ASSESSMENT OF PREDICTORS FOR STREAM EUTROPHICATION POTENTIAL1

ABSTRACT: Predicting stream eutrophication potential from non-point source nutrient loading across large temporal and spatial scales is a significant problem. In this paper we describe how two physiological indicators of P stress of stream bioflims, alkaline phosphatase activity (APA) and stored (surplus) P relate to two predictors of P loading: annual P loading predicted by the watershed model SIMPLE, and stream concentrations of soluble reactive P (SRP) in eight subbasins in the illinois River basin in Oklahoma. Data for APA, surplus P, nutrients and water chemistry were obtained at watershed outlets once during the cold season and twice during the warm season. There was a negative curvilinear relationship between APA and both predictors. Best fit was achieved by APA vs. annual predicted P loading. Both SRP and P. load are potentially useful to identify subbasins requiring no pollution abatement and to establish a regional target for P-load reduction. Surplus P is not as useful as APA in establishing these thresholds.     

Periphyton and Sediment Bioassessment in North Florida Bay

Periphyton colonization and sediment bioassessment were used ina survey to compare the relative environmental condition ofsampling sites located in Florida Bay and four peripheral sloughareas during the summer of 1995. Periphyton biomass, pigmentcontent, tissue quality and community composition weredetermined. In addition, benthic community composition and thetoxicities of whole sediments and associated pore waters weredetermined for two species of rooted macrophytes, an epibenthicinvertebrate and bioluminescent bacteria. Several locational differences were observed for the response parameters.Periphyton biomass was significantly greater in the Taylor Riverand the least in Shell Creek (P < 0.05). Most sediments were notacutely toxic to mysid shrimp nor phytotoxic. However, sedimentsfrom the Taylor River were more phytostimulatory than others (P< 0.05). Contaminant bioresidues were similar at most sites,however, mercury, chromium and nickel concentrations weregreater for periphyton colonized in the Taylor River and TroutCreek areas. Structural characteristics of the periphytic algalcommunity usually were statistically similar but a consistenttrend of lower density and diversity was evident for ShellCreek. The benthic community was the least diverse and dense inthe Canal C-111. The results of this study provide an initialindication of differences in the role of several slough areas aspossible sources of bioavailable contaminants to Florida Baywhich warrants additional investigation.     

Northern Rivers Ecosystem Initiative: Nutrients and Dissolved Oxygen – Issues and Impacts

Anthropogenic inputs of nitrogen (N), phosphorus (P) and oxygen-consuming material to aquatic ecosystems can change nutrient dynamics, deplete oxygen, and change abundance and diversity of aquatic plants and animals. The Northern Rivers Ecosystem Initiative required a research and assessment program to establish the contribution of pulp mill and sewage discharges to eutrophication and depressions in dissolved oxygen (DO) in the Athabasca and Wapiti rivers of northern Alberta, Canada and examine the adequacy of existing guidelines for protecting these systems. Analysis of long-term data showed that total N (TN) and total P (TP) concentrations in exposed river reaches exceeded concentrations in reference reaches by ≤ 2 times for the Athabasca River, and by 9.6 (TP) and 2.6 (TN) times for the Wapiti River. Results from nutrient limitation experiments conducted in situ and in mesocosms showed that benthic algal production was nutrient sufficient downstream of pulp mill discharges but constrained in upper river reaches by insufficient P (Athabasca River) or N + P (Wapiti River). Dissolved oxygen (DO) concentrations in both rivers declined during winter such that median concentrations in the Athabasca River 945 km downstream of the headwaters were approximately 8 mg L⁻¹ in mid-February. Although water column DO rarely approached the guideline of 6.5 mg L⁻¹, DO studies undertaken in the Wapiti River showed that pore water DO often failed to meet this guideline and could not be predicted from water column DO. Results from this integrated program of monitoring and experimentation have improved understanding of the interactions between nutrients, DO and aquatic ecosystem productivity and resulted in recommendations for revisions to nutrient and DO guidelines for these northern rivers.The Canadian Crown reserves the right to retain a non-exclusive, royalty free licence in and to any copyright.     

