Comparison of macroinvertebrate community structure and driving environmental factors in natural and wastewater treatment ponds

Eutrophication still continues to be an issue of major concern for the protection of water quality, and accordingly, the European Union Water Framework Directive has set a minimum target for all waters where “good status” is defined as a slight departure from the biological community which would be expected in conditions of minimal anthropogenic impact. The use of constructed ponds for wastewater treatment aimed at achieving this target has shown to be an effective alternative to conventional systems in the farm landscape. Their applicability in these areas is of great interest since these ponds have the added potential to combine their wastewater treatment properties with that of biodiversity enhancement. This article focuses on exploring the community structure of both natural and constructed ponds used for wastewater treatment and the driving environmental factors. A total of 15 constructed and 5 natural ponds were sampled for aquatic macroinvertebrates and hydrochemistry in spring and summer 2006. Results showed that the most important factors responsible for the differences in the community structure between these two types of ponds were pH, vegetation structure and pollution levels. These gradients helped to structure a large proportion of the communities with some taxa being associated with the constructed ponds. These results highlight the potential contribution of constructed ponds used for wastewater treatment to the landscape biodiversity. The present findings also open the possibility for a more integrated management of water quality and biodiversity enhancement in farmland areas. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Guest editors: B. Oertli, R. Cereghino, A. Hull & R. Miracle Pond Conservation: From Science to Practice. 3rd Conference of the European Pond Conservation Network, Valencia, Spain, 14–16 May 2008     

Habitat-dependent population regulation and community structure

Summary Density-dependence provides a causal link between processes acting at different levels of ecological organization. The linkage between density-dependent habitat use, population regulation and community organization is examined on the basis of qualitative and quantitative differences between habitats. These differences are expressed as characteristic shapes on isodars which are lines of equal fitness, and are plotted in density space as lines at every point of which the fitness of individuals in one habitat is equal to that of individuals in another. Isodars can be constructed for single species or modified to include the effects of interacting species. Isodars are easily analyzed by linear regression to differentiate between alternative modes of population regulation and to suggest patterns of community structure. Different isodars are causally related to different kinds of community structure, and suggest the existence of four new forms of community organization; equal, differential, switched and mixed preferences. A preliminary isodar analysis on a common rodent species demonstrates that population regulation depends upon habitat, and that mixed preferences probably organize the rodent community. Habitat-dependent population regulation has farreaching implications to studies of temporal and spatial scale, and to all ecological processes that are density-dependent.     

渭河流域大型底栖动物群落结构及其与环境因子的关系

于2011年10月对渭河流域45个采样点的大型底栖动物进行调查采样.共采集到大型底栖动物116属(种),其中水生昆虫91(属)种,占78.4％;软体动物12种,占10.3％;环节动物9种,占7.8％;甲壳动物4种,占3.4％.利用大型底栖动物的物种组成以及物种相对丰度数据,应用双向指示种分析和无偏对应分析将45个样点分为3组.第1组样点的指示物种为锯形蜉属1种(Serratella sp.)、纹石蛾属1种(Hydropsyche sp.)和朝大蚊属1种(Antochasp.);第2组样点指示物种为虻属1种(Tabanus sp.)、Alotanypus venustus、Pelecorhynchidae 1 种、Liodessus sp.和霍甫水丝蚓(Limnodrilus hoffineistteri);第3组指示物种为黑翅蜉(Ephemera nigroptera)和半球多脉扁螺(Polypylis hemisphaerula).典范对应分析表明,卵石+砾石型底质、流速、电导率、水深和总氮显著影响了渭河流域底栖动物群落的空间分布.     

Impact of bleached kraft pulp mill effluent on benthic community structure in relation to environmental factors

