Water Quality Of Aquatic Ecosystems Research Articles

Severe western Canadian wildfire affects water quality even at large basin scales

Wildfires can have severe and lasting impacts on the water quality of aquatic ecosystems. However, our understanding of these impacts is founded primarily from studies of small watersheds with well-connected runoff regimes. Despite the predominance of large, low-relief rivers across the fire-prone Boreal forest, it is unclear to what extent and duration wildfire-related material (e.g., ash) can be observed within these systems that typically buffer upstream disturbance signals. Following the devastating 2016 Fort McMurray wildfire in western Canada, we initiated a multi-faceted water quality monitoring program that suggested brief (hours to days) wildfire signatures could be detected in several large river systems, particularly following rainfall events greater than 10 mm. Continuous monitoring of flow and water quality showed distinct, precipitation-associated signatures of ash transport in rivers draining expansive (800–100,000 km2) and partially-burned (<1–22 percent burned) watersheds, which were not evident in nearby unburned regions. Yields of suspended sediment, nutrients (nitrogen, phosphorus) and metals (lead, others) from impacted rivers were 1.2–10 times greater than from those draining unburned regions. Post-fire suspended sediment concentrations in impacted rivers were often larger than pre-fire 95% prediction intervals based on several years of water sampling. These multiple lines of evidence indicate that low-relief landscapes can mobilize wildfire-related material to rivers similarly, though less-intensively and over shorter durations, than headwater regions. We propose that uneven mixing of heavily-impacted tributaries with high-order rivers may partially explain detection of wildfire signals in these large systems that may impact downstream water users.

Secchi Disk Depth Estimation from China’s New Generation of GF-5 Hyperspectral Observations Using a Semi-Analytical Scheme

Water clarity, commonly measured as the Secchi disk depth ( Z s d ), is an important parameter that depicts water quality in aquatic ecosystems. China’s new generation Advanced HyperSpectral Imager (AHSI) on board the GF-5 satellite has significant potential for applications of more accurate water clarity estimation compared with existing multispectral satellite imagery, considering its high spectral resolution with a 30-m spatial resolution. In this study, we validate the semi-analytical model with various Quasi-Analytical Algorithms (QAA), including Q A A V 5 , Q A A V 6 , Q A A L 09 and Q A A M 14 , for the AHSI images with concurrent in situ measurements in four inland water bodies with a Z s d range of 0.3–4.5 m. The semi-analytical method with Q A A V 5 can yield the most accurate Z s d predictions with approximated atmospheric-corrected remote sensing reflectance. For 84 concurrent sampling sites, the estimated Z s d had a mean absolute error (MAE) of 0.35 m, while the mean relative error (MRE) was 25.3%. Specifically, the MAEs of estimated Z s d were 0.22, 0.46, and 0.24 m for Z s d of 0.3–1, 1–3, and 3–4.5 m, respectively. The corresponding MREs were 33.1%, 29.1% and 6.3%, respectively. Although further validation is still required, especially in terms of highly turbid waters, this study indicates that AHSI is effective for water clarity monitoring.

Climate Variability Induced Shifts in Nitrogen Loading from Terrestrial to Aquatic Ecosystems

Nitrogen is one of the critical nutrients regulating terrestrial and aquatic productivity, and is linked to degradation of water quality of freshwater and marine ecosystems worldwide. The landscape patterns of stream nitrogen components, concentrations and loadings and their relationships with climate variability and landuse, were analyzed and quantified in this study. We used stream nitrogen concentration data collected at 2,125 sites and climate data at 301 weather stations during 1976 to 2005 in 30 eco-regions across British Columbia, Canada. While the patterns of stream nitrogen component, concentration, and loading distributions were found to be related to landscape patterns of climate variability, human activities, landuse, natural vegetation, and relief across British Columbia, the climate variability on both temporal a d spatial scales were found to be the dominant driver of variability in loading and concentrations of nitrogen. Elevated air temperature gradient across the landscape of British Columbia resulted in a significant increase in stream nitrogen loading from terrestrial into aquatic ecosystems. Precipitation, nitrogen deposition, population density and urban area also significantly affected the stream nitrogen components, concentrations and loadings. We suggest that climate change, especially shifts in temperature and precipitation, along with increased human activities tend to have important implications for loading of nitrogen from terrestrial to aquatic ecosystems and associated water quality in aquatic ecosystems

Physico-chemical and bacteriological quality assessment of surface water at Lake Tonga in Algeria

