Can be the environmental and biotic factors responsible for macroinvertebrate communities’ alterations in Portuguese alpine ponds?

Alpine ponds are shallow waterbodies formed in alpine zones characterized by usual pristine conditions, however subject to harsh conditions that enable the emergence of unique communities with high conservational value. Therefore, it is important to gather information about these ecosystems and understand the changes in the biota. This work aimed to use Portugal’s alpine ponds as a case of study in assessed the macroinvertebrates communities in the Mediterranean ecozone. To fulfill this goal, we aimed to understand the alterations on macroinvertebrates community and how are they modulated by environmental variables. Five alpine ponds in Serra da Estrela (Portugal) were studied for one year. Macroinvertebrate communities and physical and chemical water parameters were determined in June/16, October/16, and April/17. Water chemistry values were similar to other studied lentic waterbodies in alpine zones in Europe, with slightly acidic water and low conductivity. Although accentuated macroinvertebrates differences between ponds, no significant differences in diversity were recorded, indeed the main differences recorded were influenced by ponds habitat types and environmental variables. Canonical Correspondence Analysis showed differences in the communities between ponds, namely the high influence of several physical and chemical parameters (conductivity, phosphate content, and pH) in the macroinvertebrates community composition. Indeed, Spearman’s correlation revealed significant interaction in diversity, abundance and richness of macroinvertebrates and several physical and chemical parameters (pH, dissolved oxygen and nitrates concentration).     

Incorporating intensity bounds for assessing the seismic safety of structures: Does it matter?

The closed‐form solution for assessing the proportion of the mean annual frequency of limit‐state exceedance as a function of integration limits is introduced, in order to study whether or not the mean annual frequency of limit‐state exceedance is overestimated if the lower and(or) upper integration limit of the risk equation are(is) not selected in a physically consistent manner. Simple formulas for assessing the threshold value of the lower and upper integration limits are also derived. These formulas can be used to quickly assess the significant range of ground motion intensity that affects the mean annual frequency of limit‐state exceedance. It is shown that the threshold values of the integration limits depend on the median intensity causing a limit‐state, the corresponding dispersion and the slope of the hazard curve in the log domain. For several reinforced concrete buildings located in a region with moderate seismicity, it is demonstrated that the mean annual frequency of collapse can be significantly overestimated when assessed by integrating the risk equation over the entire range of ground motion intensity. Copyright © 2013 John Wiley & Sons, Ltd.     

Does streambed heterogeneity matter for hyporheic residence time distribution in sand-bedded streams?

Stream water residence times within streambed sediments are key values to quantify hyporheic processes including sediment thermal regime, solute transient storage, dilution rates and biogeochemical transformations, such as those controlling degassing nitrous oxide. Heterogeneity of the streambed sediment hydraulic properties has been shown to be potentially an important factor to characterize hyporheic processes. Here, we quantify the importance of streambed heterogeneity on residence times of dune-like bedform induced hyporheic fluxes at the bedform and reach scales. We show that heterogeneity has a net effect of compression of the hyporheic zone (HZ) toward the streambed, changing HZ volume from the homogenous case and thus inducing remarkable differences in the flow field with respect to the homogeneous case. We unravel the physical conditions for which the commonly used homogenous field assumption is applicable for quantifying hyporheic processes thus explaining why predictive measures based on a characteristic residence time, like the Damköhler number, are robust in heterogeneous sand bedded streams.     

Assessing fertilization success of the coral Montipora capitata under copper exposure: Does the night of spawning matter?

Metal pollution is a major threat in tropical areas due to increasing pressure from anthropogenic activities along coastlines. Unfortunately there are very few toxicological studies that assess the effects of metals on marine organisms in tropical areas. To help fill this gap, this study investigated how Cu alters the fertilization success of the coral Montipora capitata over several nights of spawning. Results indicate that gametes of M. capitata are sensitive to Cu pollution, with EC₅₀ after 3 h ranging from 16.6 to 31.7 μg l^?1. Moreover, the sensitivity of the gametes to Cu toxicity was influenced by the night of spawning during which fertilization experiments were performed. This result likely reflected changes in the quality of gamete over the spawning period.     

Definitions of climatological and discharge days: do they matter in hydrological modelling?

