Energy-Based Land Use Predictors of Proximal Factors and Benthic Diatom Composition in Florida Freshwater Marshes

The Landscape Development Intensity index (LDI), which is based on non-renewable energy use and integrates diverse land use activities, was compared to other measures of LU (e.g., %agriculture, %urban) to determine its ability for predicting benthic diatom composition in freshwater marshes of peninsular Florida. In this study, 70 small, isolated herbaceous marshes located along a human disturbance gradient (generally agricultural) throughout peninsular Florida were sampled for benthic diatoms and soil and water physical/chemical parameters (i.e., TP, TKN, pH, specific conductance, etc.). Landscape measures of percent agriculture, percent urban, percent natural, and LDI index values were calculated for a 100 m buffer around each site. The strongest relationships using Mantel's r statistic, which ranges from −1 to 1, were found between benthic diatom composition, the combined soil and water variables, and LDI scores (r=0.51, P<0.0001). Although similar, soil and water variables alone (r=0.45, P<0.0001) or with percent agriculture or percent natural were not as strongly correlated (both Mantel's r=0.46, P<0.0001). Little urban land use was found in the areas surrounding the study wetlands. Diatom data were clustered using flexible beta into 2 groups, and stepwise discriminant analysis identified specific conductance, followed by LDI score, soil pH, water total phosphorus, and ammonia, as cluster-separating variables. The LDI explained slightly more of the variation in species composition than either percent agriculture or percent natural, perhaps because the LDI can combine disparate land uses into a single quantitative value. However, the ecological significance of the difference between land use metrics and diatom composition is controvertible, and additional tests including more varied land uses appear warranted.     

Epilithic Diatoms in an Alpine Lake (Traunsee,Austria) Affected by Soda and Salt Mining Industries

Traunsee, a 191 m deep Alpine lake in Austria, is affected by industrial tailings from the soda and salt mining industries since 1883. In 1998 littoral water chloride concentrations ranged between 40 and 85 mg L^-1 and the highest conductivity was 560 S cm^-1, which is almost double as high as the values reported from the two nearby reference lakes. Chloride concentrations increased towards the location of the industrial salt and soda emission into the lake. Analogously to the chloride gradient, the epilithic littoral diatom flora changes towards the waste inlet. Shifts in the species percentages towards the emission source, a high percentage of taxa with large conductivity tolerances, the presence of a small Achnanthes minutissima Kützing morphotype, and occurrences of taxa focused at habitats of higher electrolyte content, indicate subtle impacts on the epilithic diatom flora. An analysis of the seasonal succession of the epilithic diatoms at the waste inlet compared to a lake intern reference site, reveals that only during the late summer period in 1998 the diatom assemblage at the waste inlet became significantly different, indicating seasonally restricted effects of the industrial emissions.     

Factors driving the seasonal dynamics of Pseudo-nitzschia species and domoic acid at mussel farming in the SW Mediterranean Sea

ABSTRACT

The seasonal variations in Pseudo-nitzschia species and domoic acid (DA) concentration were investigated, at three shellfish farms in SW coastal Mediterranean. In parallel, the toxicity of mussels was tested. Two distinct groups of species were enumerated according to morphology and size (Pseudo-nizschia delicatissima and P. seriata groups). DA was detected over a nine-week period from July to October 2012 in the Lagoon, with a maximum concentration recorded in July (12.71?ng?DA?L^?1). DA was positively correlated with the presence of P. seriata-group and P. delicatissima-group and was mostly occurred during P limitation period in seawater. No DA was found in mussels that were collected during the period of DA absence in seawater. Our results suggest that temperature, salinity, inorganic and organic nutrients were significant for the seasonal dynamics of P. seriata and P. delicatissima groups, but that the P limitation was the most driving factor for DA production in these areas. The relative influence of environmental factors should be further studied to better understand the recent surfacing of massive blooms of toxigenic Pseudo-nitzschia in SW Mediterranean coast.     

