioaccumulated by aquatic organisms and humans through various pathways. Benthonic invertebrate animals and aquatic plants with a lot of fibers in the root can accumulate PCDD/F from sediment and water. Snail (Bellamya aeruginosa), shrimp (Macrobranchium sp.) and freshwater mussel (Acuticosta chinensis (Lea)) took up PCDD/F from the water and maintained the emission patterns, whereas fish tended to selectively accumulate 2,3,7,8-substituted isomers. The tissues of fish-eating bird and duck (Anas platyrhynchos) were very highly contaminated by PCDD/F due to ingestion of fish and other aquatic organisms from sediment. The residual concentration in breast milk depended on the original concentration of PCDD/F in the food. A resident in Ya-Er Lake area showed a daily intake of PCDD/ F of about 9.14 pg TEQ/kg body weight/day. This is higher than the tolerable daily intake (TDI) for PCDD/F (1 pg TEQ/kg body weight/day), which was recommended by the World Health Organization (WHO). (C) 2001 Elsevier Science Ltd. All rights reserved.

Seasonal patterns in feeding ecology of three small fishes in the Biandantang Lake, China

Feeding ecology of three small fish species, Hypseleotris swinhonis, Ctenogobius giurinus and Pseudorasbora parva was studied seasonally in the Biandantang Lake, a small, shallow lake in central China. Gut length, adjusted for total body length, was significantly higher in spring than in other seasons for all the three species. Seasonal changes in gut length were not associated with changes in food quality. Weight of fore-gut contents, adjusted for body weight, was significantly higher in winter and spring than in summer and autumn in H. swinhonis and C. giurinus, and significantly higher in autumn than in spring and summer for P. parva. Percentage of empty fore-guts was highest in summer and lowest in spring for I-I. swinhonis and C. giurinus, and highest in winter and lowest in autumn for P. parva. Diet of the three small fishes showed apparent seasonal changes, and these changes reflected partly the seasonal fluctuations of food resources in environment. Diet breadth was high in winter and low in autumn for H. swinhonis, high in winter and low in spring and summer for C. giurinus, and high in autumn and low in spring for P. parva. Diet overlaps between pairs of species were biologically significant in most cases, except between H. swinhonis and P. parva in summer and autumn and between C. giurinus and P. parva in autumn. (C) 2000 The Fisheries Society of the British Isles.

Induction of triploidy in large yellow crocker Pseudosciaena crocea (Richardson, 1846): effects of pressure shocks and growth performance in the first rearing year

The precociously sexual maturation in large yellow crocker Pseudosciaena crocea has become a serious problem. In an attempt to solve this problem, the production of sterile triploids could be an effective strategy. In this study, triploid P. crocea was obtained by subjecting fertilized eggs to pressure shock. Flow-cytometry analysis was used to assess ploidy level. In terms of triploid rate and hatching rate, the optimal conditions of pressure shock for triploidy induction in P. crocea were 7500 psi for 3 min shock at 3 min after fertilization at 20 degrees C. With the application of these parameters, 100% triploid fish were produced. During the first rearing year, triploid P. crocea had a similar growth performance compared with its diploid counterpart before the age of 8 months and showed a significant advantage at the age of 10 and 12 months in body weight and body length (P < 0.05). At the age of 12 months, the carcass weight of triploids was markedly higher than that of diploid control, and gonadal somatic index was significantly lower than that of their diploid control. During the first rearing year, survival in triploid group was 76.44%, inferior to its diploid control (83.21%).

Early expressed genes showing a dichotomous developing pattern in the lancelet embryo

Lancelets (amphioxus), although showing the most similar anatomical features to vertebrates, never develop a vertebrate-like head but rather several structures specific to this animal. The lancelet anatomical specificity seems to be traceable to early developmental stages, such as the vertebrate dorsal and anterior-posterior determinations. The BMP and Wnt proteins play important roles in establishing the early basis of the dorsal structures and the head in vertebrates. The early behavior of BMP and Wnt may be also related to the specific body structures of lancelets. The expression patterns of a dpp-related gene, Bbbmp2/4, and two wnt-related genes, Bbwnt7 and Bbwnt8, have been studied in comparison with those of brachyury and Hnf-3 beta class genes The temporal expression patterns of these genes are similar to those of vertebrates; Bbbmp2/4 and Bbwnt8 are first expressed in the invaginating primitive gut and the equatorial region. respectively, at the initial gastrula stage. However, spatial expression pattern of Bbbmp2/4 differs significantly from the vertebrate cognates. It is expressed in the mid-dorsal inner layer of gastrulae and widely in the anterior region, in which vertebrates block BMP signaling, The present study suggests that the lancelet embryo may have two distinct developmental domains from the gastrula stage, the domains of which coincide later with the lateral diverticular and the somitocoelomic regions. The embryonic origin of the anterior-specific structures in lancelets corresponds to the anterior domain where Bbbmp2/4 is continuously expressed.

