黑尾近红鲌人工繁殖研究

报道了2001~2003年对长江上游特有鱼类黑尾近红鲌开展人工繁殖试验的结果。黑尾近红鲌亲鱼来源于四川泸州长江上游一级支流龙溪河。催产剂为促黄体素释放激素类似物(LRH A)，绒毛膜促性腺激素(HCG) 与鲤鱼脑垂体(PG)。采用一次注射法，并用干法进行人工授精。共进行了23次人工催产，催产成功的占16次，有效的占3次，失败的占4次；共注射雌鱼70尾，其中46尾雌鱼排卵，平均催产率65.71%，受精率8.33%~100.0%，孵化率0.50%~94.71%，获得仔鱼29.3万尾。对亲鱼选择、催产方法、孵化与苗种培育等技术细节进行了讨论。     

The Ratio of Rubidium to Caesium in Threespine Stickleback (Gasterosteus Aculeatus), Benthic and Limnetic Sticklebacks (Gasterosteus), and Juvenile Sockeye Salmon (Oncorhynchus Nerka)

The ratios of rubidium to caesium were investigated in juvenile sockeye salmon (Oncorhynchus nerka), threespine stickleback (Gasterosteus aculeatus) and benthic and limnetic sticklebacks (Gasterosteus) as a means of separating zooplankton consumers from benthic prey consumers. Only benthic and limnetic sticklebacks had Rb to Cs ratios that were influenced by diet. Ratios were higher in limnetic stickleback whose diet consists mainly of zooplankton compared with benthic stickleback which consume benthic prey. Ratios in juvenile sockeye appeared to be influenced by the concentrations of rubidium and caesium in the egg yolk during the early period of growth. in three-spine stickleback that inhabited both the littoral and limnetic zone of the same lake, results suggested that fish must occupy each area for several months before rubidium to caesium ratios in tissues reflect concentrations in prey.     

广西龙江鱼类镉含量分布特征及生物积累特性分析

突发镉污染事件能引起江河水体恶化,破坏水生态环境和威胁人类健康.本研究为证实突发镉污染事件引起生态环境风险,以不同类型鱼类以及鱼类不同组织器官为研究对象,分别前后6次对龙江进行采样调查,并对各鱼类根据水层和食性进行分类及分析.调查结果表明,前3次调查鱼类肌肉镉含量显著高于后3次调查鱼类肌肉镉含量;草食性,肉食性和杂食性鱼类不同组织器官镉的含量大小均可排序为:肾肝肠鳃卵鳞≈肌肉,且3种类型肾的镉含量均显著高于其他任何组织器官(P0.05);鱼类同一组织器官镉的含量根据不同水层鱼类依次为:底层鱼类中下层鱼类中上层鱼类.不同食性鱼类肌肉中镉平均富集系数BAF从大到小依次为杂食性,肉食性和草食性,分别为8.32、6.33和5.15;不同生活水层鱼类肌肉中镉平均富集系数大小排序为:底层鱼类(8.18)中下层鱼类(7.70)中上层鱼类(4.99).     

Prenatal exclusion of Leigh syndrome due to T8993C mutation in the mitochondrial DNA

Leigh syndrome (LS) is a mitochondrial encephalopathy that is caused by a mutation either in the mitochondrial DNA (mtDNA) or in the nuclear encoded genes of the mitochondrial proteins. Prenatal diagnosis of defects in the mtDNA is usually problematic because of mtDNA heteroplasmy and tissue specificity. However, the mutations T8993 G/C in the ATP synthase subunit 6 gene of the mtDNA show a more even tissue distribution and do not appear to change significantly over time. There are only few reports of prenatal diagnosis of the T8993G mutation in Leigh disease. Here we describe the first prenatal genetic testing of T8993C in a fetus of a mother whose previous child had died of Leigh syndrome due to the T8993C mutation. Mutant load in the chorionic villus sample (CVS) as well as in amniocytes was undetectable, thus predicting a very high likelihood of an unaffected outcome, indicative of a healthy baby. The diagnosis was confirmed after birth. Gathering data on the prenatal diagnosis of mtDNA mutations is of great importance so that prenatal diagnosis of both T8993G and T8993C mutations can be offered routinely. Copyright © 2002 John Wiley & Sons, Ltd.     