Maintaining standard water quality of aquatic ecosystems requires continuous monitoring of water physicochemical and bacteriological characteristics. This study aimed at assessing water physicochemical and microbiological proprieties of Lake Tonga (northeastern Algeria). Water samples were collected monthly (January–June) from three different stations at different depths. Several physicochemical parameters (pH, electrical conductivity, turbidity, hardness, biological oxygen demand (BOD5), concentrations of suspended solid materials, dry residuals, dissolved oxygen, phosphate, nitrites, nitrates, ammonium, calcium, magnesium, chloride, potassium and sulfur dioxide) and bacterial group sdensity (total heterotrophic bacteria, total coliforms, faecal coliforms and faecal Streptococci) were measured. Physicochemical analysis of Tonga Lake water revealed a slightly alkaline environment pH (6.5 < pH < 8.5), electrical conductivity < 1500 μS/cm, turbidity > 7.02 NTU, dry residues < 2000 mg/L, suspended solid materials (11.8 mg/L, < 30 mg/L), dissolved oxygen < 5 mg/L, phosphates > 5 mg/L, BOD5 < 5 mg/L, nitrate < 50 mg/L, nitrite > 0.1 mg/L, and NH4+ > 0.5 mg/L, Ca2+ < 200 mg/L, Mg2+ < 150 mg/L, Cl–> 500 mg/L, K+ > 20 mg/L and sulfates < 200 mg/L. In addition, microbiological results indicated the presence of different groups of faecal bacteria with an average of 32.3 × 10³ CFU/100 mL for total heterotrophic bacteria, 24 × 10³ CFU/100 mL for total and faecal coliforms, and 37 × 10³ CFU/100 mL for faecal Streptococci. Tonga Lake is currently in an eutrophication state and further severe ecosystem degradations may occur if the appropriate management measures are not taken in short term.

A disposable bulk-acoustic-wave microalga trapping device for real-time water monitoring

Recently, there has been an increase in the use of algal physiology as a convenient and useful indicator for monitoring of water quality in aquatic ecosystems. However, current methods for monitoring algal physiology are high-cost, power intensive, and have limited sensitivity for practical samples in which algal concentration is low. In order to alleviate these problems, we developed a simple-to-fabricate acoustophoretic particle trapping device that can effectively enrich various types of microalgae such as chlorella and diatoms for real-time monitoring of water quality. This microalgae trap is fabricated by embedding a piezoelectric resonator in a single channel. In comparison to previously reported acoustophoretic particle traps, this device has a simple structure and does not require sheath flows, which makes the device low cost and simple to fabricate and operate. Using Chlorella kessleri and the marine diatom Thalassiosira pseudonana as model algae, the microalgae trap has demonstrated notable particle trapping efficiencies between 82 % to 74 % for Chlorella with a through-flow of 0.5 μl/min to 2.7 μl/min and 85 % to 79 % for diatoms with a 0.5 μl/min to 4 μl/min through-flow. The trap has also shown to simultaneously trap Chlorella and diatoms at different heights of the microchannel. This device has high promise for trapping, separating and manipulating microalgae.

Evaluation of mass bathing effects on water quality status of eight prominent ponds of Haryana (India): A multi-location study

Amongst the various anthropogenic activities, mass bathing and other religious rituals also affect the water quality of aquatic ecosystem. The present research has been conducted to evaluate the impact of mass bathing and other religious activities on the eight famous religious water bodies of Haryana (Kapalmochan tirth, Kulotarn tirth, Ban-Ganga tirth, Brahmsarovar, Jyotisar, Saraswati tirth, Phalgu tirth and Pandu-Pindara tirth). The water samples were collected from three sampling stations (A, B and C) at each of the eight selected sites (S1 to S8) before and after the religious rituals and also seasonally. The samples were analyzed for Dissolved oxygen (DO), Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD) ammonia and heavy metals . The study highlighted the seasonal variations of physicochemical characteristics and also the effects of mass bathing and religious activities on water quality of the religious sites. Although the water was reported as safe in terms of DO content, total ammonia, BOD and the values of COD before the religious rituals but the values exceeded the maximum permissible limit {DO (0.8±0.1, 0.76±0.11), BOD (25.07±0.13, 18.13±0.13),COD (131.9±2.08), Ammonia (2.31±.23, 6.57±0.02) Iron (5890 µg L-1) and Zinc (200 µg L-1)} after mass bathing and religious rituals indicating that the water was not suitable for drinking as well as bathing purposes after the rituals/mass bathing. So, bathing during/after such rituals may become a health hazards to the bathers or users of the water and also may affect the aquatic biota, further depleting it. There is thus a need of regular monitoring and regular application of suitable remedial measures to prevent the depletion of the quality of lentic waters.

