Influence of Hydrologic Conditions of the Lower Ob Floodplain on Reproduction in Coregonids

The influence of the water level in the period of the open river channel and the duration of lower floodplain inundation on the feeding conditions, abundance, and population state of coregonids in the Lower Ob was investigated. The long-term dynamics of catches of some coregonid species was analyzed and compared with changes in the hydrologic conditions in the floodplain. The relationship between basic hydrologic conditions in the Lower Ob (water level in the period of the open channel, the duration of the lower floodplain inundation), the coregonid population sizes, the state of spawners, and the size of catches is demonstrated.     

Ecological Integrity Assessment of Lakes Using Fish Communities: An Example from Traunsee Exposed to Intensive Fishing and to Effluents from the Soda Industry

In order to analyse potential influences of soda industryeffluents on the ecological integrity of Traunsee (TS) weinvestigated the fish community of the lake in comparison witha reference lake (Hallstättersee HS) and used a reconstructionfrom the (older) literature concerning the original speciescomposition of Traunsee. Published `Index of Biotic Integrity(IBI)' metrics were considered to be of limited value due tothe relatively low species number in the oligotrophic, Alpinelake. Therefore we included, in addition to speciescomposition, studies on egg distribution, larval fishdensities, life-history parameters (i.e. growth, maturity,fecundity, age and size composition), stress levels and heavymetal content of the dominant whitefish (Coregonuslavaretus), as well as overall fish density and biomass (usinghydroacoustics) to assess the ecological status of the fishcommunity. Two of the original 18 species have disappearedfrom the lake, presumably in connection with the introductionof non-native eel (Anguilla anguilla) and theconstruction of a power plant in the outflow. Silt from grindedlimestone together with highly alkaline pore waters is emittedvia industrial wastewater from Sodaworks and covers part of thelake bottom. We observed that eggs of whitefish were spawnedmainly in the main inflowing river and close to the shore, thusavoiding the silty areas and making the anticipated damage tothe reproductive potential of whitefish neglectable. This wascorroborated by larval surveys done weekly on both lakes fromJanuary to May, which showed halve the density of whitefishlarvae in TS compared to HS. Estimates of potentially spawningfish from hydroacoustic surveys resulted in a ratio of 1(TS) :3 (HS). Analysis of whitefish revealed that they are growingfaster in TS and have higher fecundity leading to somecompensation of lower abundance. High levels of fishing in TSmight have led to this pattern and to depressed yields asindicated by the age composition. Level of oxidative stress andheavy metal content were not discernible from the referencelake. Therefore we concluded that negative impacts on theecological status of the fish community resulted from fisheriesmismanagement and a power plant situated in the outflow of thelake, considered to have damaged spawning places for somespecies, but not from soda industry effluents.     

Long-term assessment of insecticides treatments in West Africa: aquatic entomofauna

For the control of the Onchocerca volvulus vector in West Africa, up to 18,000 km of rivers from 1975 and up to 50,000 km from 1989 had been partly sprayed weekly with insecticides as part of the Onchocerciasis Control Programme (OCP). To evaluate the possible short-term and long-term effects of the application of insecticides on the non-target fauna, an aquatic monitoring programme was set up during the initial phase of the programme. By analysing the invertebrate data, which were collected using various sampling strategies from four different countries between 1977 and 1996, this paper evaluates the long-term changes of the invertebrate populations with respect to their taxonomic composition as well as their trophic structures. The discussed results of the applied numerical analysis strategy suggest that neither the taxonomic nor the trophic structures are greatly altered from the range of biological, flow-related variation that normally occurs in the studied river systems. This allows us to conclude that the biological variation found here is ecologically acceptable.     

Comparative toxic effects of formulated simazine on Vibrio fischeri and gilthead seabream (Sparus aurata L.) larvae

The use of Early Life Stage (ELS) tests is a useful tool in risk assessment. The purpose of this study was to compare the sensitivity of the seabream (Sparus aurata) larvae with the extensively used Microtox^® test on a commercial formulation containing simazine, an s-triazine herbicide. To this end, survival, growth and histopathological changes displayed by seabream yolk sac larvae exposed during 72 h post-hatching to nominal concentrations of the commercial preparation up to its saturating concentration in water, and bioluminescence of the marine bacteria Vibrio fischeri (Microtox^®) were studied. Survival of larvae after three days of exposure was significantly reduced in the highest (4.5 mg/l) concentration, but no effects on growth were found in any of the simazine treatments. The 72 h LC50 value for yolk sac larvae was estimated as 4.19 mg/l. Commercial grade simazine did not exert any significant toxicity to the marine bacterium V. fischeri at the concentrations tested.     

