Adjacent Water Bodies Research Articles

Spatial decoupling of legacy phosphorus in cropland: Soil erosion and deposition as a mechanism for storage

Agricultural production continues to be implicated as one cause of eutrophication of water courses and water bodies in many agro-ecosystems. The generally-held consensus is that soil erosion by water is a major mechanism for loss of phosphorus (P) to adjacent water bodies and down-stream reservoirs from crop and grazing lands. Nonetheless, it does not explain the whole story of the fate of P losses applied to soils. This study assessed the spatial distribution of P as a consequence of historical erosion and redistribution of soil in an agricultural field in the Lake Erie basin in southern Ontario. Combining stratified random sampling with geospatial analysis of landscape position, plant-available (Olsen) P concentrations and stocks were measured and compared to other soil properties and related to soil erosion and redistribution. Toe-slope and foot-slope positions had two to three times the Olsen P stocks compared to summit landscape positions (mean of 52 +/- 9 kg P ha−1 and 47 +/- 9 kg P ha−1 versus 20 +/- 2 kg P ha-1, respectively) which was attributed to both water and tillage erosion. Burial of P beneath the plowing depth showed that the toe-slopes had over two to three times more Olsen P stocks below 25 cm depth compared to all other landscape positions. Olsen P stocks were significantly related (R2 = 0.50; p < 0.001) to soil organic carbon (SOC) stocks which was a consequence of historical soil erosion and redistribution in the field. The fate of legacy P in soils may be dependent upon the history of erosion and redistribution resulting in deposition of P in toe-slope and foot-slope positions in an agricultural landscape.

Attenuation of insecticide impact by a small wetland in a stream draining a horticultural basin in Argentina

Horticulture has greatly increased in Argentina in recent decades mainly due to increasing greenhouse utilization and agrochemical consumption, thus representing a threat to adjacent water bodies. Riparian wetlands, however, could attenuate agrochemical contamination. The present work therefore compared insecticide concentrations in bottom sediments in addition to sediment toxicity to the amphipod Hyalella curvispina and investigated the macroinvertebrate composition upstream and downstream from a natural wetland in a small stream draining a basin undergoing intense horticultural production. The wetland surface was covered by macrophytes, mainly Thypha sp., and the insecticide concentrations measured downstream from the wetland were significantly lower, at roughly 19% of the upstream values. The growth rates of H. curvispina were significantly higher when exposed to the sediments downstream from the wetland, while the macroinvertebrate-assemblage composition was significantly different upstream and downstream: the snail Pomacea canaliculata was the dominant species upstream while the amphipod H. curvispina was dominant downstream. Pomacea canaliculata is often the dominant species in the regional streams draining agriculture and horticultural basins. Hyalella curvispina is sensitive to pesticide toxicity and is often dominant in streams draining extensive livestock basins and within a biosphere reserve. We conclude that riparian wetlands effectively attenuate horticulture contamination in pampean streams and should therefore be preserved and restored.

Can nutrient uptake by Carex counteract eutrophication in fen peatlands?

Ground- and surface-water-fed peatlands (i.e., fens) of temperate Europe face high anthropogenic nutrient loads from atmospheric deposition, agricultural catchment areas, and from peat decomposition, if drained. As a result, nitrogen loads may exceed a fen's natural nutrient removal capacity, leading to increased eutrophication of adjacent water bodies. Therefore, it is important to address possible means to decrease a fen's nutrient load, including nutrient uptake by fen plants. To assess how much fen plants can contribute to nutrient removal by uptake, nutrient stocks of above- and below-ground biomass need to be quantified. Therefore, we investigated nitrogen, phosphorous, and potassium uptake capacities of sedges (Carex species), which are common dominants in fen plant communities. We grew specimens of five Carex species with varying preferences in nutrient availability under controlled, different nutrient levels. We show that Carex above-ground biomass harvest can remove up to one third of a system's total nitrogen even at high loads of about 40 g nitrogen m−2. Species-specific differences in biomass production, rather than preferences in nutrient availability under natural conditions, were drivers of standing nutrient stocks: Highly productive species, i.e., C. acutiformis and C. rostrata, had highest nutrient standing stocks across all nutrient levels. Amounts of nutrients stored in shoots increased almost linearly with increasing nutrient levels, whereas below-ground nutrient stocks species-specifically increased, saturated, or decreased, with increasing nutrient levels. As a rough estimate, depending on the species, 6–16 cycles of annual above-ground harvest would suffice to decrease nitrogen concentrations from the highest to the lowest level used in this study. Overall, our results indicate that Carex biomass harvest can be an efficient means to counteract anthropogenic nitrogen eutrophication in fens.

