Using drift nets to capture early life stages and monitor spawning of the Yangtze River Chinese sturgeon (Acipenser sinensis)

P>A sampling system for capturing sturgeon eggs using a D-shaped bottom anchored drift net was used to capture early life stages (ELS) of Chinese sturgeon, Acipenser sinensis, and monitor annual spawning success at Yichang on the Yangtze River, 1996-2004, before and just after the Three Gorges Dam began operation. Captured were 96 875 ELS (early life stages: eggs, yolk-sac larvae = eleuthero embryos, and larvae); most were eggs and only 2477 were yolk-sac larvae. Most ELS were captured in the main river channel and inside the bend at the Yichang spawning reach. Yolk-sac larvae were captured for a maximum of 3 days after hatching began, indicating quick dispersal downstream. The back-calculated day of egg fertilization over the eight years indicated a maximum spawning window of 23 days (20 October-10 November). Spawning in all years was restricted temporally, occurred mostly at night and during one or two spawning periods, each lasting several days. The brief temporal spawning window may reduce egg predation by opportunistic predators by flooding the river bottom with millions of eggs. During 1996-2002, the percentage of fertilized eggs in an annual 20-egg sample was between 63.5 to 94.1%; however, in 2003 the percentage fertilized was only 23.8%. This sudden decline may be related to the altered environmental conditions at Yichang caused by operation of the Three Gorges Dam. Further studies are needed to monitor spawning and changes in egg fertilization in this threatened population.

Communities of gastrointestinal helminths of fish in historically connected habitats: habitat fragmentation effect in a carnivorous catfish Pelteobagrus fulvidraco from seven lakes in flood plain of the Yangtze River, China

Background: Habitat fragmentation may result in the reduction of diversity of parasite communities by affecting population size and dispersal pattern of species. In the flood plain of the Yangtze River in China, many lakes, which were once connected with the river, have become isolated since the 1950s from the river by the construction of dams and sluices, with many larger lakes subdivided into smaller ones by road embankments. These artificial barriers have inevitably obstructed the migration of fish between the river and lakes and also among lakes. In this study, the gastrointestinal helminth communities were investigated in a carnivorous fish, the yellowhead catfish Pelteobagrus fulvidraco, from two connected and five isolated lakes in the flood plain in order to detect the effect of lake fragmentation on the parasite communities. Results: A total of 11 species of helminths were recorded in the stomach and intestine of P. fulvidraco from seven lakes, including two lakes connected with the Yangtze River, i.e. Poyang and Dongting lakes, and five isolated lakes, i.e. Honghu, Liangzi, Tangxun, Niushan and Baoan lakes. Mean helminth individuals and diversity of helminth communities in Honghu and Dongting lakes was lower than in the other five lakes. The nematode Procamallanus fulvidraconis was the dominant species of communities in all the seven lakes. No significant difference in the Shannon-Wiener index was detected between connected lakes (0.48) and isolated lakes (0.50). The similarity of helminth communities between Niushan and Baoan lakes was the highest (0.6708), and the lowest was between Tangxun and Dongting lakes (0.1807). The similarity was low between Dongting and the other lakes, and the similarity decreased with the geographic distance among these lakes. The helminth community in one connected lake, Poyang Lake was clustered with isolated lakes, but the community in Dongting Lake was separated in the tree. Conclusion: The similarity in the helminth communities of this fish in the flood-plain lakes may be attributed to the historical connection of these habitats and to the completion of the life-cycles of this fish as well as the helminth species within the investigated habitats. The diversity and the digenean majority in the helminth communities can be related to the diet of this fish, and to the lacustrine and macrophytic characters of the habitats. The lake isolation from the river had little detectable effect on the helminth communities of the catfish in flood-plain lakes of the Yangtze River. The low similarities in helminth communities between the Dongting Lake and others may just be a reflection of its unique water environment and anthropogenic alterations or fragmentation in this lake.

Pseudobagrus fui Miao, a valid bagrid species from the Yangtze River drainage, South China (Teleostei: Bagridae)

Pseudobagrus fui Miao is a valid bagrid species that can be separated from all its congeners in having 27-33 anal-fin rays. Among the species of Pseudobagrus, it forms part of a group of approximately 20 species putatively characterized by having a smooth anterior margin of the pectoral-fin spine and short maxillary barbels not extending to the base of the pectoral-fin spine. Pseudobagrus fui, together with P. nitidus and P. vachelli, can be differentiated from all other fork-tailed species of this group by having no fewer than 20 branched anal-fin rays, the posterior end of the anal-fin base posterior to the vertical through the posterior end of the adipose-fin base, and anal-fin base longer than the adipose-fin base. It further differs from P. nitidus in having a gas bladder without beaded lateral and posterior margins, and from P. vachelli in having short maxillary barbels not extending to the base of the pectoral-fin spine. Pseudobagrus fui is currently known from the main stream of the upper Yangtze River and its tributaries, the Min River, Jialing River, Tuo River, Wu River and Chishui River in Sichuan Province, Guizhou Province, and the Chongqing City. The identity and nomenclature of Pseudobagrus nitidus is also discussed.