浮桥河水库的营养状况与水质调控措施

浮桥河水库总磷含量、浮游植物的初级生产力和浮游动物的生物量有逐渐增加的趋势。上、中、下游水体的总磷含量分别为 0 .0 72mg/L、0 .0 6 6mg/L和 0 .0 4 4mg/L ;浮游植物的生物量分别为9.2 8mg/L、6 .51mg/L和 3.37mg/L。夏季和秋季上游部分区域伴有大面积的“水华” ,优势种类主要为微囊藻。浮游植物水柱日生产量分别为 2 .80 gO2 /m2 .d、2 .78gO2 /m2 .d和 2 .36 gO2 /m2 .d ;浮游动物的生物量分别为 2 .52mg/L、1.2 5mg/L和 1.2 2mg/L。浮桥河水库有富营养化的趋势且上游已经富营养化。导致富营养化的原因主要是外源营养物输入量的增加、大库鲢鳙放养比例失调、上游滤食性网箱放养结构的不合理和食鱼性鱼类的过度捕捞。建议在保持现有鳙放养量的前提下增大大库鲢的放养量和网箱内鲢鱼种的放养量、减少食鱼性鱼类的捕捞量、减少外源营养物的输入以控制水库的富营养化。     

Methylmercury, total mercury and total selenium in four common freshwater fish species from Ya-Er Lake, China

Snakehead fish (Ophiocephalus argus cantor), silver carp (Hypophthalmichthys molitrtix), crucian carp (Carassius carassius), and common carp (Cyprinus carpio) are four common freshwater fish species in China. In this study, the level of methylmercury (MeHg), total mercury (T-Hg), and total selenium (T-Se) in muscle samples of these four fish species from Ya-Er Lake, China, were analyzed using atomic fluorescence spectrometry coupled with high-performance liquid chromatography, and inductively coupled plasma mass spectrometry. The concentrations of MeHg in all the fish species were significantly correlated with those of T-Hg. Higher T-Hg and MeHg concentrations had accumulated in the snakehead fish, which is a strongly predatory fish, than in the other three species. The concentration ratios of MeHg and T-Hg in the muscles of these four fish species were almost equal. Conversely, there was negative correlation between the concentrations of T-Hg and T-Se, which implies that there is a competition between these two elements with respect to bioaccumulation. It is noteworthy that of all the muscle samples tested, the level of T-Hg exceeded the maximum allowable limit in fish [0.4 mg kg⁻¹ (w/w) recommended by the World Health Organization] in 38.46% of those of the silver carp, 18.18% of those of the crucian carp, and 100% of those of snakehead fish. These results show that the consumption of contaminated fish is a potential threat to human health and that necessary preventive measures to safeguard public health should be emphasized.     

Seasonal variation of the distribution of PCBs in sediments and biota in a PCB-contaminated estuary

To elucidate the effects of seasonal variation of precipitation on the distribution of polychlorinated biphenyls (PCBs) in estuarine sediments and benthic feeders, PCB concentrations of river surface sediments and mullet fish (Liza macrolepis) were investigated in the estuary of Er-Jen River near former PCB contamination sites before and after each wet season from 2002 to 2004. Analyses of grain size distribution and organic matter revealed that the pre-existing surface sediments were covered by and mixed with the soil particulates brought by surface runoff after each wet season. Obvious increment of PCB content and significantly elevated fraction (p < 0.005) of light PCBs of the river mouth’s sediments after each wet season indicated that the invading particles were rich in unweathered PCBs. PCBs previously buried in the surface soil of heavily contaminated sites were flushed into this estuary through surface runoff. The precipitation altered the PCB patterns in sediment organic matter, the dietary source of mullet, and consequently changed that of mullets accordingly, which all possessed significant greater fraction of light PCBs. In this study, it was demonstrated that seasonal summer precipitation affected the distribution of PCBs on surface sediments and the mullets of this estuary. PCB residuals retained in this region still pose potential threats to biota resided here.     

pp´DDT and pp´DDE Accumulation in a Food Chain of Lake Maggiore (Northern Italy): Testing Steady-State Condition

