Limnological study of Dokan, Derbendikhan and Duhok lakes, Kurdistan region of Iraq

The present study deals with the assessment of physico-chemical characteristics of Dokan, Derbendikhan and Duhok lakes. The physico-chemical characteristics of these lakes have been studied and analyzed for a year, during January-April-July and October 2009. Seasonal variations of two sampling sites of the lakes have been observed. Various parameters including air temperature, water temperature, electrical conductivity, TDS, pH, total alkalinity, total hardness, dissolved oxygen, calcium, magnesium, sodium, potassium, sulfate, chloride, nitrite and phosphate have been analyzed. The study has revealed that there are significant seasonal variations in some physico-chemical parameters and as a whole most of the parameters are different in the three lakes.

Historical Evolution of the Trophic and Limnological Relationships in the Itaipu Reservoir:Top-Down and Bottom-Up Effects upon Fish Production

Many experimental studies have contributed to the development of the theory of trophic chains in lacustrine habitats. They have revealed the important role played by fish, a subject that has been mostly ignored by limnological studies for the past few decades. Most of these studies were developed in Europe and in the United States. The general applicability of this theory has not yet been tested in subtropical and tropical habitats. In spite of controversies, the bottom-up: top-down trophic cascade hypotheses are the most adopted conceptual models. In this context, we examined if these hypotheses may be corroborated by data from the subtropical Itaipu Reservoir. A negative effect was verified between water transparency and total suspended solids. The detritivorous fish exerted a controlling effect on chlorophyll-a concentrations. Bottom-up effects were detected in four trophic levels, and top-down was detected in just one trophic level. The limnological variates influenced the chlorophyll-a concentration, which indicated that the lnTKN plus the effect of the quarter and the reservoir zone (and their interaction) were important.

Experimental Study of the <i>Aphanizomenon ovalisporum</i>Response to Nitrogen Fertilization in the Sub-Tropical Eu-Meso-Trophic Lake Kinneret (Israel)

First record of a bloom of filamentous-heterocystous nitrogen fixer cyanobacterium, Aphanizomenon ovalisporum, was documented in the summer of1994 inLake Kinneret (Israel). Awareness of such a bloom outbreak was predicted earlier based on documentation of Nitrogen deficiency and Phosphorus Sufficiency developed conditions. The concept of Nitrogen fertilization aimed at suppression of Nitrogen fixers Cyanobacteria was worldwide discussed and successfully implemented, but mostly in temperate oligotrophic lake ecosystems. This paper presents an experimental testing of this concept by additional Nitrogen. The results of the present study did not verify this hypothesis probably related to the ecological differences between Kinneret and the temperate ecosystems and using only one factor (Nitrogen) to test it.

Evolution on the Water Quality in Sergipe Hinterland Reservoirs, Northeast Brazil

Population growth has consequences for intense use of aquatic ecosystems. Samples were taken, between 2013 and 2014, in the reservoirs ＂Algodoeiro＂ and ＂Gloria＂ in Sergipe, Brazil. TSI （Trophic State Index） and WQI （Water Quality Index） were used. It was determined the parameters such as conductivity, dissolved oxygen, total nitrogen, total phosphorus and chlorophyll. TSI has been applied, in ＂Algodoeiro＂, which was classified as mesotrophic. With the increase of rainfall in 2014, this reservoir changed its condition to eutrophic. ＂Gloria＂ reservoir was already classified in super-eutrophication. Regarding the WQI, the reservoirs were classified in Class IV, indicating a critically degraded condition.

Carbon and Oxygen Isotopic Compositions: How Lacustrine Environmental Factors Respond in Northwestern and Northeastern China

Surface lake sediments, 28 from Hoh XU, 24 from northeastern China, 99 from Lake Bosten, 31 from Ulungur and 26 from Heihai were collected to determine δ13C and δ18O values. Considering the impact factors, conductivity, alkalinity, pH, TOC, C/N and carbonate-content in the sediments, CI, P, S, and metal element ratios of Mg/Ca, Sr/Ca, Fe/Mn of bulk sediments as environmental variables enable evaluation of their influences on δ13C and δ18O using principal component analysis （PCA） method. The closure and residence time of lakes can influence the correlation between δ13C and δ18O. Lake water will change from fresh to brackish with increasing reduction and eutrophication effects. Mg/Ca in the bulk sediment indicates the characteristic of residence time, Sr/Ca and Fe/Mn infer the salinity of lakes. Carbonate formation processes and types can influence the 6~3C--~1So correlation. ~180 will be heavier from Mg-calcite and aragonite formed in a high-salinity water body than calcite formed in freshwater conditions. When carbonate content is less than 30%, there is no relationship with either 613C or 6180, and also none between δ13C and δ18O. More than 30%, carbonate content, however, co-varies highly to δ13C and δ18O, and there is also a high correlation between δ13C and δ18O. Vegetation conditions and primary productivity of lakes can influence the characteristics of δ13C and δ18O, and their co-variance. Total organic matter content （TOC） in the sediments is higher with more terrestrial and submerged plants infilling. In northeastern and northwestern China, when organic matter in the lake sediments comes from endogenous floating organisms and algae, the δ13C value is high. δ13C is in the range of-4‰ to 0‰ when organic matter comes mainly from floating organisms （C/N〈6）; in the range of-4‰ to 8‰ when organic matter comes from diatoms （C/N=6 to 8）; and -8‰ to -4‰ when organic matter comes from aquatic and terrestrial plants （C/N〉8）.

