Article

Impacts of climate change, land-use change and phosphorus reduction on phytoplankton in the River Thames (UK)

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

Potential increases of phytoplankton concentrations in river systems due to global warming and changing climate could pose a serious threat to the anthropogenic use of surface waters. Nevertheless, the extent of the effect of climatic alterations on phytoplankton concentrations in river systems has not yet been analysed in detail. In this study, we assess the impact of a change in precipitation and temperature on river phytoplankton concentration by means of a physically-based model. A scenario-neutral methodology has been employed to evaluate the effects of climate alterations on flow, phosphorus concentration and phytoplankton concentration of the River Thames (southern England). In particular, five groups of phytoplankton are considered, representing a range of size classes and pigment phenotypes, under three different land-use/land-management scenarios to assess their impact on phytoplankton population levels. The model results are evaluated within the framework of future climate projections, using the UK Climate Projections 09 (UKCP09) for the 2030s. The results of the model demonstrate that an increase in average phytoplankton concentration due to climate change is highly likely to occur, with the magnitude varying depending on the location along the River Thames. Cyanobacteria show significant increases under future climate change and land use change. An expansion of intensive agriculture accentuates the growth in phytoplankton, especially in the upper reaches of the River Thames. However, an optimal phosphorus removal mitigation strategy, which combines reduction of fertiliser application and phosphorus removal from wastewater, can help to reduce this increase in phytoplankton concentration, and in some cases, compensate for the effect of rising temperature.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... The INCA model is a dynamic semi-distributed hydrological and water quality model originally developed for the simulation of the nitrogen (Whitehead et al. 1998) and phosphorus (Wade et al. 2002b) cycles in a catchment. The INCA model has been used extensively for catchments in the UK (Whitehead et al. 2014, Lu et al. 2016, Bussi et al. 2016b, 2016c, 2017b, although the INCA model has not been applied before to the River Trent catchment. INCA is the third most cited catchment-scale water quality model, according to a recent water quality model review (Fu et al. 2019). ...
... In the Trent catchment, most of the phosphorus comes from point sources such as wastewater treatment plants, and therefore an increase/decrease of low flows is likely to have a major impact. This result is in agreement with previous studies conducted in other catchments in the UK, such as Bussi et al. (2017a) and Bussi et al. (2016c), which also pointed out the increase of summer phosphorus concentrations due to decreased dilution capacity in the River Thames. The predominance of point sources over diffuse sources of phosphorus is typical of several rivers in the UK and Europe, and therefore it is expected that these findings can be extended also to several other catchments with similar nutrient inputs. ...
... The coincidence of increased nitrate and phosphorus concentration highlights a need for more research in order to unveil the potential consequences of an increase in nutrients and its effects on phytoplankton population, especially on large phytoplankton such as diatoms. Increased phytoplankton concentrations might have negative impacts on power plants, such as filter clogging (Whitehead et al. 2015, Bussi et al. 2016c. Furthermore, it is important to bear in mind that the impact of non-natural flows on low flows in the Trent is important, and these flows might change in the future subject to factors not considered in this study. ...
... In this study, the INCA-P 1.4.11 model version was used (henceforth INCA-P; also used in Bussi et al., 2017;Bussi et al., 2016a;Bussi et al., 2016b). The structure of the hydrological sub-model in INCA-P is described fully in Wade et al. (2002). ...
... The sediment transport component of the model is described in Jarritt and Lawrence (2006) and Lázár et al. (2010). A detailed description can also be found in Bussi et al. (2016aBussi et al. ( , 2016b. This sediment transport component of the INCA model can be divided into two subcomponents: the land phase, which reproduces soil erosion and transport processes from the hillslope to the river network, and the channel phase, which simulates entrainment and storage processes within the river channel system. ...
... A list of the calibrated parameters is reported in Table 2, together with the corresponding feasibility range. A description of the parameters and their physical meaning is provided in Wade et al. (2002) and Bussi et al. (2016aBussi et al. ( , 2016b. Second, a large set of parameter values (50,000) was generated randomly from uniform distributions within Finally, a small number (15) of parameter sets was selected based on their performance and used to conduct the simulations described in this paper. ...
... Agriculture and urbanisation can increase the transport of nutrients into water bodies via run-off (Xu & Zhang 2016;Shi et al. 2017), and therefore also influence phytoplankton abundance and composition (Katsiapi et al. 2012). The effect of climate is more difficult to quantify since precipitation and temperature affect the flow of water, whilst nutrient loading is known to alter phytoplankton assemblage, diversity and biomass (Michalak 2016;Bussi et al. 2016). Poor water quality and higher temperatures are often associated with high cyanobacterial biomass (Abirhire et al. 2016;Bussi et al. 2016), while the Chrysophyceae, Dinophyceae and Bacillariophyceae are often associated with lower nutrient levels (Katsiapi et al. 2012). ...
... The effect of climate is more difficult to quantify since precipitation and temperature affect the flow of water, whilst nutrient loading is known to alter phytoplankton assemblage, diversity and biomass (Michalak 2016;Bussi et al. 2016). Poor water quality and higher temperatures are often associated with high cyanobacterial biomass (Abirhire et al. 2016;Bussi et al. 2016), while the Chrysophyceae, Dinophyceae and Bacillariophyceae are often associated with lower nutrient levels (Katsiapi et al. 2012). The biodiversity and biomass of the Chrysophyceae are known to decrease as the Cyanophyceae cell concentrations increase (Katsiapi et al. 2012). ...
... These sites are, however, downstream from areas more impacted on by agriculture and peri-urban settlements and nutrients and organic waste could have been transported to collect in the lower reaches of the river. Bussi et al. (2016) found in their study that the class Cyanophyceae was the most sensitive to climatic variations and these variations can impact directly on to the physiological characteristics of phytoplankton (Winder & Sommer 2012). Shifts like this can have far-reaching effects ...
Article
Full-text available
Background: The understanding of the impact of land-use on the dynamics of phytoplankton assemblages during varying climate conditions on rivers is limited.Objective: To determine the impact of land-use types and flow on phytoplankton assemblages in the Sabie River.Methods: The relationships between land-use patterns, water quality and phytoplankton assemblages were analysed using canonical correspondence analyses (CCA).Results: Six main land-use types could be distinguished in the eight identified sub-catchments of the river. The CCA results showed that the land-use had a stronger correlation with phytoplankton classes during the higher flow conditions than during low flow conditions. The forestry land-use type had the strongest correlation with nitrate–nitrite concentrations in the Sabie River. Chlorophyll-a concentrations were higher during 2016, and a slightly lower number of genera were observed for the class Chlorophyceae. During 2017 the number of genera of the class Cyanophyceae decreased together with chlorophyll-a and total cell concentrations.Conclusion: Low flow conditions favoured filamentous genera that are common to mesotrophic conditions while higher flow conditions favoured single-celled small genera more common to oligotrophic waters with higher disturbance. This study showed that flow has the potential to enhance the impact of land-use on phytoplankton community dynamics in a river system and thereby may have further impacts on the health and activities of surrounding communities.
... Furthermore, a recent study documented that there was no correlation between the percentage of farmland and the water quality factors (e.g., TN and TP) in eastern China (Ding et al. 2019). These inconsistent results may be explained by field investigations that occurred under different climatic conditions (Bussi et al. 2016), different landscape features of the study areas, and intensity of anthropogenic activities (such as farming practices and land use changes) (Delkash et al. 2018). Similarly, our results illustrated that woodland was negatively correlated with TN, TP, and COD and positively correlated with SD in all SEMs (Fig. 2), although these results were slightly different from those of the correlation analysis (Table 2). ...
... Our study also demonstrated that the composition of land uses significantly influenced the phytoplankton communities in both the SEM and the linear regression model. Similar results were found by Bussi et al. (2016) and Katsiapi et al. (2012). Although a previous study detected a negative relationship between woodland and phytoplankton biomass (i.e., total Chl-a) (Catherine et al. 2008), we did not find such a correlation in all SEMs. ...
... As supported by previous studies, land use types significantly affected the nutrient concentrations in surface water bodies (Dzinomwa and Ndagurwa 2017;Jordan et al. 2018;Camara et al. 2019;Marmen et al. 2020); furthermore, nutrients (e.g., phosphorus and nitrogen) were considered the most important factors affecting the distribution and composition of phytoplankton communities in freshwater ecosystems (Zhou et al. 2016;Ferencz et al. 2018;Wu et al. 2019). This study also identified that land use mediated the phytoplankton communities through the nutrient concentrations in rivers, which was consistent with the results of Bussi et al. (2016), Dzinomwa and Ndagurwa (2017), and Li et al. (2019). Regarding n (Table S3 and Fig. 2b), the direct effects of built-up land (0.291) and woodland (0) were further strengthened by a mediator (TN), resulting in a positive total effect of 0.375 and a negative total effect of − 0.438, respectively. ...
Article
Full-text available
Understanding the factors that control biodiversity in rivers is challenging due to the variety of potential sources, linkages, and processes. This research assesses the effects of land use on phytoplankton communities across water quality gradients. By employing abiotic and biotic datasets of 149 catchments in Lake Chaohu basin, China, and a structural equation model (SEM), the direct and indirect effects of land use and water quality on phytoplankton dynamic were analyzed. Both land use and water quality had statistically significant direct effects on phytoplankton community attribute and diversity, although these effects differed among these indices. For instance, farmland was found to positively affect the abundance and diversity indices, while, total nitrogen (TN) had significant positive effects on species richness and abundance. Importantly, the average indirect effects strengthened the effects of land use (e.g., built-up land and woodland) up to 82.4% mainly through nutrients, while the average indirect effects weakened the effects of land use (e.g., farmland) by as much as 49.9% mainly due to nutrients, thus indicating the prevailing role of the effects of land use on phytoplankton based on nutrient concentrations. The results suggest that nutrients can regulate the effect of land use on phytoplankton community attribute and diversity indices. This study highlights the advantages of using an SEM because the potential linkages for phytoplankton diversities are more likely to be identified with this method than with a classical linear regression model. Therefore, SEM has wide application prospects in the field of the conservation of biodiversity in freshwater rivers.
... Water quality modelling is a useful technique to improve our understanding of the spatio-temporal dynamics of chemicals and water quality in river systems and can be used to explore the potential effects of different management and pollution control strategies on river water hydro-chemical dynamics. The INCA model has already been used in many parts of the world [17][18][19], also in complex river systems like the Ganga River, including Dhaka [6,10,[20][21][22]. ...
... INCA has proved to be a powerful model for studying water flow and quality over the years, as it captures the main dynamical process in rivers and evaluates complex interacting hydrological and hydro-chemical systems. It has been widely used to assess such issues as land use change, effluent treatment systems, population change, and climate change, and is thus the best tool to use for the current study [17,18]. ...
Article
Full-text available
Long-term development and pollution clean-up plans are a continuing feature of megacities such as Dhaka, Bangladesh. Bangladesh needs to deal with a legacy of past pollution and manage current pollution from a rapidly expanding economy. Surveys in the rivers around Dhaka show extremely high pollution and very low dissolved oxygen levels, with subsequent ecological impacts. Millions of people are not on public treatment of effluents and thousands of factories discharge into the rivers. The Bangladesh Government is planning to install over 12 large Sewage Treatment Plants (STPs) over the next 20 years. To assess the efficacy of these, a water quality model has been applied to the Dhaka River System. Results show that the proposed plan has beneficial effects in the short term for the most densely populated areas of Dhaka, along the Turag and Buriganga Rivers, and in the medium term in other parts of the city (Tongi Khal). However, in several reaches dissolved oxygen levels will remain low or very low due to the lack of STP capacity, remaining misconnections of untreated sewage and large effluent loads. The proposed STPs, while certainly beneficial, will need to be upgraded in the future if the predicted rates of population growth are confirmed and industrial pollution is not significantly reduced alongside. Climate change is expected to have an impact on the Dhaka River System water quality, with increased monsoon flows and lower summer flows, but these changes will not greatly affect the extremes of water quality to any great extent due to the overwhelming impact of pollutant discharges into the system.
... River water temperatures are in close equilibrium with air temperatures, and climate warming is already impacting river thermal regimes (Whitehead et al. 2009;Minaudo et al. 2021;Rozemeijer et al. 2021). Warmer water temper-atures intensify in-stream and near-stream nutrient cycling processes as a result of increased rates of microbial activity, the proliferation of plant biomass (including algae and macrophytes), and enhancement of chemical reaction kinetics (Bussi et al. 2016;Jin et al. 2012;Whitehead et al. 2006). Under climate warming, higher rates of in-stream nutrient processing are also likely to be further magnified by low flows, increasing water residence times, and therefore water contact time with benthic, riparian, and hyporheic (i.e., sediment and porous space adjoining a stream bed) sediments and biota (Whitehead et al. 2009;Rozemeijer et al. 2021). ...
