Benthic invertebrates of streams on the Alburz Mountain range near Tehran,Iran

Samples of benthic invertebrates were collected from riffle sites on two river systems in the southern Alburz Mountains in the neighbourhood of Tehran. Iran. Main river channels had a fauna of Oligochaeta, Plecoptera, Ephemeroptera, Trichoptera, Coleoptera, Diptera and Potamonidae and downstream changes in community structure were observed. Tributary streams had few or no benthic invertebrates. The main factors determining fauna appeared to be frequent flooding and high levels of suspended solids caused by quick run-off of rain and melting snow from the bare, eroded and degraded mountain sides.     

Benthic invertebrates of Rutland Water

The colonisation of Rutland Water by benthic invertebrates has been monitored from 1976 when the reservoir was first filled. A modified Ekman grab was used to sample populations quantitatively while false substrates and dredge samples were used to obtain supplementary data. Hand net and hand-sorting were used to study the littoral zone.The dominant taxa in the reservoir are Asellus aquaticus, A. meridianus, Gammarus pulex, Crangonyx pseudogracilis, Helobdella stagnalis, Erpobdella octoculata, Polycelis tenuis, larval Chironomidae and Oligochaeta. Other species which appeared abundantly, such as Limnaea pereger and Planorbis albus, have now disappeared and it is suggested that the generally low levels of gastropods might account for the poor performance of species such as Dugesia lugubris and Glossiphonia complanata.Other aspects of abundance are discussed, as are the effects of maturation of the system.     

Compensation effect of phytoplankton on nutrients from a sewage outfall in summer

This paper investigates the relationship between nutrients, chlorophyll a and physical variables in the upper Saronikos Gulf, an oligotrophic marine environment south of the Greater Athens Metropolitan Area. Phosphate, silicate, ammonia, nitrite, nitrate, temperature, salinity and dissolved oxygen were determined at eight stations on 9 occasions during summer 1982. A thermocline led to the stratification of the water column and the pycnocline was related to the thermocline. The values of oxygen were more or less normal. The Eutrophication of the seawater in the vicinity of the sewage outfall was demonstrated by surface levels of chlorophyll a being forty to two hundred times above background. This parameter provides evidence for a high phytoplankton standing stock. However, there were no appreciable differences between the nutrients in the outfall area and those in the background. This suggests rapid uptake of nutrients and/or effective dispersal from the outfall.     

Influence of food availability and other factors on the composition,structure and density on a subarctic population of benthic invertebrates

The factors influencing the composition, structure and density of benthic invertebrate communities in Yellowknife Bay in the Canadian subarctic were determined between June 1975 and April 1977. Attached algae, primarily Fragilaria vaucheriae, Fragilaria pinnata, Cymbella ventricosa and Cocconeis placentula were ingested in large numbers by several dominant species including the oligochaetes Rhyacodrilus sodalis, Lumbriculus variegatus and Limnodrilus claparendeianus and the mollusc Valvata sincera helicoidea. Although up to 7 × 10⁵ cells/oligochaeta, representing 65% by volume of the gut contents, were recorded for littoral zone populations, specimens in the profundal zone contained < 7.5 × 10⁴ cells in their guts. V. sincera helicoidea also ingested large numbers of attached algae (up to 2.3 × 10⁴ cells/animal), these representing 15–18% by volume of the gut contents. Consequently, multiple regression analysis indicated that the availability of attached algae was the major factor influencing the benthic communities. While 31–64% of the population variability could be accounted for by this factor, other parameters such as phytoplankton availability, water depth, temperature, dissolved oxygen levels, total amount of food in the gut, and the organic content of the sediments had little if any direct effect on the benthic populations.     

Effects of sewage waste stabilization lagoon effluent on stream invertebrates

The ecological impact of discharge to streams of domestic sewage waste stabilization lagoon effluent was investigated. Benthic invertebrates were compared upstream and downstream of discharges to eight New Zealand streams where effluent dilution ranged from 6- to 484-fold. The percentage of common invertebrate taxa whose density changed significantly (ANOVA, P<0.05) downstream declined in proportion with the log of the effluent dilution (r=-0.87) and increased with downstream increase in benthic respiration (r=0.91) and several intercorrelated indicators of organic enrichment (log biochemical oxygen demand, r=0.91; log suspended solids (SS), r=0.84). However, these changes in invertebrate densities did not always reflect degraded community structure. The nature and direction of changes suggests a subsidy-stress gradient of responses. Increases in SS of > 4 g m^-3 were associated with significant changes in density of > 50 percent of the common taxa and > 50 percent reduction of the densities of the sensitive Ephemeroptera, Plecoptera, and Trichoptera (EPT). However, EPT densities increased by up to 50 percent at lower organic solids loadings. No general relationships were found between relative densities of functional feeding groups and metabolic or water quality variables. These findings confirm that early warning of enrichment stress is more easily seen at the species level than at the functional level.     