The performance of hydrological models is affected by uncertainty related to observed climatological and discharge data. Although the latter has been widely investigated, the effects on hydrological models from different starting times of the day have received little interest. In this study, observational data from one tropical basin were used to investigate the effects on a typical bucket-type hydrological model, the HBV, when the definitions of the climatological and discharge days are changed. An optimization procedure based on a genetic algorithm was used to assess the effects on model performance. Nash-Sutcliffe efficiencies varied considerably between day definitions, with the largest dependence on the climatological-day definition. The variation was likely caused by how storm water was assigned to one or two daily rainfall values depending on the definition of the climatological day. Hydrological models are unlikely to predict high flows accurately if rainfall intensities are reduced because of the day definition.     

Allochthonous subsidies of organic matter across a lake–river–fjord landscape in the Chilean Patagonia: Implications for marine zooplankton in inner fjord areas

Ecosystems can act as both sources and sinks of allochthonous nutrients and organic matter. In this sense, fjord ecosystems are a typical interface and buffer zone between freshwater systems, glaciated continents, and the coastal ocean. In order to evaluate the potential sources and composition of organic matter across fjord ecosystems, we characterized particulate organic matter along a lake–river–fjord corridor in the Chilean Patagonia using stable isotope (δ¹³C) and lipid (fatty acid composition) biomarker analyses. Furthermore, estimates of zooplankton carbon ingestion rates and measurements of δ¹³C and δ¹⁵N in zooplankton (copepods) were used to evaluate the implications of allochthonous subsidies for copepods inhabiting inner fjord areas. Our results showed that riverine freshwater flows contributed an important amount of dissolved silicon but, scarce nitrate and phosphate to the brackish surface layer of the fjord ecosystem. Isotopic signatures of particulate organic matter from lakes and rivers were distinct from their counterparts in oceanic influenced stations. Terrestrial allochthonous sources could support around 68–86% of the particulate organic carbon in the river plume and glacier melting areas, whereas fatty acid concentrations were maximal in the surface waters of the Pascua and Baker river plumes. Estimates of carbon ingestion rates and δ¹³C in copepods from the river plume areas indicated that terrestrial carbon could account for a significant percentage of the copepod body carbon (20–50%) during periods of food limitation. Particulate organic matter from the Pascua River showed a greater allochthonous contribution of terrigenous/vascular plant sources. Rivers may provide fjord ecosystems with allochthonous contributions from different sources because of the distinct vegetation coverage and land use along each river’s watershed. These observations have significant implications for the management of local riverine areas in the context of any human project that may modify terrestrial habitats as well as the productivity, food webs, and community structure of rivers, lakes, fjords, and the coastal ocean in the Chilean Patagonia.     

Amplification of hydrological model uncertainties in projected climate simulations of the Upper Indus Basin: Does it matter where the water is coming from?

There is a growing appreciation of the uncertainties in the estimation of snow-melt and glacier-melt as a result of climate change in high elevation catchments. Through a detailed examination of three hydrological models in two catchments, and interpretation of results from previous studies, we observed that many variations in estimated streamflow could be explained by the selection of a best parameter set from the possible good model parameters. The importance of understanding changing glacial dynamics is critically important for our study areas in the Upper Indus Basin where Pakistan's policymakers are planning infrastructure to meet the future energy and water needs of hundreds of millions of people downstream. Yet, the effect of climate on glacial runoff and climate on snowmelt runoff is poorly understood. With the HBV model, for example, we estimated glacial melt as between 56% and 89% for the Hunza catchment. When rainfall was a scaled parameter, the models estimated glacial melt as between 20% and 100% of streamflow. These parameter sets produced wildly different projections of future climate for RCP8.5 scenarios in 2046–2075 compared to 1976–2005. Assuming no glacial shrinkage, for one climate projection, we found that the choice among good parameter sets resulted in projected values of future streamflow across a range from +54% to +125%. Parameter selection was the most significant source of uncertainty in the glaciated catchment and amplified climate model uncertainty, whereas climate model choice was more important in the rainfall dominated catchment. Although the study focuses on Pakistan, the overall conclusions are instructive for other similar regions in the world. We suggest that modellers of glaciated catchments should present results from at least the book-ends: models with low sensitivity to ice-melt and models with high sensitivity to ice-melt. This would reduce confusion among decision makers when they are faced with similar contrasting results.     

