Communities of hydrobionts developing at the water-rock interface in Lake Baikal

Development of benthic communities on rocks from the interdisciplinary test site near Cape Berezovyi (southern Baikal) is analyzed. Rock plates were placed on the bottom in the shallow-water zone of Baikal for six months, and a community consisting of microorganisms, microphytobenthos, and meiobenthos developed on them. The development and activity of hydrobionts depended on the chemical composition and structure of the rock. Marble and granite plates were populated by them more selectively than amphibolite plates. It is supposed that the biota plays an important role in destruction of rocks in the shallow-water zone of Baikal.     

Linking Excess Nutrients,Light, and Fine Bedded Sediments to Impacts on Faunal Assemblages in Headwater Agricultural Streams1

Griffith, Michael B., F. Bernard Daniel, Matthew A. Morrison, Michael E. Troyer, James M. Lazorchak, and Joseph P. Schubauer‐Berigan, 2009. Linking Excess Nutrients, Light, and Fine Bedded Sediments to Impacts on Faunal Assemblages in Headwater Agricultural Streams. Journal of the American Water Resources Association (JAWRA) 45(6):1475‐1492. Abstract: Biological impairments in streams are typically defined by regulatory agencies in terms of altered invertebrate or fish assemblages. While nutrients, canopy cover, and sediment fines contribute to these impairments, these stressors are often defined, at least in part, by their impacts on periphyton. Path analysis can extend these assessments to impacts on invertebrates and fish by characterizing the direct and indirect relationships among variables along defined model pathways. With data from headwater tributaries in the Little Miami River, Ohio, we tested models of the impacts of nutrients [total nitrogen (TN), total phosphorus (TP), and the nitrogen to phosphorus (N/P) ratio], the percentage of (%) open canopy, and the % sand and fines on three periphyton metrics [periphytic ash‐free dry mass (AFDM), the percent abundance of cyanobacteria (% cyanobacteria), and the percent abundance of Chlorophyta (% Chlorophyta)] and, in turn, on selected invertebrate or fish metrics. Our objective was to develop and evaluate a statistical model that assesses the direct and indirect impacts of excess nutrients on macroinvertebrate and fish in these streams and demonstrate how this approach might be applicable elsewhere. The results suggest indirect pathways for the influences of nutrients, canopy cover, and fine bedded sediments on invertebrates or fish that are mediated by their influences on periphyton. This is in addition to any direct impacts of these stressors on the invertebrate and fish metrics. In most models, all three periphyton metrics increased with % open canopy. Periphytic AFDM increased with TN, while % cyanobacteria decreased. The % cyanobacteria also decreased with % sand and fines, but % Chlorophyta increased. The metrics, percent abundance of (%) three most dominant (macroinvertebrate) taxa, % Trichoptera, and % herbivorous fish all increased with periphytic AFDM, while % climbers, % swimmers, and %Lepomis cyanellus Rafinesque decreased. Lepomis cyanellus is an indicator species, because it is generally common in these streams and relatively tolerant to various common environmental stressors. The % three most dominant macroinvertebrate taxa increased while % Hydropsychidae (Trichoptera) and %L. cyanellus decreased with % cyanobacteria. The % Trichoptera and %L. cyanellus increased with % Chlorophyta. Some macroinvertebrate metrics, such as the % burrowers and number of burrower taxa, did not have any statistically significant relationships with the periphyton metrics but did exhibit a direct pathway with % sand and fines. These analyses illustrate how path analysis can be used to estimate the relationships among the variables in a conceptual model, modify the model, assess the relative importance of different paths, and explore responses resulting from stressors with interacting and indirect impacts.     

Twenty Years of New Zealand’s National Rivers Water Quality Network: Benefits of Careful Design and Consistent Operation1