Formation and evolution of the modern warm current system in the East China Sea and the Yellow Sea since the last deglaciation

To reconstruct the formation and evolution process of the warm current system within the East China Sea (ECS) and the Yellow Sea (YS) since the last deglaciation, the paleoceangraphic records in core DGKS9603, core CSH1 and core YSDP102, which were retrieved from the mainstream of the Kuroshio Current (KC), the edge of the modern Tsushima Warm Current (TWC) and muddy region under cold waters accreted with the Yellow Sea Warm Current (YSWC) respectively, were synthetically analyzed. The results indicate that the formation and evolution of the modern warm current system in the ECS and the YS has been accompanied by the development of the KC and impulse rising of the sea level since the last deglaciation. The influence of the KC on the Okinawa Trough had enhanced since 16 cal kyr BP, and synchronously the modern TWC began to develop with the rising of sea level and finally formed at about 8.5 cal kyr BP. The KC had experienced two weakening process during the Heinrich event 1 and the Younger Drays event from 16 to 8.5 cal kyr BP. The period of 7-6 cal kyr BP was the strongest stage of the KC and the TWC since the last deglaciation. The YSWC has appeared at about 6.4 cal kyr BP. Thus, the warm current system of the ECS and the YS has ultimately formed. The weakness of the KC, indicated by the occurrence of Pulleniatina minimum event (PME) during the period from 5.3 to 2.8 cal kyr BP, caused the main stream of the TWC to shift eastward to the Pacific Ocean around about 3 cal kyr BP. The process resulted in the intruding of continent shelf cold water mass with rich nutrients. Synchronously, the strength of the YSWC was relatively weak and the related cold water body was active at the early-mid stage of its appearance against the PME background, which resulted in the quick formation of muddy deposit system in the southeastern YS. The strength of the warm current system in the ECS and the YS has enhanced evidently, and approached to the modern condition gradually since 3 cal kyr BP.

Geological records of marine environmental changes in the southern Okinawa Trough

Indexes of sediment grain size, sedimentation rates, geochemical composition, heavy minerals, benthic foraminiferal fauna, indicator species of the Kuroshio Current, paleo-SST and carbonate dissolution of core E017 conformably suggest a great marine environmental change occurring at about 10.1-9.2 cal. kaBP in the southern Okinawa Trough, which may correspond to the strengthening of the Kuroshio Warm Current and re-entering the Okinawa Trough through the sea area off northeast Taiwan. The invasion of Kuroshio current has experienced a process of gradual strengthening and then weakening, and its intensity became more fluctuation during the last 5000 years. Compared to the transition of sediment grain size, geochemical composition and heavy minerals, the foraminiferal faunas show a 900-year lag, which may indicate that the invasion of Kuroshio Current and the consequent sea surface and deep-water environmental changes is a gradual process, and fauna has an obvious lag compared to environment altering. The carbonate dissolution of the Okinawa Trough has had an apparent strengthening since 9.2 cal. kaBP, and reached a maximum in the late 3000 years, which may be caused by the deep-water environmental changes due to the invasion of Kuroshio Current.

Mineralogy of smectites in the surface sediments from the East Pacific and its significance

XRD, TEM, SEM and EDS are employed to analyze smectites in the clay fraction of the surface sediments from the East Pacific. It is shown from the XRD results that the clay fraction consists of about 20% smectites. Three types of smectites are identified, Fe-rich (Type I), Fe, Mg-rich (Type II) and Na,Ca smectite (Type III), and most of them are not well-crystallized. Type I is widely distributed in sediments, showing honeycomblike in the SEM, and aggregated or dispersive hairlike, or cloudy assemblage with a bit curl near its edge in the TEM. This type is considered to be typomorphic type of authigenic smectite in the East Pacific. Type II is similar to Type I in micromorphology in the TEM, showing a transition micronite, while Type III is tabletlike in the TEM with an unclear edge. Type I may be altered from volcanics and some of them even precipitated from the low subthermal water. Type II could also be formed in the ocean floor, while Type III comes from dry and distant continental area. This study suggests that the characteristic of chemical composition and morphology of smectite may give a clue to understand sediment source, origin of minerals and sedimentation in the deep sea.

Sedimentary changes during the Holocene in the Bohai Sea and its paleoenvironmental implication

Samples of two cores, Cores M5-5 and M7-4 in the Bohai Sea were analyzed in isotopes, grain size, heavy minerals, chemical compositions, and 14 C dating to reconstruct the sedimentation during the Holocene. Abrupt change in carbon and oxygen stable isotopes was recognized at Core M5-5 at about 6400 a BP, which was likely due to the intrusion of the Yellow Sea Warm Current (YSWC) extension into the Bohai Sea. At Core M7-4, sediments between 5900 and 6600 a BP (150-260 cm depth) became coarse-grained, containing rich garnet, high manganese content, and nil autogenic pyrite, indicating a very dynamic sedimentary event during which the ambience was transformed from reductive to oxidative, and sedimentation boosted. Meanwhile, the YSWC had invaded into the Bohai Sea indicated by rich planktonic foraminifera in this event. (c) 2008 Elsevier Ltd. All rights reserved.