Eutrophic Ecosystems Research Articles

Methods for management of eutrophication in freshwater ecosystems in Vojvodina

Many techniques are available for improvement of water quality within the body of reservoirs: artificial mixing and oxygenation, sediment removal, sediment aeration, sediment covering, phosphorus inactivation, biomanipulation (fish management), hydraulic regulation, algaecides, light reduction, macrophyte control and ecoremediation. Ecoremediation presents a sustainable use of natural and creation of artificial ecosystems for environmental protection and restoration with a special importance for the Vojvodina water ecosystems, due to their seasonal pollution patterns and overall lack of fresh water in Republic of Serbia. ERM is already established as perspective long-term approach, utilizing natural processes and such that imitate natural processes, and systems in favor of the remediation of degraded ecosystems and environmental protection. .

Soft Paths in Wastewater Management – The Pros and Cons of Urine Source Separation

Although our water-borne urban wastewater system is successful, it has drawbacks in industrialized and developing countries alike, particularly in arid regions. It is inflexible and often inefficient. Of late, source control measures are being postulated as a paradigm change. In the Swiss transdisciplinary project Novaquatis, urine source separation, or NoMix technology, was studied. We compare NoMix technology with central wastewater treatment. Separate collection of urine has the potential to eliminate 70 to 80 percent of nitrogen from wastewater, 15 to 50 percent of phosphorus, and at least 50 percent of human pharmaceuticals. Hence, NoMix technology can contribute substantially in the reduction of eutrophication of marine ecosystems near fast-growing cities. We discuss the shortcomings of using sewage sludge or urine as fertilizers in agriculture – concerning pharmaceuticals, we also consider the societal perspective. Furthermore, NoMix technology introduces flexibility to waste-water management, important especially in light of growing uncertainties with respect to population development and climate change.

Nutrient dependent effects of consumer identity and diversity on freshwater ecosystem function

Summary1. Over the past decade, ecologists have tried to determine how changes in species composition and diversity affect ecosystem structure and function. Until recently, the majority of these studies have been conducted in terrestrial ecosystems and have not taken into account environmental variability. The purpose of this research was to determine how species identity and diversity in the freshwater zooplankton affected biomass of algae and zooplankton at two levels of nutrient enrichment.2. Several species of cladocerans were grown alone and together in microcosms at both ambient and raised phosphorus concentrations to determine if the effects of consumer identity and diversity were nutrient dependent.3. Total zooplankton biomass was greater, while algal biomass was lower, in mixed culture than in monoculture. The effects of zooplankton diversity on algal biomass, however, were only observed at raised phosphorus concentrations, suggesting that diversity effects were nutrient dependent. Specifically, diversity effects appeared to be related with biological mechanisms such as complementarity in resource use and/or facilitation.4. More diverse communities of zooplankton appear to be better able to control algae than single species of zooplankton at high nutrient concentrations; therefore, zooplankton diversity may provide a buffer against eutrophication in freshwater ecosystems.

Hydrological Variability and Agricultural Drainage Ditch Inorganic Nitrogen Reduction Capacity

The application of inorganic nitrogen fertilizers on agricultural landscapes has the potential to generate concerns of environmental degradation at fine to coarse scales across the catchment and landscape. Inorganic nitrogen species (NO3*, NO2*, and NH3) are typically associated with subsurface flow processes; however, surface runoff from rainfall events in no-till agriculture with inorganic surface fertilizers might contribute to downstream eutrophication. Inorganic nitrogen reduction capacity of agricultural drainage ditches under no-till cotton was determined under natural, variable rainfall conditions in northern Mississippi. Monthly grab baseflow samples and storm-generated flow samples were variably sampled temporally within two experimental farm ditches over 2 yr. Inorganic nitrogen concentrations, in conjunction with Manning's equation and Natural Resources Conservation Service dimensionless hydrographs, provided individual water volumes per storm event and thus maximum effluent and outflow nitrogen loads. Base and stormflow regression results indicate drainage ditches reducing NO3* and NH3 over the length of the ditch for growing and dormant seasons. Overall, maximum storm loads of dissolved inorganic nitrogen (DIN) from the farm over the 2-yr sampling period accounted for 2.2% of the initial fertilizer application, of which 1.1% left the ditch (0.84 kg ha(-1) yr(-1)) (a 57% ditch reduction of DIN load over 2 yr). Long-term sampling incorporating data on application and loss of fertilizers and farm management will provide critical information for farmers and scientists on the potential of economic gains and downstream ecosystem eutrophication, respectively.