Hydrologic modeling of reach scale fluxes from flood irrigated fields

Agricultural water is of considerable interest to water managers and policymakers as irrigation—particularly flood irrigation—accounts for the largest portion of freshwater use. However, characterization of how and when flood applied water contributes to storage and adjacent surface water bodies via return flow remains limited, particularly relative to the volume of studies addressing surface processes. This study focuses on improving our understanding of return flow paths and explicitly quantifying subsurface return flow contributions using hydro-geophysical observations coupled with a vadose zone transport flow model. Our approach, which simulates return flow in agricultural fields in a small, heavily instrumented field site in northern Wyoming, leverages daily measured values of evapotranspiration obtained from a large aperture scintillometer and atmospheric conditions, and uses seismic data to characterize heterogeneous structure of the soil profiles at field scale. We use these high-resolution, site specific datasets to parameterize a process-based vadose zone flow model that quantifies hydrologic response to flood irrigation along the stream reach, allowing us to identify return flow fluxes out of the fields. Using our approach, we found that the majority of applied irrigation water (60%) left the fields through subsurface flow paths, while only 13% was consumed by vegetation. Subsurface runoff over less-permeable soil layers, governed by the subsurface structural characteristics, was identified as the dominant subsurface flow process contributing to fluxes out of the fields. Importantly, our findings about the importance of subsurface return flow paths nuance previous research which has emphasized surface flow paths. By improving our understanding of return flow processes through a high- resolution vadose zone model that leverages climatological, geophysical, and hydrological observations, this study advances our understanding of return flow processes. Understanding how subsurface characteristics influence return flow generation in semi-arid agriculturally productive regions will help managers and policy makers balance desires for improved irrigation efficiency against concerns about irrigation-dependent ecosystem services.

A simple model for the simulation of the flow behavior in unconfined double porosity aquifers

The flow processes in unconfined double porosity aquifers consisting of a porous matrix and a dense network of fractures are investigated using the equivalent continuum approach, the Dupuit assumption and a depth-integrated formulation. We show that, unlike in the case of confined double porosity aquifers, in the case we investigate the term describing the internal flux between the two equivalent continua is non-linear. For the case of dewatering processes, a system of Partial Differential Equations, which involves only four parameters is developed. It is demonstrated that for the opposite case of recharging aquifer, at least for some cases, a much more complicated mathematical description is necessary. For the dewatering aquifer case fully explicit analytical solutions for both the variations of water table and discharge to an adjacent water body are developed. We verified the accuracy of the solutions for the head by comparison against numerical results.