... Models have predicted that climate warming will result in lower river concentrations ofNO − 3 and NH + 4 as a result of higher rates of denitrification and nitrification, particularly during low summer flows (Jin et al. 2012;Vaighan et al. 2018;Whitehead et al. 2015). Increased nutrient availability, higher water temperatures and residence times, and a longer aquatic plant growing season are expected to promote higher rates of riverine primary production and assimilatory uptake of nutrients by algae and macrophytes, further impacting seasonal and daily nutrient dynamics (Bussi et al. 2016;Jarvie et al. 2020;Whitehead et al. 2009). Wider climate and trophic feedbacks on river nutrient dynamics may also arise from changes in invertebrate grazing pressures, including the proliferation of invasive filter-feeding bivalves (Minaudo et al. 2021). ...
Article
Full-text available
This study is a meta-analysis of global articles on hydrological nutrient dynamics to determine trends and consensus on: (1) the effects of climate change-induced hydrological and temperature drivers on nutrient dynamics and how these effects vary along the catchment continuum from land to river to lake; (2) the convergence of climate change impacts with other anthropogenic pressures (agriculture, urbanization) in nutrient dynamics; and (3) regional variability in the effects of climate change on nutrient dynamics and water-quality impairment across different climate zones. An innovative web crawler tool was employed to help critically synthesize the information in the literature. The literature suggests that climate change will impact nutrient dynamics around the globe and exacerbate contemporary water-quality challenges. Nutrient leaching and overland flow transport are projected to increase globally, promoted by extreme precipitation. Seasonal variations in streamflow are expected to emulate changing precipitation patterns, but the specific local impacts of climate change on hydrology and nutrient dynamics will vary both seasonally and regionally. Plant activity may reduce some of this load in nonagricultural soils if the expected increase in plant uptake of nutrients prompted by increased temperatures can compensate for greater nitrogen (N) and phosphorus (P) mineralization, N deposition, and leaching rates. High-temperature forest and grass fires may help reduce mineralization and microbial turnover by altering N speciation via the pyrolysis of organic matter. In agricultural areas that are at higher risk of erosion, extreme precipitation will exacerbate existing water-quality issues, and greater plant nutrient uptake may lead to an increase in fertilizer use. Future urban expansion will amplify these effects. Higher ambient temperatures will promote harmful cyanobacterial blooms by enhancing thermal stratification, increasing nutrient load into streams and lakes from extreme precipitation events, decreasing summer flow and thus baseflow dilution capacity, and increasing water and nutrient residence times during increasingly frequent droughts. Land management decisions must consider the nuanced regional and seasonal changes identified in this review (realized and predicted). Such knowledge is critical to increasing international cooperation and accelerating action toward the United Nations’s global sustainability goals and the specific objectives of the Conference of Parties (COP) 26.
... The hydrological and water quality sub-models of INCA have been applied to several basins around the world Whitehead et al. 2021b) and in England (Crossman et al. 2021), and, in particular, to the River Thames catchment (Jin et al. 2012;Crossman et al. 2013;Whitehead et al. 2013Whitehead et al. , 2016Whitehead et al. , 2021aBussi et al. 2016aBussi et al. , 2016bBussi et al. , 2017Lu et al. 2016;Nizzetto et al. 2016) and the River Lee catchment (Flynn et al. 2002;Snook & Whitehead 2004). The inputs to INCA are daily time series of precipitation, temperature, hydrologically effective rainfall and soil moisture deficit (SMD). ...
... The results show that, while flows are expected to be slightly reduced in summer, the average water quality of the rivers is not expected to change significantly, probably because the increase of nutrient concentrations triggered by the reduction in the dilution potential of the rivers is partially compensated by the reduction in nutrients from diffuse sources caused by lower summer rainfall. Nevertheless, the model results point to some increase in phosphorus concentrations in August, September and October, consistently with other studies in the area (Bussi et al. 2016b(Bussi et al. , 2017. At the same time, the model results seem to suggest that climate change should not have a relevant impact on the nutrient removal efficiency of wetlands, thus confirming the strong potential of this green infrastructure for nutrient load control and reduction in urban catchments. ...
... The hydrological and water quality sub-models of INCA have been applied to several basins around the world Whitehead et al. 2021b) and in England (Crossman et al. 2021), and, in particular, to the River Thames catchment (Jin et al. 2012;Crossman et al. 2013;Whitehead et al. 2013Whitehead et al. , 2016Whitehead et al. , 2021aBussi et al. 2016aBussi et al. , 2016bBussi et al. , 2017Lu et al. 2016;Nizzetto et al. 2016) and the River Lee catchment (Flynn et al. 2002;Snook & Whitehead 2004). The inputs to INCA are daily time series of precipitation, temperature, hydrologically effective rainfall and soil moisture deficit (SMD). ...
... The results show that, while flows are expected to be slightly reduced in summer, the average water quality of the rivers is not expected to change significantly, probably because the increase of nutrient concentrations triggered by the reduction in the dilution potential of the rivers is partially compensated by the reduction in nutrients from diffuse sources caused by lower summer rainfall. Nevertheless, the model results point to some increase in phosphorus concentrations in August, September and October, consistently with other studies in the area (Bussi et al. 2016b(Bussi et al. , 2017. At the same time, the model results seem to suggest that climate change should not have a relevant impact on the nutrient removal efficiency of wetlands, thus confirming the strong potential of this green infrastructure for nutrient load control and reduction in urban catchments. ...
Article
Full-text available
Poor water quality is a widespread issue in urban rivers and streams in London. Localised pollution can have impacts on local communities, from health issues to environmental degradation and restricted recreational use of water. The Salmons and Pymmes Brooks, located in the London Borough of Enfield, flow into the River Lee, and in this paper, the impacts of misconnected sewers, urban runoff and atmospheric pollution have been evaluated. The first step towards finding a sustainable and effective solution to these issues is to identify sources and paths of pollutants and to understand their cycle through catchments and rivers. The INCA water quality model has been applied to the Salmons and Pymmes urban catchments in north-east London, with the aim of providing local communities and community action groups such as Thames21 with a tool they can use to assess the water quality issue. INCA is a process-based, dynamic flow and quality model, and so it can account for daily changes in temperature, flow, water velocity and residence time that all affect reaction kinetics and hence chemical flux. As INCA is process-based, a set of mitigation strategies have been evaluated including constructed wetland across the catchment to assess pollution control. The constructed wetlands can make a significant difference reducing sediment transport and improving nutrient control for nitrogen and phosphorus. The results of this paper show that a substantial reduction in nitrate, ammonium and phosphorus concentrations can be achieved if a proper catchment-scale wetland implementation strategy is put in place. Furthermore, the paper shows how the nutrient reduction efficiency of the wetlands should not be affected by climate change. HIGHLIGHTS Modelling urban flows and water quality in London streams is demonstrated.; Impacts of pollution, deposition and urban runoff are illustrated under future climate change.; The paper uses a dynamic process-based water quality model to assess impacts of wetlands.; Constructed wetlands can make a significant difference improving nutrient control.; Mitigation measures significantly reduce nitrate, ammonium and phosphorus.;
... Sensitivity analysis [Spear and Hornberger, 1980;Whitehead et al., 2015] was used to identify the following parameters as being the most influential on model performance: Flow parameters (direct runoff residence time, soil water residence time, ground water residence time, threshold soil zone flow, rainfall excess proportion, maximum infiltration rate, discharge/velocity relationship coefficient and exponent), nitrate and ammonium parameters (denitrification rate in soil and river, nitrification rate in soil and river, mineralisation rate in soil, immobilisation rate in soil, fertiliser addition rate in soil, plant uptake), phosphorus parameters (fertiliser addition rate in soil, plant uptake, liquid manure/fertiliser usage), sediment parameters (splash and flow erosion parameters, transport capacity parameters, entrainment and bank erosion parameters) (see Bussi et al. [2016b] and Jackson-Blake and Starrfelt [2015] for more details). 10,000 different sets of these parameters were generated. ...
... defined: i) LU-baseline: current land use; ii) LU-future: future land use, i.e. expansion of agricultural land due to increased food demand and iii) LU-future+mitigation: future land use with enhanced phosphorus mitigation strategies. These scenarios are consistent with the ones used in[Bussi et al., 2016b]. The future land use scenario (ii) describes an increase in agricultural land area. ...
... Nutrients are important as they have a significant impact on the ecosystems of rivers, creating algal blooms that affect water supply and even blooms of highly toxic cyanobacteria [18]. Furthermore, there are direct health effects of nitrates in waters which need to be reduced or avoided if possible. ...
... The first is to use a physically-based model, whose reliability has been tested in several catchments all over the world, both under scenarios of good data availability [26,28] and in data-scarce regions [33,34]. The second one is to calibrate the model using a Monte Carlo-based objective technique and using an ensemble of 15 model parameter sets rather than a single realisation of the model, to account for parametric uncertainty [18,49]. Such measures are always advisable when conducting quantitative assessments of environmental variables and have the advantage of providing a representation of the model results uncertainty. ...
... Cyanobacteria growth rates are optimized at higher temperatures relative to algal species (Carey et al. 2012). Both higher water temperatures (Bussi et al. 2016, Cha et al. 2017, Wood et al. 2017) and reduced discharge and turbidity (Hoetzel & Croome 1994, Cha et al. 2017 have been shown to increase cyanobacteria abundance in rivers. Thus, re duced July water temperatures in the CR between 2010 and 2013 likely played a role in the absence of the cyanobacteria/ chlorophyte cluster during that time. ...
... It is also possible that by including different forms of nutrients, such as total nitrogen and phosphorus, further analyses may uncover additional relationships with phytoplankton assemblage patterns. Overall, we did not find a strong correlation between dissolved nutrient concentrations and phyto plankton assemblages in the CR, despite the typically important role of nutrients in phytoplankton (Reynolds 2006, Wehr et al. 2015 and cyanobacterial bloom dynamics (Paerl 2014, Bussi et al. 2016, Rose et al. 2019a) in other freshwater systems. ...
Article
Full-text available
Understanding the influence of biotic and abiotic factors on riverine phytoplankton dynamics is challenging, particularly as anthropogenic stressors such as eutrophication, invasive species, and climate change alter these relationships. We examined a 14 yr (January 2005 to December 2018) dataset of phytoplankton and water quality variables, along with zooplankton and nutrient concentrations, from the Columbia River (the largest river in the US Pacific Northwest) to identify seasonal and interannual patterns of phytoplankton assemblage structure and their environmental associations. Non-metric multidimensional scaling, cluster, and indicator species analyses revealed: (1) a diatom/flagellate cluster in spring/summer, associated with chlorophyll a , discharge, ciliates, and Sarcodina; (2) a cyanobacteria/chlorophyte cluster in late summer/early fall, associated with higher water temperatures, increased clarity, the invasive copepod Pseudodiaptomus forbesi , and veligers of the invasive Asian clam Corbicula fluminea ; and (3) a mixed-taxa winter cluster of minimal abundance and biomass. Nutrients were not strongly associated with the observed structural patterns. Phytoplankton bloom duration varied interannually, between years with short springtime blooms vs. years when blooms extended across multiple months. Springtime blooms of the diatom Asterionella formosa decreased in recent years, giving way to blooms of a mixed diatom assemblage. Further, high temperature, low discharge, and more invasive zooplankton were associated with cyanobacterial blooms, suggesting that increased temperature and reduced river flows predicted due to climate change in the Pacific Northwest may lead to further impacts on the late summer/early fall Columbia River plankton community.
... Nutrients are important as they have a significant impact on the ecosystems of rivers, creating algal blooms that affect water supply and even blooms of highly toxic cyanobacteria [18]. Furthermore, there are direct health effects of nitrates in waters which need to be reduced or avoided if possible. ...
... The first is to use a physically-based model, whose reliability has been tested in several catchments all over the world, both under scenarios of good data availability [26,28] and in data-scarce regions [33,34]. The second one is to calibrate the model using a Monte Carlo-based objective technique and using an ensemble of 15 model parameter sets rather than a single realisation of the model, to account for parametric uncertainty [18,49]. Such measures are always advisable when conducting quantitative assessments of environmental variables and have the advantage of providing a representation of the model results uncertainty. ...