Spatial planning for lowland stream basins using a bioeconomic model

Most lowland stream drainage-basins have a high population density and the land use is very intensive. The permeable subsoil acts as an integrating medium, thus providing a widespread dispersal of leached nutrients and transmission of water-table lowering. This leads to eutrophication and desiccation of stream ecosystems. For providing suggestions with respect to cost-effective and sustainable spatial planning solutions, the ‘Waterwise’ bioeconomic model has been developed. It combines the accuracy of simulation models with the versatility of optimization techniques to generate land-use patterns along with the appropriate water management, taking into account the preferences of stakeholders with respect to peak discharges, nutrient loading on groundwater and surface water, the biological value of nature areas, and the revenue from agriculture. Computational experiments with the model show, for instance, that a certain goal for the nitrogen load on surface water can be reached at a 40% lower cost if the measures are ‘tailored’ to the region instead of using generic-style measures towards the same end.

Aquatic eutrophication promotes pathogenic infection in amphibians

The widespread emergence of human and wildlife diseases has challenged ecologists to understand how large-scale agents of environmental change affect host-pathogen interactions. Accelerated eutrophication of aquatic ecosystems owing to nitrogen and phosphorus enrichment is a pervasive form of environmental change that has been implicated in the emergence of diseases through direct and indirect pathways. We provide experimental evidence linking eutrophication and disease in a multihost parasite system. The trematode parasite Ribeiroia ondatrae sequentially infects birds, snails, and amphibian larvae, frequently causing severe limb deformities and mortality. Eutrophication has been implicated in the emergence of this parasite, but definitive evidence, as well as a mechanistic understanding, have been lacking until now. We show that the effects of eutrophication cascade through the parasite life cycle to promote algal production, the density of snail hosts, and, ultimately, the intensity of infection in amphibians. Infection also negatively affected the survival of developing amphibians. Mechanistically, eutrophication promoted amphibian disease through two distinctive pathways: by increasing the density of infected snail hosts and by enhancing per-snail production of infectious parasites. Given forecasted increases in global eutrophication, amphibian extinctions, and similarities between Ribeiroia and important human and wildlife pathogens, our results have broad epidemiological and ecological significance.

Analysis of the bacterial community developing in the course of Sphagnum moss decomposition

Slow degradation of organic matter in acidic Sphagnum peat bogs suggests a limited activity of organotrophic microorganisms. Monitoring of the Sphagnum debris decomposition in a laboratory simulation experiment showed that this process was accompanied by a shift in the water color to brownish due to accumulation of humic substances and by the development of a specific bacterial community with a density of 2.4 x 10(7) cells ml(-1). About half of these organisms are metabolically active and detectable with rRNA-specific oligonucleotide probes. Molecular identification of the components of this microbial community showed the numerical dominance of bacteria affiliated with the phyla Alphaproteobacteria, Actinobacteria, and Phanctomycetes. The population sizes of Firmicutes and Bacteroidetes, which are believed to be the main agents of bacterially-mediated decomposition in eutrophic wetlands, were low. The numbers of planctomycetes increased at the final stage of Sphagnum decomposition. The representative isolates of Alphaproteobacteria were able to utilize galacturonic acid, the only low-molecular-weight organic compound detected in the water samples; the representatives of Planctomycetes were able to decompose some heteropolysaccharides, which points to the possible functional role of these groups of microorganisms in the community under study. Thus, the composition of the bacterial community responsible for Sphagnum decomposition in acidic and low-mineral oligotrophic conditions seems to be fundamentally different from that of the bacterial community which decomposes plant debris in eutrophic ecosystems at neutral pH.