Enhancement of primary production during drought in a temperate watershed is greater in larger rivers than headwater streams

AbstractDrought is common in rivers, yet how this disturbance regulates metabolic activity across network scales is largely unknown. Drought often lowers gross primary production (GPP) and ecosystem respiration (ER) in small headwaters but by contrast can enhance GPP and cause algal blooms in downstream estuaries. We estimated ecosystem metabolism across a nested network of 13 reaches from headwaters to the main stem of the Connecticut River from 2015 through 2017, which encompassed a pronounced drought. During drought, GPP and ER increased, but with greater enhancement in larger rivers. Responses of GPP and ER were partially due to warmer temperatures associated with drought, particularly in the larger rivers where temperatures during summer drought were &gt; 10°C higher than typical summer baseflow. The larger rivers also had low canopy cover, which allowed primary producers to take advantage of lower turbidity and fewer cloudy days during drought. We conclude that GPP is enhanced by higher temperature, lower turbidity, and longer water residence times that are all a function of low discharge, but ecosystem response in temperate watersheds to these drivers depends on light availability regulated by riparian canopy cover. In larger rivers, GPP increased more than ER during drought, even leading to temporary autotrophy, an otherwise rare event in the typically light‐limited heterotrophic Connecticut River main stem. With climate change, rivers and streams may become warmer and drought frequency and severity may increase. Such changes may increase autotrophy in rivers with broad implications for carbon cycling and water quality in aquatic ecosystems.

Effects of common carp (Cyprinus carpio) on water quality in aquatic ecosystems dominated by submerged plants: a mesocosm study

Common carp (Cyprinus carpio) have been introduced into aquatic systems across the world, where their benthivorous feeding behavior has resulted in serious water quality problems. A 12-week mesocosm experiment was set up to test the hypotheses that common carp increase water column nutrient levels and decrease water clarity in aquatic ecosystems dominated by submerged plants. Further, we tested whether the effect of common carp on macrophytes depended on the species of plants. Relative to the controls, the presence of carp decreased water clarity by increasing total suspended solids (TSS) and light attenuation. However, levels of total nitrogen (TN) and total phosphorus (TP) in the water column were reduced. No significant change in phytoplankton biomass (measured as chlorophylla) and the biomass ofHydrilla verticillatawas observed between common carp treatment mesocosms and controls, but the common carp did reduce the biomass of the submerged macrophyteVallisneria denseserrulata. We conclude that removal of common carp is likely to improve water clarity in aquatic ecosystems dominated by submerged plants primarily by decreasing TSS and that the effect of common carp on macrophytes is stronger for the meadow formingVallisneriathan for the canopy formingHydrilla.

Does species richness affect the growth and water quality of submerged macrophyte assemblages?

Biodiversity commonly plays important roles in ecosystem functioning. While many studies have tested effects of species diversity on productivity, carbon and nitrogen cycling and resistance to biological invasion, few have examined how diversity of submerged macrophytes affects the water quality of aquatic ecosystems. We assembled aquatic microcosms with 1, 2, 3 and 4 submerged macrophyte species (Hydrilla verticillata, Ceratophyllum demersum, Myriophyllum verticillatum and Elodea nuttallii), and measured growth of the macrophytes and physical and chemical properties of the water (total nitrogen and phosphorus, transparency, dissolved oxygen content, chemical and biochemical oxygen demand) in the microcosms after 36 days. Species diversity of submerged macrophytes did not significantly affect biomass and the vegetative reproduction of the macrophytes or the water factors such as total nitrogen and phosphorus, chlorophyll a content, chemical and biochemical oxygen demand of the aquatic ecosystems. Exceptionally, the 3-species treatment had higher light transmittance than the monoculture and the 2- and 3-species treatments also ended up with higher dissolved oxygen compared to the 1- or 4-species treatment. However, since only functionally similar submerged macrophyte species were involved in this study, it is still difficult to draw clear conclusions. Therefore, we suggest to include multiple types of submerged macrophytes to test the effect of species richness on vegetation growth and water quality in future studies.

Modeling Fecal Indicator Bacteria in Urban Waterways Using Artificial Neural Networks

AbstractFecal indicator bacteria (FIB) are used as proxies to measure the microbial water quality of aquatic ecosystems. Methods of modeling FIB have evolved in order to provide accurate and timely...