Effects of dynamic factors of erosion on soil nitrogen and phosphorus loss under freeze-thaw conditions

Soil erosion directly leads to the decline of soil fertility, and under hydraulic erosion, the soil nitrogen and phosphorus released by hydrolysis enter the adjacent water body along with surface runoff and soil erosion. This causes potential hazards such as eutrophication and river siltation in the watershed, seriously affecting the safety of the ecological environment. The mechanism of action of the dynamic factors of erosion on nitrogen (N) and phosphorus (P) loss remains unclear. In this study, a series of laboratory experiments were carried out to characterize the N and P loss and its influencing factors under freeze–thaw conditions. Two treatments (i.e., LC: loess control and FT: freeze–thaw treatment) and five soil water contents on a gravimetric basis (SWCs) (i.e., 10%, 15%, 20%, 25% and 30%) were considered. The results showed that the total runoff was higher under 30% SWC and lower under 20% SWC for the LC and FT treatments. The freeze–thaw action caused higher sediment loss under low water content (10% and 15%). The runoff-associated total nitrogen (RTN), runoff-associated total phosphorus (RTP), and sediment-associated total phosphorus (STP) loss rate showed a larger fluctuation for FT than for LC. Freeze-thaw action not only caused the instability of the N and P loss behavior but also caused increased diversity among individual samples. The soil erodibility, runoff energy and runoff power were important dynamic factors associated with erosion, and the freeze–thaw action had a very large impact on these factors. Under freeze–thaw action, the effect of dynamic factors on phosphorus and nitrogen loss was significantly enhanced. For the LC treatments, the SWC could explain 60% of the variation in RTN loss and 63% of the variation in RTP loss; the runoff explained 90% of the variation in STN loss and the runoff time explained 97% of the variation in STP loss. For the FT treatments, the runoff time explained 63% of the variation in STN loss and 53% of the variation in STP loss. The results enable us to understand further the relationship between dynamic factors of rainfall erosion and nitrogen and phosphorus loss under freeze–thaw conditions.

Towards enhancing tidally-induced water renewal in coastal lagoons

In order to address the problem of limited water renewal in restricted lagoons of moderate size having at least two tidal inlets, a method is proposed to enhance water exchange between the lagoon and the open sea. The method consists of altering either the amplitude or the phase of the tide in one of the inlets. It is shown in the paper that this will result in an alteration of the function of the lagoon, from a lagoon periodically exchanging water equal to a tidal prism within each tidal cycle with the adjacent water body, towards an effectively flow through system, substantially improving the flushing rate of the lagoon. The method is confirmed by running a series of numerical experiments simulating tidal hydrodynamics in the Papas lagoon. The question of how to alter the tidal amplitude is briefly touched upon, by numerically testing the performance of artificially macro-roughening an inlet and alternatively, designing an inlet to have a meandering shape. It was found that both modifications produce a diminished tidal amplitude, providing positive evidence for the applicability of the proposed method.

Effects of Shallow Water Table Depth on Vegetative Filter Strips Retarding Transport of Nonpoint Source Pollution in Controlled Flume Experiments

Vegetative filter strips (VFSs) have been recommended as the best management practice for reducing runoff nonpoint source (NPS) pollution. The efficiency of VFSs located adjacent to water bodies can vary with shallow water table depths (WTD). A vegetated soil tank containing silt loam soil and Shortleaf Lilyturf vegetation was designed to study the effects of VFSs under shallow WTD (0.08, 0.22, and 0.36 m) on retentions of surface runoff, sediment, phosphorus, and bromide. Experiments were conducted with a simulated rainfall intensity of 28 mm h−1 and inflow rates of 4.02–4.56 L min−1. The results revealed that a deep WTD, low grass spacing, and low slope had high VFS retention efficiencies. The retention efficiencies varied greatly from 35%, 70%, 64%, and 55% at the 0.08-m WTD in the experimental group with high grass spacing (6.69 cm) and low slope (5%) to 96%, 98%, 96%, and 95% at the 0.36-m WTD in the experimental group with low grass spacing (4.18 cm) and low slope (5%) for surface runoff, sediment, phosphorus, and bromide, respectively. A steeper slope (at the same grass spacing) increased the effects of the WTD on VFS performance. For each experimental group, the average surface runoff outflow rate decreased with the WTD, whereas the average subsurface lateral flow rate increased. The transport of phosphorus in the surface runoff almost resembled that of bromide, and the average concentration (C/C0 Ave) of phosphorus and bromide decreased with the WTD. For the subsurface lateral flow, the transport of bromide and phosphorus exhibited typical breakthrough behaviors during each experiment, and both the normalized phosphorus and bromide concentrations in increasing limbs could be described by power equations. The high concentration of pollutants in the subsurface lateral flow may have affected the adjacent water bodies and groundwater. In quantification of the impact of WTD on effectiveness of VFS, we can effectively control the NPS pollutants in a watershed.