In this study, we assessed the impact of bleachedkraft pulp mill effluent (BKME) on the distributionand composition of benthic communities at JackfishBay, Lake Superior. Sediment samples were collectedfrom 44 stations from which several environmentalvariables (extractable organic chlorine [EOCl],metals, organic carbon, particle size, secchi depth,and water depth) and benthic community compositionwere determined. Relationships between environmentalvariables and benthic community structure wereassessed using canonical correspondence analysis(CCA). CCA revealed two distinct biological gradientsat Jackfish Bay, the first associated with degradedbottom sediments and nutrient enrichment and thesecond associated with water depth. Both gradientsrevealed three distinct regions at Jackfish Bay: 1) anarea of highly degraded sediments, located 300–1200 mbelow the outfall, 2) a small, mesotrophic (nutrientenriched) area adjacent to this zone, and 3) remainingareas of Jackfish Bay, including the internalreference sites in Tunnel Bay. Sediments in theimpaired region contained high concentrations oforganic matter (7–21% as loss on ignition [LOI]) andEOCl (up to 5200 mg/kg dw); together these variablesaccounted for 73% of the variation associated withthe first canonical axis of the CCA. This region wasdominated by the oligochaetes Tubifex tubifexand Limnodrilus hoffmeisteri (64–100% of thebenthic community). Sediments in the second regionwere characterized by an abundant and diverse benthiccommunity comprised of benthic harpacticoids,Chironomidae, and oligochaetes. Stations outside ofthese two regions were characterized by a benthiccommunity similar in composition to that expected foroligotrophic Lake Superior waters, including Diporiea sp., Stylodrilus heringianus, Mysis relicta, Sphaerium, Pisidium and benthicharpacticoids. Based on a Monte Carlo significancetest, benthic community structure was significantly(p = 0.01) related to the environmental variablescomprising the first axis of the CCA. Water depth wasthe most important explanatory variable associatedwith the second axis of the CCA; both taxa richnessand abundance declined significantly with increasingdepth. The comprehensive approach employed in thisstudy clearly delineated the occurrence and degree ofimpact on the benthic environment and may be useful infuture risk assessments of sites affected byanthropogenic activity.     

Relating macroinvertebrate community structure to environmental characteristics and sediment contamination at the scale of the St. Lawrence River

There is still no assessment of the impact of sediment chemicals and environmental conditions on macroinvertebrates at the scale of the St. Lawrence River. In order to assess these impacts in the fluvial section of the St. Lawrence River including the Montreal harbour, the community structure of macroinvertebrates using different taxonomic aggregations (genus and family) and taxa attributes (abundance, presence–absence, indicator taxa) was assessed. The goal of the study was to determine the indicator taxa of macroinvertebrates along the fluvial continuum and relate changes in macroinvertebrate community to sediment chemical conditions and environmental characteristics of habitats using variance partitioning. This study also evaluated which taxonomic level and taxa attributes of macroinvertebrates were the most suitable for bioassessment of quality of sediments and habitat environment in the St. Lawrence River. Four different macroinvertebrate assemblages were found distributed along the fluvial continuum using either abundance or presence–absence data and genus or family levels. Indicator taxa characteristic of the different macroinvertebrate communities were associated with the sediment contamination gradient. However, habitat environmental characteristics (water masses, sulphur and DOC in sediments) had more influence on macroinvertebrate assemblages than sediment contamination. Our study confirms that family level analysis can give information comparable to the genus level analysis using presence–absence or abundance of macroinvertebrates, yet a higher number of indicator taxa were detected at the genus level.     

Bacterial community structure in a latitudinal gradient of lakes: the roles of spatial versus environmental factors

1. We analysed the latitudinal variation of bacterioplankton in 45 freshwater environments (lakes, shallow lakes and ponds) across a transect of more than 2100 km stretching from Argentinean Patagonia (45°S) to Maritime Antarctica (63°S), to determine the factors that mainly determine bacterioplankton community structure. 2. Bacterioplankton community composition (BCC) was assessed by a fingerprinting method (denaturing gradient gel electrophoresis) followed by band sequencing, whereas the abundances of total bacteria and picocyanobacteria were estimated by epifluorescence microscopy. 3. Bacterioplankton community composition was controlled by a combination of spatial (latitude and longitude) and environmental [e.g. phosphate, light diffuse attenuation coefficient (K_d) and dissolved organic carbon] factors. Total bacterioplankton abundance declined with latitude. A multiple regression analysis showed that phosphate, K_d and latitude had significant effects on total bacterioplankton abundance. 4. Of 76 operational taxonomic units identified in the studied lakes, 45 were shared between Patagonian and Antarctic water bodies, 28 were present only in Patagonian lakes and three were restricted to the Antarctic lakes. Significant differences were found in BCC between Patagonia and Antarctica. Among the sequences, 54% were similar (>97% sequence similarity) to others reported from cold habitats elsewhere on the planet (glaciers, high mountain lakes, Arctic). 5. Our results provide new evidence that supports the hypotheses of biogeographic patterns of bacterial assemblages and suggest that both spatial and environmental factors control bacterioplankton community structure.     