Prey composition in the carnivorous plants Utricularia inflata and U. gibba (Lentibulariaceae) from Paria Peninsula, Venezuela

Carnivorous aquatic plants, genus Utricularia (Lentibulariaceae), capture small aquatic organisms, such as rotifers, copepods, and cladocerans, by means of anatomical structures named bladders. The present study aimed to determine prey size and composition in U. gibba and U inflata, which were collected from a small lake and an herbaceous wetland, respectively, located in Paria Peninsula (Sucre State, Venezuela). Water pH, conductivity, dissolved oxygen, and salinity were measured in situ at each sampling location, and water samples were collected to determine N-Kjeldahl, total-P, Na+, K+, Ca++, Mg++, and Cl-. Fifty bladders from each plant species were measured and their contents were analyzed. N-Kjeldahl and total-P values were similar in both sites, and were also similar to values reported for eutrophic ecosystems, although Na+, K+, Ca++, Mg++ concentrations and in situ water parameter values were higher in the herbaceous wetland. Bladder content showed the following zooplankton groups: rotifers, cladocerans, copepods, annelids, rhizopodeans, and insects; and the following phytoplankton divisions: Bacillariophyta, Chlorophyta, Cyanophyta, and Euglenophyta. U. inflata presented smaller and fewer bladders, but higher abundance and total algal and animal morphospecies richness than U. gibba. Prey composition similarity at the taxon level between the two carnivorous species was low.

A whole-farm assessment of the efficacy of slurry acidification in reducing ammonia emissions

Livestock slurry in animal houses, in manure stores and applied on fields is in Denmark the most important source of ammonia (NH 3) in the atmosphere. The emitted NH 3 is a source of NH 3 and ammonium (NH 4 +) deposition, which causes eutrophication of N-deficient ecosystems and may form NH 4 +-based particles in the air, which are a risk to health. This study examines the reductions in NH 3 emissions from pig houses, manure stores and manure applied in the field achieved by acidifying the slurry in-house. Sulphuric acid was used to acidify pig slurry to pH < 6 and the system was constructed is such a way as to prevent foaming in the animal house as well as during storage. Acidification of the pig slurry reduced the NH 3 emission from pig houses by 70% compared with standard techniques. Acidification reduced NH 3 emission from stored slurry to less than 10% of the emission from untreated slurry, and the NH 3 emission from applied slurry was reduced by 67%. The mineral fertilizer equivalent (MFE) of acidified slurry was 43% higher compared with the MFE of untreated slurry when applied to the soil. The odour emission from the slurry was not affected significantly by the treatment. The slurry acidification system is approved Best Available Technology (BAT) in Denmark.

Environmental factors influencing the biodeposition of the suspension feeding bivalve Dreissena polymorpha (Pallas): Comparison of brackish and freshwater populations

Invasive suspension feeders have been particularly successful in shallow eutrophic estuarine and freshwater ecosystems. The impact of an invasive species is strong under favourable conditions. However, suboptimal feeding conditions may significantly reduce the impact to ambient environment. The invasive bivalve Dreissena polymorpha (Pallas) is able to colonize both fresh and brackish waterbodies. In an in situ experiment the seasonal variability in the biodeposition of D. polymorpha from fresh and brackish water populations was quantified at different temperature, salinity and chlorophyll a (Chl a) regimes. Salinity fluctuations in brackish water areas, temperature and water Chl a content were all important factors in the model of mussels' feeding. The results indicated that D. polymorpha fed significantly more in fresh than in brackish water. Mussels acclimated more easily to acute transfer from brackish to freshwater than vice versa. The biodeposition of zebra mussels increased with temperature and water Chl a content but these effects were less straightforward than that of salinity. The results suggest that the impact of D. polymorpha on recipient ecosystem is more pronounced in fresh than in brackish water environments.