A bio-optical model for the estimation of chlorophyll a using animal-borne instruments in an optically complex ecosystem

Studies using marine animals instrumented with biologging devices to estimate phytoplankton biomass have typically omitted continental shelf regions due to the confounding effects of optically active constituents other than phytoplankton present. The lack of algorithms for these regions is problematic, as they are some of the most biologically productive in the world and are often inhabited by the species of interest. We developed a bio-optical model to estimate chlorophyll a concentration (chl a) using light attenuation (LA) measured using a standard oceanographic instrument in an optically complex water body that is applicable to data collected by animal-borne devices. To achieve this, we conducted a replicated experiment to compare measurements made using time-depth-light recorders (TDLRs) to those of a standard oceanographic instrument (the HyperPro) in an adjacent water body, the Bedford Basin, Nova Scotia, Canada. Measurements of LA made by TDLRs were comparable to those of the HyperPro atdepth. The best supported bio-optical model for the estimation of chl a included both LA measured by the HyperPro and season as a fixed effect. The use of animal-borne devices to collect subsurface chl a data not only provides an opportunity to collect valuable oceanographic data but also allows for the exploration of broader ecological questions relating to the influence of primary productivity on the movement patterns of wide-ranging marine species.

ЦИФРОВАЯ МОДЕЛЬ ПРОЦЕССА РАЗЛИВА НЕФТЕПРОДУКТОВ НА ПОВЕРХ-НОСТИ ЗЕМЛИ

The possibility of creating a digital model of the process of oil spills with their penetration into the ground and the adjacent water body, which causes significant damage to the environment and the economy, especially in the northern regions, is being considered. An approach to solving this problem is proposed, based on the representation of the soil contamination area in the form of a set of flat layers, each of which is calculated by the method of moving grids.

Research progress on nitrogen and phosphorus runoff loss models for rice paddy

水稻是全球最重要的粮食作物，但种植过程中不合理的水肥管理引起了稻田氮磷径流流失，对邻近水体造成污染风险.稻田氮磷径流流失模型是理解区域水体污染排放时空特征和评估水污染风险的有效手段.论文阐述了稻田氮磷径流流失的发生机制和关键过程，梳理了统计经验模型、物理机理模型、水文过程模型和生态系统模型的研发历程.结果表明，当前模型缺乏水-土-气界面过程的有效参数化，基于高分辨率、多年多站点、全通量的模型参数的合理化，以及区域尺度农艺管理（种植制度、施肥制度、灌排制度）和田-沟-塘联合调控措施（分布、规模、运行规则）的模块化，造成了稻田氮磷径流流失的不确定性.同时，提出了面向稻田氮磷循环的高分辨率全通量观测网络建设、农艺管理与调控措施的区域数据集研发、模型开发与先进技术手段的集成与融合、稻田氮-磷-水耦合的多模型集合等，为稻田氮磷径流流失模型的改进、农艺管理措施的优化以及气候智能型稻田的建设提供科学依据.;Rice is the most significant food crop in the world, but nitrogen and phosphorus runoff loss, a risk of pollution to adjacent water bodies, would occur during cultivation by unreasonable water and fertilizer management. Nitrogen and phosphorus runoff loss model for rice paddies is an effective way, in addition to assessing the risk of water pollution, to understand the spatial and temporal characteristics of regional water pollution discharge. Here, the authors expound the occurrence mechanism and key processes of nitrogen and phosphorus runoff loss in rice paddies, and then systematically reviews the research and development history of statistical empirical model, physical mechanism model, hydrological process model and ecosystem model. The authors point out that current models are limited by the uncertainty of nitrogen and phosphorus runoff losses in paddy fields, due to deficiency in the effective parameterization of the water-soil-air interface process, rationalization of model parameters based on high resolution, multi-year, multi-site and full flux, as well as regional-scale agricultural management (planting, fertilization, irrigation and drainage system) and the modularization of the joint control measures (distribution, scale, operation rules) of paddy-ditch-pond. Finally, the authors propose outlook on the establishment of high-resolution and full flux observation network for rice paddies' nitrogen and phosphorus cycles, regional data set research and development of agricultural management and control measures, integration and fusion of model development and advanced technological means, and multi-model integration of nitrogen-phosphorus-water coupling in rice paddies. Achieving these prospects will provide scientific support for the improvement of nitrogen and phosphorus runoff models for a rice paddy, the optimization of agricultural management measures, and the construction of climate-smart rice paddies.