Long-term survey of heavy-metal pollution, biofilm contamination and diatom community structure in the Riou Mort watershed, South-West France

In a metal-polluted stream in the Riou Mort watershed in SW France, periphytic biofilm was analyzed for diatom cell densities and taxonomic composition, dry weight and metal bio-accumulation (cadmium and zinc). Periphytic diatom communities were affected by the metal but displayed induced tolerance, seen through structural impact (dominance of small, adnate species) as well as morphological abnormalities particularly in the genera Ulnaria and Fragilaria. Species assemblages were characterized by taxa known to occur in metal-polluted environments, and shifts in the community structure expressed seasonal patterns: high numbers of Eolimna minima, Nitzschia palea and Pinnularia parvulissima were recorded in Summer and Autumn, whereas the species Surirella brebissonii, Achnanthidium minutissimum, Navicula lanceolata and Surirella angusta were dominant in Winter and Spring. Commonly used indices such as the Shannon diversity index and Specific Pollution Sensitivity Index reflected the level of pollution and suggest seasonal periodicity, the lowest diversities being observed in Summer.     

Pairing Modern and Paleolimnological Approaches to Evaluate the Nutrient Status of Lakes in Upper Midwest National Parks

Understanding what constitutes a reference (background) nutrient condition for lakes is important for National Park Service managers responsible for preserving and protecting aquatic resources. For this study we characterize water quality conditions in 29 lakes across four national parks, and compare their nutrient status to U.S. Environmental Protection Agency (USEPA) nutrient reference criteria and alternative criteria recently proposed by others. Where appropriate we also compare the nutrient status of these 29 lakes to state or tribal nutrient reference criteria or standards. For lakes that exceed reference criteria we investigate physical and chemical patterns, and for a subset of lakes compare modern nutrient conditions to paleolimnological (i.e., diatom‐inferred [DI]) nutrient reconstructions. Many lakes exceeded USEPA nutrient reference criteria, but met alternative less restrictive criteria. Modern nutrient conditions were also largely consistent with DI historic (pre‐1900) nutrient conditions. Lakes exceeding alternative nutrient criteria and with elevated nutrient levels relative to DI historic conditions were mostly small, shallow, and dystrophic; continued attention to their nutrient dynamics and biological response is warranted. Coupling modern and paleolimnological data offer an innovative and scientifically defensible approach to understand long‐term nutrient trends and provide greater context for comparison with reference conditions.     

DEVELOPING BIOLOGICAL INFORMATION SYSTEMS FOR WATER QUALITY MANAGEMENT1

ABSTRACT. Management of aquatic ecosystems requires a clear understanding of the goals to be achieved, appropriate information and the means to achieve the goals. Control measures applied to aquatic ecosystems, in the absence of information on the condition of the system, are apt to be inappropriate and thus may overprotect the receiving system at times and underprotect it at other times since the ability of ecosystems to receive wastes is not constant. A major determinant of the effectiveness and efficiency of ecological quality control is the lag time in the feedback of information. If the lag is too great, the control measures may repeatedly overshoot or undershoot the desired goal. Present techniques for measuring the responses of aquatic organisms and communities require days or weeks, whereas information for ecosystem quality control and prevention of ecological crises should be generated in minutes or hours as is the case for other quality control systems. Two biological monitoring systems have been developed to generate information rapidly. One system measures changes in the movement and breathing of fish in order to provide an early warning of developing toxicity in the wastes of an industrial plant. The other system measures changes in the diversity of algal comunities in streams by means of laser holography. The incorporation and use of these systems in industrial plants is discussed.     

Past changes in the abundance of diatoms as inferred from a sediment core from Hebe Haven, Saikung, Hong Kong

１　Ｉｎｔｒｏｄｕｃｔｉｏｎ１－１　ＤｉａｔｏｍｓＤｉａｔｏｍｓ（ＣｌａｓｓＢａｃｉｌｌａｒｉｏｐｈｙｃｅａｅ）ａｒｅｃｏｍｍｏｎａｎｄｗｉｄｅｌｙｄｉｓｔｒｉｂｕｔｅｄｉｎｂｏｔｈｆｒｅｓｈａｎｄｍａｒｉｎｅｗａｔｅｒｓ（Ｍｏｓｅｒ，１９９６）．ＴｈｅｓｅｍｉｃｒｏｓｃｏｐｉｃｕｎｉｃｅｌｌｕｌａｒｐｌａｎｔｓｆｉｘａｍａｊｏｒｐｏｒｔｉｏｎｏｆｔｈｅＥａｒｔｈ○ｓｃａｒｂｏｎ，ｇｅｎｅｒａｔｅｏｘｙｇｅｎ，ａｎｄｓｕｐｐｌｙｆｏｏｄｔｏａｎｉｍａｌｓｗｈｉｃｈｆｅｅｄｏｎｔｈｅｍ（Ｄｉｘｉｔ…     