环境因子在植物成花诱导中的作用及其机理

高等植物的碾化规律决定于其遗传性,但是成花的基因表达还受到多和中环境因子没程度的影响。光和温度是成花诱导中最有影响的环境因子。对于光和温度等成花诱导中的作用机理,人们先后提出很多学说。     

The effect of environmental stability on hyporheic community structure

Interstitial water samples were collected from two well depths (30 and 60 cm) from 8 rivers in the Cass-Craigieburn region, South Island (New Zealand) during January 1998 to assess the hyporheos in streams of differing stability. Hyporheic water chemistry was more similar to surface water chemistry at unstable sites than at stable sites. The greatest diversity of both epigean and hypogean animals occurred at intermediate levels of disturbance; however, invertebrate density declined with increasing bed movement. Abundance of epigean animals also increased with declining environmental stability (i.e., increasing bed movement). Water chemistry was most like the river channel at unstable sites, probably because less stable substrates had increased interstitial flow facilitating a greater supply of water from the surface channel. In contrast, stable sites were spring fed and groundwater had a greater influence. Thus, substrate stability may influence hyporheic water chemistry and porosity by changing the interaction between ground and surface waters. Epigean taxa may be less abundant at stable sites because the chemical nature of the water is least like the river channel (e.g. low dissolved oxygen, higher temperature and higher conductivity), while the abundance of hypogean animals is greater, as these taxa are more tolerant of this water chemistry, and are thus capable of persisting in the stable substrates.     

Zooplankton community structure and environmental conditions in a set of interconnected ponds

We studied the zooplankton community structure in a set of 33 interconnected shallow ponds that are restricted to a relatively small area (`De Maten', Genk, Belgium, 200 ha). As the ponds share the same water source, geology and history, and as the ponds are interconnected (reducing chance effects of dispersal with colonisation), differences in zooplankton community structure can be attributed to local biotic and abiotic interactions. We studied zooplankton community, biotic (phytoplankton, macrophyte cover, fish densities, macroinvertebrate densities), abiotic (turbidity, nutrient concentrations, pH, conductivity, iron concentration) and morphometric (depth, area, perimeter) characteristics of the different ponds. Our results indicate that the ponds differ substantially in their zooplankton community structure, and that these differences are strongly related to differences in trophic structure and biotic interactions, in concordance with the theory of alternative equilibria. Ponds in the clear-water state are characterised by large Daphnia species and species associated with the littoral zone, low chlorophyll-a concentrations, low fish densities and high macroinvertebrate densities. Ponds in the turbid-water state are characterised by high abundances of rotifers, cyclopoid copepods and the opposite environmental conditions. Some ponds show an intermediate pattern, with a dominance of small Daphnia species. Our results show that interconnected ponds may differ strongly in zooplankton community composition, and that these differences are related to differences in predation intensity (top-down) and habitat diversity (macrophyte cover).     

Spatial and temporal community structure of desmids on a small spatial scale

Besides spatial heterogeneity, another important component of the diversity of protist communities is the variation in species assemblages through time. Despite its importance, temporal turnover of benthic communities has been studied to a lesser extent than spatial heterogeneity has. In this study, we examine the desmid assemblages on small spatial scale in relation to the spatial, temporal, and environmental parameters. The samples were collected within two different types of peatland localities in the Czech Republic over 3 years. The differences in species composition between samples were mainly correlated with the geographic distance, while the effects of the environmental and temporal variables were much weaker. Since the spatial heterogeneity of the assemblages was not induced by the variation of the environmental factors or by the restricted dispersal ability at such a small spatial scale, we assume that both the temporal stability and strong spatial autocorrelation might have been the result of a priority effect, with subsequent monopolization of resources. Stochasticity in colonization can introduce noise into the match between community composition and environmental conditions, which may result in stronger effect of the spatial parameters on the community structure.     