Assessment of surface water quality around a landfill using multivariate statistical method, Sylhet, Bangladesh

Solid waste generation is rising consequently with the increasing population growth in Sylhet city. Mogla Bazar, an only dumping zone is affecting the surrounding environment enormously. This study aims to determine the surface water quality of the adjacent water bodies that lie within the 500 m buffer zone of the landfill utilizing multivariate statistical methods. Physicochemical and microbial parameters along with anions were considered for evaluating water quality. Multivariate statistical techniques viz. Principal Component Analysis (PCA), Factor Analysis (FA) and Cluster Analysis (CA) were applied to assess the water quality. Besides, the Pearson correlation matrix was performed to detect the interrelation among the variables and water quality index (WQI) was also used to classify the pollution sources. All the parameters were compared with the established acceptable limit given by the World Health Organization (WHO)/ Bureau of Indian Standards (BIS). PCA/FA resulted in three principal components with a total variance of 59.89 % and 57.14 % for haor and fishing zone, wetland respectively. Factor analysis derived from principal components shows that organic substances, anthropogenic activity, fertilization, chemical waste, and wastewater runoff are responsible for deteriorating the water quality. CA and WQI detect that sampling sites of haor and fishing zone that lies on the 200 m buffer zone were highly susceptible to water pollution. Besides, topographical variation, changes in slope, and seasonal variation were also treated as an influencing factor. Finally, all the analysis implied that the declining water quality would be dangerous to the neighbourhood of the landfill and there is a high chance of exposure to the dwellers residing nearby.

Implementation of a constructed wetland for the sustainable treatment of inland shrimp farming water

In the Mekong delta, inland-based shrimp breeding requires significant inflow of high-quality freshwater. In turn, discharge of substantial loads of poor-quality effluents negatively impacts adjacent water bodies and favors disease outbreaks. This project describes the implementation of a laboratory-based continuous closed recirculation aquaculture system composed of a constructed wetland (CW) with horizontal subsurface flow as a water treatment filter for mesohaline conditions, functioning under high loading rate (HLR = 1.54 m/d with HRT = 1.31 h). This CW was equipped of successive compartment dedicated to the successive elimination of the contaminants of interests. CW performance was measured over a complete growth cycle of the White-leg shrimps (Litopenaeus vannamei). Results showed that the designed system was pertinent, improving water quality of the shrimp culture substantially. Complete removal of nitrite was attained, with a concomitant reduction of respectively 78% and 76% of nitrate and COD. Bacteria enumeration tests showed that Vibrio sp. cells were fully removed, and that a 3 Log reduction was reached in total aerobic bacteria.

