Effect of temperature on contents of essential highly unsaturated fatty acids in freshwater zooplankton     

Michail I. Gladyshev  Vitaliy P. Semenchenko  Olga P. Dubovskaya  Elena B. Fefilova  Olesia N. Makhutova  Zhanna F. Buseva  Nadezhda N. Sushchik  Vladimir I. Razlutskij  Ekaterina V. Lepskaya  Mariya A. Baturina  Galina S. Kalachova  Olga N. Kononova 《Limnologica》2011,41(4):339-347

In 11 lakes from cold and warm regions we studied the content of highly unsaturated fatty acids (HUFA) in seston (<130 μm) and crustacean zooplankton using gas chromatography–mass spectrometry. An increase of temperature correlated with a decrease of HUFA content in zooplankton. A multivariate canonical correlation analyses revealed, that the decrease of HUFA content was related with a decrease of per cent of copepods in zooplankton communities, which are known to have higher HUFA levels in their biomass, than cladocerans. This means that temperature primarily affected the HUFA levels indirectly, via changing of taxonomic structure of zooplankton community, while the homeoviscous adaptation of zooplankton individuals had comparatively lower importance. As found, water temperature was better predictor of HUFA contents of zooplankton, than the fatty acid composition of seston. Thus, it can be predicted, that a probable climate warming will decrease the content of the essential HUFA in freshwater zooplankton with possible negative consequences for animals of higher trophic levels.  相似文献   

Laboratory and pilot studies on reclamation of a salt-affected alluvial soil     

V. I. Diamantis  E. A. Voudrias 《Environmental Geology》2008,54(3):643-651

Soil column experiments showed that a surficial sodic soil is efficiently reclaimed using freshwater, after the addition of saturated gypsum solution. Gypsum application in the field was beneficial in terms of maintaining high soil permeability, increased water infiltration and neutral pH after a rainfall event. In the present paper, two different reclamation techniques for the plough layer of a sandy loam sodic soil were tested in laboratory columns, 25 cm long and 10 cm in diameter; the first using freshwater alone and the second using a saturated gypsum solution. The dynamics of salt removal were studied by continuous analysis of the water drained from the bottom of the columns. When freshwater was used, sodium presented the lower removal rate and adversely affected soil permeability. When gypsum solution was used, calcium was present in the flushing solution and the effect of sodium dominance on clay dispersion and soil clogging was limited. The results presented in this study are of practical importance with respect to the reclamation of sodic soils found in the coastal area of the east Nestos Delta, Greece, where freshwater is limited, due to seawater intrusion, and saline groundwater is used for irrigation.  相似文献   

IPCC AR6报告解读：陆地和淡水生态系统及其服务变化     

胡轶伦  冀国旭  李积宏  干珠扎布  胡国铮  高清竹 《气候变化研究进展》2022,18(4):395-404

IPCC第六次评估报告（AR6）第二工作组（WGII）报告的第二章表明,气候变化对陆地和淡水生态系统影响的范围和程度较前期评估结果更为严峻。人为气候变化导致生态系统结构、功能和恢复力恶化,生物群落转移,疾病的传播范围和发病率增加,野火燃烧面积增加和持续时间延长,局部地区物种灭绝,极端天气的频率和强度增加。未来气温升高2~4℃情景下,陆地和淡水生态系统中高灭绝风险物种占比为10%~13%,野火燃烧面积增加35%~40%,森林地区50%以上树木面临死亡风险,15%~35%的生态系统结构发生转变,碳损失持续增加,气温的升高将进一步加剧这些风险造成的严重且不可逆的影响。通过生态系统保护和恢复等人为适应和减缓措施,可以在一定程度的气候变化范围内保护生态系统的生物多样性并增强生态系统服务在气候变化下的恢复力。加剧的气候变化将阻碍适应措施的制定和实施,为保证措施的有效性需要考虑气候变化的长期影响并加快适应措施的部署。  相似文献   

南大洋淡水通量的气候效应研究进展     

马浩  李春 《地球科学进展》2010,25(2):140-146

南大洋淡水通量在古气候演变中曾经发挥过重要作用,全球变暖背景下的南极融冰事件使南大洋淡水通量成为气候学家关注的焦点。从南大洋淡水通量异常对热盐环流和海平面变化的影响以及异常信号传播路径等3个方面系统分析了各种海洋—大气耦合数值模式的已有研究结果,总结了与这一问题有关的各种不同学术观点,对目前存有争议的问题进行了讨论,并对未来有价值的研究方向和全球变暖背景下这一问题的研究前景进行了展望。  相似文献   