Article
Full-text available
Assessing the impact of climate change and population growth on river water quality is a key issue for many developing countries, where multiple and often conflicting river water uses (water supply, irrigation, wastewater disposal) are placing increasing pressure on limited water resources. However, comprehensive water quality datasets are often lacking, thus impeding a full-scale data-based river water quality assessment. Here we propose a model-based approach, using both global datasets and local data to build an evaluation of the potential impact of climate changes and population growth, as well as to verify the efficiency of mitigation measures to curb river water pollution. The upper Awash River catchment in Ethiopia, which drains the city of Addis Ababa as well as many agricultural areas, is used as a case-study. The results show that while decreases in runoff and increases in temperature due to climate change are expected to result in slightly decreased nutrient concentrations, the largest threat to the water quality of the Awash River is population growth, which is expected to increase nutrient loads by 15 to 20% (nitrate) and 30 to 40% (phosphorus) in the river by the second half of the 21st century. Even larger increases are to be expected downstream of large urban areas, such as Addis Ababa. However, improved wastewater treatment options are shown to be efficient in counteracting the negative impact of population growth and returning water pollution to acceptable levels.
... Changes in the abundance, composition and biomass of phytoplankton significantly influence the resilience, structure and function of aquatic environments (Padisák et al., 2006). Changes in the composition and distribution of phytoplankton are often associated with the decline of regional biodiversity and ecosystem services (Bussi et al., 2016). Despite their significance, current knowledge about the distribution and abundance of various phytoplankton groups remains limited, posing challenges to their integration into ecological studies and applications (Moore & Brown, 2020). ...
Article
Full-text available
Phytoplankton are diverse photosynthetic organisms in estuarine ecosystems and sensitive indicators of environmental changes. This study employed Generalized Additive Model (GAM) to explore the impact of environmental variables on the abundance of six dominant phytoplankton species in the tropical Karanja estuary, India. Data were collected from five sampling stations between January 2022 and March 2023. The GAM model explained ≥ 55% of the variability in species distribution, predicting that the Karanja estuary provides a suitable habitat for these phytoplankton. Spatiotemporal predictions revealed higher abundances of Asterionellopsis glacialis, Coscinodiscus sp., Pseudo-nitzschia pungens, Skeletonema costatum and Thalassionema frauenfeldii during post-monsoon and lower in pre-monsoon. Conversely, Odontella sinensis thrived during pre-monsoon. Optimal growth conditions included a water temperature range of 24–32 °C for O. sinensis, P. pungens and S. costatum, while chlorophyll-b concentrations between 1 and 20 mg/m³ favored A. glacialis, O. sinensis, P. pungens, S. costatum and T. frauenfeldii. P. pungens, S. costatum and T. frauenfeldii exhibited broad salinity tolerance ranging from 10–40‰. Additionally, Coscinodiscus sp., P. pungens and T. frauenfeldii were found in environments with nitrate content of 0.1–1 mg/L, while O. sinensis preferred silicate levels of 1–10 mg/L. Notably, these species serve as indicators of eutrophication, providing insights into ecosystem health. This study represents the first application of GAM for exploring phytoplankton-environment interactions in India, offering critical data for water quality management, pollution control and food web preservation. Policymakers can use these findings to develop evidence-based regulations that support proactive coastal management, enhance estuarine resilience to climate stressors and ensure sustainable resource conservation.
... In addition, changes in land-use patterns and introduced species have become entwined in the complex formula controlling phytoplankton dynamics in rivers (Bussi et al., 2016;DeBoer, Anderson, & Casper, 2018;Yang et al., 2022). These controls set forth by human need may in turn produce bottom-up countereffects on the food web, affecting not only direct consumers like microcrustaceans, macroinvertebrates, and fish, but the upper trophic levels as well (Hillebrand & Shurin, 2005). ...
Thesis
Full-text available
Much like the response to naturally occurring physical, chemical, and biological variables controlling phytoplankton dynamics, anthropogenic modification to those variables may have profound implications on phytoplankton density and community structure in aquatic systems. We theorized that extensive land use and river channel modifications would result in (1) an increase in basin-wide phytoplankton density in the Middle Missouri River Basin (MMRB), and (2) a shift in community structure within and downstream of reservoirs filled after 1950 by examining data collected from 2020 and 2021 across the Middle Missouri River Basin to data collected in 1950. Our results suggest that system-wide increases in algal cell density were uncommon, yet variable with only two systems showing increases with high confidence and one showing a decrease. Some systems like the Missouri River reservoir sites and the James River showed an interannual shift in dominant phytoplankton genera, while other systems shared at least one dominant genus in 1950, 2020, and 2021. Our results suggest that despite modifications to land and water use, changes in phytoplankton density and community structure are clear but not consistent across the MMRB. Chlorophyll has been used extensively in ecological monitoring as a proxy for phytoplankton density or biovolume due to the relative simplicity of processing samples. We regressed the predictor variable of total chlorophyll and response variable of algal cell density as well as the predictor variable of log10 transformed Secchi depth (Secchi) and the response variables of either total chlorophyll or algal cell density from 161 samples across nine rivers of the MMRB. A positive relationship was observed between chlorophyll and algal cell density, while an inverse relationship was observed between Secchi and either chlorophyll or algal cell density. These findings suggest that using chlorophyll as a proxy for algal cell enumeration may provide an option to monitor phytoplankton dynamics in rivers. High suspended sediment loads may have confounded the relationship between Secchi and either chlorophyll or algal cell density. Chlorophyll determined by in vivo fluorescence provides a good proxy to rapidly monitor phytoplankton dynamics in lowland rivers. Thesis Advisor ___________________
... Bouma-Gregson et al. (2022) noted that dynamic environmental conditions (e.g., hydrologic regime) should select for different bacterial genera. Several studies have assessed stressors to riverine phytoplankton communities, finding hydrologic regime and land use patterns to be particularly important (Bussi et al., 2016;Wu et al., 2019;Guo et al., 2020;Qu et al., 2022). Rosero-López et al. (2022) explored the impact of hydrologic alteration on benthic cyanobacterial growth. ...
Article
Proliferations of benthic cyanobacteria are increasingly in the public eye, with rising animal deaths associated with benthic rather than planktonic blooms. In early June 2021, two dogs died after consuming material on the shore of Shubenacadie Grand Lake, Nova Scotia. Preliminary investigations indicated anatoxins produced by benthic cyanobacterial mats were responsible for the deaths. In this study, we monitored the growth of a toxic benthic cyanobacterial species (Microcoleus sp.) along a stream-lake continuum where the canine poisonings occurred. We found that the species was able to proliferate in both lentic and lotic environments, but temporal growth dynamics and the predominant sub-species were influenced by habitat type, and differed with hydrodynamic setting, nutrient and sunlight availability. Toxin concentration was greatest in cyanobacterial mats growing in the oligotrophic lakeshore environment (maximum measured total anatoxins (ATXs) >20 mg/kg wet weight). This corresponded with a shift in the profile of ATX analogues, which also indicated changing subspecies dominance along the stream-lake transition.
... The geology varies across the catchment: the headwaters are mainly underlain by limestone (e.g., the Thames at Farmoor subcatchment-6001 station in Fig. 1) and clay or mudstone (e.g., the Cherwell subcatchment-6002 station in Fig. 1). A chalk strip crosses the catchment from SW to NE, especially affecting the Kennet and Colne subcatchments (Bussi et al. 2016). ...
Article
Full-text available
Sediment dynamics of lowland rivers are of importance in building resilient strategies to manage environmental change. Yet the effects of natural and anthropogenic disturbances on sediment dynamics are poorly understood. Here a low-frequency suspended sediment sampling data set is used to assess the spatial and temporal variations of suspended sediment fluxes in the River Thames (United Kingdom). Sediment rating curves (SRCs) were used to analyze both the spatial and the temporal variation of catchment-suspended sediment transport. SRC exponents for the River Thames were found to be between 0.21 and 1.13. The 95% confidence interval was also determined through a bootstrapping technique. The seasonal and interannual variability of SRC parameters were analyzed to reveal seasonal and secular changes. The results are used to quantify the seasonal flushing effect, in which suspended sediment concentrations are typically substantially higher during the first floods after the summer dry period. The suspended sediment concentrations of the River Thames during the first floods after summer are estimated to be around 1.5-2 times those of other floods, for a given water discharge. A decrease in the flushing effect which began in the 1990s is observed (around 50% of its original magnitude), which may be attributable to changes in catchment and river channel management.
... Considerando uma possível relação do uso e ocupação do solo, não houve resposta correlata com as áreas de agricultura e pastagem, no entanto, para áreas urbanas houve relação, já que as RHs com maiores áreas urbanas foram 6 (Baixada Norte), 8 (Litoral Centro) e 10 (Extremo Sul), sendo que para o PO4 3 a RH 6 (Baixada Norte) foi a responsável pela maior concentração. A degradação da qualidade da água em várias partes do globo é resultado das mudanças no uso e na ocupação do solo, associados aos impactos das mudanças climáticas (Bussi et al., 2016;Rodríguez-Lloveras et al., 2015). Na Europa, a saúde de rios teve decréscimo principalmente por altas concentrações de N e P geralmente provenientes de atividades antropogênicas (Beusen et al., 2005), o que não é o caso de Santa Catarina, já que os locais com maiores agricultura e pastagem, não foram os responsáveis por maiores concentrações de N ou P. ...
Conference Paper
Full-text available
Este estudo fez uma análise dos pontos de monitoramento de vazão e qualidade (de sedimento, nitrogênio e fósforo) investigando padrões e dados existentes em bacias hidrográficas do Estado de Santa Catarina.
... Water parts are very vulnerable to hydrological change, particularly when other sources of disturbance like climate change, pollution, urbanization, and land use accentuate this change [70,71].Water levels will always fluctuate since wetlands are frequently situated in an Eco-region where an aquatic and a terrestrial ecosystem coexist. In terms of environmental science and water resources, water is the most valuable. ...
Article
Full-text available
This bibliographic article on Drought and Water Level examined the relationship between organizations, nations, institutions, authors, references, and publishers. It examined 742 papers from Web of Science at the Nanjing University of Information Science and Technology’s. The total annual publication volume of articles was increased steadily from 2012 to 2021, with China and the United States ranking first and second in terms of publication volume and citations but in quality Switzerland and England were top-level. Institutional-partnership analyses indicated disparities in network density and connections, with the Chinese Academy of Sciences (2012) receiving the highest citations and degrees. The document co-citation analysis (DCA) network was created to improve understanding of the frequency and amplitude of bursts of various publications in separate clusters. The most cited work was J Hydrol (2012), with 302 citations. The analytical tool from CiteSpace collected high-frequency keywords and performed co-occurrence, grouping, and emerging word recognition. Gorges Dam is the most crowded cluster, followed by drought stress. The greatest burst duration and most significant phrase is reservoir (2019), followed by “water quality,” which has a 5 year burst period. Estuaries perform important functions such as water purification and coastal. “Reservoir, water quality, restoration, phytoplankton, temperature, wetland, time series, diversity and carbon dioxide” are the most important terms, while “climate change, drought, water level, impact, growth, variability, response, dynamics, management and model” are the most frequently used keywords. In terms of citations, references, and academic influence, Zhang Q. (2012), the R Core team (2014), and Jappen E. (2015) were the top three contributors. Cook, ER (2013), and Allen, R.G. (2019) ranked first and second in terms of frequency, respectively. In this review work, significant information gaps were discovered in the areas of microbiological dynamics, environmental variables, fen peat incubation, lake water, drought risk reduction, biological ecology, lake acidification, salinity variations, and attribution. Future researchers should focus on these and similar topics, while Chinese and USA authors should concentrate on article quality rather than publishing numbers.
... Cai et al., 2009), irrigated agriculture economic risk (Salmoral et al., 2019), or ecological impacts (e.g. Bussi et al., 2016). ...
Article
Full-text available
Appropriate adaptation planning is contingent upon information about the potential future impacts of climate change, and hydrological impact assessments are of particular importance. The UKSCAPE-G2G datasets were produced, as part of the Natural Environment Research Council (NERC) UK-SCAPE (UK Status, Change and Projections of the Environment) programme, to contribute to this information requirement. They use the Grid-to-Grid (G2G) national-scale hydrological model configured for both Great Britain and Northern Ireland (and the parts of the Republic of Ireland that drain to rivers in NI). Six separate datasets are provided, for two sets of driving data – one observation-based (1980–2011) and one climate-projection-based (1980–2080) – for both river flows and soil moisture on 1 km × 1 km grids across Great Britain and Northern Ireland. The river flow datasets include grids of monthly mean flow, annual maxima of daily mean flow, and annual minima of 7 d mean flow (m3 s-1). The soil moisture datasets are grids of monthly mean soil moisture content (m water / m soil), which should be interpreted as depth-integrated values for the whole soil column. The climate-projection-based datasets are produced using data from the 12-member 12 km regional climate model ensemble of the latest UK climate projections (UKCP18), which uses RCP8.5 emissions. The production of the datasets is described, along with details of the file format and how the data should be used. Example maps are provided, as well as simple UK-wide analyses of the various outputs. These suggest potential future decreases in summer flows, annual minimum 7 d flows, and summer/autumn soil moisture, along with possible future increases in winter flows and annual maximum flows. References are given for published papers providing more detailed spatial analyses, and some further potential uses of the data are suggested. The datasets are listed in Table 1.