达标污水离岸排海末端处置技术研究综述

达标污水离岸排海处置具有低成本、高处理率等优点,是国内外沿海港口和临港工业园区进行污水处置的重要选择。介绍了国内外达标污水离岸排海末端处置技术的发展情况,分析了排污口位置选划、扩散器射流参数及水力结构优化等研究技术上存在的问题。认为排污口位置选划应在水动力、污染物扩散、泥沙冲淤及工程经济因素分析的基础上,还需要重点考虑污水排放对区域生态要素长期的影响;排海末端扩散器射流参数及水力结构优化也尤为关键,不仅直接影响稀释扩散效果,而且涉及到主管、上升管、喷口等多个可控因子,可以采用建立物理模型、数值模型及量纲分析等方法,合理优化扩散器的结构参数和扩散器的型式,对提高达标污水离岸处置的效果具有重要意义。     

Factors influencing the species composition,distribution and abundance of benthic invertebrates in the profundal zone of a eutrophic northern lake

Factors influencing the species composition, distribution and abundance of benthic invertebrates were determined in a eutrophic subarctic lake from April 1978 to April 1979. Collections were made at five stations located at depths of 4 to 13 m. The largest populations of up to 5 × 10³ animals m^–2 were found in the deepest part of the lake. of the 24 species recorded in this area, the chironomidsProcladius denticulatus, Dicrotendipes modestus, Chironomus decorus andGlyptotendipes barbipes were most common. The strong development of benthos in the profundal zone was attributed to a consistently large supply of food and warm (4 °C) winter temperatures on bottom. Slightly smaller populations (up to 4 × 10³ animals, m^–2), composed of 19–23 species, occurred in shallower water, a reflection of lower (1.5 °C) winter temperatures. In the anoxic northern part of the lake, only 4–8 species were found in low numbers (400–1 000 animals m^–2). This was likely due to low (<5% saturation) oxygen levels in water and high organic content (18.5%) of the sediments.     

自然曝气生物滤床对二级污水处理厂尾水中抗生素的去除效果及影响因素研究

采用自然曝气生物滤床工艺处理污水处理厂尾水中抗生素,对生物滤床中抗生素的去除特点和影响因素进行研究。研究结果发现,自然曝气生物滤床能够有效地去除四环素类抗生素(58±2)%、喹诺酮类抗生素(48±20)%和大环内酯类抗生素(18±11)%。微生物降解和物理吸附是生物滤床去除抗生素的主要途径,而这两种途径的协同作用则延长了生物滤床的运行周期。结果还表明,水力负荷对抗生素的去除效率影响较大,当水力负荷为4.8～6.4m/d时,生物滤床对抗生素有较好的处理效果。此外,水质参数(水温、pH、COD浓度和硝化作用等)在一定程度上也可以影响生物滤床对抗生素的处理效果。     

Distribution of echinoderms and their larvae in the southwestern Peter the Great Bay, Sea of Japan

Based on results of processing planktonic and benthic samples collected in 1996 and 1997, a spatial distribution of echinoderms in the bottom and of their larvae in the plankton were collated for the water area of the Southern region of the Far Eastern State Biosphere Marine Reserve. Some correlation between distributions of the adult and larval sea star Asterias amurensis in July was revealed. At the same time, there was no correlation between distributions of larvae and adult individuals of the brittle star Ophiura sarsi and sea urchin Echinocardium cordatum, which are most abundant in the area. The size structure of bottom populations of the brittle stars O. sarsi and Amphiodia fissa in the studied area was assessed. The correlation coefficient between the distribution of young-of-the-year and the population density was 0.47 in O. sarsi and 0.74 in A. fissa respectively, which implied a selective settling of larvae of those species in areas inhabited by adult brittle stars. Recruitment of bottom populations from 1996 spawning was 5% in O. sarsi and 3.3% in A. fissa.     