Davies‐Colley, Robert J., David G. Smith, Robert C. Ward, Graham G. Bryers, Graham B. McBride, John M. Quinn, and Mike R. Scarsbrook, 2011. Twenty Years of New Zealand’s National Rivers Water Quality Network: Benefits of Careful Design and Consistent Operation. Journal of the American Water Resources Association (JAWRA) 47(4):750‐771. DOI: 10.1111/j.1752‐1688.2011.00554.x Abstract: This paper reviews New Zealand’s National Rivers Water Quality Network (NRWQN), which is now in its third decade of monitoring. The NRWQN is noteworthy for being operationally stable throughout its history, and the resulting consistency is increasingly valuable for detecting water quality trends and for “anchoring” temporary special purpose monitoring campaigns. The NRWQN was carefully designed following considerable effort to learn from monitoring experiences elsewhere. Monthly visits are made to 77 sites (all near hydrometric stations) on 35 river systems that cumulatively drain about one half of the national landscape. “Core” (routinely measured) variables are: conductivity, pH, temperature, dissolved oxygen, visual clarity, turbidity, colored dissolved organic matter, fecal indicator bacteria, and different forms of nitrogen and phosphorus (italics indicate field measurements). Associated benthic biological monitoring comprises monthly visual assessment of periphyton and annual sampling for macro‐invertebrates. We overview the conception, design, initiation, and operational history of the NRWQN, and highlight the diverse applications of its datasets including numerous scientific applications, national‐scale modeling of material fluxes, and state‐of‐environment reporting and practical water management at both regional and national scale. The qualified success of the NRWQN can probably be attributed to careful (and parsimonious) design and consistent operation.     

SPATIAL VARIATION OF NUTRIENT BALANCE IN THE TRUCKEE RIVER,CALIFORNIA‐NEVADA1

ABSTRACT: Because the Truckee River connects two lakes along the Eastern Sierra Nevada Mountains with different limiting nutrients, this research addresses whether the nitrogen:phosphorus (N:P) balance of the river ecosystem changes longitudinally. Historical (1990 to 2000) total nitro‐gen:total phosphorus (TN:TP) ratios in river water exhibited the expected gradient from high N:P ratios upstream to low N:P ratios downstream, with the major gradient of the N:P balance occurring within the transition between montane and high desert terrain. During 2001, the river contained anomalously low total nitrogen concentrations in the far upper reaches and dissolved inorganic nitrogen concentrations in the lower reaches, resulting in a less apparent longitudinal gradient of N:P ratios. Measurements of periphyton growth and physiology (nutrient bioassays and ectoenzyme activities) and stoichiometry during the summer of 2001 also exhibited a complex picture of the spatial variation of N:P balance that was not entirely consistent with a strong N:P gradient. However, the compendium of the indicators did support the overall picture of an overarching longitudinal gradient from high to low N:P ratios. The results suggest that periphyton management efforts in the Truckee River should consider the overall spatial gradient as well as the small‐scale dynamics of the stream ecosystem structure.     

PATTERNS OF PERIPHYTON CHLOROPHYLL α IN AN AGRICULTURAL NONPOINT SOURCE IMPACTED STREAM1

ABSTRACT: An agricultural nonpoint source polluted stream in northern Idaho was examined to determine seasonal and longitudinal patterns of periphyton chlorophyll α. Chlorophyll a was measured at eight sites along Lapwai Creek, a fifth order stream impacted by agricultural runoff containing nutrients and eroded soils. Seasonally, periphyton chlorophyll α was lowest in the spring (cumulative x?= 60.4 mg m^?2) and highest in the summer (cumulative x?= 222 mg m^?2). Winter concentrations were higher than expected (cumulative x?= 168.6 mg m^?2). The headwaters, flowing through an open grassy meadow, had the lowest concentrations of the study (two-year x?= 49.7 mg m^?2). Immediately below a small, eutrophic reservoir, periphyton chlorophyll α increased markedly (two-year x?= 155.8 mg m^?2) and remained high through a deep canyon (two year x?= 135.5 mg m^?2) and down to the mouth of the stream (two-year x?= 172.3 mg^?2). Periphyton chlorophyll α in Lapwai Creek was at least two times greater than values reported in the literature for comparable, undisturbed Idaho streams. We suggest that increased nutrient concentrations via agricultural nonpoint source pollution and increased light penetration from the removal of large, woody riparian vegetation have resulted in high periphyton chlorophyll α along the continuum of Lapwai Creek.     

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.     

The Influence of Varying Planktonic and Periphytic Algal Biomass On Exposure to Polychlorinated Biphenyls in Mesocosms

Algal populations, either suspended in the water column (planktonic) or present on the walls of an enclosure (periphytic), develop differently depending upon the physical scale of the system. This study determined whether these variations altered the speciation and therefore exposure of polychlorinated biphenyls (PCBs) in estuarine mesocosms. Exposure was defined as the fraction of applied contaminant taken up by plankton after two hours. Using a three phase equilibrium model, the partitioning of a suite of PCBs within variously-sized mesocosms was predicted using laboratory derived distribution coefficients and measured levels of planktonic and periphytic algal biomass. in mesocosms having large wall surface area to volume ratios, sorption of hydrophobic PCBs to periphyton significantly decreased contaminant exposure. However, within the range of planktonic algal biomasses observed in this study, the regulation of PCB exposure was relatively invariant between variously-sized mesocosms. to minimize sorption of hydrophobic organic contaminants (HOCs) to periphyton and reduce artefacts inherent with this partitioning, we suggest using mesocosms with low wall surface area to volume ratios (less than or equal to 1). in addition, periphytic biomass should be quantified regularly and a three-phase equilibrium approach used to predict the actual exposure concentrations.     