Fisheries management influences phytoplankton biomass of Amazonian floodplain lakes

Abstract Tropical floodplains secure the protein supply of millions of people, but only sound management can ensure the long‐term continuity of such ecosystem services. Overfishing is a widespread threat to multitrophic systems, but how it affects ecosystem functioning is poorly understood, particularly in tropical freshwater food webs. Models based on temperate lakes frequently assume that primary producers are mostly bottom‐up controlled by nutrient and light limitations, with negligible effects of top‐down forces. Yet this assumption remains untested in complex tropical freshwater systems experiencing marked spatiotemporal variation. We use consolidated community‐based fisheries management practices and spatial zoning to test the relative importance of bottom‐up versus top‐down drivers of phytoplankton biomass, controlling for the influence of local to landscape heterogeneity. Our study focuses on 58 large Amazonian floodplain lakes under different management regimes that resulted in a gradient of apex‐predator abundance. These lakes, distributed along ~600 km of a major tributary of the Amazon River, varied widely in size, structure, landscape context, and hydrological seasonality. Using generalised linear models, we show that community‐based fisheries management, which controls the density of apex predators, is the strongest predictor of phytoplankton biomass during the dry season, when lakes become discrete landscape units. Water transparency also emerges as an important bottom‐up factor, but phosphorus, nitrogen and several lake and landscape metrics had minor or no effects on phytoplankton biomass. During the wet‐season food pulse, when lakes become connected to adjacent water bodies and homogenise the landscape, only lake depth explained phytoplankton biomass. Synthesis and applications. Tropical freshwaters fisheries typically assume that fish biomass is controlled by bottom‐up mechanisms, so that overexploitation of large predators would not affect overall ecosystem productivity. Our results, however, show that top‐down forces are important drivers of primary productivity in tropical lakes, above and beyond the effects of bottom‐up factors. This helps us to understand the enormous success of community‐based ‘fishing agreements’ in the Amazon. Multiple stakeholders should embrace socio‐ecological management practices that shape both bottom‐up and top‐down forces to ensure biodiversity protection, sustainable fisheries yields and food security for local communities and regional economies.

Carbon source characterisation and historical carbon burial in three mangrove ecosystems on the South West coast of India

Tropical mangrove environments have high carbon sequestration potential and this ecosystem service is currently used in mitigating climate change. However, these environments are declining rapidly in developing countries, diminishing their carbon sequestration potential and may ultimately transforming them as carbon dioxide sources. This study investigated the carbon sequestration potential through sediment burial at three mangrove habitats of Cochin, South-West coast of India. High burial estimates were recorded at two mangrove stations (2.95 ± 0.79–10.41 ± 2.50 t C ha−1 yr−1), but consistent with other tropical mangrove areas. Lower burial rates were estimated at one station (0.57 ± 0.24 t C ha−1 yr−1). Eighty percent of the mangrove net primary productivity through litterfall (NPPL) was stored in the sediment at the station with the highest burial rate, which is demonstrative of a robust carbon sink. However, at a different site, which is subject to aquaculture, only 7.23 % of NPPL was buried in the sediment. A major portion of the fixed carbon at this site is presumably emitted back to the atmosphere or exported to adjacent water bodies. The median total regional mangrove carbon burial rate in this study was 2.95 t C ha−1 yr−1 and the organic carbon burial rate was 1.93 ± 0.75 t C ha−1 yr−1. Biological factors such as mangrove biomass, litterfall and crab density have played a major role in controlling the sediment carbon burial rate. Sediment texture and bulk sediment accumulation acted as secondary controlling factors. The carbon source characterisation in the sediment profile using stable isotope techniques revealed the organic carbon origin as mangrove litter. Gaining a better understanding of carbon sources, burial rates and their controlling factors in mangrove habitats aids in regional climate mitigation efforts and global efforts to increase the carbon sequestration potential of tropical mangrove systems.