Effects of stream-crossing by a pipeline on the benthic macroinvertebrate communities of a small mountain stream

Aquatic environmental impact associated with stream-crossing by a pipeline was monitored at Archibald Creek, B.C. for two years. Water chemistry and benthic macroinvertebrates were used as monitoring tools. Results indicated that impacts arising from stream-crossing were short-term and non-residual.Funded by a contract from Canadian Arctic Gas Study Limited, calgary, to Aquatic Environments Limited, Calgary.Aquatic Environments Limited, Calgary.Aquatic Environments Limited, Calgary.     

Determining the density dependence of immigration and emigration of benthic stream invertebrates: theoretical considerations

Simple mathematical models are formulated to describe density independent and density dependent dispersal. These models clarify hypotheses of density dependence and may be manipulated easily to suit particular applications. The models demonstrate that the initial composition of a species aggregate must be controlled before valid conclusions can be drawn about the density dependency of the aggregate's dispersal. Stochastic models of emigration are derived to assess the power of particular experimental designs and statistical techniques to discriminate a known form of density dependent emigration. Contribution No. 369, Great Lakes Research Division, University of Michigan Contribution No. 369, Great Lakes Research Division, University of Michigan     

The pressure-responses of marine invertebrates: a psychophysical perspective

The responses of marine invertebrates to changes in hydrostatic pressure within the + 1000 mbar range are reviewed and some response parameters are considered in an attempt to set the phenomenon of barosensitivity in the more general context of animal irritability. Possible mechanisms of transduction are discussed and, in the absence of any identifiable baroreceptor, a comparative psychophysical approach is advocated as a possible means of elucidating further the fundamental properties of such pressure-sensitive systems.     

Natural recolonisation of seagrasses at a disused sewage sludge outfall

Digested sludge from a sewage outfall that operated for 15 years adjacent to Adelaide in South Australia caused total seagrass loss in a 365 ha area around the outfall. Eight years after its closure, an underwater survey was conducted to determine the extent of seagrass recovery in a 2 ha area immediately adjacent to the disused outfall. Total seagrass cover was estimated to be 28% comprising 23% Halophila australis, 3% Posidonia angustifolia, 1% Posidonia sinuosa, and less than 1% each for Zostera tasmanica and Amphibolis antarctica. The recovery of seagrasses at the outfall site is probably due to recolonisation by propagules from a distant source. While results from this study suggest that seagrasses can return to a severely polluted site if the pollution source is removed and that Posidonia can be a primary coloniser of disturbed sites, they also suggest that it will take many decades for the seagrass community to recover to its former state.     

Vertical migration of infaunal invertebrates in response to dosing with secondary treated sewage effluent: a microcosm experiment

Short-term experiments testing behaviouralresponses to a toxicant are liable to besensitive indicators of the potential effectsof a pollutant and allow predictions abouthabitat preferences of organisms in the field.We have undertaken short-term microcosmexperiments with intact assemblages ofintertidal invertebrate infauna andinvestigated the responses of these assemblagesto dosing with a secondary treated sewageeffluent. Infaunal assemblages were taken fromsites that differed in their proximity toeffluent discharges and in recent exposure todisturbances. We observed a range of responsesto different dose treatments during theseexperiments with differential migration intothe water column by the corophiid amphipodCorophium insidiosum and changes in depthdistribution within the sediment by severalannelid taxa. We discuss these results withrespect to potential field responses followingexposure to treated sewage effluents andbiological monitoring programs.     

Roughness and color of artificial substratum particles as possible factors in colonization of stream invertebrates

We tested the null hypothesis that neither roughness nor color of artificial substrata (tiles) affects abundance of stream invertebrates colonizing these substrata. The studies were carried out in a third-order aspen-parkland stream and first- and second-order foothills streams of Alberta, Canada. Dark-colored tiles were slightly more attractive to some colonizing invertebrates than light-colored tiles, but results were not conclusive. Generally, more individuals and more taxa were found on the rough tiles than on the smooth tiles. And several taxa were found in significantly (P 0.05) larger numbers on the rough tiles. Chironomids, especially, had a strong preference for the rough tiles. A major exception was heptageniid (Ephemeroptera) nymphs, which were consistently found in larger numbers on the smooth tiles.     