... These methods are often relying on sampling data that are collected at a given time, and the potential biases caused by temporal changes are ignored, especially over different hydrological periods (Cupertino et al., 2019). The current agriculture practice and urban waste treatment processes lead to severe deterioration of freshwater quality and biodiversity by altering water flow and causing nutrient over-enrichment through the polluting effects of fertilizers, pesticides, and sewage (Bussi et al., 2016;Katsiapi et al., 2012). Feng et al. (2021) identified the main socioeconomic factors that influence the water quality of Dongting Lake, which included agricultural and urban water consumption, arable land area, total nitrogen input from agricultural surface sources, and anthropogenic regulations such as industrial effluent compliance rate and sewage treatment rate. ...
Article
Full-text available
Identifying the drivers that impact phytoplankton biomass and dynamics of functional groups (FGs) is crucial to the management of lake aquatic systems. To explore the interactive effects of hydrological characteristics, physicochemical parameters and phytoplankton FGs in the largest river-connected lake, a case study was carried out at Dongting Lake, China. We analyzed the changes in the hydrological characteristics of the lake as well as in the phytoplankton biomass throughout the year to explore the driving factors that influence phytoplankton FGs. Four periods were defined in our study based on water level (WL) fluctuations including the rising periods (RI and RII) and the falling periods (FI and FII). The phytoplankton biomass in Dongting Lake was the highest in RII, followed by RI, FI, and FII. And the trend of FGs dominance through the four periods were P/MP/D (RI) → P/ MP/J (RII) → MP (FI) → MP/P/Y (FII). Changes in phytoplankton biomass and FGs were the result of a combination of hydrological characteristics and physicochemical parameters. Throughout the water period, the hydrological characteristics did not directly influence phytoplankton, instead exerting a more indirect effect on phytoplankton biomass and FGs by affecting the water's physicochemical parameters, e.g., permanganate index (COD Mn), nitrogen nutrients, dissolved oxygen (DO), water temperature (WT), and conductivity (Cond). COD Mn might be a significant predictor of phytoplankton biomass and FGs in all water periods, explaining 36.6% of the variability, followed by Cond, WT, ammonia nitrogen (NH 4 +-N), and DO explaining 17.6%, 12.3%, 11.3%, and 7.2%, respectively. However, according to each water phase analysis, the WL was the key factor for phyto-plankton growth in RII. Nitrogen nutrients, WT and Cond had more pronounced effects on phytoplankton in RI, FI and FII, respectively., Based on the findings of our study, we suggest that increased control of organic matter input into the lake and nitrogen fertilizer use at nearby agricultural surface sources are effective actions that are needed to prevent and control algal blooms in Dongting Lake.
... A very recent study highlighted that 51-60% of lotic habitats, mainly but not exclusively lower order streams, are affected by periodical flow cessations worldwide (Messager et al., 2021). Therefore, it is no exaggeration to say that extremes in water regime can be considered as key drivers shaping algal assemblages and lead to diversity changes both in the case of phytoplankton (Thompson et al., 2015;Bussi et al., 2016) and phytobenthos (B-Béres et al., 2019;Tornés et al., 2021). ...
... Currently, the main landscape-modifying anthropic activities are related to urbanization, agriculture, and deforestation (Vörösmarty et al., 2010;Yu et al., 2013;Kim et al., 2019), directly influencing ecosystems at local, regional, and global scales (Wan et al., 2014). These activities generate impacts on the limnological characteristics of rivers, increasing the concentration of nutrients and pollutants (fertilizers, pesticides, and sewage flows), and altering water quality (Schulz & Martins-Junior, 2001;Bussi et al., 2016;Xiao et al., Resumo: Objetivo: A urbanização, a agricultura e o desmatamento são os principais fatores antropogênicos que modificam o solo, alterando a qualidade da água e influenciado os fatores limnológicos e a biota aquática em rios. Nós investigamos a resposta taxonômica e funcional baseada na morfologia (GFBM) da comunidade fitoplanctônica entre diferentes rios de abastecimento público em distintas bacias hidrográficas com características ultraoligotróficas, oligotróficos e mesotróficas. ...
Article
Full-text available
Aim Urbanization, agriculture, and deforestation are the main anthropogenic factors that modify the soil, altering the quality of water, and influencing limnological aspects and the aquatic biota in rivers. We investigated the morphology-based taxonomic and functional response (MBFG) of the phytoplankton community among different public supply rivers in distinct hydrographic basins with ultraoligotrophic, oligotrophic, and mesotrophic characteristics. Methods We sampled the phytoplankton community and environmental variables in nine rivers along three hydrographic basins in western Paraná. In order to evaluate the taxonomic and functional relationship of the community with the environmental variables, we applied both variance and redundancy analyses. Results Differences in temperature, pH, turbidity, total phosphorus, chemical oxygen demand, and total dissolved solids were identified among river basins and/or trophic states. The highest taxonomic contributions to richness and biovolume were from green algae and diatoms, while the highest functional contributions were from MBFG IV (algae without specialized traits), MBFG V (unicellular flagellated algae), MBFG VI (algae with a siliceous exoskeleton) and MBFG (large colonial algae). The taxonomic approach was sensitive to environmental variability in the rivers, while for the functional approach no relationship to environmental variability was identified. Conclusions The taxonomic approach of the phytoplankton community was more sensitive to the environmental variability of the studied rivers than the functional approach based on morphology. Therefore, we reinforce the importance of biological indicators for understanding the dynamics in aquatic ecosystems, providing crucial information for the management of water resources used for public supply.
... Although we did not explicitly test for a relationship between multiple disciplinary teams and conservation 'impact' in our review, we noted that studies with a more obvious and direct link to conservation actions often had authors with non-academic affiliations including government, environmental non-profit organizations and industry [e.g. 45,74,82,83]. To promote an effective multiple disciplinary approach, we recommend that teams foster early and regular collaboration with decision-makers and other stakeholder and rightsholder groups to facilitate a stronger link to policy and on-the-ground conservation actions. ...
Article
Full-text available
Purpose of Review Multiple stressor studies conducted in real-world environments play an important role in discovering how stressor pathways may vary relative to ecological complexity and study scale. We reviewed the evidence for climate and landscape change impacts on freshwater biodiversity in real-world ecosystems at the global scale. Using our compiled database of 150 studies, we asked (1) what are the study characteristics within the available evidence base and (2) what are the main knowledge gaps and recommendations for future research? Recent Findings Most studies employed an observational design and examined climatic and landscape change trends over a broad regional spatial scale (median = 97 sites/study). Ecological complexity was well represented in studies with a median of 11 predictor variables that characterized the relevant climate, landscape condition, and many other environmental attributes. Community-level metrics were common response types across all biota including larger, more mobile organisms such as fish that are challenging to examine in an ecologically-relevant context within controlled laboratory settings. Summary We identified several knowledge gaps including the need for more published time-series data, particularly with respect to understanding climate change impacts. Other opportunities for improved future research included incorporating more stressor and biological interactions, examining potential climate stressors over multiple seasons and streamlining methods for dealing with the pervasive challenges of multicollinearity in real-world systems. We emphasize the unique role of ‘natural experiments’ in validating experimental findings and provide a suite of recommendations for creating more strategic field studies to inform conservation efforts.
... Higher abundance attributed to higher waterbody area in the catchment (Qu et al., 2018a(Qu et al., , 2018b. Tributaries connected to lentic waterbody, which have slower flow and higher residence time, resulting in more favorable condition for phytoplankton growth (Bussi et al., 2016). Higher phytoplankton abundance may be due to increases in urban land use and decreases in forest habitat (Kakouei et al., 2021). ...
Article
Given the many threats to freshwater biodiversity, we need to be able to resolve which of the multiple stressors present in rivers are most important in driving change. Phytoplankton are a key component of the aquatic ecosystem, their abundance, species richness and functional richness are important indicators of ecosystem health. In this study, spatial variables, physiochemical conditions, water flow alterations and land use patterns were considered as the joint stressors from a lowland rural catchment. A modeling approach combining an ecohydrological model with machine learning was applied. The results implied that land use and flow regime, rather than nutrients, were most important in explaining differences in the phytoplankton community. In particular, the percentage of water body area and medium level residential urban area were key to driving the rising phytoplankton abundance in this rural catchment. The proportion of forest and pasture area were the leading factors controlling the variations of species richness. In this case deciduous forest cover affected the species richness in a positive way, while, pasture share had a negative effect. Indicators of hydrological alteration were found to be the best predictors for the differences in functional richness. This integrated model framework was found to be suitable for analysis of complex environmental conditions in river basin management. A key message would be the significance of forest area preservation and ecohydrological restoration in maintaining both phytoplankton richness and their functional role in river ecosystems.
... The exchange of tidal waters, the freshwater contribution from the rainfall, groundwater, and rivers input results in the dynamic environment with fluctuating temperature, salinity, and other physiochemical properties (Barnes 1980). It is generally accepted on larger scales that the abiotic drivers, such as temperature and nutrient fluctuations, are fundamentally altering the biological process, while in local and micro-scales, biotic component is more important (Bussi et al. 2016). Many multidisciplinary studies have shown that the ecology of coastal lagoons is highly variable in their physical and chemical environment (Domingues et al. 2017;Roselli et al. 2013;Coelho et al. 2015;Cevirgen et al. 2020). ...
Article
Full-text available
This paper summarizes the spatio-temporal variation of phytoplankton and zooplankton assemblages in Kavaratti lagoon and offshore water of Lakshadweep Archipelago, India. The objective of this study was to evaluate phytoplankton and zooplankton assemblage with responses to changing environmental conditions in Kavaratti lagoon and offshore water. Samples were collected and analysed during the pre-monsoon and post-monsoon season during 2016. During this period, in total, 69 species of zooplankton and 54 species of phytoplankton were identified. The population density of various groups of zooplankton found to be of the following order: Crustacea > Foraminifera > Porifera > Chaetognatha > Ciliophora > Appendicularia. Similarly, phytoplankton composed of the order of Bacillariophyceae > Dinophyceae > Chlorophyceae > Cyanophyceae. The highest population densities were recorded in the pre-monsoon period of the study. The lagoon region recorded the maximum plankton distribution than the offshore region. Crustaceans exhibit maximum diversity and richness in all the stations and seasons studied. Macrosetella gracilis (711 nos/m³) was the most dominant zooplankton species observed and which may be attributed to the availability of preferential food and favorable environmental conditions. There is a significant effect of water salinity on the population density of Daphnia magna (652 nos/m³) has been noticed during the pre-monsoon season of the study. Daphnia magna is well adapted to certain fluctuations, such as low oxygen conditions, high pH, wide ranges of salinity, and temperature. Among the phytoplankton, diatoms, such as Bellerochea malleus (20,160 nos/m³), Coscinodiscus gigas (1180 nos/m³), Eucampia zodiacus (880 nos/m³), and Rhizosolenia alata (2380 nos/m³), were dominant during the study. The Shannon–Wiener Diversity Index (0.183–2.587) for phytoplankton represents moderate level of pollution in the Kavaratti Island. The canonical correspondence analysis (CCA) confirms that the positive correlation of environmental parameters, such as water temperature, salinity, ammonia, nitrates, and silicates, on the distribution and assemblages of the plankton community.
... Using a model cascade, Bussi et al. (2016) projected likely impacts of a combination of changing climate and land management on phytoplankton concentrations in the River Thames. Specifically, the study suggests that a combination of reduced precipitation and rising air temperature in the future, coupled with increased conversion of land to intensive arable agriculture, is likely to result in increased phytoplankton (especially cyanobacteria) growth in the Thames. ...
Technical Report
Full-text available
The CCRA is a comprehensive assessment of the risks to the UK from climate change, as required by Act of Parliament every 5 years (Climate Change Act)
... Temperature also affects the spread of waterborne diseases, although a rise in global temperature is expected to increase the likelihood of other types of health threats, such as for example toxins derived from cyanobacteria (Bussi et al., 2016b;Hunter, 2003). It is also hypothesised that higher water temperatures will lead to a pathogen survival increase, although there is still no clear evidence (Hunter, 2003), and the INCA-Pathogens model does not take this phenomenon into account. ...
... (1) simple statistical methods (O'Donoghue et al. 2021;Tu 2011), (2) watershed models (Bussi et al. 2016), (3) multiple regression models (Eslamian et al. 2016) and (4) canonical correlation analysis methods (Wei et al. 2018). The above methods have distinct advantages and disadvantages. ...