Response of antioxidase in viscera of Pagrosuma major larvae to water soluble fraction of hydrocarbons in No.0 diesel oil

Pagrosomus major larvae were to the water-soluble fraction of hydrocarbon in No.0 diesel oil(corresponding to No.2 fuel oil) at concentration of 0,0.17,1.22 and 8.82mg/L for up to 15 days.Larvae were sampled on days 9 and 15 of the experiment.Supernatants of viscera tissue extractions were assayed for biochemical response in terms of oxidative stress-superoxide dismutase(SOD),activity of selenium-dependant glutathione peroxidase(Se-GPx) and catalase(Ca),and the concentration of reduced glutathione(CSH).On day 9 of exposure ,statistically significant dose-related increases in Se-GPx and SOD activity,and GSH concentration were observed in all cases except for Se-GPx activity under the highest dosage of hydrocarbon.However,on day 15 of exposure, a similar dose-related in all cases except for Se-GPx activity under the highest dosage of hydrocarbon.However,on day 15 of exposure, a similar dose-related response was only observed for Se-GPx activity.GSH concentration decreased and SOD activity showed no statistical difference as compared to controls.However, a significant decrease in compared to day 9 Se-GPx activity and GSH concentration, in contrast to increase SOD activity at day 15 as indicates an accelerated accumulation of H2O2 and potential oxidative damage under long term exposure of larvae to hydrocarbons.No statistical changes were observed in Ca activity throughout the experiment, possibly owing to the high efficiency of Se-GPx.A recovery experiment was performed on indicating that the response of antioxidants measured tending to returm to return to their control levels.These results prove the function of the antioxidant defense system of the larvae to the water-soluble fraction of hydrocarbons in No.0 diesel oil.     

Response of antioxidase in viscera of Pagrosuma Major larvae to water soluble fraction of hydrocarbons in No.0 diesel oil

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温度、盐度、铜、氨对对虾仔虾(Penaues orientalis K)和光滑河兰蛤(Potamocorbula laevis)的影响

在室内模拟条件下,进行了热冲击及其与盐度、铜、氨联合对对虾仔虾和光滑河兰蛤的急性影响研究。结果表明,两种动物的起始致死温度(TL_(50))和最高临界温度(CTM)随驯化温度的升高而增大;随盐度的降低,仔虾的耐高温能力明显降低,而兰蛤对盐度变化反应不明显;高温明显提高铜、氨对仔虾的毒性。也提高铜对兰蛤的毒性,但降低氨对兰蛤的毒性影响。仔虾对高温、低盐、铜离子及非离子氨反应敏感。     

氯霉素对斑马鱼早期发育的毒性效应

通过氯霉素对斑马鱼(Daniorerio)胚胎及仔鱼的毒性暴露实验,研究了氯霉素对斑马鱼早期发育的致死和亚致死毒性效应.结果表明,氯霉素对斑马鱼胚胎的自主运动、心跳和孵化能力均造成了明显的不利影响,并且胚胎和仔鱼在毒性暴露过程中均产生了明显的畸形特征.其中,低浓度的氯霉素对胚胎的自主运动产生抑制作用,而高浓度的氯霉素对其自主运动产生明显的刺激作用.高浓度的氯霉素抑制胚胎和仔鱼的心跳及孵化能力,且对胚胎和仔鱼造成致死效应,其96hLC50值分别为56.6mg·mL-1和116.8mg·mL-1,而低浓度的氯霉素对胚胎和仔鱼产生致畸效应,胚胎和仔鱼表现出的主要畸形特征有心包水肿、卵黄囊肿胀、凝血、脊柱弯曲和鳔缺失.     

Distribution of Chironomidae (Insecta: Diptera) in polluted rivers of the Juru River Basin, Penang, Malaysia

The influence of physical and chemical parameters on the abundance and diversity of chironomids was studied in six rivers with moderate to highly polluted water in the Juru River Basin. The rivers: Ceruk Tok Kun (CTKR) as reference site, and polluted rivers of Pasir (PR), Juru (JR), Permatang Rawa (PRR), Ara (AR) and Kilang Ubi (KUR) were sampled over a period of five months (November 2007–March 2008). Nine chirnomid species: Chironimus kiiensis, C. javanus, Polypedilum trigonus, Microchironomus sp., Dicrotendipes sp., Tanytarsus formosanus, Clinotanypus sp., Tanypus punctipennis and Fittkauimyia sp. were identified. Assessment of their relationships with several environmental parameters was performed using the canonical correspondence analysis (CCA). Tanytarsus formosanus was the most dominant in the relatively clean CTKR and moderately polluted JR with mean densities of 19.66 and 25.32 m?2, respectively while C. kiiensis was abundant in more polluted rivers. Tanytarsus formosanus, Dicrotendipes sp. and Microchironomus sp. were grouped under moderate to high water temperature, total organic matter (TOM), total suspended solids (TSS), velocity, pH, phosphates and sulphates. However, Tanypus punctipennis, Fittkauimyia sp., and Clinotanypus sp. were associated with high contents of river sediment such as TOM, Zn and Mn and water ammonium-N and nitrate-N and they were associated with higher dissolved oxygen (DO) content in the water. Chironomus kiiensis, C. javanus and P. trigonus showed positive relationships with TOM, ammonium-N and nitrate-N as well as trace metals of Zn, Cu and Mn. These three species could be considered as tolerant species since they have the ability to survive in extreme environmental conditions with low DO and high concentrations of pollutants. Based on the water parameter scores in all rivers, the highest diversity of chironomid larvae was reported in CTKR. With higher concentrations of organic and/or inorganic pollutants as reported in PPR, KUR and AR, the chironomid larval diversity decreased, and the abundance of tolerant species, mainly Chironomus spp., increased.     

河北沿岸硬骨鱼类鱼卵和仔雅鱼分布

2006年夏季(7月)、冬季(12月)和2007年春季(4月)、秋季(9月)用浅海型标准浮游生物网在河北沿岸海域进行了鱼卵和仔稚鱼生态调查.结果显示,4个季度月共采集鱼卵和仔稚鱼19种,分别隶属4目6科11属,优势种为石首鱼科.夏季出现的种类和数量最多.分布密集区主要集中在渤海湾.