Thymidine phosphorylating enzymes in the gonads of marine invertebrates

The activities of enzymes involved in the consecutive phosphorylation of thymidine were revealed in the gonad extracts of marine invertebrates. Along with thymidine kinase activity, thymidilate kinase activity was revealed in all the studied species; however, the specific activities of nucleoside and nucleotide kinases varied in different species of mollusks, sea stars and sea urchins. Thymidine and thymidilate kinases were isolated from the gonads of the scallop Mizuhopecten yessoensis and some of their enzymat properties were studied. The thymidine kinase of M. yessoensis catalyzed the phosphorylation of thymidine and deoxycytidine at a lesser rate, but didn’s use purine ribo-and deoxyribonucleosides or pyrimidine ribonucleosides as phosphate acceptors. The thymidilate kinase carried out both TMP and dCMP phosphorylation. As well as ATP, the enzymes of M. yessoensis were also able to use dATP, dGTP, GTP, UTP and CTP as donors of phosphate groups. The thymidine kinase activity was inhibited by TMP, TTP and dCTP.     

Metabarcoding of freshwater invertebrates to detect the effects of a pesticide spill

Biomonitoring underpins the environmental assessment of freshwater ecosystems and guides management and conservation. Current methodology for surveys of (macro)invertebrates uses coarse taxonomic identification where species‐level resolution is difficult to obtain. Next‐generation sequencing of entire assemblages (metabarcoding) provides a new approach for species detection, but requires further validation. We used metabarcoding of invertebrate assemblages with two fragments of the cox1 “barcode” and partial nuclear ribosomal (SSU) genes, to assess the effects of a pesticide spill in the River Kennet (southern England). Operational taxonomic unit (OTU) recovery was tested under 72 parameters (read denoising, filtering, pair merging and clustering). Similar taxonomic profiles were obtained under a broad range of parameters. The SSU marker recovered Platyhelminthes and Nematoda, missed by cox1, while Rotifera were only amplified with cox1. A reference set was created from all available barcode entries for Arthropoda in the BOLD database and clustered into OTUs. The River Kennet metabarcoding produced matches to 207 of these reference OTUs, five times the number of species recognized with morphological monitoring. The increase was due to the following: greater taxonomic resolution (e.g., splitting a single morphotaxon “Chironomidae” into 55 named OTUs); splitting of Linnaean binomials into multiple molecular OTUs; and the use of a filtration‐flotation protocol for extraction of minute specimens (meiofauna). Community analyses revealed strong differences between “impacted” vs. “control” samples, detectable with each gene marker, for each major taxonomic group, and for meio‐ and macrofaunal samples separately. Thus, highly resolved taxonomic data can be extracted at a fraction of the time and cost of traditional nonmolecular methods, opening new avenues for freshwater invertebrate biodiversity monitoring and molecular ecology.     

Trace metals in the benthic habitat of the Maarsseveen Lakes system,The Netherlands

The cadmium, zinc, lead and copper concentrations in benthic invertebrates and sediment were determined during two consecutive winters in the Maarsseveen Lakes system. A sequential extraction procedure was applied to estimate the bioavailability of the trace metals in the sediment. Based on the trace metal analyses of organisms and sediment, it is concluded that the Maarsseveen Lakes system has background levels of cadmium, zinc, lead and copper. As the majority of metals was present in geochemically more stable sediment phases, the sequential extractions provided limited additional information on trace metal bioavailability.     

An overview of the assessment of aquatic ecosystem health using benthic invertebrates

Community structure or species composition of benthic invertebrates has frequently been used in environmental monitoring and assessment of aquatic systems. Three general approaches have been taken: the saprobic approach, which requires detailed knowledge of taxonomy and is most effective in measuring impacts from sewage effluents; diversity indices, which do not require detailed knowledge of species requirements but ignore information provided by important species and tend to lose information; and biotic indices, which combine both approaches. In the past few years considerable advances have been made by applying multivariate statistical techniques to large data matrices and relating benthic community structure to key environmental variables. Using these techniques it is possible to establish reference communities for a set of environmental conditions, to predict the benthic community that should occur at new sites and thus measure deviation from an expected community type. This suggests that environmental criteria and objectives can be established based on biological variables as opposed to the more traditional chemical approach.Measurement of ecosystem health using functional attributes of benthic invertebrates is generally in the development stage. In the future, functional measures of ecosystem health, such as chronic measures of toxicity or stress, should be incorporated into any assessment process.