甘河着生藻类群落结构及其与环境因子的关系

2018年8月(丰水期),在嫩江支流甘河,调查了19个点位的着生藻类群落结构和水环境特征。并运用聚类分析、Mcnaughton优势度分析和IBD(biological diatom index,硅藻生物指数)3种方法研究了甘河着生硅藻群落结构和优势种清洁状况,使用主成分分析、Spearman相关分析和冗余分析等统计分析方法研究了甘河着生硅藻群落和环境因子的响应关系。结果表明:甘河共鉴定出着生藻类90种(属),以硅藻门、绿藻门和蓝藻门为主,生物量丰富。丰水期甘河水生态环境质量状况较为健康,着生硅藻主要由清洁种构成,其中Achnanthidium minutissimum优势度0.48,为绝对优势种。聚类分析结果表明,甘河采样点位可分为3组;其中组1和组2点位主要位于甘河上、中游,上、中游水质、生境质量较好,健康程度较高,优势种均为清洁种,上游Achnanthidium minutissimum优势度达到了0.64;组3点位均位于甘河下游,下游人为干扰较强,健康程度较其余两组偏低,Nitzschia palea和Nitzschia paleaeformis等耐污种在组3的优势度较高。导致甘河着生硅藻群落清洁度由上游到下游逐渐变差的主要水环境因子为电导率、总磷和高锰酸盐指数,其中影响中游硅藻群落结构变化的主要水环境因子为高锰酸盐指数,影响下游硅藻群落结构变化的主要水环境因子为电导率和总磷。由此可见,着生硅藻群落可以较好的指示甘河流域水体有机污染程度和营养富集程度。     

The distribution of,and relation among,mercury and methylmercury,organic carbon,carbonate, nitrogen and phosphorus,in periphyton of the South Florida ecosystem

Periphyton samples from Water Conservation Areas, Big Cypress National Preserve, and Everglades National Park in south Florida were analyzed for concentrations of total mercury, methylmercury, nitrogen, phosphorus, organic carbon, and inorganic carbon. Concentrations of total mercury in periphyton decrease slightly along a gradient from north‐to‐south. Both total mercury and methylmercury are positively correlated with organic carbon, nitrogen and phosphorus in periphyton. In horizontal sections of periphyton mats, total mercury concentrations tend to be largest at the tops and bottoms of the mats. Methylmercury concentrations tend to be the largest near the bottom of mats. These localized elevated concentrations of methylmercury suggest that there are “hot spots”; of methylmercury in periphyton.     

FOOD QUALITY OF AUFWUCHS FROM ARTIFICIAL STREAMS RECEIVING LOW LEVELS OF PERTURBATIONS1

ABSTRACT: Protein, carbohydrate, and organic content of Aufwuchs samples from artificial streams dosed separately With chlorine, copper, or dextrose were altered by changes in the taxonomic composition or physiological condition of the community. Protein content increased as community composition shifted toward a dominance. by blue-green algae or heterotrophs. Bluegreens or cyanobacteria were dominant most often in Aufwuchs developing under copper or chlorine treatments and when water temperatures approached the seasonal maximum (22.8 C-25.8 0, while heterotrophs proliferated in the dextrose-enriched stream. Due to the associated extracellular mucilage, carbohydrate content also tended to be higher when blue-green algae or bacteria were abundant. However, carbohydrate content decreased in communities developing under chlorine or copper treatments at low or moderate temperatures (3 C-22.8 C), indicating a utilization of stored photosynthetic products to adapt to the stress. The organic content of Aufwuchs was related to the extent of mucilage production and the tendency of the community to accumulate detritus and suspended inorganic sediment. Protein and carbohydrate estimates were significantly correlated with dry weight and ash-free dry weight, a result of the copious extracellular mucilage associated with rapidly growing blue greens and other bacteria. Estimates of Aufwuchs food quality are important in evaluating the impact of pollutants on higher trophic levels; however, the tendency of change with both taxonomic shifts and physiological adaptations tends to confound interpretations for water quality assessment.     