Acute toxicity of the insecticide cypermethrin to three common European mayfly and stonefly nymphs     

《Limnologica》2021

Freshwaters are particularly vulnerable to pesticide contamination from adjacent agriculture and forestry. Cypermethrin is a commonly used pyrethroid insecticide, but information on its toxicity to non-target freshwater invertebrates is limited to a small number of taxa. We assessed cypermethrin toxicity to nymphs of the common European mayflies Baetis rhodani and Ecdyonurus venosus, and the stonefly Isoperla grammatica in 96 h static bioassays. The 96 h median lethal concentrations (LC50) we recorded for the three species were 0.08 μg/L, 0.15 μg/L, and 0.13 μg/L, respectively. The effective concentration (EC50), quantified as lack of escape response (implying inability to avoid drift, predation or abiotic stress), was usually 32 % of the LC50. All 96 h LC50 values were lower than the maximum concentrations detected in streams in UK and continental Europe. Alarmingly, the 96 h LC50 for B. rhodani was below the currently applied single-pesticide EU safe drinking water standard of 0.1 μg/L. Contrasts among species were most evident at 24 h LC50, when B. rhodani was approximately ten times more sensitive than the other two taxa. B. rhodani is a key algal grazer, ubiquitous in European streams, and its decline could exacerbate algal blooms. The order of taxa sensitivity to cypermethrin in our study contrasts with their sensitivity to organic pollution in the same region, which suggests a tolerance trade-off, and thus a compounding effect of simultaneous stressors. Mayflies and stoneflies are important prey for instream and riparian predators, and key components of most eutrophication indices globally, all of which could be compromised in presence of cypermethrin.  相似文献   

Micropollutants in four Brazilian water reservoirs     

《Limnologica》2021

The concern about emerging contaminants such as pharmaceuticals is growing, mainly due to the increased global consumption of synthetic chemicals and the potential risk to environmental and human health. Although developing countries may be hotspots of pharmaceutical pollution, the knowledge about the occurrence of pharmaceuticals is still limited and patchy. Brazil holds one of the largest freshwater volumes globally, yet, little is known about the occurrence of pharmaceuticals in reservoirs although they make up key water sources. The aim of this study was, therefore, to investigate micropollutant occurrence, mainly pharmaceuticals, in four freshwater reservoirs distributed in Brazil. Water samples were collected in the Curuá-Una (CUN, Amazon region), Chapéu D’Uvas (CDU, Atlantic Forest region), Funil (FUN, Atlantic Forest region), and Simplício (SIM, Atlantic Forest region) reservoirs. The occurrence of 28 different micropollutants, including 26 pharmaceuticals, was investigated with target analysis on a UHPLC-Orbitrap-MS/MS, and a non-target screening approach was performed on all water samples to identify the presence of additional contaminants. The highest micropollutant concentrations were observed in FUN and SIM, which are the reservoirs with the largest population size in the catchment. Only caffeine was detected in CDU and CUN, which are reservoirs less influenced by urbanization. Metformin was the pharmaceutical with the highest concentrations, reaching 2 191 ng L⁻¹ in FUN. The non-target screening identified 125 chemicals, of which most were pharmaceuticals. The numbers of compounds identified and which were above the LOQ were higher in FUN and SIM, in agreement with results from the target analysis. Metformin is the compound with the highest risk to affect FUN reservoir negatively, based on calculated risk quotients. Considering that the reservoirs are used for multiple purposes, including water supply, irrigation, and aquaculture, it is important to continue investigating micropollutant occurrence to guarantee environmental and human health.  相似文献   

Insights into the diversity,distribution and phylogeny of three ergasilid copepods (Hexanauplia: Ergasilidae) in lentic water bodies of the Morava river basin,Czech Republic     

《Limnologica》2021

Ergasilidae are a globally distributed group of copepods parasitising fish. Despite their common occurrence in European freshwaters, there is relatively little molecular data available. In this study, we recorded three ergasilid copepod species parasitising six fish species (families Cyprinidae, Percidae, Centrarchidae) in lentic water bodies along the River Morava in the Czech Republic: Ergasilus sieboldi infecting fish gills, Paraergasilus longidigitus infecting nasal cavities and Neoergasilus japonicus infecting fins. This represents a further occurrence of N. japonicus as a non-native European species, and the first report of P. longidigitusis from Central Europe waters. While strong niche selection potentially offers a free niche for each of these ergasilids in all hosts, parasite co-infections were relatively rare, with species distribution among hosts reflecting host preference. This study provides the first molecular data for E. sieboldi and P. longidigitus as native European ergasilid copepods. Phylogenetic analysis based on combined 18S and 28S rDNA showed a close relationship between P. longidigitus with other Paraergasilus species, supporting a monophyletic origin of this genus. The phylogenetic position of E. sieboldi was not clearly resolved, highlighting the need for more data and further intensive genetic investigations of other ergasilid species.  相似文献   