Does canopy wetness matter? Evapotranspiration from a subtropical montane cloud forest in Taiwan

Evapotranspiration (ET) and canopy wetness were measured over a 2‐year intensive field campaign at the Chi‐Lan Mountain cloud forest site in Taiwan. Eddy covariance and sap flow methods were applied to measure ET and tree sap flow of the endemic yellow cypress (Chamaecyparis obtusa var. formosana). ET was 553 mm yr^?1 over the study period with an annual rainfall and fog deposition of 4893 and 288 mm yr^–1, respectively. The duration of canopy wetness exceeded actual fog or rain events (mostly in the afternoon), and the intercepted water was evaporated later in the following dry morning. The cumulative wet duration accounted for 52% of time over the study period, which was longer than the duration of rainfall and fog altogether (41%). As it adapted to the extremely moist environment, the yellow cypress behaved in a wet‐enhanced/dry‐reduced water use strategy and was sensitive to short periods of dry atmosphere with high evaporation potential. During dry days, the sap flow rate rose quickly after dawn and led to conservative water use through midday and the afternoon. During periodically wet days, the canopy was mostly wetted in the morning, and the interception evaporation contributed largely to the morning ET. The initiation of morning sap flow was postponed 1–3 h, and the sap flow rate tended to peak later at midday. The midday canopy conductance was higher in the periodically wet days (10.6 mm s^–1) as compared with 7.6 mm s^?1 in the dry days. Consequently, the dry‐reduced water use strategy led to much lower annual ET with respect to the available energy (~46%) and high precipitation input (~11%). The moist‐adapted ecohydrology we report reveals the vulnerability of montane cloud forests to prolonged fog‐free periods. More research is urgently needed to better understand the resilience of these ecosystems and formulate adaptive management plans. Copyright © 2012 John Wiley & Sons, Ltd.     

Evidence of Self‐Organized Criticality in riverbank mass failures: a matter of perspective?

A growing body of field, theoretical and numerical modelling studies suggests that predicting river response to even major changes in input variables is difficult. Rivers are seen to adjust rapidly and variably through time and space as well as changing independently of major driving variables. Concepts such as Self‐Organized Criticality (SOC) are considered to better reflect the complex interactions and adjustments occurring in systems than traditional approaches of cause and effect. This study tests the hypothesis that riverbank mass failures which occurred both prior to, and during, an extreme flood event in southeast Queensland (SEQ) in 2011 are a manifestation of SOC. Each wet‐flow failure is somewhat analogous to the ‘avalanche’ described in the initial sand‐pile experiments of Bak et al. (Physical Review Letters, 1987, 59(4), 381–384) and, due to the use of multitemporal LiDAR, the time period of instability can be effectively constrained to that surrounding the flood event. The data is examined with respect to the key factors thought to be significant in evaluating the existence of SOC including; non‐linear temporal dynamics in the occurrence of disturbance events within the system; an inverse power‐law relation between the magnitude and frequency of the events; the existence of a critical state to which the system readjusts after a disturbance; the existence of a cascading processes mechanism by which the same process can initiate both low‐magnitude and high‐magnitude events. While there was a significant change in the frequency of mass failures pre‐ and post‐flood, suggesting non‐linear temporal dynamics in the occurrence of disturbance events, the data did not fit an inverse power‐law within acceptable probability and other models were found to fit the data better. Likewise, determining a single ‘critical’ state is problematic when a variety of feedbacks and multiple modes of adjustment are likely to have operated throughout this high magnitude event. Overall, the extent to which the data supports a self‐organized critical state is variable and highly dependent upon inferential arguments. Investigating the existence of SOC, however, provided results and insights that are useful to the management and future prediction of these features. Copyright © 2014 John Wiley & Sons, Ltd.     

Does the complexity in temporal precipitation disaggregation matter for a lumped hydrological model?

ABSTRACT

Flood peaks and volumes are essential design variables and can be simulated by precipitation–runoff (P–R) modelling. The high-resolution precipitation time series that are often required for this purpose can be generated by various temporal disaggregation methods. Here, we compare a simple method (M1, one parameter), focusing on the effective precipitation duration for flood simulations, with a multiplicative cascade model (M2, 32/36 parameters). While M2 aims at generating realistic characteristics of precipitation time series, M1 aims only at accurately reproducing flood variables by P–R modelling. Both disaggregation methods were tested on precipitation time series of nine Swiss mesoscale catchments. The generated high-resolution time series served as input for P–R modelling using a lumped HBV model. The results indicate that differences identified in precipitation characteristics of disaggregated time series vanish when introduced into the lumped hydrological model. Moreover, flood peaks were more sensitive than flood volumes to the choice of disaggregation method.     

Fate of persistent organic pollutants in the water column: does turbulent mixing matter?