Trends of Superoxide Dismutase and Soluble Protein of Aquatic Plants in Lakes of Different Trophic Levels in the Middle and Lower Reaches of the Yangtze River, China

A limnological study was carried out to determine the responses of superoxide dismutase (SOD) activities and soluble protein (SP) contents of 11 common aquatic plants to eutrophication stress. Field investigation in 12 lakes in the middle and lower reaches of the Yangtze River was carried out from March to September 2004. Our results indicated that non-submersed (emergent and floating-leafed) plants and submersed plants showed different responses to eutrophication stress. Both SOD activities of the non-submersed and submersed plants were negatively correlated with their SP contents (P < 0.000 1). SP contents of non-submersed plants were significantly correlated with all nitrogen variables in the water (P < 0.05), whereas SP contents of submersed plants were only significantly correlated with carbon variables as well as ammonium and Secchi depth (SD) in water (P < 0.05). Only SOD activities of submersed plants were decreased with decline of SD in water (P < 0.001). Our results indicate that the decline of SOD activities of submersed plants were mainly caused by light limitation, this showed a coincidence with the decline of macrophytes in eutrophic lakes, which might imply that the antioxidant system of the submersed plants were impaired under eutrophication stress.

Abundance and conservation status of the Yangtze finless porpoise in the Yangtze River, China

middle and lower reaches of the Yangtze River, China. It is the only freshwater population of porpoises in the world and is currently listed as Endangered by IUCN. In November and December 2006 we used two boats and line transect methods to survey the entire current range of the population, except for two lakes (Poyang and Dongting). Sighting results were similar for both boats, so we pooled all data and analyzed them using two line transect models and a strip transect model. All models produced similar estimates of abundance (1111, 1225 and 1000). We then added independent estimates of the number of porpoises from the two lakes for a total estimate of approximately 1800 porpoises. Our findings indicate that the population continues to decline and that its distribution is becoming more fragmented. Our current estimate in the main river is slightly less than half the estimate from surveys between 1984 and 1991 (which was probably an underestimate). We also found an apparent gap in the distribution of porpoises between Yueyang and Shishou (similar to 150 km), where sightings had previously been common. Continued threats to Yangtze finless porpoises include bycatch in unregulated and unselective fishing, habitat degradation through dredging, pollution and noise, vessel strikes and water development. Immediate protective measures are urgently needed to ensure the persistence of finless porpoises in the Yangtze River. The survey design and analytical methods developed in this study might be appropriate for surveys of cetaceans in other river systems. (c) 2008 Elsevier Ltd. All rights reserved.

Food web of benthic macro invertebrates in a large Yangtze River-connected lake: the role of flood disturbance

This Study was conducted in Lake Dongtinghu, a large river-connected lake on the Yangtze River flood-plain, China. Our goal was to determine trophic relationships among benthic macroinvertebrates, as well as the effects of flood disturbance on the benthic food web of a river-connected lake. Macroinvertebrates in the lake fed mainly on detritus and plankton (both zooplankton and phytoplankton). Food web Structure in Lake Dongtinghu was characterized by molluscs as the dominant group, low connectance, high level of omnivory. based oil detritus and primary production, and most ingestion concentrating on a few links. Our analyses showed that flood disturbance is an important factor affecting the benthic food web in Lake Dongtinghu. The numbers of species and functional feeding groups (FFGs), and the density and biomass of macroinvertebrates decreased significantly during flooding. Connectance was higher during the flood season than in other seasons, indicating that floods have a strong effect on connectance in this Yangtze River-connected lake. Flood effects on the benthic web were also evident in the decrease of niche overlaps within and anion, FFGs. Our results provide useful information regarding biodiversity conservation on the Yangtze floodplain. Reconstructing and maintaining natural and regular flow regimes between Yangtze lakes and the river is essential for restoration of macroinvertebrates on the floodplain.