Seasonal variations of rotifers from a high altitude urban shallow water body, La Cantera Oriente (Mexico City, Mexico)

La Cantera Oriente is a shallow freshwater volcanic water body located at an altitude of 2 270 m above sea level in the Ecological Reserve of San Angel Pedregal of Mexico City （Mexico）. In order to ensure the conservation of its biological heritage including zooplankton, the present work was undertaken to quantify the seasonal changes in the diversity and density of rotifers and the selected physico- chemical variables during 2013-2014. Qualitative analysis of the zooplankton samples yielded 68 rotifer species which represented 24 genera in 15 families. Brachionus calyciflorus Pallas, 1766, B. quadridentatus Hermann, 1783, Polyarthra vulgaris Carlin, 1943, Lecane closterocerca （Schmarda, 1859） and Keratella cochlearis （Gosse, 1851） were the most common species. Preston plots of species frequency-density revealed that as many as 30% of the rotifer taxa were dominant throughout the year. The species with high population densities were Brachionus quadridentatus, Lecane closterocerca, Keratella cochlearis, and Lepadellapatella; their peak densities were 2 000, 1 000, 180 and 90 ind./L, all occurring in summer. Canonical correspondence analysis showed that Platyias quadricornis was related to the concentration of phosphates available in the environment and the conductivity, while B. quadridentatus was positively correlated with chlorophyll-a. The trophic status of the lake was eutrophic based on Chl-a content but oligotrophic with relation to the Braehionus： Trichocerca ratio.

Chinese Journal of OCEANOLOGY and LIMNOLOGY

Edited by:The Chinese Society of Oceanology and Limnology, 7 Nanhai Road, Qingdao, ChinaEditor-in-ChiefC.K.Tseng Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071Members of the BoardCheng Lanna Scripps Institution of Oceanography, University of California, 92093, USACHEN Shu-peng Institute of Geography, Chinese Academy of Sciences, Beijing 100012C. T. A. Chen Marine Sciences Research Center, National SUN Yat-sen University,Kaohsiung 80424HU Dun-xin Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071JIANG Li-jin Institute of Photographic Chemistry, Chinese Academy of Sciences,Beijing

Chinese Journal of OCEANOLOGY and LIMNOLOGY

Edited by:The Chinese Society of Oasnology and Limnology, 7 Nanhai Road, Qingdao, ChinaEditor-in-ChiefC.K.TSeng Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071Members of the BoardCheng Lanna Scripps Institution of Oceanography, University of California, 92093, USACHEN Shu-peng Institute of Geography, Chinese Acadrmy of Sciences, Bejing 100012C. T. A. Chen Marine Sciences Research Center, National SUN Yat-sen University,Kaohsiung

Chinese Journal of OCEANOLOGY and LIMNOLOGY

Edited by:The Chinese Society of Oceanology and Linmology, 7 Nanhai Road, Qingdao, ChinaEditor-in-ChiefC.K.Tseng Institute of Oceanology, Chinese Academy of Sciences Qingdao 266071Members of the BoardCheng Lanna Scripps Institution of Oceanography, University of California 92093, USACHEN Shu-peng Institute of Geography, Chinese Academy of Sciences, Beijing 100012C. T. A. Chen Marine Sciences Research Center, National SUN Yat-sen University,Kaohsiung 80424HU Dun-xin Institute of Oceanology, Chinese Academy of Scieaces, Qingdao 266071JIANG Li-jin Institute of Photographic Chemistry, Chinese Academy of Sciences,Beijing

Aqueous Geochemistry and Limnology of the Sleeper Pit Lake, Nevada, USA: Evidence for Long-Term Subaqueous Solute Generation in Mine Pit Lakes

Predictive geochemical and limnologic modeling of pit lakes is an important aspect of modern mine-site permitting. One of the key assumptions of many predictive pit-lake models is that open-pit high walls and in-pit backfill become geochemically unreactive once submerged by the filling pit lake. Existing pit lakes provide useful data to test this assumption. The Sleeper pit lake (northwestern Nevada, USA) is approaching hydrologic equilibrium and contains good-quality water that generally meets regulatory requirements for pit lakes. Despite the overall stable geochemical composition, seasonal trends in the hypolimnion indicate the generation of dissolved metals associated with the ore deposit (e.g., Mn and Zn) and cyclical variations in pH. This study applies mass balance, analysis of subaqueous pyrite oxidation, and trends in solute concentrations to evaluate the potential causes of long-term solute generation in the hypolimnion of the Sleeper pit lake. Three separate conceptual models (subaqueous pyrite oxidation;redox reactions;and diffusion of solutes from a permanently stratified bottom layer) were tested against the high-quality dataset available for the pit lake. Evaluation of the monitoring dataset for the pit lake indicates that the Sleeper pit lake has variable limnologic behavior, wherein the lake is consistently stratified (meromictic) in some years, while it undergoes full mixing (holomixis) in other time periods. Comparison of the data with the three conceptual models illustrates that none of these models can be completely implicated as causing the seasonal geochemical variations in the bottom of the pit lake, but that a combination of the processes is likely partially responsible. Additional data collection including sediment cores and in-situ pore-water analysis would aid in understanding geochemical processes occurring over time.