Article
Full-text available
Social and economic development processes require large amounts of natural resources and in some cases seriously deteriorate river water quality. Since the reform and expansion era began, China has vigorously pursued socioeconomic development but neglected environmental protection. However, in recent years, improvements in environmental awareness and the implementation of environmental protection measures have led to a balanced relationship between economic development and the environment. In this study, the Yangtze River Basin and the Yellow River Basin were selected as research areas. We used a combination of canonical correlation analysis (CCA) and a distance-based influence assessment method to quantitatively assess the influence of socioeconomic development on river water quality. The results revealed a strong correlation between socioeconomic development and river water quality. The degree of influence of socioeconomic development on water quality varied not only temporally but also spatially due to differences in socioeconomic development and hydrometeorology in the two basins in North and South China. The average degree of influence in the Yangtze River Basin was between 0.22 and 0.27, and that in the Yellow River Basin was between 0.2 and 0.36. Moreover, the degree of influence in the Yangtze River Basin in the wet season was greater than that in the dry season, whereas the opposite pattern was observed in the Yellow River Basin. The degree of influence in both basins gradually declined after 2011, indicating that the coupling and coordination between socioeconomic development and environmental protection have continuously improved and that the water quality has gradually improved. By analysing the influences of various socioeconomic indicators on water quality, we found that the main factors that influence water quality are per capita GDP and urbanization rate in the Yangtze River Basin and urbanization rate in the Yellow River Basin. The results provide a basis for future sustainable development in the Yangtze River Basin and the Yellow River Basin.
... well as disruption of human agriculture, food production, and water supply [4][5][6]. The extent of future climate change depends on the actions of the people and societies in managing the search for energy resources and reducing anthropogenic pollutions [7][8][9]. ...
Article
Full-text available
Background: The global commitment to climate change mitigation enforces the worldwide development of renewable energy sources. Therefore, various studies have investigated the growth of renewable energy in Malaysia, most commonly based on biogas and hydropower. In this article, the dynamics of Malaysia's renewable energy development is critically examined by using the latest official national reports and other reliable resources. Results: The study reveals the influencing factors that shape renewable energy growth in a developing country endowed with substantial biomass resources, such as Malaysia. Likewise, it evaluates the evolution of renewable energy in the electricity sector. In 2017, renewable energy represented about 3.5% of the Malaysian electricity generation mix with 1122 MW of installed capacity. A closer look into the renewable energy resources, i.e. biomass, biogas, solar and small hydro power, revealed that over 47% of the grid-connected power generation came from solar pho-tovoltaic (PV) energy. While solar PV capacity continues to accelerate, the development of other renewable resources, especially biomass, is seeing growth at a significantly slower pace. This article investigates the underlying causes of the skewed development rate as well as the potential strategies that may be adopted to promote a diversification of renewable energy resources. In light of this, introduction of a new national bioenergy policy is proposed, through which four essential programmes could be implemented: (i) enhanced bioenergy conversion efficiency and waste management, (ii) biomass co-firing in coal power plants, (iii) conversion of biogas to biomethane and bio-compressed natural gas (bio-CNG), (iv) large-scale biomass power plants. A total of 4487 MW of additional power could be connected to the grid upon successful implementation of a large-scale biomass power plant programme. Conclusions: The establishment of a comprehensive and inclusive national bioenergy policy will lead towards a sustainable future of renewable energy development in Malaysia.
... Many aspects of land use and land management, including the use of agricultural fertilizers, have important consequences for water quality and ecology [18], and these will need to be included in models. From an Earth System perspective, these riverine nutrient fluxes are important inputs to estuaries and shelf seas, and the interface between land and marine models will need to be developed accordingly. ...
Article
Full-text available
Land surface models have an increasing scope. Initially designed to capture the feedbacks between the land and the atmosphere as part of weather and climate prediction, they are now used as a critical tool in the urgent need to inform policy about land-use and water-use management in a world that is changing physically and economically. This paper outlines the way that models have evolved through this change of purpose and what might the future hold. It highlights the importance of distinguishing between advances in the science within the modelling components, with the advances of how to represent their interaction. This latter aspect of modelling is often overlooked but will increasingly manifest as an issue as the complexity of the system, the time and space scales of the system being modelled increase. These increases are due to technology, data availability and the urgency and range of the problems being studied.
... The hydrological and water quality sub-models of INCA have been applied to several basins across the UK and Europe, and, in particular, to the River Thames catchment [31][32][33][34][35][36][37][38]. INCA is a semi-distributed process-based model which simulates the transformation of rainfall into runoff and the propagation of water through a river network [28]. ...
Article
Full-text available
With widespread, long-term historical use of plastics and the presence of microplastics in a range of new and existing products, there is rising concern about their potential impacts on freshwater ecosystems. Understanding how microplastics are transported and distributed along river systems is key to assessing impacts. Modelling the main flow dynamics, mixing, sedimentation and resuspension processes is essential for an understanding of the transport processes. We use the new, processed based, dynamic, integrated catchments (INCA) microplastics model and apply this to the whole of the freshwater catchment of the River Thames, UK, to evaluate inputs, loads and concentrations along the river system. Recent data from UK water industry studies on microplastics in effluent discharges and sewage sludge disposal has been utilised to drive the INCA microplastics model. Predicted concentrations and microplastic loads moving along the river system are shown to be significant, with a build-up of concentrations along the river, with increasing deposition on the riverbed. The potential impacts on aquatic ecosystems are evaluated and a review of policy implications is explored.
... In fact, policy frameworks for assessing water quality increasingly employ phytoplankton composition and distribution as indicators to evaluate degradation in water resources arising from persistent eutrophication, nutrient loading, and climate change (Garmendia et al., 2013). A change in the phytoplankton composition and distribution is often associated with a loss of ecosystem services and biodiversity at a regional scale (Harding et al., 2015;Bussi et al., 2016). ...
Article
Spatial and seasonal heterogeneity in phytoplankton communities are governed by many biotic and abiotic drivers. However, the identification of long-term spatial and temporal trends in abiotic drivers, and their interdependencies with the phytoplankton communities’ structure is understudied in tropical brackish coastal lagoons. We examined phytoplankton communities' spatiotemporal dynamics from a 5-year dataset (n = 780) collected from 13 sampling stations in Chilika Lagoon, India, where the salinity gradient defined the spatial patterns in environmental variables. Generalized additive models showed a declining trend in phytoplankton biomass, pH, and dissolved PO4 in the lagoon. Hierarchical modelling of species communities revealed that salinity (44.48 ± 28.19%), water temperature (4.37 ± 5.65%), and season (4.27 ± 0.96%) accounted for maximum variation in the phytoplankton composition. Bacillariophyta (Indicator Value (IV): 0.74) and Dinophyta (IV: 0.72) emerged as top indicators for polyhaline regime whereas, Cyanophyta (IV: 0.81), Euglenophyta (IV: 0.79), and Chlorophyta (IV: 0.75) were strong indicators for oligohaline regime. The responses of Dinophyta and Chrysophyta to environmental drivers were much more complex as random effects accounted for ~70–75% variation in their abundances. Prorocentrum minimum (IV: 0.52), Gonyaulax sp. (IV: 0.52), and Alexandrium sp. (IV: 0.51) were potential indicators of P–limitation. Diploneis weissflogii (IV: 0.43), a marine diatom, emerged as a potential indicator of N–limitation. Hierarchical modelling revealed the positive association between Cyanophyta, Chlorophyta, and Euglenophyta whereas, Dinophyta and Chrysophyta showed a negative association with Cyanophyta, Chlorophyta, and Euglenophyta. Landsat 8-Operational Land Imager satellite models predicted the highest and lowest Cyanophyta abundances in northern and southern sectors, respectively, which were in accordance with the near-coincident field-based measurements from the lagoon. This study highlighted the dynamics of phytoplankton communities and their relationships with environmental drivers by separating the signals of habitat filtering and biotic interactions in a monsoon-regulated tropical coastal lagoon.
... The hydrological and water quality sub-models of INCA have been applied to several basins across the UK and Europe, and, in particular, to the River Thames catchment [31][32][33][34][35][36][37][38]. INCA is a semi-distributed process-based model which simulates the transformation of rainfall into runoff and the propagation of water through a river network [28]. ...
Article
Full-text available
With widespread, long-term historical use of plastics and the presence of microplastics in a range of new and existing products, there is rising concern about their potential impacts on freshwater ecosystems. Understanding how microplastics are transported and distributed along river systems is key to assessing impacts. Modelling the main flow dynamics, mixing, sedimentation and resuspension processes is essential for an understanding of the transport processes. We use the new, processed based, dynamic, integrated catchments (INCA) microplastics model and apply this to the whole of the freshwater catchment of the River Thames, UK, to evaluate inputs, loads and concentrations along the river system. Recent data from UK water industry studies on microplastics in effluent discharges and sewage sludge disposal has been utilised to drive the INCA microplastics model. Predicted concentrations and microplastic loads moving along the river system are shown to be significant, with a build-up of concentrations along the river, with increasing deposition on the riverbed. The potential impacts on aquatic ecosystems are evaluated and a review of policy implications is explored. View Full-Text https://www.mdpi.com/2073-4441/13/6/861
... nutrients, fluvial factors, anthropogenic influence) poses a further challenge (Paerl and Huisman, 2008;Pasztaleniec and Poniewozik, 2010). Currently, water management of many developed countries is conducted in an interdisciplinary manner in an attempt to link water risk assessment and management with the phytoplankton community (Wehr and Descy, 1998;Bussi et al., 2016;Hu et al., 2016). Therefore, under the influence of local and regional environmental variables, the phytoplankton community functions as early warning indicators of river ecosystem deterioration, and a reliable predictor of phytoplanktonderived toxins (Dufrêne and Legendre, 1997). ...
Article
Full-text available
Knowledge of the phytoplankton community dynamics is fundamentally important for river ecological management. Disentangling the relative impacts of co-occurring factors is critical to understanding the community responses to environmental heterogeneity, as well as anthropogenic activities. Taking phytoplankton community as the indicative variable, this study aimed at elucidating the impacts of driving forces (local factors: water environments; regional factors: land-use, fertilizers application, and socio-economic factors) on the phytoplankton community dynamics. We found that spatial and seasonal processes played a vital role in structuring the phytoplankton community, with Bacillariophyta and Chlorophyta accounting for>79.0% of taxa composition. Bacillariophyta had the highest cell density (>41%), followed by Cyanophyta (>20%) and Chlorophyta (>11%), which mainly contributed to the spatial and seasonal differences in the composition and abundance of the phytoplankton community. Meanwhile, local factors (such as total phosphorus, permanganate index, flow velocity, transparency, and stream depth) and regional factors (the application of phosphate fertilizers) (p < 0.05) were the dominant factors that influenced the phytoplankton community. Here, the phosphorus related factors interfered with the phytoplankton community on both local and regional scales. On the whole, the local factors (including nutrients and hydrology factors) have a more direct impacts on the phytoplankton community in a temperate river. It is of guiding significance for river ecology monitoring and improvement in north China, while paying attention to terrestrial influences, the eutrophication of the river itself still needs to be focused on accompanied with the hydrology factors.
... Los humedales ubicados en la llanura de inundación de los cursos de agua mantienen una gran diversidad de organismos debido a la heterogeneidad del hábitat, las fluctuaciones hidrológicas y la calidad de sus aguas (Rodrigues et al., 2015). Los cambios en el uso del suelo, como el aumento del área dedicada a la agricultura fertilizada, suponen una amenaza para estos ambientes que afecta a los organismos que los habitan (Bussi et al., 2016;. De este modo se generan modificaciones en los ecosistemas acuáticos que son evidenciadas a través de las comunidades (Allan, 2004). ...
Article
Full-text available
Los bañados de desborde fluvial (BDF) desempeñan un papel integral en la ecología de las cuencas fluviales y en su capacidad de autodepuración. La demanda antrópica de espacio y agua pone en riesgo su biota y los beneficios ecosistémicos que brindan. Los objetivos del trabajo fueron analizar los ensambles de microorganismos que habitan en BDF, relacionar sus variaciones al impacto antrópico y evaluar cómo la microbiota puede ser indicadora de estos cambios ambientales. Se estudiaron los ensambles de diatomeas bentónicas, fitoplancton, zooplancton, ostrácodos y hongos de cuatro BDF: dos de ubicación periurbana con uso del suelo agrícola y hortícola (Del Gato y Carnaval), y dos de ubicación rural y uso ganadero (Cajaravillas y Chubichaminí). En la mayoría de los grupos las diferencias vinculadas a la ubicación geográfica se expresaron claramente, resultando en una agrupación de ensambles en: BDF rurales (con un número de especies sensibles a la contaminación y a la eutrofización comparativamente mayor) y BDF periurbanos (donde fueron más importantes las especies muy tolerantes a la contaminación y a la eutrofización). En estos últimos, tanto la participación de los grandes grupos taxonómicos como los niveles tróficos estuvieron más restringidos y relacionados a la vía detritívora por sobre la fotosintética, y allí también se acentuaron las estrategias para afrontar el estrés hídrico. Los resultados evidencian los efectos de la presión humana, la importancia que adquieren los microorganismos y la necesidad de una planificación adecuada del uso del territorio para evitar la pérdida de funciones y beneficios en estos ambientes.