白洋淀典型抗生素与底栖藻类群落指标相关性研究

底栖藻类作为湖泊中主要的生产者,其对抗生素较为敏感,目前有关喹诺酮类抗生素(quinolones, QNs)与底栖藻类群落的相关性研究较为缺乏,因此本研究选取白洋淀为研究区,利用超高效液相色谱串联质谱法(HPLC-MS/MS)检测水体QNs浓度,并分析底栖藻类群落结构和功能指标,利用商值法(RQ)计算QNs的生态风险值,建立QNs生态风险与底栖藻类群落指标的相关性。研究结果如下。(1)白洋淀QNs浓度存在明显时空差异。就空间分布而言,QNs的最高浓度出现在生境1(1 309.80ng·L~(-1));就时间变化而言,4月QNs浓度最高;就QNs种类而言,氟甲喹(flumequine, FLU)浓度最高(1 054.38 ng·L~(-1));(2)就藻类群落指标的空间分布而言,除藻密度(AD)、叶绿素a(Chl a)、叶绿素b(Chl b)、叶绿素b/a(Chl b/a)、绿藻比例(CHL)、蓝藻比例(CYA)、碱性磷酸酶(APA)、β-葡萄糖苷酶(GLU)、亮氨酸氨基肽酶(LEU)和无灰干重(AFDW)等指标最大值出现在生境2外,其他指标最大值出现在生境3;就时间分布而言,大部分底栖藻类群落指标11月值高于4月和8月;(3)除FLU的生态风险处于中等水平外,其余QNs生态风险较低;其中,8月生境2的生态风险值最高(RQ最大值为0.9446);(4) AD、Chl a、Chl b、叶绿素c(Chl c)、Chl b/a与RQ_(CIP)和RQ_(FLU)呈显著相关,其中Chl a与RQ_(FLU)的相关性显著(r=0.827,P<0.01)。结果表明,底栖藻类结构指标与QNs风险值相关性较为显著,因此,可考虑筛选较为敏感的底栖藻类群落结构指标,为富营养化湖泊生态监测方法研究提供理论基础及相关数据支撑。     

渭河流域河流着生藻类的群落结构与生物完整性研究

以渭河流域为研究范例,调查了全流域范围河流内45个样点的着生藻类群落和水环境理化特征,并在此基础上应用着生藻类生物完整性评价指数(P-IBI),对渭河流域水生态系统进行健康评价.同时讨论了水环境理化因子与着生藻类群落结构的相互关系,并对比分析了渭河流域不同区域水生态系统健康水平差异的原因.结果表明,渭河流域着生藻类群落结构具有明显的空间异质性,典范对应分析结果显示,驱动着生藻类群落结构形成的水环境因子为电导率和流量.P-IBI结果表明,渭河干流的上游及渭河干流的右岸支流健康状况较好,而渭河干流中下游区域及左岸支流的健康状况较差.泾河全流域及洛河下游地区健康状况较差,而洛河中上游区域永生态系统着生藻类生物完整性较高.     

附着生物对沉水植物伊乐藻生长的研究

以沉水植物伊乐藻(Elodea nuttalii(Plant.)ST.John.)为研究对象,室内利用原位湖水进行培养,通过测定伊乐藻的生物量、叶绿素质量分数、光合作用速率等指标,研究了附着生物量的增加对沉水植物伊乐藻的影响。结果表明,随着附着生物处理量的增加,伊乐藻的生物量、叶绿素质量分数以及光合作用速率随之下降,50d后,各处理的生物量与对照相比分别减少了约5%~15%,叶绿素质量分数以及光合作用速率下降了20%~43%、10%~36%。同时也分析了丝状藻对沉水植物伊乐藻的遮阴作用,初步推测附着生物对沉水植物伊乐藻的影响可能是由于附着生物的遮荫作用。研究的结果为揭示富营养化湖泊沉水植被衰退的机理提供了理论依据。