A new subspecies of Ranularia (Mollusca,family cymathdae) from the Kermadec Islands     

A. G. Beu 《新西兰海洋与淡水研究杂志》2013,47(1):23-28

A new geographic subspecies, Ranularia dunkeri iredalei, is described from beach specimens from Raoul Island in the Kermadec Islands. Ranularia dunkeri dunkeri (Lischke, 1868) is restricted to southern Japan.  相似文献   

Interocean circulation and heat and freshwater budgets of the South China Sea based on a numerical model   总被引：11，自引：0，他引：11  

Guohong Fang  Yonggang Wang  Zexun Wei  Yue Fang  Fangli Qiao  Xiaomin Hu 《Dynamics of Atmospheres and Oceans》2009,47(1-3):55

The South China Sea (SCS) interocean circulation and its associated heat and freshwater budgets are examined using the results of a variable-grid global ocean model. The ocean model has a 1/6° resolution in the SCS and its adjacent oceans. The model results from 1982 to 2003 show that the western Pacific waters enter the SCS through the Luzon Strait with an annual mean volume transport of 4.80 Sv, of which 1.71 Sv returns to the western Pacific through the Taiwan Strait and East China Sea and 3.09 Sv flows toward the Indian Ocean. The heat in the western Pacific is transported to the SCS with a rate of 0.373 PW (relative to a reference temperature 3.72 °C), while the total heat transport through the outflow straits is 0.432 PW. The net heat transport out of the SCS is thus 0.059 PW, which is balanced by a mean net downward heat flux of 17 W/m² across the SCS air–sea interface. Therefore, the interocean circulation acts as an “air conditioner”, cooling the SCS and its overlaying atmosphere. The SCS contributes a heat transport of 0.279 PW to the Indian Ocean, of which 0.240 PW is from the Pacific Ocean through the Luzon Strait and 0.039 PW is from the SCS interior gained from the air–sea exchange. The Luzon Strait salt transport is greater than the total salt transport leaving the SCS by 3.97 Gg/s, implying a mean freshwater flux of 0.112 Sv (or 3.54 × 10¹² m³/year) from the land discharge and P − E (precipitation minus evaporation). The total annual land discharge to the SCS is estimated to be 1.60 × 10¹² m³/year, the total annual P − E over the SCS is thus 1.94 × 10¹² m³/year, equivalent to a mean P − E of 0.55 m/year. The SCS freshwater contribution to the Indian Ocean is 0.096 Sv. The pattern of the SCS interocean circulation in winter differs greatly from that in summer. The SCS branch of the Pacific-to-Indian Ocean throughflow exists in winter, but not in summer. In winter this branching flow starts at the Luzon Strait and extends to the Karimata Strait. In summer the interocean circulation is featured by a north-northeastward current starting at the Karimata Strait and extending to the Taiwan and Luzon Straits, and a subsurface inflow from the Luzon Strait that upwells into the surface layer in the SCS interior to supply the outward transports.  相似文献   

Accuracy of kinematic wave and diffusion wave approximations for space-independent flows with lateral inflow neglected in the momentum equation     

V. P. Singh 《水文研究》1994,8(4):311-326

Error equations for the kinematic wave and diffusion wave approximations with lateral inflow neglected in the momentum equation are derived under simplified conditions for space-independent flows. These equations specify error as a function of time in the flow hydrograph. The kinematic wave, diffusion wave and dynamic wave solutions are parameterized through a dimensionless parameter γ which is dependent on the initial conditions. This parameter reflects the effect of initial flow depth, channel-bed slope, lateral inflow and channel roughness when the initial condition is non-vanishing; and it reflects the effect of bed slope, channel roughness and acceleration due to gravity when the initial condition is vanishing. The error equations are found to be the Riccati equation. The structure of the error equations in the case when the momentum equation neglects lateral inflow is different from that when the lateral inflow is included.  相似文献