An examination of multiple factors affecting community structure in an aquatic amphibian community

Summary The potential effects of multiple factors structuring certain larval amphibian communities were studied using a pen experiment in a natural pond. Potential factors (predation and competition from other species) were allowed to act in a stepwise fashion such that their relative importance could be evaluated. Based on a previous study, it was hypothesized that predation by Ambystoma salamander larvae on other larval amphibian species would be the most important factor. Survival of Ambystoma jeffersonianum salamander larvae and Rana sylvatica tadpoles was significantly depressed only by Ambystoma opacum predation. Survival of Ambystoma maculatum salamander larvae was significantly greater in the absence of both A. opacum and A. jeffersonianum predators. The virtual elimination of Hyla chrysoscelis larvae in all treatments also can be largely attributed to Ambystoma predation. Thus, Ambystoma predation was the dominant factor determining larval survival of four amphibian prey species in the experimental communities.     

Tocopherol biosynthesis: chemistry, regulation and effects of environmental factors

Tocopherols are lipophilic antioxidants and together with tocotrienols belong to the vitamin-E family. The four forms of tocopherols (??-, ??-, ??- and ??-tocopherols) consist of a polar chromanol ring and lipophilic prenyl chain with differences in the position and number of methyl groups. The biosynthesis of tocopherols takes place mainly in plastids of higher plants from precursors derived from two metabolic pathways: homogentisic acid, an intermediate of degradation of aromatic amino acids, and phytyldiphosphate, which arises from methylerythritol phosphate pathway. The regulation of tocopherol biosynthesis in photosynthetic organisms occurs, at least partially, at the level of key enzymes as such including p-hydroxyphenylpyruvate dioxygenase (HPPD, EC 1.13.11.27), homogentisate phytyltransferase (HPT, EC 2.5.1.-), tocopherol cyclase (TC, EC 5.4.99.-), and two methyltransferases. Tocopherol biosynthesis changes during plant development and in response toward different stresses induced by high-intensity light, drought, high salinity, heavy metals, and chilling. It is supposed that scavenging of lipid peroxy radicals and quenching of singlet oxygen are the main functions of tocopherols in photosynthetic organisms. The antioxidant action of tocopherols is related to the formation of tocopherol quinone and its following recycling or degradation. However, until now, the mechanisms of tocopherol degradation in plants have not been established in detail. This review focuses on mechanisms of tocopherols biosynthesis and its regulation in photosynthetic organisms. In addition, available information on tocopherol degradation is summarized.     

Zoobenthos of the Cheshskaya Bay (southeastern Barents Sea): spatial distribution and community structure in relation to environmental factors

Structural and functional characteristics of zoobenthos of the Cheshskaya Bay (SE Barents Sea) were studied at 21 stations in June/July 1995. Strong prevailing cyclonic and tidal currents result in relatively uniform temperature and salinity in the area. Sediments consist mainly of sand and pebbles, while the flux of suspended matter from rivers locally increases the share of finer fractions. Analysis of species composition (419 taxa), abundance (up to 4,200 ind m⁻² and up to 29,000 ind m⁻² with juveniles) and biomass (up to >6,000 g wet wt m⁻²) indicates high species richness in most parts of the bay, especially in the northeast. Analysis of community structure using production characteristics of species revealed a general predominance of suspension feeders partitioned into seven communities. The dominant species of these communities were Mytilus edulis and Balanus crenatus (Type 1), B. crenatus (Type 2), Modiolus modiolus and Verruca stroemia (Type 3), Flustra foliacea and V. stroemia (Type 4), Hydrallmania falcata (Type 5), V. stroemia and Chirona hameri (Type 6), and Ophelia limacina (Type 7). The structure of the communities is mainly regulated by sediment type, water depth and, to some extent, by riverine input. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Abiotic factors control invasion by Argentine ants at the community scale

1. A prominent and unresolved question in ecology concerns why communities differ in their susceptibility to invasion. While studies often emphasize biotic resistance, it is less widely appreciated how the physical environment affects community vulnerability to invasion. 2. In this study we performed field experiments to test how abiotic variation directly and indirectly influences the extent to which Linepithema humile Mayr (Argentine ants) invade seasonally dry environments in southern California. 3. In controlled and replicated experiments involving drip irrigation, we demonstrate (i) that elevated levels of soil moisture increased both the abundance of Argentine ants and their ability to invade native ant communities and (ii) that cessation of irrigation caused declines in the abundance of Argentine ants and led to their withdrawal from previously occupied areas. 4. Because drip irrigation stimulated plant growth, in an additional experiment we manipulated both soil moisture and plant cover to assess the direct vs. indirect effects of added water on the abundance of L. humile. 5. Local abundance of Argentine ants increased in irrigated plots but was 38% higher in irrigated plots with plants compared to irrigated plots where plant growth was suppressed. The results of this experiment thus argue for a direct role of soil moisture in influencing Argentine ant abundance but suggest that that the indirect effects of added water may also be important. 6. Our study illustrates more generally that fine-scale variation in the physical environment can control whether communities become invaded by non-native species and suggests that an understanding of community susceptibility to invasion will be improved by a better appreciation of interactions between the biotic and abiotic environment.     