Population differentiation of Procypris rabaudi (Tchang) in the upper reaches of the Yangtze River revealed by mitochondrial DNA and RAPD markers

Procypris rabaudi (Tchang) is a cyprinid fish endermic to middle and upper reaches of the Yangtze River. Besides in main stream and large tributaries, there exists an early matured, small-sized ecological type in a small tributary, Tang River. In this study, mitochondrial DNA cytochrome h (cyt b) gene sequence analysis and randomly amplified polymorphic DNA (RAPD) analysis were performed to investigate the differentiation of the Tang River population from the Mudong reach population of the Yangtze River, with the purpose of conservation and exploitation of this fish. In the 1140 bps of cyt b gene sequence surveyed, 20 sites were found polymorphic, which defined 23 haplotypes. Among them, four haplotypes accounted for 54.4% of all individuals, while population-specific haplotypes occurred in low frequencies. Analysis of molecular variation on cyt b data revealed no significant partition existing between Tang River population and Mudong reach population. Analyses of 132 RAPD loci suggested that genetic variation between populations was significant, though values of different F-ST were not very high. The results revealed low genetic diversity and the beginning of population differentiation, suggesting that Tang River population should be designated as a separate Management Unit.

Pseudobagrus brachyrhabdion, a new catfish (Teleostei : Bagridae) from the middle Yangtze River drainage, South China

Pseudobagrus brachyrhabdion sp. nov., from the Yuan Jiang and Xiang Jiang of the middle Yangtze River drainage in Hunan and Guizhou Provinces, South China, is described herein. It is distinguished from all other Pseudobagrus species with a truncate or slightly emarginated caudal fin by an unique combination of the following characters: supraoccipital plate and nuchal plate broadly interspaced and covered with skin; nasal barbels only at most reaching anterior margin of eye; maxillary barbels reaching slightly beyond posterior margin of eye; outer mandibular barbels extending to posterior margin of eye; dorsal fin with a somewhat convex distal margin, origin nearer to pectoral-fin insertion than to pelvic-fin insertion; dorsal-fin spine shorter than pectoral spine, with a somewhat serrated posterior margin; pectoral-fin spine with a smooth anterior margin; anal fin with 20-23 rays, base length 23.8-32.0% of standard length, posterior end of anal-fin base anterior to posterior end of adipose fin base; no longitudinal black band extending along flank; eyes large, diameter 16.3-23.7% of head length; and number of vertebrae 5 + 43-46.

Field studies on the environmental factors in controlling microcystin production in the subtropical shallow lakes of the Yangtze River

Microcystin (MC) problem made more and more care about in China, intercellular MC (Int-MC) and cellular MC (Cel-MC) were important contents to reflect the producing-MC ability by cyanobacteria and by lakes. To study the correlations between Int-MC, Cel-MC concentration and biological and environmental factors, eight cyanobacterial blooming lakes were studied in the middle and lower reaches of the Yangtze River. Microcystin-RR (MC-RR) and Microcystin-LR (MC-LR) were the primary toxin variants in our data. From the linear correlations between MC and environmental factors, cellular-YR had significant correlation with most of chemical factors except total nitrogen (TN) and the ratio of total nitrogen and total phosphorus (TN/TP), most intracellular MC analogues had significant correlations with total dissolved nitrogen (TDN), ammonium (NH4+), nitrite (NO2-), TP, total dissolved phosphorus (TDP), Microcystis. From the canonal correspondence analysis, Int-MC concentrations were closely related with the chemical and biological factors, such as TP, total organic carbon (TOC), chlorophyll a (Chl a), Microcystis biomass, et al. While Cel-MC contents, especially Cel-RR and Cel-LR, were closely related with light environmental in the lakes such as water depth and transparence.

Annual variations of biotic integrity in the upper Yangtze River using an adapted index of biotic integrity (IBI)

Adaptive modification and use of Karr's index of biotic integrity (IBI) for the upper Yangtze River, including 12 metrics in five categories, have typically occurred in line with the data collected by 6-year commercial fisheries investigation. These investigations were undertaken annually in four sections of the Upper Yangtze main channel between 1997 and 2002. These four monitoring sections (Yibin - YB, Hejiang - HJ, Mudong - MD, and Yichang - YC) were selected because they represent the part of the river that will be covering a 1000 kin stretch that includes the future Three Gorges Reservoir (TGR), upstream of the Three Gorges Dam (TGD), an area influenced by the construction of TGD. in addition, historical data were used to show changes in the watershed by comparison with field investigations recently. The biotic integrity of the four sections were calculated and classified into different levels annually for recognizing its spatial and temporal variations. It was observed that IBI scores were becoming lower diminishingly since 1997 in all the four sections. Because all the data were collected before the impoundment of the Three Gorges Reservoir, it is obvious that human activities, especially over-fishing, must be crucial factor instead of damming in the upper Yangtze River in that period. (C) 2008 Published by Elsevier Ltd.