Assessment of deicing salt storage and distribution as a salinization point source: the influence of permitting standards on water quality

BackgroundRoad deicing salts are impacting freshwater ecosystems in snowy regions worldwide. Rock salt (typically sodium chloride) is transported to and stored in regional facilities that operate year-round and are continuous potential sources of chloride discharge to adjacent water bodies, resulting in different impacts to aquatic ecosystems than chloride pollution from spatially diffuse road networks. The regulatory tools and associated monitoring regimes used by state and federal agencies related to permitting of these facilities is inconsistent. Selection of the regulatory standards and monitoring location in the receiving water body (and how the definition of ‘receiving water body’ is applied) can have a significant influence on the measured or modeled impact of a facility on aquatic ecosystems. Additionally, selection of the monitored media (surface water, soil pore water, shallow ground water, or vegetation) can further influence findings, resulting in inconsistent conclusions of environmental impact and potentially allow exceedances of regulatory thresholds of chloride. This study evaluates chloride pollution from salt loading over two years from a state-permitted salt storage and transport facility in Shelburne, Vermont, USA to an adjacent wetland and river that drains to Lake Champlain. Water quality results and modeled assumptions made by the permittee were compared to monitoring data at two discharge points from the site including a drainage channel downstream of the site’s stormwater pond and at a shallow ground water seep below the rail car unloading area.ResultsResults indicate elevated chloride concentrations (average of 243 and 643 mg L−1) at the discharge points to the receiving water body, in conflict with findings from annual permittee assessments. Soil cores taken in the wetland in the vicinity of the control and two discharge points also indicate elevated Cl− (p ≤ 0.035) and Na+ (p ≤ 0.0006). Samples of Tsuga canadensis at the discharge points and at the control site indicate elevated chloride in plant tissues.ConclusionsDetermination of exceedances of chronic and acute standards vary based on the sampling location and medium, indicating a need for consistency and outcome-based monitoring point selection criteria and a move away from reliance on self-reporting by permittees.

Modeling of phosphorus loss from field to watershed: A review.

Phosphorus (P) losses from nonpoint sources into surface water resources through surface runoff and tile drainage play a significant role in eutrophication. Accordingly, the number of studies involving the modeling of agricultural P losses, the uncertainties of such models, and the best management practices (BMPs) supported by the modeling of hypothetical P loss reduction scenarios has increased significantly around the world. Many improvements have been made to these models: separate manure P pools, variable source areas allowing the determination of critical source areas of P loss, analyses of modeling uncertainties, and understanding of legacy P. However, several elements are still missing or have yet to be sufficiently addressed: the incorporation of preferential flow into models, the modification of P sorption-desorption processes considering recent research data (e.g., pedotransfer functions for labile, active, or stable P, along with P sorption coefficients), BMP parameterization, and scale-up issues, as well as stakeholder-scientist and experimentalist-modeler interactions. The accuracy of P loss modeling can be improved by (a) incorporating dynamic P sorption-desorption processes and new P subroutines for direct P loss from manure, fertilizer, and dung, (b) modeling preferential flow, connectivity between field and adjacent water bodies, and P in-stream processes, (c) including an assessment of model uncertainty, (d) integrating field and watershed models for BMP calibration and scaling field results up to larger areas, and (e) building a holistic interaction between stakeholders, experimentalists, and modelers.

Design features of constructed floodplain ponds influence waterbird and fish communities in northern New Zealand