Assessment of water quality in Iran’s Anzali Wetland, using qualitative indices from 1985, 2007, and 2014

In the present study, the water quality of the Anzali Wetland, located southwest of the Caspian Sea in Iran, was compared for the years 1985, 2007, and 2014, using a weighted arithmetic mean function (National Sanitation Foundation Water Quality Index: NSFWQIa), a weighted geometric mean function (NSFWQIm), and the Oregon Water Quality Index (OWQI). To that end, nine water quality parameters [pH, turbidity (TURB), temperature (T), dissolved oxygen (DO), nitrate (NO3), total solids (TS), phosphate (PO4), biological oxygen demand (BOD5), and fecal coliforms (FC)] were analyzed at eight selected stations. According to the proposed classification for water quality indices (higher value (0–100), better water quality), the Wetland water quality was classified as the mean values of the three indices for the three sampled years, as follows: NSFWQIa (13.72, 12.81, 12.07); NSFWQIm (63.049, 52.388, 49.108); and OWQI (26.867, 14.477, 15.53). The values of NSFWQIa, NSFWQIm, and OWQI for the western stations were better than for the other stations in the region over the 29-year span of investigation; however, the remainders of the stations’ values were very poor. Because wastewaters discharged from industrial and agricultural areas are more concentrated in the eastern part of the Anzali Wetland, the eastern stations of the Wetland showed lower water quality compared to the central and western stations. The water of the Anzali Wetland has different quality classes according to the aggregation methods employed. It is concluded that when evaluating water quality of aquatic ecosystems, several indices should be used to obtain more comprehensive results.

Testate amoebae as indicators of water quality and contamination in shallow lakes of the Middle and Lower Yangtze Plain

Testate amoebae are micro-organisms characterized by an agglutinated or autogenous shell enclosing the cytoplasm. Testate amoebae have been widely proposed as valuable bioindicators in a range of ecosystems (such as soils, peatlands and lakes). The use of testate amoebae as bioindicators of water quality in aquatic ecosystems is much less developed than for other microorganisms and previous research is geographically restricted. We investigated a large range of environmental variables and their relations to testate amoeba communities from 37 shallow lakes in the middle and lower Yangtze River Plain of China. Multiple factor analysis, redundancy analysis (RDA) and a forward-selection approach were used to explore the overall community structure and the links between the environmental variables and testate amoeba composition. Results showed that testate amoebae are widely distributed in most of the lakes despite often high levels of pollution. Our data highlight some links between water quality variables and testate amoeba communities. In particular, our results suggest that heavy metals have a role in shaping testate amoeba assemblage structure, although correlations are comparatively weak, perhaps due to lagged responses. Our results support previous suggestions that testate amoebae may be useful bioindicators in aquatic ecosystems but emphasize the need for an improved mechanistic understanding.

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Aquaculture activities are often blamed for the degradation of water quality of aquatic ecosystem. Present study was conducted to determine the water quality of Taal Lake at two different study sites viz. one under intense fish cage farming activities and the other without aquaculture activities. The study aims to assess the effect of aquaculture activities on selected water quality parameters, which include transparency, temperature, pH, nitrates, phosphates, salinity, total dissolved solids (TDS) and dissolve oxygen (DO). The study was conducted over a ten-month period in 2013-2014. Results of the study revealed no significant differences in water temperature, pH, salinity, transparency and DO between the aquaculture and non-aquaculture sites of the lake, although DO and transparency were consistently lower in the aquaculture sampling stations throughout the 10-month sampling period. DO dipped to critical level (<4 ppm) for aquatic organisms in the months of January and February. Nitrates, phosphates and TDS were significantly higher in the area with fish cage farming activities as compared to the non aquaculture site. Further, the study also reports the efforts of stakeholders to sustain fish cage farming in the lake which include participative, multi-sectoral action planning, information and education, policy formulation, regulation and licensing.

Improving real-time forecasting of water quality indicators with combination of process-based models and data assimilation technique

Water quality indicators can be used to characterize the status and quantify and qualify the change of aquatic ecosystems under different disturbance regimes. Although many studies have been done to develop and assess indicators and discuss interactions among them, few studies have focused on how to improve the predicted indicators and explore their variations in receiving water bodies. Accurate and effective predictions of ecological indictors are critical to better understand changes of water quality in aquatic ecosystems, especially for the real-time forecasting. Process-based water quality models can predict the spatiotemporal variations of the water quality indicators and provide useful information for policy-makers on sound management of water resources. Given their inherent constraints, however, such process models alone cannot actually guarantee perfect results since water quality models generally have a large number of parameters and involve many processes which are too complex to be efficiently calibrated. To overcome these limitations and explore a fast and efficient forecasting method for the change of water quality indictors, we proposed a new framework which combines the process-based models and data assimilation technique. Unlike most traditional approaches in which only the model parameters or initial conditions are updated or corrected and the models are run online, this framework allows the information extracted from observations and outputs of process models to be directly used in a data-driven local/modified local model. The results from the data-driven model are then assimilated into the original process model to further improve its forecasting ability. This approach can be efficiently run offline to directly correct and update the output of water quality models. We applied this framework in a real case study in Singapore. Two of the water quality indicators, namely salinity and oxygen were selected and tested against the observations, suggesting that a good performance of improving the model results and reducing computation time can be obtained. This approach is simple and efficient, especially suitable for real-time forecasting systems. Thus, it can enhance forecasting of water quality indictors and thereby facilitate the effective management of water resources.