汝溪河浮游硅藻功能群特征及其与环境因子相关性分析

基于不同水文期特点,分别在平水期(2014年4月)、丰水期(2014年7月)、枯水期(2014年12月)对三峡库区支流汝溪河的浮游硅藻及理化参数进行采样监测,应用功能群分类和数理统计分析等手段,探讨汝溪河不同水文期浮游硅藻功能群特征及其与环境因子间的相互关系.结果表明:3个水文期,汝溪河共发现浮游硅藻功能群10个,分别为A、B、C、D、L_o、MP、P、T_B、X3、S1类群,其中种类最多的功能群是MP类群,数量最多的是D类群.多元逐步回归分析发现,影响平水期功能类群密度最重要的环境因子为总氮(TN);与丰水期功能群密度显著相关的环境因子为透明度(SD);浊度(Tur)、碱度和pH以及电导率则是影响枯水期功能群密度的主要环境因子.RDA分析结果显示,影响汝溪河浮游硅藻功能群多样性的主要环境因子含水温(WT)、电导率(Spc)、氧化还原电位(ORP)、溶解氧(DO)、硝态氮(NO_3~--N)等.因此,功能群能较好反映汝溪河的生境特点,而氮营养元素对汝溪河浮游植物功能群变化及水质的影响应引起关注.     

基于硅藻完整性指数的辽河上游水质生物学评价

年9月对辽河上游12个采样点的着生硅藻进行了生物调查,同时测定了ρ(DO)、pH、ρ(TP)、ρ(TN)、ρ(NH₃-N)、ρ(COD_Cr)和ρ(BOD₅)等水质参数. 共检测到硅藻16属,以针杆藻属(Synedrasp.)、舟形藻属(Naviculasp.)、异极藻属(Gomphonema sp.)、桥弯藻属(Cymbella sp.)为优势种. 根据硅藻香农多样性指数确定了5个相对清洁采样点和7个受污染采样点,对10个硅藻生物指数进行了辨别力分析和Pearson相关分析. 结果表明,硅藻香农多样性指数、敏感性硅藻百分比和IDP硅藻指数最适合辽河上游的水质生物学评价. 采用5、3、1生物指数记分法统一量纲后,获得变化范围在3～15的D-IBI(硅藻完整性指数). 利用四分法划分辽河流域水质级别的标准,13～15为较好,10～12为一般,7～9为较差,3～6为差,并对12个采样点进行了重新评价,评价结果与水质参数的评价结果一致. 总体看来,该D-IBI基本适宜于评价辽河上游的水质状况. 收稿日期:┣┣(中)收稿日期┫┫2011-12-08修订日期:2012-03-08┣┣(中)修回日期┫┫基金项目:┣┣(中)基金项目┫┫国家水体污染控制与治理科技重大专项(2009ZX07528-002)作者简介:┣┣(中)作者简介┫┫李国忱(1985-),男,辽宁阜新人,liguochen1001@126.com.*责任作者,┣┣(中)通信作者┫┫ 刘录三(1975-),男,山东莒县人,副研究员,博士,主要从事水生生物多样性、生态系统健康评价方面研究,liuls@craes.org.cn      

Aptamers are an innovative and promising tool for phytoplankton taxonomy and biodiversity research

Nucleic acid aptamers are small-size ligands that selectively bind to molecular segments even when they protrude from cell surfaces. Due to their high specificity, aptamers are widely used in biomedical research and as probes for different applications. Here, we tested whether aptamers can also discriminate among phytoplankton cells. As a proof of concept we focused on the widespread centric diatom Leptocylindrus danicus and generated two aptamers that selectively bind to its cell surface. The aptamers did not bind to other diatoms tested, which included both pennate (Pseudo-nitzschia multistriata) and centric (Skeletonema marinoi, Chaetoceros socialis) species. They also showed negative binding to closely related species (Tenuicylindrus belgicus, Leptocylindrus aporus, Leptocylindrus convexus), which are hardly recognizable with microscopy techniques. In addition, aptamers discriminated also among cells of the same clone, suggesting a potential use of aptamers as clone-specific/stage-specific probes to track phytoplankton life stages in their natural environment. While the method still needs to be tested with natural algal samples, it can complement in a unique way the existing approaches to discriminate among species and possibly life stages of marine phytoplankton. The method can find useful application in taxonomic and ecological studies as well as in environmental monitoring including early warning strategies.