The effect of vertical turbulent mixing on the dynamics of persistent organic pollutants has long been overlooked and its role is still hardly understood. Here we present the first comprehensive analysis of the role of turbulent diffusion on the distribution of those contaminants and its interplay with sinking fluxes. To this end, a 1D dynamic coupled hydrodynamic-contaminant model has been developed and applied to a Mediterranean continental shelf environment. The hydrodynamic sub-model is adapted from COHERENS, the contaminant sub-model is an improvement from the BIODEP model and considers the contaminant in 3 phases: dissolved-colloidal-particulate. The simulation highlights the role of turbulence in determining the POP distribution and variability in the water column. In short, turbulent flux of contaminants strengthens the upward diffusion of sediment entrained contaminants and determines the extent to which inputs from the atmosphere mix into the water column. It acts in parallel with degradation and sinking fluxes, the combined effect yielding a surface enriched - depth depleted - benthic layer enriched region distribution, which presents similarities to reported experimental measures.     

Size of anal papillae in chironomids: Does it indicate their salinity stress?

Salinity of inland waters is affected by a range of human activities and is regarded as a major environmental contaminant in many parts of the world. Changes in salinity are well known to be associated with changes in macroinvertebrate communities of flowing waters. However, as many environmental factors co-vary with salinity, it is not known whether, and if so how, salinity causes communities to change. Being able to measure the osmoregulatory stress that individual stream macroinvertebrates are experiencing would be useful to understand if and how salinity affects their populations and thus communities. Additionally, inferring salinity stress in individual invertebrates could provide a valuable biomonitoring tool to detect the initial effects of salinity before major ecological changes have occurred. Osmoregulation in larval Chironomidae (Diptera) takes place in the anal papillae and their size is believed to be associated with osmoregulatory stress. In two laboratory experiments and a field survey in southern Victoria, Australia, we determine if the size of the anal papillae of larva chironomids is a useful biomarker of salinity stress. Experiments with Chironomus oppositus showed that the surface area of the anal papillae was similar in larva hatched across 5 egg masses collected from 3 sites but were affected by salinity treatments. Furthermore, the (transformed) ratio of this surface area to the body length of the larva was independent of the size of C. oppositus. However, for Chironomus cloacalis, this surface area differed between larva hatched from egg masses collected from the same site. The expected trend in surface area of the anal papillae relative to the size of larva (Chironomu alternans, C. cloacalis, Dicrotendipes sp., Criptochironomus sp. and Tanypodinae) was not duplicated in the field survey. It would appear that unknown factors, other than salinity, are affecting the size of the anal papillae of chironomids in southern Victoria.     

Does grazing change algal communities from grassland and pine afforested streams?: A laboratory approach

Drastic changes in the composition and physiognomy of riparian vegetation, such as the conversion of grassland to forest, are expected to alter interactions among light availability, primary producers and herbivores. Our aim was to examine in laboratory the influence of a ubiquitous grazer on periphyton grown in a grassland unshaded stream (reference) vs. periphyton from a nearby pine afforested stream. Besides, we evaluated how the community responds to the removal of grazing. Given that grassland streams are exposed to higher light intensity and grazers are more abundant compared to afforested streams, we proposed that if biofilm grown in the afforested stream are dominated by grazing-vulnerable algal species, grazing pressure by Helicopsyche sp. should be stronger. In addition, if biofilm from the afforested stream has low quality or is less abundant as food for consumers, the effects of Helicopsyche sp. may be stronger or weaker depending on their feeding decisions. Helicopsyche sp. caused a decrease in richness and diversity in periphyton grown in the grassland stream and its net grazing effect on chlorophyll a (Chl a) was higher. Algal community composition from grassland stream was strongly changed after grazing, with a decrease in the proportion of overstory algae. In contrast, algal community structure of periphyton from the afforested stream was neither affected by grazing nor by grazing exclusion. Helicopsyche sp. produced significant changes in a short time in structural attributes of algal communities, mainly in periphyton from the grassland stream suggesting that herbivory, as a functional factor, is diminished following afforestation.     

Can plankton communities be considered as bio-indicators of water quality in the Lagoon of Venice?

This study examines whether plankton of the Lagoon of Venice could be considered as a bio-indicator of areas subjected to various anthropogenic influences. This study was a two year hydrochemical and biological survey in five areas of the Lagoon of Venice, each with different environmental conditions due to pollution from urban, industrial, thermal and agricultural wastes. Phytoplankton associations did not show any promising species. In the different lagoonal areas, this community was differentiated into its major groups. In contrast, the copepod Acartia tonsa Dana could be considered as a target species in highly eutrophic areas.     