Triplophysa lixianensis, a new nemacheiline loach species (Pisces : Balitoridae) from the upper Yangtze River drainage in Sichuan Province, South China

Triplophysa lixianensis, a new nemacheiline loach species, is described from the Min Jiang of the upper Yangtze River drainage in Sichuan Province, South China. It can be separated from all other species of Triplophysa by having a unique combination of the following characters: posterior chamber of gas bladder greatly reduced or absent; caudal peduncle columnar with a roughly round cross- section at its beginning; anterior edge of lower jaw completely exposed or uncovered by lower lip; intestine short, forming a zigzag loop below stomach; dorsal- fin origin closer to caudal- fin base than to snout tip; pelvic fin inserted anterior to dorsal- fin origin; snout length 50.6 - 57.5 % of head length; eye diameter 12.3 15.4 % of head length; caudal peduncle length 25.1 - 27.1 % of standard length; anal fin with five branched rays; lower lip greatly furrowed with two thick lateral lobes; and body smooth or scaleless.

Perfluorinated compounds in the Pearl River and Yangtze River of China

A total of 14 perfluorinated compounds (PFCs) were quantified in river water samples collected from tributaries of the Pearl River (Guangzhou Province, south China) and the Yangtze River (central China). Among the PFCs analyzed, perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) were the two compounds with the highest concentrations. PFOS concentrations ranged from 0.90 to 99 ng/1 and < 0.01-14 ng/1 in samples from the Pearl River and Yangtze River, respectively; whereas those for PFOA ranged from 0.85 to 13 ng/l and 2.0-260 ng/l. Lower concentrations were measured for perfluorobutane sulfonate (PFBS), perfluorohexane sulfonate (PFHxS), perfluorooctanesulfoamide (PFOSA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorononaoic acid (PFNA), perfluorodecanoic acid (PFDA), and perfluoroundecanoic acid (PFUnDA). Concentrations of several perfluorocarboxylic acids, including perfluorododecanoic acid (PFDoDA), perfluorotetradecanoic acid (PFTeDA), perfluorohexadecanoic acid (PFHxDA) and perfluorooctadecanoic acid (PFOcDA) were lower than the limits of quantification in all the samples analyzed. The highest concentrations of most PFCs were observed in water samples from the Yangtze River near Shanghai, the major industrial and financial centre in China. In addition, sampling locations in the lower reaches of the Yangtze River with a reduced flow rate might serve as a final sink for contaminants from the upstream river runoffs. Generally, PFOS was the dominant PFC found in samples from the Pearl River, while PFOA was the predominant PFC in water from the Yangtze River. Specifically, a considerable amount of PFBS (22.9-26.1% of total PFC analyzed) was measured in water collected near Nanjing, which indicates the presence of potential sources of PFBS in this part of China. Completely different PFC composition profiles were observed for samples from the Pearl River and the Yangtze River. This indicates the presence of dissimilar sources in these two regions. (c) 2007 Elsevier Ltd. All rights reserved.

Stable isotope variations in particulate organic matter and a planktivorous fish in the Yangtze River

Temporal and spatial changes in delta(13) C and delta 15 N of particulate organic matter (POM) and Hemiculter leucisculus were studied in the Yangtze River of China. Isotopic signatures of POM showed seasonal variations, which was assumed to be associated with allochthonous organic input and autochthonous phytoplankton growth. delta C-13 of H. leucisculus was 1.1 % higher than that of POM, which suggested that the food source of H. leucisculus was mostly from the POM. A mass balance model indicated the trophic position of H. leucisculus in the food web of Yangtze River was estimated to be 2.0 - 2.1, indicating that this fish mainly feeds on planktonic organic matter, which agreed with previous gut content analysis.

Post-impoundment biomass and composition of phytoplankton in the Yangtze River

Damming, and thus alteration of stream flow, promotes higher phytoplankton populations and encourages algal blooms (density > 10(6) cells L-1) in the Three Gorges Reservoir (TGR). Phytoplankton composition and biomass were studied in the Yangtze River from March 2004 to May 2005. 107 taxa were identified. Diatoms were the dominant group, followed by Chlorophyta and Cyanobacteria. In the Yangtze River, algal abundance varied from 3.13 x 10(3) to 3.83 x 10(6) cells L-1, and algal biomass was in the range of 0.06 to 659 mg C m(-3). Levels of nitrogen, phosphorus and silica did not show consistent longitudinal changes along the river and were not correlated with phytoplankton parameters. Phytoplankton abundance was negatively correlated with main channel discharge (Spearman r = -1.000, P < 0.01). Phytoplankton abundance and biomass in the Yangtze River are mainly determined by the hydrological conditions rather than by nutrient concentrations.