Phylogenetic structure illuminates the mechanistic role of environmental heterogeneity in community organization

1. Diversity begets diversity. Numerous published positive correlations between environmental heterogeneity and species diversity indicate ubiquity of this phenomenon. Nonetheless, most assessments of this relationship are phenomenological and provide little insight into the mechanism whereby such positive association results. 2. Two unresolved issues could better illuminate the mechanistic basis to diversity begets diversity. First, as environmental heterogeneity increases, both productivity and the species richness that contributes to that productivity often increase in a correlated fashion thus obscuring the primary driver. Second, it is unclear how species are added to communities as diversity increases and whether additions are trait based. 3. We examined these issues based on 31 rodent communities in the central Mojave Desert. At each site, we estimated rodent species richness and characterized environmental heterogeneity from the perspectives of standing primary productivity and number of seed resources. We further examined the phylogenetic structure of communities by estimating the mean phylogenetic distance (MPD) among species and by comparing empirical phylogenetic distances to those based on random assembly from a regional species pool. 4. The relationship between rodent species diversity and environmental heterogeneity was positive and significant. Moreover, diversity of resources accounted for more unique variation than did total productivity, suggesting that variety and not total amount of resource was the driver of increased rodent diversity. Relationships between environmental heterogeneity and phylogenetic distance were negative and significant; species were significantly phylogenetically over-dispersed in communities of low environmental heterogeneity and became more clumped as environmental heterogeneity increased. 5. Results suggest that species diversity increases with environmental heterogeneity because a wider variety of resources allow greater species packing within communities.     

Assessing mineralization rates of petroleum hydrocarbons in soils in relation to environmental factors and experimental scale

Mineralization rates of non-volatile petroleum hydrocarbons (HCs) in five different oil-contaminated soils with initial HC contents ranging from 0.1 to 13 g kg^-1 are estimated as a function of environmental factors. The aim of the study is threefold, (i) to study the relevance of environmental factors that may influence the mineralization rate, (ii) to compare mineralization rates estimated in two experiments at different scales, after standardizing them to environmental reference conditions, (iii) to evaluate the CO₂ production rate as a measure for the mineralization rate of HCs. Experiments were performed at laboratory scale (30–50 cm³ soil volume) in closed-jars under constant environmental conditions and in lysimeters (0.81 m³ soil volume) under dynamic climatic and hydrological conditions. A biodegradation model, coupled to transport models for soil heat, water, and gas dynamics is employed for data interpretation. The transport models are used to simulate the environmental conditions that influence the mineralization rate in the non-steady lysimeter experiments. The results show that temperature, O₂ concentration and HC content have an effect on the mineralization rates. Water content could not be identified as a direct governing environmental factor. However, an indirect effect of water content is that it influences the effective gas diffusion coefficient in soils. The CO₂ production rate seems to be a good quantity to express the mineralization rate of HCs for HC contents>1 g kg^-1. Measured CO₂ production rates standardized to reference conditions are similar for the two different experimental scales. This demonstrates that the usage of biodegradation rates obtained in the laboratory to predict the biodegradation rates under field conditions is sound, as long as the differences in environmental conditions have been taken into account.     

Role of environmental factors on the reproducibility of Lemna test

Lemna minor is a species easy to collect and culture in laboratory, and can give rapid test results. However, in order to standardise toxicity tests using Lemna minor as test organism, it is important to find out what natural variability different populations might have. Five Lemna populations were used for comparison. It contained two standard cultures and three populations collected in natural habitats. Potassium dichromate was applied as test material. Lemna populations cultured under the same conditions showed different T(D) and LC50 values. There is an inverse relation between the sensitivity and T(D) of the strains. It is supposed that growth rate and sensitivity of Lemna populations depend on environmental factors characterising the habitat in which the given popluation originally lives.