Inter-annual changes in fish communities of a tropical bay in southeastern Brazil: What can be inferred from anthropogenic activities?

We assessed inter-annual changes in fish assemblages of a tropical bay which experienced a heavily industrialized process in the last decades. A highly significant difference in community structure among the bay zones, and a decrease in fish richness and abundance over time were found. Changes in fish richness and abundance between the two first (1987–1988 and 1993–1995) and the two latter time periods (1998–2001 and 2012–2013) were sharpest in the inner bay zone, the most impacted bay area, and in the middle zone, whereas the outer zone remained comparatively stable over time. These changes coincided with increased metal pollution (mainly, Zn and Cd) in the bay and with the enlargement of the Sepetiba Port. Spatial changes in the fish community structure among the bay zones were related to differences in salinity, transparency and depth with this latter variable acting as a buffer stabilizing temporal community changes.     

Unique recovery stage of reef communities after F/F event in a huge coral reef of Carboniferous, Southern Guizhou,China

Carboniferous is a global recession period of reef-building. There were fewer reefs at that times due to massive extinction and the great glacial catastrophe in the southern hemisphere in Frasnian/Famennian[1]. So far, however, most of the researches concerning Carboniferous reefs have been limited, which leads to insufficient knowledge regarding the composition, structure, ecological characteristics of reef-building communities, the reef growth models, etc. Interna-tional studies conducted o…     

Does Pumping Volume Affect the Concentration of Micropollutants in Groundwater Samples?

Information on concentrations of micropollutants (such as pharmaceuticals, pesticides, and industrial chemicals) in most highly dynamic riverbank filtration (RBF) systems is lacking, in contrast to data on standard chemical parameters. Sampling protocols have thus far been based on the stabilization of standard chemical parameters in relatively pristine environments. To determine whether groundwater samples for micropollutant analysis can be taken at a similar pumping volume as samples for testing standard chemical parameters in both environments, three groundwater monitoring wells in an RBF system were sampled at two points in time (after pumping of 3 well volumes and after pumping of 15 well volumes). Micropollutant concentrations were not significantly different between the two sampling points; therefore, appropriate samples can be drawn after pumping 3 well volumes. For a specific microbiological parameter (leucin incorporation), a statistically significant difference was found.     

Plastic marine debris on the Portuguese coastline: a matter of size?

Plastic debris is a worldwide threat to marine environments and Portugal is not immune to it. Though never quantified, items of all sizes can be found in the Portuguese coastline; therefore the objective of this work is the identification of main size classes in stranded plastic debris. Beaches sediment was sampled and in the laboratory plastic items were sorted in 11 classes from <1 to >10 mm, counted and weighted. Plastic size ranged from 50 μm to 20 cm and microplastics (<5 mm) were the majority (72%). Most plastic fits in the smaller size classes, due to expected high residence time in the sea enhancing degradation processes, which increase surface exposure and potentially persistent organic pollutants (POP) adsorption. These results point out the important contribution of microplastics to marine debris pollution, its risks, and the need to set a higher focus on this size class.     

Livability assessment of 101,630 communities in China’s major cities: A remote sensing perspective

Science China Earth Sciences - Some of China’s major cities have entered the middle and late stages of urbanization, and the development focus of these cities has gradually shifted from...     

The sustainability of drinking water supply in rural China: Does the provision of drinking water investment mismatch the demand of residents?

It is doubted that the top down nature of investment planning may lead to mismatches between drinking water investment and the demands of local residents in rural China. Statistical and econometric analysis based on data of 2020 rural households from five Chinese provinces from 1998 to 2011 are used to illustrate the linkage between demand for drinking water investment and construction of drinking water projects. Household's demand significantly affects drinking water projects implemented by upper level governments and implemented jointly, but is not significant in explaining the projects implemented by village. There is evidence to suggest that the demands of local leaders override those of households in the implementation of drinking water projects provided by village in the early stage of 2005–2008. The situation improves in the latter stage of 2008–2011when the village level participatory bodies begin to provide opportunities for households to voice their preferences on public goods investment. The results of this study imply that it is important to explore appropriate regulations and policies that enabling local cadres to better meet local demands of their communities to ensure the sustainability of rural drinking water supply.