Diversity and structure of Chironomidae communities in relation to water quality differences in the Swartkops River

The Swartkops River is an important freshwater ecosystem in South Africa. But owing to its location, it suffers varying degrees of human induced impacts which include industrial and domestic effluent discharges, deforestation as well as agricultural land use which have negatively impacted on the water quality. Diversity and community composition of aquatic insects are frequently used to assess environmental water quality status. Chironomids occupy extremely varied biotopes. Their extraordinary ecological range and environmental sensitivity make them particularly useful for assessing and interpreting changes in water quality of aquatic ecosystems. The community structure of chironomid larvae was investigated at four sites in the Swartkops River and effects of different chemical and physical variables on their distribution were explored. Chironomid larvae were collected using the South African Scoring System version 5 (SASS5) protocol. A total of 26 taxa from four sampling sites in the Swartkops River were identified. Margalef’s species richness index, equitability, Shannon and Simpson diversity indices were highest at site 1 (reference site). The downstream sites contained 6–20 taxa compared to the 25 taxa at site 1. Site 1 was characterised by the subfamilies Orthocladiinae, Tanypodinae and the tribe Tanytarsini while the impacted sites were characterised by Orthocladiinae and Chironomini. Chironomus spp., Dirotendipes sp., Kiefferulus sp. and Tanypus sp. seemed to be tolerant to pollution, occurring in high abundance at sites 2, 3 and 4. In contrast, Polypedilum sp., Tanytarsus sp., Orthocladius sp., Cricotopus spp. and Ablabesmyia sp. appeared to be more sensitive taxa, being less common at the impacted sites (sites 2, 3 and 4). Five days biochemical oxygen demand, dissolved oxygen, electrical conductivity, orthophosphate–phosphorus and total inorganic nitrogen were among the important variables that determine the observed chironomid community structure. Results revealed that the family Chironomidae, identified to species or genus, can be use to assess environmental water quality status in South African freshwater ecosystems.

Dissolved Oxygen Measurements in Aquatic Environments: The Effects of Changing Temperature and Pressure on Three Sensor Technologies

Dissolved oxygen (DO) is probably the most important parameter related to water quality and biological habitat in aquatic environments. In situ DO sensors are some of the most valuable tools used by scientists and engineers for the evaluation of water quality in aquatic ecosystems. Presently, we cannot accurately measure DO concentrations under variable temperature and pressure conditions. Pressure and temperature influence polarographic and optical type DO sensors compared to the standard Winkler titration method. This study combines laboratory and field experiments to compare and quantify the accuracy and performance of commercially available macro and micro Clark-type oxygen sensors as well as optical sensing technology to the Winkler method under changing pressure and temperature conditions. Field measurements at various lake depths revealed sensor response time up to 11 min due to changes in water temperature, pressure, and DO concentration. Investigators should account for transient response in DO sensors before measurements are collected at a given location. We have developed an effective model to predict the transient response time for Clark-type oxygen sensors. The proposed procedure increases the accuracy of DO data collected in situ for profiling applications.

Benthic cyanobacterial assemblages as indicators of nutrient enrichment regimes in a Spanish river

AbstractThe relationships between cyanobacterial abundance and the physical and chemical characteristics of waters were studied to identify the environmental variables responsible for the changes in species composition observed in a river characterized by variations in water quality. Principal component analysis showed that some communities had significantly different species composition and relationships with environmental variables than others. These analyses allowed us to identify indicator species with contrasting responses to nutrient conditions. One of the four cyanobacterial groups distinguished in the analysis was negatively correlated with variables related to aspects of water disturbance, including nutrients. The results indicate that the eutrophication gradient structured species composition and affected cyanobacterial community distribution. Since organisms have an integrating response to their environment, the use of cyanobacterial assemblages to indicate eutrophication gradients could help in the assessment of water quality in aquatic ecosystems.