... well as disruption of human agriculture, food production, and water supply [4][5][6]. The extent of future climate change depends on the actions of the people and societies in managing the search for energy resources and reducing anthropogenic pollutions [7][8][9]. ...
Article
Full-text available
Background The global commitment to climate change mitigation enforces the worldwide development of renewable energy sources. Therefore, various studies have investigated the growth of renewable energy in Malaysia, most commonly based on biogas and hydropower. In this article, the dynamics of Malaysia’s renewable energy development is critically examined by using the latest official national reports and other reliable resources. Results The study reveals the influencing factors that shape renewable energy growth in a developing country endowed with substantial biomass resources, such as Malaysia. Likewise, it evaluates the evolution of renewable energy in the electricity sector. In 2017, renewable energy represented about 3.5% of the Malaysian electricity generation mix with 1122 MW of installed capacity. A closer look into the renewable energy resources, i.e. biomass, biogas, solar and small hydro power, revealed that over 47% of the grid-connected power generation came from solar photovoltaic (PV) energy. While solar PV capacity continues to accelerate, the development of other renewable resources, especially biomass, is seeing growth at a significantly slower pace. This article investigates the underlying causes of the skewed development rate as well as the potential strategies that may be adopted to promote a diversification of renewable energy resources. In light of this, introduction of a new national bioenergy policy is proposed, through which four essential programmes could be implemented: (i) enhanced bioenergy conversion efficiency and waste management, (ii) biomass co-firing in coal power plants, (iii) conversion of biogas to biomethane and bio-compressed natural gas (bio-CNG), (iv) large-scale biomass power plants. A total of 4487 MW of additional power could be connected to the grid upon successful implementation of a large-scale biomass power plant programme. Conclusions The establishment of a comprehensive and inclusive national bioenergy policy will lead towards a sustainable future of renewable energy development in Malaysia.
... A properly planned landscape pattern could effectively reduce the transportation of non-point source pollutants to waterbodies. In addition, the hydrodynamic conditions of the reservoir bays and their exchange with the main stream could affect the Chl a concentration; there is necessity to develop a phytoplankton model of reservoir bay under complex hydrological rhythms (Whitehead et al., 2015;Bussi et al., 2016). However, these hypotheses are beyond our main focus, although they are very important issues, and further investigation is needed in future studies. ...
Article
The frequency of harmful algal blooms caused by eutrophication is increasing globally, posing serious threats to human health and economic development. Reservoir bays, affected by water environment and local watershed landscape, are more prone to eutrophication and algal blooms. The chlorophyll a (Chl a) concentration is an important indicator for the degree of eutrophication and algal bloom. Exploring the complex relationships between water environment and landscape background, and Chl a concentration in the reservoir bays are crucial for ensuring high-quality drinking water from reservoirs. In this study, we monitored Chl a concentrations of 66 bays in Danjiangkou Reservoir and the related water quality parameters (e.g., water temperature, turbidity, nutrients) in waterbodies of these reservoir bays in the storage and discharge periods from 2015 to 2018. Partial least squares-structural equation modeling (PLS-SEM) was used to quantify the relationship between water environmental factors and watershed landscapes, and Chl a concentrations in reservoir bays. The results showed that mean Chl a concentration was higher in storage period than that in discharge period. Two optimal PLS-SEMs explained 66.8% and 53.6% of Chl a concentration variation in the storage and discharge periods, respectively. The net effect of water chemistry on Chl a concentration was more pronounced during the discharge period (total effect = 0.61, 37% of the total effect on Chl a), while the net effect of land-use composition on Chl a concentration was more significant during the storage period (total effect = 0.57, 30% of the total effect on Chl a). The landscape pattern had significant indirect effects on Chl a concentration, especially during the discharge period (indirect effect = −0.31, 19% of the total effect on Chl a). Our results provide valuable information for managers to make rational decisions, thereby contributing to the prevention of eutrophication and algal blooms in reservoir bays.
Article
Full-text available
1. A robust understanding of the interactions between global and local anthro-pogenic stressors is crucial for ecosystem management in the Anthropocene. Manipulative experiments in the laboratory or in the field can be used to build knowledge about the physiological and ecological effects of stressors, but predicting the combined landscape-scale effects of global stressors such as climate change, and local stressors such as land-use change requires a different approach. 2. Here we used water quality and hydrology process-based models of entire river catchments in combination with a large biomonitoring dataset to predict the responses of macroinvertebrate communities under different climate change and land-use change scenarios. Using the River Thames in the U.K. as a model system, we predicted changes in water quality (temperature, flow, phosphorus [P], nitrogen , dissolved oxygen [DO]) and subsequent changes in macroinvertebrate communities for two climate change scenarios, individually and in combination with intensified agriculture and reduced P pollution (representing improved wastewa-ter treatment). 3. Our models predicted that water-quality changes associated with climate change may not influence total species richness, but that community composition will shift towards more pollution-tolerant and common taxa based on responses of community indices and taxon-specific responses. We also found that the negative impacts of climate change on water quality (e.g., increased P concentration, decreased DO concentration) accumulate through the catchment, but that local land-use practices influencing P dynamics can modify this trend. Furthermore, although the intensified agriculture scenario was predicted to have minimal impacts on macroinvertebrate communities (a result potentially related to shifting baselines as the Thames is already heavily polluted), we found that reduced P pollution resulting from improved wastewater treatment was able to mostly offset the negative impacts of climate change on macroinvertebrate communities.
Article
Full-text available
A robust understanding of the interactions between global and local anthropogenic stressors is crucial for ecosystem management in the Anthropocene. Manipulative experiments in the laboratory or in the field can be used to build knowledge about the physiological and ecological effects of stressors, but predicting the combined landscape‐scale effects of global stressors such as climate change, and local stressors such as land‐use change requires a different approach. Here we used water quality and hydrology process‐based models of entire river catchments in combination with a large biomonitoring dataset to predict the responses of macroinvertebrate communities under different climate change and land‐use change scenarios. Using the River Thames in the U.K. as a model system, we predicted changes in water quality (temperature, flow, phosphorus [P], nitrogen, dissolved oxygen [DO]) and subsequent changes in macroinvertebrate communities for two climate change scenarios, individually and in combination with intensified agriculture and reduced P pollution (representing improved wastewater treatment). Our models predicted that water‐quality changes associated with climate change may not influence total species richness, but that community composition will shift towards more pollution‐tolerant and common taxa based on responses of community indices and taxon‐specific responses. We also found that the negative impacts of climate change on water quality (e.g., increased P concentration, decreased DO concentration) accumulate through the catchment, but that local land‐use practices influencing P dynamics can modify this trend. Furthermore, although the intensified agriculture scenario was predicted to have minimal impacts on macroinvertebrate communities (a result potentially related to shifting baselines as the Thames is already heavily polluted), we found that reduced P pollution resulting from improved wastewater treatment was able to mostly offset the negative impacts of climate change on macroinvertebrate communities. Our results demonstrate that using process‐based models to study networks of interacting stressors at a landscape scale can provide useful insights into the ecological impacts of anthropogenic global change, and adds support to the idea that management of local stressors has the potential to mitigate some of the impacts of climate change on ecosystems.
Article
Full-text available
Both natural and anthropogenic processes can lead to the increasing salinity of surface waters. The knowledge about the ecological consequences of salinization on the biota is limited especially in case of microbiota, like diatoms. We collected the existing knowledge about the relationship between salinity and diatoms in fresh and saline waters. Based on the available papers, conductivity and ion composition are the most important variables shaping diatom communities. Secondary salinization can mask regional differences in diatom assemblages. Trait-based analyses highlight the competitive advantages of motile guild and the extreme trait categories in these environments. The increasing conductivity along a wide conductivity scale decreases the alpha-diversity. Salinization induces the spread and invasion of marine and brackish species into inland freshwaters as well as that of freshwater species tolerating elevated conductivity and/or need specific ions. Concerning food webs, salinity can directly change diatom communities and the subsequent upper trophic levels but most likely this effect manifests as a top-down regulation. Applicable diatom indices are available to assess the level of salinization. Furthermore, diatom-inferred salinity reconstructions are widely applied to assess the past changes of salinity. However, future models predicting ecological consequences of salinization are scarce and sometimes contradictory.
Preprint
Full-text available
Appropriate adaptation planning is contingent upon information about the potential future impacts of climate change, and hydrological impact assessments are of particular importance. The UKSCAPE-G2G datasets were produced, as part of the NERC UK-SCAPE programme, to contribute to this information requirement. They use the Grid-to-Grid (G2G) national-scale hydrological model configured for both Great Britain and Northern Ireland (and the parts of the Republic of Ireland that drain to rivers in NI). Six separate datasets are provided, for two sets of driving data — one observation-based (1980–2011) and one climate projection-based (1980–2080) — for both river flows and soil moisture on 1 km x 1 km grids across GB and NI. The river flow datasets include grids of monthly mean flow, annual maxima of daily mean flow, and annual minima of 7-day mean flow (m3s-1). The soil moisture datasets are grids of monthly mean soil moisture content (m water / m soil), which should be interpreted as depth-integrated values for the whole soil column. The climate projection-based datasets are produced using data from the 12-member 12km regional climate model ensemble of the latest UK climate projections (UKCP18), which uses RCP8.5 emissions. The production of the datasets is described, along with details of the file format, and how the data should be used. Example maps are provided, as well as simple UK-wide analyses of the various outputs. These suggest potential future decreases in summer flows, annual minimum 7-day flows, and summer/autumn soil moisture, along with possible future increases in winter flows and annual maximum flows. References are given for published papers providing more detailed spatial analyses, and some further potential uses of the data are suggested.
Article
Full-text available
The production of common carp (Cyprinus carpio) was studied in pond fertilized with cow-dung @ 0.1g N/10g in the presence of planktonic biomass. The correlation of planktonic biomass with water quality physicochemical parameters of three fish ponds, was studied. The parameters such as pH, temperature, dissolved oxygen, total alkalinity, total dissolved solids, total hardness, magnesium, calcium, light penetration, total solids, carbonates and bicarbonates, were analyzed in a laboratory using standard protocols. Data collected at the end of the present experimental study was subjected to an appropriate statistical analysis to appraise the correlation coefficients of planktonic biomass with several physicochemical parameters of three ponds under study. In most cases significant correlations were recorded between biomass and key physico-chemical attributes of the ponds.
Preprint
Full-text available
This study presents the first integrated water quality assessment of the Sauce Grande River Basin. This South American freshwater environment contains two water bodies that interrupt its course before the river discharges into the ocean: a dam for water supply and a shallow lake. We analyzed the spatial distribution of the phytoplankton community, the physicochemical parameters, and the metal concentrations in the particulate fraction. According to the trophic indices and the phytoplankton abundance, composition and diversity, the water quality showed significant deterioration in the lower basin after the Sauce Grande lake. The conductivity, turbidity and most metal concentrations increased towards the downstream area, even exceeding recommended levels for some metals. This study generates a database for the water quality of the Sauce Grande River Basin and its contribution to the sea. It shows an example of how the water quality varies along a basin that crosses different topographic environments and land covers.