Chinese Journal of OCEANOLOGY and LIMNOLOGY

Edited by:The Chinese Society of Oceanology and Limnology, 7 Nanhai Road, Qingdao, ChinaEditor-in-ChiefC.K.Tseng Institute of Oceanology,Chinese Academy of Sciences, Qingdao 266071Members of the BoardCheng Lanna Scripps Institution of Oceanography, University of California, 92093, USACHEN Shu-peng Institute of Geography, Chinese Academy of Schaces Boping 100012C. T. A. Chen Marine Sciences Research Ceahe, National SUN Yat-sen University,Kaohsiung 80424HU Dun-xin Institute of Oceanology, Chinase Acatwy of Scences, Qingdao 266071JIANG Li-jin Institute of Photographic Chrmistry, Chinese Acatmy of Sdeaces,Beijing

The Limnology of Ohana Lake, a Potential Manmade Aquaculture System in Nigeria

The concentrations of heavy metals (Fe > Zn > Cu > Pb > Ag) in bottom sediments and fish gills in Ohana Lake, were found to be significantly high and far exceeded FEPA and WHO environmental standards for water quality by 1.5 to 18 times, respectively. Six classes of each of phytoplankton and zooplankton with a total of 35 phytoplankton taxa comprising 46 species i.e. 35(46) and 22(28) faunal were observed. The class Chlorophyceae dominated the phytoplankton community with 18(22) followed by Cyanobacteria 6(10). The aquatic fauna was dominated by the Rotifera 8(11), followed by the Copepoda 6(9). The benthic flora community consisted of five classes of phytoplankton made up of 28(36). The class Bacillariophyceae 11(15) dominated the group followed by Chlorophyceae 10(11). Benthic fauna were made up of seven classes of 13(13). The dominant class Nemata 4(4) was followed closely by Protozoa 2(3). Ohana Lake is fast turning to a eutrophic ecosystem with accompanied algal bloom due to very high nutrient contents. The equitability or evenness indices (J) for both phytoplankton and zooplankton were lowly indicating generally low species diversities as well as predominantly unstable ecosystem. The aquacultural implications of these parameters are discussed.

Multivariate Analysis in the Climate Change Studies and Water Quality of Lake Patzcuaro （Mexico）

In this study, the authors carried out the systemic analysis of water quality of Lake Patzcuaro in relationship with the climate change during a period of 85 years. The statistical comparison （medians, ＂t＂ Student test, regressions and correlations） for the precipitation, evaporation, observed temperature, minimum and maximum for the periods 1969-1988 （pre-impact） and 1988-2007 （post-impact） was realized. The ＂t＂ Student test for water quality during the period of 1981-2011, as well as, the regression analysis and multiple linear correlation of water quality from 2006 to 2011 were applied in joint way of the Cluster and Principal Component to observe the effects of climate change on water quality and vulnerability of Lake Patzcuaro. The comparative analysis of the meteorological data for 1921-1960 and 1973-2007 by the KOppen classification showed a climate change. The comparative Box Plots diagrams for 1973-1989 and 1989-2007, as well as, the ＂t＂ Student test, linear regression and correlation indicated significant changes in time for precipitation, evaporation, observed temperature, minimum and maximum （P ≤ 0.05）. The correlation and regression analysis indicated significant positive trends for turbidity, conductivity, total phosphorus, aluminum, oils and grease, in contrast with Secchi disk depth, transparency, Redox potential and dissolved oxygen concentration. The ＂t＂ Student test showed significant differences between 1981 and 2011 for transparency, hardness, alkalinity, conductivity, nitrite, and phosphate. Cluster and Principal Components of the physicochemical and biological of 2006-2011 confirmed the vulnerability of the system by human growth and climate change influence.

Spatial and Temporal Quality of Water in the Itupararanga Reservoir,Alto Sorocaba Basin(SP),Brazil

Considering the great importance of the Itupararanga Reservoir, Upper Alto Sorocaba basin/SP, this study aimed to report the variations of some parameters of water quality in the spatial and temporal gradients in this multipurpose reservoir. The eutrophication of this reservoir was checked using the Carlson Index Modified and the results indicate that the surface water were classified as eutrophic and mesotrophic in wet and dry periods, being characterized the better quality of water in wet period. In the vertical gradient the results showed a stratiphication in all parameters analyzed, except for the electrical conductivity, with good correlation between total phosphorous and chlorophyll-a, indicating that eutrophication of the reservoir changes the conditions of algal growth, mainly in its initial area. Immediate interventions are needed, which must be directed to planning of land use, domestic effluents treatment, taking to an integrated management of this important watershed located in the Sao Paulo State.