- DOI: http://dx.doi.org/10.1065/espr2006.01.010 Background, Aims and Scope Although pp'DDT usage was strongly limited or banned in most parts of the world during the last three or four decades, the parent compound, its homologues and their metabolites still occur at levels which might pose a risk for many ecosystem components. A case of DDT pollution of industrial origin was discovered in 1996 in Lake Maggiore, the second largest (212 km2) and deepest (370 m) lake in Italy, causing concern for wildlife and human health. The extensive monitoring of many biotic and abiotic compartments which followed from 1998 in order to assess the pollution level and its trend in time, provided a great availability of data referring to DDT contamination of the different fish species of the lake. In this study, the recent contamination levels in selected fish species were compared to those measured in 1998 to evaluate the temporal pollution trend of the lake and its natural recovery, given that no remediation measures were carried out on the contaminated soils and sediments in this time span. Moreover, a modelling approach to test the equilibrium condition between water and pelagic fish species was used. Analytical results of pp'DDT and pp'DDE concentrations in lake water were used as input data in the bioenergetic model by Connolly & Pedersen (1988) to calculate concentrations in two fish species and to compare the predicted and the measured contamination. Methods Sampling and analytical determination of DDT homologues in lake water: Five water sampling campaigns were carried out from May 2002 to February 2004 in three sampling sites of Lake Maggiore. Suspended and dissolved pollutants were determined separately. Quantitative DDT homologue analyses were performed by HRGC coupled with ECD detection by the external standard method. Single water extracts were put together in correspondence with the stratification zones of the water column inferred on the basis of the temperature profile to improve analytical sensitivity. Selection of fish data: Concentrations of DDT and DDE in fishes were selected from recent literature (CIPAIS 2003, 2004). Bioaccumulation model: The bioenergetic model proposed by Connolly & Pedersen (1988) was used to assess the bioaccumulation of pp'DDT and pp'DDE of Alosa fallax (landlocked shad) and Coregonus spp. (whitefish), selected among the different species as representative of a secondary consumer level. Results and Discussion The average concentrations of pp'DDT and pp'DDE in water to be used as input data in the bioenergetic model were obtained considering all the concentrations measured at the three sampling stations in the epylimnion where the fish species considered in this study spend most of their life. The resulting values were 0.05 and 0.16 ng/L for pp'DDT and pp'DDE, respectively. Average measured pp'DDT and pp'DDE concentrations in landlocked shad were 0.81 +/- 0.39 and 1.69 +/- 0.71 mg/kg lipids, respectively, and were 0.29 +/- 0.12 and 1.06 +/- 0.41 mg/kg lipids for the whitefish. Calculated and measured values turned out to be in quite good agreement for pp'DDT, while measured pp'DDE concentrations were higher than expected on the basis of the bioenergetic model in both species. Probably metabolic transformations of pp'DDT accumulated in fish tissues in the past are responsible for the observed differences between calculated and expected pp'DDE concentrations in fish. Conclusions Pelagic fishes of Lake Maggiore seem to maintain the DDT accumulated during their life time and the most efficient mechanism responsible for the fish population recoveries is probably their generation changes; for this reason, equilibrium models cannot be used until negligible pp'DDT concentrations are reached in fish tissues. Recommendations and Outlook The limit proposed for pp'DDT in water by the EU Directive 2000/60, which will come in force in 2008, is 0.2 ng/L, four times higher than the average concentration measured in Lake Maggiore waters. Nevertheless, concentrations measured in Lake Maggiore fish were very close and sometimes exceeded the Maximum residue limits (MRLs) settled by the Italian legislation for foods (0.1 mg/kg w.w. for fish containing 5–20% lipid). It seems, therefore, that the 'environmental quality standard' of 0.2 ng/L cannot guarantee the suitability of fish for human consumption.     

Boosting freshwater fish conservation with high-resolution distribution mapping across a large territory

The lack of high-resolution distribution maps for freshwater species across large extents fundamentally challenges biodiversity conservation worldwide. We devised a simple framework to delineate the distributions of freshwater fishes in a high-resolution drainage map based on stacked species distribution models and expert information. We applied this framework to the entire Chinese freshwater fish fauna (>1600 species) to examine high-resolution biodiversity patterns and reveal potential conflicts between freshwater biodiversity and anthropogenic disturbances. The correlations between spatial patterns of biodiversity facets (species richness, endemicity, and phylogenetic diversity) were all significant (r = 0.43–0.98, p < 0.001). Areas with high values of different biodiversity facets overlapped with anthropogenic disturbances. Existing protected areas (PAs), covering 22% of China's territory, protected 25–29% of fish habitats, 16–23% of species, and 30–31% of priority conservation areas. Moreover, 6–21% of the species were completely unprotected. These results suggest the need for extending the network of PAs to ensure the conservation of China's freshwater fishes and the goods and services they provide. Specifically, middle to low reaches of large rivers and their associated lakes from northeast to southwest China hosted the most diverse species assemblages and thus should be the target of future expansions of the network of PAs. More generally, our framework, which can be used to draw high-resolution freshwater biodiversity maps combining species occurrence data and expert knowledge on species distribution, provides an efficient way to design PAs regardless of the ecosystem, taxonomic group, or region considered.