Article
Climate-related disasters (CRDs) and hazards such as droughts, floods, and storms are the main patterns of natural events in long-term weather cycles which are potentially affected by climate change. Unsustainable use of land has contributed to the increase of vulnerability to natural disasters. Disasters and land use change have become major concerns all over the world. Agricultural land conversion (ALC) has been identified as one of the most significant drivers that influences ecosystems, and poses numerous challenges to agricultural development and human life. This systematic review study aimed to review the drivers and effects of ALC and CRDs on the one hand and their relations on the other. The paper further proposes a prevention policy framework towards the management of ALC and CRDs including three dimensions, i.e. monitoring-based policies, driver-based policies, and effect-based policies. All three types of these policies are important and essential because ALC and CRDs and their effects and drivers are interdependent. The study concludes that managing these phenomena not only needs to control and monitor their drivers but also requires preventing the effects. Avoiding the drivers and effects also involves monitoring the past, present, and future of ALC and CRD trends. ARTICLE HISTORY
Article
The identification of the main sources and the impact of the current comprehensive water quality is important in improving the precision and pertinence of water quality management, which will have a significant bearing on the quality of the water environment and the ecological system. This paper focuses on the Yangtze River and Yellow River Basins, employs panel data from 2004–2019 from prefecture-level cities and water quality monitoring sections along the Yangtze and Yellow River main streams, and conducts an empirical study on the effects of pollution sources from cultivation, livestock farming, aquaculture, industry, and domestic activities on the overall water quality. It is found that: (1) Increased pollution from agriculture (cultivation, livestock farming and aquaculture), industry and domestic pollution all contribute to the deterioration of water quality. Industry is still the major source of China’s ambient water pollution. It is then followed by domestic source of pollution and agricultural source of pollution, with the latter having the least impact on water quality. (2) Impact of pollution sources on water quality vary from basin to basin significantly.The main sources of water pollution in the Yangtze and Yellow River Basins are industry and domestic life respectively. Cultivation and aquaculture are the main agricultural sources of water pollution in the two basins respectively. (3) Impact of cultivation pollution sources on water quality is subject to seasonal variations. It means that pollutants from cultivation enter the rivers through the carrying effect of precipitation, and this effect is more often reflected in the busy season. (4) In the long term, the negative impact of cultivation and livestock farming on water quality pollution form a cumulative effect. It grows as the number of lag periods increases. Therefore, in the subsequent environmental pollution control processes, priority should be given to industrial and urban pollution control with more targeted regional pollution management. It is also important to strengthen inter-basin and inter-regional synergistic control, taking top-level design of environmental policies and other conditions of the basin areas into full account to reduce the undesired environmental consequences caused by production.
Article
Full-text available
The application of metaldehyde to agricultural catchment areas to control slugs and snails has caused severe problems for drinking water supply in recent years. In the River Thames catchment, metaldehyde has been detected at levels well above the EU and UK drinking water standards of 0.1 mg l À1 at many sites across the catchment between 2008 and 2015. Metaldehyde is applied in autumn and winter, leading to its increased concentrations in surface waters. It is shown that a process-based hydro-biogeochemical transport model (INCA-contaminants) can be used to simulate metaldehyde transport in catchments from areas of application to the aquatic environment. Simulations indicate that high concentrations in the river system are a direct consequence of excessive application rates. A simple application control strategy for metaldehyde in the Thames catchment based on model results is presented. Environmental impact The River Thames is the longest river in England and it supplies drinking water to around 14 million people in the surrounding areas. In recent years, there is a great concern on the presence of metaldehyde at levels exceeding drinking water standards in the Thames water. Metaldehyde breaks slowly in water and is very difficult to remove by current technology in drinking water treatment plants, thus posing a challenge for water companies to comply with the drinking water standards and a potential threat for human health. To reduce the potential risk, it is important to understand the behaviour of metaldehyde in the catchment. But so far, there's very little focus on the analysis of the fate and transport of metaldehyde in river basins. Here, we present the rst modelling study describing the metaldehyde dynamics in the River Thames catchment. A simple application strategy for metaldehyde control was developed based on the modelling results.
Chapter
Water scarcity and degraded water quality have, of late, posed a great threat to a vast majority of mankind. Consequently, the study of the adverse impacts of global climate change (GCC) on water quality has become an emerging area of worldwide interest. It is also well accepted that human-induced climate change is, to an extent, inevitable. This chapter summarizes the latest major scientific findings and the resultant implications for managing the potential impacts of GCC especially with regard to water quality. Recent findings, detailed technical data and analyses, maps, analytical methodology, graphs, models that support the findings are summarized in this chapter that also incorporates various modeling approaches for assessment of such impacts on surface and ground water quality. The chapter, in addition, provides detailed information in a table on the various factors of GCC and their impacts on the parameters affecting water quality, types of water body, study area, and important findings and assessments.
Article
Full-text available
Article
Full-text available
Managing freshwater resources sustainably under future climatic and hydrological uncertainty poses novel challenges. Rehabilitation of ageing infrastructure and construction of new dams are widely viewed as solutions to diminish climate risk, but attaining the broad goal of freshwater sustainability will require expansion of the prevailing water resources management paradigm beyond narrow economic criteria to include socially valued ecosystem functions and services. We introduce a new decision framework, eco-engineering decision scaling (EEDS), that explicitly and quantitatively explores trade-offs in stake- holder-defined engineering and ecological performance metrics across a range of possible management actions under unknown future hydrological and climate states. We illustrate its potential application through a hypothetical case study of the Iowa River, USA. EEDS holds promise as a powerful framework for operationalizing freshwater sustainability under future hydrologi- cal uncertainty by fostering collaboration across historically conflicting perspectives of water resource engineering and river conservation ecology to design and operate water infrastructure for social and environmental benefits.
Article
Full-text available
This paper reviews the implications of climate change for the water environment and its management in England. There is a large literature, but most studies have looked at flow volumes or nutrients and none have considered explicitly the implications of climate change for the delivery of water management objectives. Studies have been undertaken in a small number of locations. Studies have used observations from the past to infer future changes, and have used numerical simulation models with climate change scenarios. The literature indicates that climate change poses risks to the delivery of water management objectives, but that these risks depend on local catchment and water body conditions. Climate change affects the status of water bodies, and it affects the effectiveness of measures to manage the water environment and meet policy objectives. The future impact of climate change on the water environment and its management is uncertain. Impacts are dependent on changes in the duration of dry spells and
Article
Full-text available
Runoff generation processes and pathways vary widely between catchments. Credible simulations of solute and pollutant transport in surface waters are dependent on models which facilitate appropriate, catchment-specific representations of perceptual models of the runoff generation process. Here, we present a flexible, semi-distributed landscape-scale rainfall-runoff modelling toolkit suitable for simulating a broad range of user-specified perceptual models of runoff generation and stream flow occurring in different climatic regions and landscape types. PERSiST (the Precipitation, Evapotranspiration and Runoff Simulator for Solute Transport) is designed for simulating present-day hydrology; projecting possible future effects of climate or land use change on runoff and catchment water storage; and generating hydrologic inputs for the Integrated Catchments (INCA) family of models. PERSiST has limited data requirements and is calibrated using observed time series of precipitation, air temperature and runoff at one or more points in a river network. Here, we apply PERSiST to the river Thames in the UK and describe a Monte Carlo tool for model calibration, sensitivity and uncertainty analysis
Article
Full-text available
Understanding the relative role of anthropogenic and environmental drivers on the timing, magnitude and composition of algal and cyanobacterial blooms is vitally important for the effective management of river catchments. Whilst taxonomic identification and enumeration of algal species can provide valuable insights, the time and specialist skills needed for this approach makes it prohibitive for high frequency and multiple-site studies. Other proxies for phytoplankton, such as total chlorophyll concentration provide little information on community composition. Here we demonstrate the use of flow cytometry (FCM) as a viable alternative approach for monitoring the changing seasonal patterns of abundance, composition and biovolume of phytoplankton in rivers. A FCM assay was set up and calibrated using a range of pure algal cultures and then applied to a year-long, weekly sampling campaign on the River Thames at Wallingford, UK. Ten groups of phytoplankton representing diatoms, chlorophytes, cryptophytes and cyanobacteria were monitored over the course of the year and examined in relation to river physiochemical parameters. Major diatom blooms occurred in spring and autumn, correlating with depletion of soluble reactive phosphorus and dissolved silicon concentrations and we also observed a significant and sustained cyanobacteria bloom between July and October. Pico-chlorophytes (0.2-2.0 μm in diameter) dominated the community throughout the summer period but were not detected using traditional colorimetric chlorophyll analysis, suggesting underestimates of actual phytoplankton standing stocks by traditional methods. We demonstrate high resolution sampling and FCM as a sensitive method for river ecosystem monitoring and that FCM data may be used as an indicator of riverine health.
Article
Full-text available
There are few methodologies for the use of climate change projections in decision making or risk assessment processes. In this paper we present an approach for climate risk assessment that links bottom-up vulnerability assessment with multiple sources of climate information. The three step process begins with modeling of the decision and identification of thresholds. Through stochastic analysis and the creation of a climate response function, climate states associated with risk are specified. Climate information such as available from multi-GCM, multirun ensembles, is tailored to estimate probabilities associated with these climate states. The process is designed to maximize the utility of climate information in the decision process and to allow the use of many climate projections to produce best estimates of future climate risks. It couples the benefits of stochastic assessment of risks with the potential insight from climate projections. The method is an attempt to make the best use of uncertain but potentially useful climate information. An example application to an urban water supply system is presented to illustrate the process.
Article
Full-text available
We present an analysis of different sources of impact model uncertainty and combine this with probabilistic projections of climate change. Climatic envelope models describing the spatial distribution of palsa mires (mire complexes with permafrost peat hummocks) in northern Fennoscandia were calibrated for three baseline periods, eight state-of-the-art modelling techniques and 25 versions sampling the parameter uncertainty of each technique - a total of 600 models. The sensitivity of these models to changes in temperature and precipitation was analysed to construct impact response surfaces. These were used to assess the behaviour of models when extrapolated into changed climate conditions, so that new criteria, in addition to conventional model evaluation statistics, could be defined for determining model reliability. Impact response surfaces were also combined with climate change projections to estimate the risk of areas suitable for palsas disappearing during the 21st century. Structural differences in impact models appeared to be a major source of uncertainty, with 60% of the models giving implausible projections. Generalized additive modelling (GAM) was judged to be the most reliable technique for model extrapolation. Using GAM, it was estimated as very likely (>90% probability) that the area suitable for palsas is reduced to less than half the baseline area by the period 2030-2049 and as likely (>66% probability) that the entire area becomes unsuitable by 2080-2099 (A1B emission scenario). The risk of total loss of palsa area was reduced for a mitigation scenario under which global warming was constrained to below 2 °C relative to pre-industrial climate, although it too implied a considerable reduction in area suitable for palsas.
Article
Full-text available
The dataset Future Flows Hydrology was developed as part of the project “Future Flows and Groundwater Levels” to provide a consistent set of transient daily river flow and monthly groundwater levels projections across England, Wales and Scotland to enable the investigation of 5 the role of climate variability on river flow and groundwater levels nationally and how this may change in the future. Future Flows Hydrology is derived from Future Flows Climate, a national ensemble projection derived from the Hadley Centre’s ensemble projection HadRM3-PPE to provide a consistent set of climate change projections for the whole of Great Britain at 10 both space and time resolutions appropriate for hydrological applications. Three hydrological models and one groundwater level model were used to derive Future Flows Hydrology, with 30 river sites simulated by two hydrological models to enable assessment of hydrological modelling uncertainty in studying the impact of climate change on the hydrology. Future Flows Hydrology contains an 11-member ensemble of transient projections from January 1951 to December 2098, each associated with a single realisation from a different variant of HadRM3 and a single hydrological model. Daily river flows are provided for 281 river catchments and monthly groundwater levels at 24 boreholes as .csv files containing all 11 ensemble members. When separate simulations are done 20 with two hydrological models, two separate .csv files are provided. Because of potential biases in the climate-hydrology modelling chain, catchment fact sheets are associated with each ensemble. These contain information on the uncertainty associated with the hydrological modelling when driven using observed climate and Future Flows Climate for a period representative of the reference time slice 1961– 25 1990 as described by key hydrological statistics. Graphs of projected changes for selected hydrological indicators are also provided for the 2050s time slice. Limitations associated with the dataset are provided, along with practical recommendation of use.Future Flows Hydrology is freely available for non-commercial use under certain licensing conditions. For each study site, catchment averages of daily precipitation and monthly potential evapotranspiration, used to drive the hydrological models, are made available, so that hydrological modelling uncertainty under climate change conditions can be explored further.
Article
Full-text available
The dataset Future Flows Hydrology was developed as part of the project "Future Flows and Groundwater Levels'' to provide a consistent set of transient daily river flow and monthly groundwater level projections across England, Wales and Scotland to enable the investigation of the role of climate variability on river flow and groundwater levels nationally and how this may change in the future. Future Flows Hydrology is derived from Future Flows Climate, a national ensemble projection derived from the Hadley Centre's ensemble projection HadRM3-PPE to provide a consistent set of climate change projections for the whole of Great Britain at both space and time resolutions appropriate for hydrological applications. Three hydrological models and one groundwater level model were used to derive Future Flows Hydrology, with 30 river sites simulated by two hydrological models to enable assessment of hydrological modelling uncertainty in studying the impact of climate change on the hydrology. Future Flows Hydrology contains an 11-member ensemble of transient projections from January 1951 to December 2098, each associated with a single realisation from a different variant of HadRM3 and a single hydrological model. Daily river flows are provided for 281 river catchments and monthly groundwater levels at 24 boreholes as .csv files containing all 11 ensemble members. When separate simulations are done with two hydrological models, two separate .csv files are provided. Because of potential biases in the climate–hydrology modelling chain, catchment fact sheets are associated with each ensemble. These contain information on the uncertainty associated with the hydrological modelling when driven using observed climate and Future Flows Climate for a period representative of the reference time slice 1961–1990 as described by key hydrological statistics. Graphs of projected changes for selected hydrological indicators are also provided for the 2050s time slice. Limitations associated with the dataset are provided, along with practical recommendation of use. Future Flows Hydrology is freely available for non-commercial use under certain licensing conditions. For each study site, catchment averages of daily precipitation and monthly potential evapotranspiration, used to drive the hydrological models, are made available, so that hydrological modelling uncertainty under climate change conditions can be explored further.