Stable isotopic composition of nitrate in Lake Taihu, China, and major inflow rivers

Identification of sources of nutrient pollution is a first step towards remediation of eutrophication in aquatic ecosystems. The stable isotope nitrogen-15 (15N) is a natural indicator of nitrogen (N) source and biogeochemistry. We sampled Lake Taihu, a hyper-eutrophic lake in eastern China, and major inflow rivers during winter and spring of 2004 to determine concentration and δ15N of nitrate (NO 3 − ). Nitrate concentrations in rivers and the lake were higher, in most cases, in spring than in winter. δ15N of NO 3 − was not correlated with NO 3 − concentration, indicating that concentrations alone are insufficient to describe N sources. Results show that riverine N inputs in winter are influenced by discharge of human sewage into rivers and the lake. In spring, however, wastewater inputs to the lake appear to be balanced by fertilizers, atmospheric, and/or N2 fixation sources. Rain NO 3 − concentrations were seasonally high and isotopically enriched compared to potential sources, indicating that rain may be a significant or even dominant source of N to the lake during the rainy season. δ15N values show that urbanized areas of the lake have more sewage-derived N than those areas dominated by agriculture, aquaculture, or industry. This observation has important implications for human health, since Lake Taihu is a source of drinking and irrigation water as well as fish for human consumption.

Phosphorus speciation, burial and regeneration in coastal lagoon sediments of the Gippsland Lakes (Victoria, Australia)

Environmental context. Eutrophication can lead to the production of harmful algal blooms and is one of the world’s most serious water quality issues. Phosphorus is potentially the limiting macro-nutrient in fresh, estuarine and some marine waters. Consequently, it plays a crucial role in determining the ecological status of many aquatic ecosystems. Considerable effort has been invested in monitoring dissolved reactive phosphorus and total phosphorus in the water column, but less is known about the speciation of phosphorus, particularly in the sediment. This compartment is an important and dynamic reservoir of phosphorus and a potential long-term source of phosphorus release to the water column by the sediment–water interface. This paper investigates the solid-phase speciation and reorganisation of phosphorus within the sediments of a shallow lake system in south-east Australia (the Gippsland Lakes) which suffers from recurring harmful algae blooms. Various strategies are proposed to determine the minimum realistic timescale required to deplete the sediment of labile and reactive phosphorus species. Abstract. Solid-phase phosphorus pools in the sediments of two shallow lakes (Wellington and Victoria) in the Gippsland Lakes coastal lagoon system of south-east Australia are discussed. Cores (20-cm depth) were taken in summer and winter in both lakes and a sequential extraction scheme (SEDEX) was used to profile the exchangeable P (Pex), iron oxide/hydroxide bound P (PFe), authigenic P (Pauth), detrital P (Pdet) and organic P (Porg). Pore-water (Ppw) dissolved reactive phosphorus concentration profiles were also measured. The dominant forms of P were PFe (up to 53%) and Porg (35–55%), with the PFe fraction playing a key role in the short-term retention of P in the sediment. Benthic phosphorus fluxes at the sediment–water interface (μmol m–2 d–1) were determined from the sequential extraction data. The results were compared with flux measurements from the complementary approaches of benthic chamber experiments and Fickian diffusion calculations, to allow an insight into the nature and seasonal variations of the fluxes. The burial flux of phosphorus was also estimated from excess 210Pb profiles in the sediment of the lakes. All of these data were used to produce a phosphorus budget for the Gippsland Lakes which suggested that the sediment represents a substantial source of phosphorus within the lakes and thus clearly highlights the importance of the sedimentary compartment in shallow eutrophic ecosystems. Minimum realistic timescales for complete labile phosphorus depletion from the sediment (assuming no resupply from the sediment–water interface) were calculated and ranged from 8 to 22 years.