Mercury Accumulation in Periphyton of Eight River Ecosystems1

Abstract: In 2003, the U.S. Geological Survey (USGS) National Water‐Quality Assessment (NAWQA) program and U.S. Environmental Protection Agency studied total mercury (THg) and methylmercury (MeHg) concentrations in periphyton at eight rivers in the United States in coordination with a larger USGS study on mercury cycling in rivers. Periphyton samples were collected using trace element clean techniques and NAWQA sampling protocols in spring and fall from targeted habitats (streambed surface‐sediment, cobble, or woody snags) at each river site. A positive correlation was observed between concentrations of THg and MeHg in periphyton (r² = 0.88, in log‐log space). Mean MeHg and THg concentrations in surface‐sediment periphyton were significantly higher (1,333 ng/m² for MeHg and 53,980 ng/m² for THg) than cobble (64 ng/m² for MeHg and 1,192 ng/m² for THg) or woody snag (71 ng/m² for MeHg and 1,089 ng/m² for THg) periphyton. Concentrations of THg in surface‐sediment periphyton had a strong positive correlation with concentrations of THg in sediment (dry weight). The ratio of MeHg:THg in surface‐sediment periphyton increased with the ratio of MeHg:THg in sediment. These data suggest periphyton may play a key role in mercury bioaccumulation in river ecosystems.     

USING ARTIFICIAL STREAMS TO EVALUATE PERTURBATION EFFECTS ON AUFWUCHS STRUCTURE AND FUNCTION1

ABSTRACT: Artificial streams can assist in assessing the potential impact of pollutants on the structure and function of aquatic communities. While most artificial streams are constructed within a controlled environment or are maintained by recirculating water, we constructed a series of artificial streams along a river bank using river water on a once through basis. This system was used to develop and test methods for structural and functional analyses of Aufwuchs communities. Only the flow rate and stream depth were controlled while individual streams were perturbed to obtain communities of altered ecological condition. This experimental system provided a relatively inexpensive series of treated and untreated streams which allowed an evaluation and comparison of methods using communities under various stressed and nonstressed conditions. Without the stabilizing effects of a controlled atmosphere or recirculating water, our approach demonstrated a degree of variability which approached that of the river. We inferred that the Aufwuchs community present in the artificial streams maintained a high degree of structural complexity and functional dynamism, providing a strong test of our methods and an opportunity to examine current ecological theory.     

附着生物对富营养化水体氮磷的去除效果

以太湖梅梁湾“863示范工程”水草恢复区原位湖水以及该区渔网围隔上的附着生物为材料，通过室内静态培养试验，研究了附着生物对富营养化湖水的氮、磷去除效果。结果表明，附着生物对水体中的氮有显著的去除效果，半个月内，附着生物对水体中总氮的累积去除率可达60%，在有附着生物的水体中总氮浓度从5 mg/L左右下降到2 mg/L左右；附着生物对水柱中氮的累积去除率和水柱中氮的浓度、附着生物的生物量以及附着生物作用时间密切相关。从培养过程中水体磷的浓度变化来说，培养初期，水体中磷的浓度比较高，附着生物对其有一定的去除作用；培养后期，水柱中磷的浓度比较低，附着生物不但不去除水中的磷，而且还向水柱中释放磷，这可能与附着生物向水体分泌碱性磷酸酶密切相关。     

Effect of periphyton community structure on heavy metal accumulation in mystery snail (Cipangopaludina chinensis):A case study of the Bai River, China

The ratio of metal:P stoichiometry was used to identify the accumulation pathways of heavy metals (V, Cr, Co, Ni, Cu, Cd, and Pb) from periphyton to snails Cipangopaludina chinensis Gray (C. chinensis) in the Bai River watershed. The results showed that periphyton communities were mainly composed of two types of algae, filamentous green algae and unicellular diatoms. The proportion of unicellular diatoms in the periphyton community is a key factor that influences metal accumulation in C. chinensis. The V, Cr, Co, Ni, and Cd content of C. chinensis increased steadily as the corresponding metal content of periphyton increased, but Cu and Pb in the snail did not increase in the periphyton. Mechanisms of V, Cr, and Ni accumulation were found to be related to the proportion of diatoms, while Cd and Pb accumulation were dependent on the physiological characteristics of C. chinensis. The accumulation of Cu in C. chinensis was closely related to their grazing behavior. The metal:P stoichiometry revealed that Cr, Ni, and Cd can reduce the potential ecological risks associated with increased P inputs to the ecosystem. V and Co were considered to be relatively safe, regardless of the periphyton P content. Finally, Pb may not be prone to transfer to higher trophic levels, and may pose the lowest ecological risks of the studied heavy metals, but Cu can cause potential ecological risks when eutrophication has occurred.