Article
Full-text available
The catchment of the River Thames, the principal river system in southern England, provides the main water supply for London but is highly vulnerable to changes in climate, land use and population. The river is eutrophic with significant algal blooms with phosphorus assumed to be the primary chemical indicator of ecosystem health. In the Thames Basin, phosphorus is available from point sources such as wastewater treatment plants and from diffuse sources such as agriculture. In order to predict vulnerability to future change, the integrated catchments model for phosphorus (INCA-P) has been applied to the river basin and used to assess the cost-effectiveness of a range of mitigation and adaptation strategies. It is shown that scenarios of future climate and land-use change will exacerbate the water quality problems, but a range of mitigation measures can improve the situation. A cost-effectiveness study has been undertaken to compare the economic benefits of each mitigation measure and to assess the phosphorus reductions achieved. The most effective strategy is to reduce fertilizer use by 20% together with the treatment of effluent to a high standard. Such measures will reduce the instream phosphorus concentrations to close to the EU Water Framework Directive target for the Thames.
Article
Full-text available
Assessing hydrological effects of global climate change at local scales is important for evaluating future hazards to society. However, applying climate model projections to local impact models can be difficult as outcomes can vary considerably between different climate models, and including results from many models is demanding. This study combines multiple climate model outputs with hydrological impact modelling through the use of response surfaces. Response surfaces represent the sensitivity of the impact model to incremental changes in climate variables and show probabilies for reaching a priori determined thresholds. Response surfaces were calculated using the HBV hydrological model for three basins in Sweden. An ensemble of future climate projections was then superimposed onto each response surface, producing a probability estimate for exceeding the threshold being evaluated. Site specific impacts thresholds were used where applicable. Probabilistic trends for future change in hazards or potential can be shown and evaluated. It is particularly useful for visualising the range of probable outcomes from climate models and can easily be updated with new results as they are made available.
Article
Full-text available
A probabilistic framework is presented for combining information from an ensemble of four general circulation models (GCMs), two greenhouse gas emission scenarios, two statistical downscaling techniques, two hydrological model structures, and two sets of hydrological model parameters. GCMs were weighted according to an index of reliability for downscaled effective rainfall, a key determinant of low flows in the River Thames. Hydrological model structures were weighted by performance at reproducing annual low-flow series. Weights were also assigned to sets of water resource model (CATCHMOD) parameters using the Nash-Sutcliffe efficiency criterion. Emission scenarios and downscaling methods were unweighted. A Monte Carlo approach was then used to explore components of uncertainty affecting projections for the River Thames by the 2080s. The resulting cumulative distribution functions (CDFs) of low flows were most sensitive to uncertainty in the climate change scenarios and downscaling of different GCMs. Uncertainties due to the hydrological model parameters and emission scenario increase with time but were less important. Abrupt changes in low-flow CDFs were attributed to uncertainties in statistically downscaled summer rainfall. This was linked to different behavior of atmospheric moisture among the chosen GCMs.
Article
Full-text available
Attempts to model surface-atmosphere interactions with greater physical realism have resulted in complex land surface schemes (LSS) with large numbers of parameters. A companion paper describes a multicriteria calibration procedure for extracting plot-scale estimates of the preferred ranges of these parameters from the various observational data sets that are now available. A complementary procedure is presented in this paper that provides an objective determination of the multicriteria sensitivity of the modeled variables to the parameters, thereby allowing the number of calibration parameters and hence the computational effort to be reduced. Two case studies are reported for the BATS model using data sets of typical quality but very different location and climatological regime (ARM-CART and Tucson). The sensitivity results were found to be consistent with the physical properties of the different environments, thereby supporting the reasonableness of the model formulation. Further, when the insensitive parameters are omitted from the calibration process, there is little degradation in the quality of the model description and little change in the preferred range of the remaining parameters.
Article
Full-text available
Cyanobacteria are the Earth's oldest known oxygen-evolving photosynthetic microorganisms, and they have had major impacts on shaping our current atmosphere and biosphere. Their long evolutionary history has enabled cyanobacteria to develop survival strategies and persist as important primary producers during numerous geochemical and climatic changes that have taken place on Earth during the past 3.5 billion years. Today, some cyanobacterial species form massive surface growths or 'blooms' that produce toxins, cause oxygen depletion and alter food webs, posing a major threat to drinking and irrigation water supplies, fishing and recreational use of surface waters worldwide. These harmful cyanobacteria can take advantage of anthropogenically induced nutrient over-enrichment (eutrophication), and hydrologic modifications (water withdrawal, reservoir construction). Here, we review recent studies revealing that regional and global climatic change may benefit various species of harmful cyanobacteria by increasing their growth rates, dominance, persistence, geographic distributions and activity. Future climatic change scenarios predict rising temperatures, enhanced vertical stratification of aquatic ecosystems, and alterations in seasonal and interannual weather patterns (including droughts, storms, floods); these changes all favour harmful cyanobacterial blooms in eutrophic waters. Therefore, current mitigation and water management strategies, which are largely based on nutrient input and hydrologic controls, must also accommodate the environmental effects of global warming.
Article
Full-text available
This paper presents a novel framework for undertaking climate change impact studies, which can be used for testing the robustness of precautionary climate change allowances used in engineering design. It is illustrated with respect to fluvial flood risk in the UK. The methodology departs from conventional scenario-led impact studies because it is based on sensitivity analyses of catchment responses to a plausible range of climate changes (rather than the time-varying outcome of individual scenarios), making it scenario-neutral. The method involves separating the climate change projections (the hazard) from the catchment responsiveness (the vulnerability) expressed as changes in peak flows. By combining current understanding of likelihood of the climate change hazard with knowledge of the sensitivity of a given catchment, it is possible to evaluate the fraction of climate model projections that would not be accommodated by specified safety margins. This enables rapid appraisal of existing or new precautionary allowances for a set of climate change projections, but also for any new set of climate change projections for example arising from a new generation of climate models as soon as they are available, or when focusing on a different planning time horizon, without the need for undertaking a new climate change impact analysis with the new scenarios. The approach is demonstrated via an assessment of the UK Government’s 20% allowance for climate change applied in two contrasting catchments. In these exemplars, the allowance defends against the majority of sampled climate projections for the 2080s from the IPCC-AR4 GCM and UKCP09 RCM runs but it is still possible to identify a sub-set of regional scenarios that would exceed the 20% threshold.
Article
Full-text available
Results are presented from a new version of the Hadley Centre coupled model (HadCM3) that does not require flux adjustments to prevent large climate drifts in the simulation. The model has both an improved atmosphere and ocean component. In particular, the ocean has a 1.25° × 1.25° degree horizontal resolution and leads to a considerably improved simulation of ocean heat transports compared to earlier versions with a coarser resolution ocean component. The model does not have any spin up procedure prior to coupling and the simulation has been run for over 400 years starting from observed initial conditions. The sea surface temperature (SST) and sea ice simulation are shown to be stable and realistic. The trend in global mean SST is less than 0.009 °C per century. In part, the improved simulation is a consequence of a greater compatibility of the atmosphere and ocean model heat budgets. The atmospheric model surface heat and momentum budget are evaluated by comparing with climatological ship-based estimates. Similarly the ocean model simulation of poleward heat transports is compared with direct ship-based observations for a number of sections across the globe. Despite the limitations of the observed datasets, it is shown that the coupled model is able to reproduce many aspects of the observed heat budget.
Article
Full-text available
Despite the many models developed for phosphorus concentration prediction at differing spatial and temporal scales, there has been little effort to quantify uncertainty in their predictions. Model prediction uncertainty quantification is desirable, for informed decision-making in river-systems management. An uncertainty analysis of the process-based model, integrated catchment model of phosphorus (INCA-P), within the generalised likelihood uncertainty estimation (GLUE) framework is presented. The framework is applied to the Lugg catchment (1,077 km2), a River Wye tributary, on the England–Wales border. Daily discharge and monthly phosphorus (total reactive and total), for a limited number of reaches, are used to initially assess uncertainty and sensitivity of 44 model parameters, identified as being most important for discharge and phosphorus predictions. This study demonstrates that parameter homogeneity assumptions (spatial heterogeneity is treated as land use type fractional areas) can achieve higher model fits, than a previous expertly calibrated parameter set. The model is capable of reproducing the hydrology, but a threshold Nash-Sutcliffe co-efficient of determination (E or R 2) of 0.3 is not achieved when simulating observed total phosphorus (TP) data in the upland reaches or total reactive phosphorus (TRP) in any reach. Despite this, the model reproduces the general dynamics of TP and TRP, in point source dominated lower reaches. This paper discusses why this application of INCA-P fails to find any parameter sets, which simultaneously describe all observed data acceptably. The discussion focuses on uncertainty of readily available input data, and whether such process-based models should be used when there isn’t sufficient data to support the many parameters.
Article
The mechanisms by which entrained planktonic organisms survive in river systems, despite an inexorable, unidirectional downstream transport, are revisited. The importance of channel retentivity to downstream population recruitment is emphasized. The aggregated dead-zone (ADZ) model is shown to be adequate to explain downstream recruitment of a growing population. The ADZ behaviour is more prevalent in sinuous, low-gradient reaches than in other parts of the river. Plankton selection and dynamics relate conspicuously to flow at higher discharges but other environmental features are important at low flows. Discharge variability is pivotal to the opportunities for potamoplankton to thrive. Copyright (C) 2000 John Wiley & Sons, Ltd.
Article
Algal models have been developed for the River Thames. Non-linear processes controlling algal growth are examined using a generalized sensitivity analysis technique, and the dominant parameters controlling system behaviour are identified. The extended Kalman filter is then used to estimate these important parameters. The technique of using generalized sensitivity analysis prior to EKF estimation is suggested as a pragmatic approach to the problem of identifying the subset of physically, chemically or biologically meaningful parameters controlling system behaviour in mechanistic models.-from Authors
Article
A process-based phytoplankton model developed to simulate the movement and growth of phytoplankton in river systems is presented in this paper. The model is based on mass-balance, and takes into account water temperature, light, self-shading, dissolved phosphorus and silicon concentrations. It was implemented in five reaches of the River Thames (UK), and the results compared to a novel dataset of cytometric data which includes concentrations of chlorophytes, diatoms, cyanobacteria and picoalgae. A Multi-Objective General Sensitivity Analysis was carried out in order to test the model robustness and to quantify the sensitivity to its parameters. The results show a good agreement between the simulations and the measured phytoplankton abundance. The most influential parameters were phytoplankton growth and death rates, while phosphorus concentration showed little influence, due to the high concentration of phosphorus in the Thames. The model is an important step forward towards understanding and predicting algal dynamics in river systems.
Article
There are still a number of gaps in our understanding regarding phytoplankton behaviour in rivers. Given predicted future changes in climate, which appear superficially at least, to favour larger phytoplankton blooms, this study was initiated to assess how well we can currently simulate this behaviour with a river water quality model. The river quality model (QUESTOR) was run for a 45 km stretch of the upper Thames for 2009-2011 (UK). To identify the most suitable model representation, phytoplankton was simulated and compared to actual observed data under three alternative assumptions. The first of these was of a Mixed Phytoplankton population and the other two being that there was domination by either of two groups (Green Algae, or cool water diatoms such as Stephanodiscus hantzschii) known to be abundant in the river. The factors for controlling the phytoplankton populations were found to be flow, temperature and radiation. Of these controlling factors, river flow has the larger effect on depletion or build-up of phytoplankton, based on residence time. The nutrient concentrations (phosphate and nitrate) seem to be in excess and not limiting or controlling of the phytoplankton behaviour. The data highlighted two main blooms in late spring and summer, which were successfully modelled with a Mixed Phytoplankton population (which explained 16-35% of the weekly variability throughout 2009-10). On a year-to-year time frame there is clear evidence of between-year differences in grazing loss rates. This can be accounted for by a combination of benthic filter feeders and zooplankton, both having been observed in sufficient numbers in the Thames. Crown Copyright