Abstract Ponds can provide important refuges for aquatic biota on developed floodplains and are increasingly being constructed in an effort to enhance native biodiversity and ecosystem services in degraded landscapes. This study examined 34 constructed ponds to investigate the influence of design features on community composition, native biodiversity, and the biomass or abundance of common fish and waterbirds on the lower Waikato River floodplain, northern New Zealand. Inundation frequency appeared to be a key factor affecting biomass of the native shortfin eel Anguilla australis and three invasive fish species (common carp [Cyprinus carpio], brown bullhead [Ameiurus nebulosus], and goldfish [Carassius auratus]), suggesting that colonisation occurred during flooding by adjacent waterbodies. Linear models indicated that shortfin eel abundance and total eel biomass were positively associated with the biomass of potential fish prey, the area occupied by islands and cover by trees in the riparian zone. Native waterbird species richness was strongly related to water area, edge length (including islands) and area:perimeter ratio, with little increase in richness for ponds &gt;1 ha in area, perimeters longer than 800 m, and ratios over 20. The protected grey teal (Anas gracilis), and the recreationally hunted species phenotypically assigned as mallard (Anas platyrhynchos + hybrids) and grey duck (Anas superciliosa + hybrids) appeared most strongly influenced, respectively, by perimeter length, water depth, and biomass of potential macroinvertebrate food supplies, suggesting variable effects of pond design attributes among waterfowl species. Overall, these results indicate that constructed ponds can be designed to promote native waterbird diversity, enhance eel fishery and waterfowl gamebird services, and also limit the proliferation of some non‐native invasive fish species in degraded floodplain landscapes. A hierarchy of constructed pond design attributes was identified, involving landscape position and connectivity, pond morphology and complexity, and riparian maturity and buffering, which were associated with direct (habitat) and indirect (food supply, physicochemistry) effects on biodiversity and provisioning services.

Evaluation of Heavy Metals in Streams of the Bacanga and Cachorros Watersheds in São Luís, Brazil.

Impacts on urban water resources are invariably caused by the development of urban centers and the occupation of the watershed. The release of untreated effluents and urban runoff are sources of metals in adjacent water bodies. It is therefore important to conduct studies on the occurrence of these trace elements in the environment and the risks posed to human health. The aim of the present study was to determine Cd, Pb, Cu, and Zn concentrations in water bodies located in the Bacanga and Cachorros watersheds and correlate the occurrence of these elements with physicochemical variables of the water (temperature, pH, dissolved oxygen, and electrical conductivity). The variables were determined at the collection site with the aid of a multiparameter kit. Heavy metal concentrations were determined using anodic stripping voltammetry. The results revealed that the streams were not contaminated with the metals analyzed. The only exception was copper in the Limoeiro and Murtura streams, both of which are located in the industrial complex.

Comparing models using air and water temperature to forecast an aquatic invasive species response to climate change

AbstractUnderstanding invasive species spread and projecting how distributions will respond to climate change is a central task for ecologists. Typically, current and projected air temperatures are used to forecast future distributions of invasive species based on climate matching in an ecological niche modeling approach. While this approach was originally developed for terrestrial species, it has also been widely applied to aquatic species even though aquatic species do not experience air temperatures directly. In the case of lakes, species respond to lake thermal regimes, which reflect the interaction of climate and lake attributes such as depth, size, and clarity. The result is that adjacent waterbodies can differ notably in thermal regime. Given these obvious limitations of modeling aquatic species distributions using climate data, we take advantage of recent advances in simulating lake thermal regimes to model the distributions of invasive spiny water flea (Bythotrephes cederströmii) for current and projected future climates in the upper Midwest of the USA. We compared predictions and future projections from models based on modeled air temperatures with models based on modeled water temperature. All models predicted that the number of suitable lakes in the region will decrease with climate change. Models based on air and water temperature differed dramatically in the extent of this decrease. The air temperature model predicted 89% of study lakes to be suitable, with suitability declining dramatically in the late century with climate warming to just a single suitable lake. Lake suitability predictions from the water temperature model declined to a much lesser degree with warming (42% of lakes were predicted to be suitable, declining to 19% in the late century) and were more spatially independent. Our results expose the limitations of using air temperatures to model habitat suitability for aquatic species, and our study further highlights the importance of understanding lake‐specific responses to climate when assessing aquatic species responses to climate change. While we project a contraction in the potential range of Bythotrephes with warming in the study region, we anticipate that Bythotrephes will likely continue to expand into new lakes that will remain suitable in the following decades.