Phosphorus Sorption by Sediments from Wetlands in the Cedar River Watershed

Excess phosphorus can lead to eutrophication of aquatic ecosystems, which can indirectly cause many species to suffer due to lower oxygen levels. The intent of this project was to determine if wetlands draining agricultural soil in the Cedar River watershed are removing phosphorus prior to empting into a tributary of the Cedar River. To determine the fate and transport of phosphorus in the wetlands, the total phosphorus (TP) of both the water and sediments was measured, and the ability for sediments to remove phosphate was also determined. The TP in the water column in the wetlands varied temporally from 700 to 1700 μg/L. Dissolved inorganic phosphate (SRP) totals were usually less than 10% of the total P, with a modest spike observed after a rainfall event. The low levels of SRP in the water led to testing of the TP levels in sediments and TP sorption capabilities. The TP of the sediment varied spatially from 500-700 μg/gdw. Sediments from the tributary (Beaver Creek) had total phosphorus levels of about 500 μg/gdw and the inlet to the wetlands varied from 300-400 μg/gdw. Depending on sampling locations, maximum sorption for sediments from the main body of the wetland ranged from 2-9 mg/gdw. Sediments from both the tributary (Beaver Creek) and the inlet to the wetlands sorbed about 7 mg/gdw. The results suggest that sediments in the wetlands are not yet saturated with phosphorus and therefore, when aerobic, can prevent phosphorus transport to rivers and streams.

Heterotrophic bacteria abundances in Rodrigo de Freitas Lagoon (Rio de Janeiro, Brazil)

The Rodrigo de Freitas Lagoon (RJ, Brazil) is an important coastal ecosystem that has been submitted to an accelerated degradation process. The aim of this work was to determine the abundance and the spatial distribution of total heterotrophic (by flow cytometry) and cultivated bacteria ("pour plate" method on R2A agar). Another objective was to evaluate the lagoon's influence on water quality of Ipanema and Leblon beaches. Physical and chemical data were acquired too. Sub-superficial water samples were taken monthly, from December 1999 to October 2000. On lagoon, the cultivated bacteria abundance varied from 6.9x10(5) to 5.0x10(7) CFU.100 mL-1. On Ipanema and Leblon beaches, this parameter yielded 1.4x10(5) and 2.8x10(6) CFU.100 mL-1, respectively. Total bacterial abundance varied from 2.9x10(7) to 3.2x10(7) cells.mL-1 on lagoon. On Ipanema and Leblon, this parameter yielded 8.7x10(6) and 1.1x10(7) cells.mL-1, respectively. Two sub-groups were determined with dominance of HNA cells. Samples were added latter to better understand the bacteria present on these environments. Bacterial abundance were analyzed only by flow cytometry and the results varied from 8.3x10(6) to 2.5x10(7) cells.mL-1 on lagoon. On the beach, this parameter yielded 6.9x10(6) cells. mL-1. Two bacterial sub-groups were also observed, with dominance of HNA on lagoon and LNA on the beach. The results showed that the Rodrigo de Freitas Lagoon is an eutrophic ecosystem where the bacterial populations and the physical and chemical parameters do not differ spatially. The data also confirmed that the outflow of the lagoon's polluted waters affect the sanitary conditions of Ipanema and Leblon beaches.

THE ENIGMA OF PROGRESS IN DENITRIFICATION RESEARCH

Humans have dramatically increased the amount of reactive nitrogen (primarily ammonium, nitrogen oxides, and organically bound N) circulating in the biosphere and atmosphere, creating a wide array of desirable products (e.g., food production) and undesirable consequences (e.g., eutrophication of aquatic ecosystems and air pollution). Only when this reactive N is converted back to the chemically unreactive dinitrogen (N2) form, do these cascading effects of elevated reactive N cease to be of concern. Among the quantitatively most important processes for converting reactive N to N2 gas is the biological process of classical denitrification, in which oxides of nitrogen are used as terminal electron acceptors in anaerobic respiration. This Invited Feature on denitrification includes a series of papers that integrate our current state of knowledge across terrestrial, freshwater, and marine systems on denitrification rates, controlling factors, and methodologies for measuring and modeling denitrification. In this paper, we present an overview of the role of denitrification within the broader N cycle, the environmental and health concerns that have resulted from human alteration of the N cycle, and a brief historical perspective on why denitrification has been so difficult to study. Despite over a century of research on denitrification and numerous recent technological advances, we still lack a comprehensive, quantitative understanding of denitrification rates and controlling factors across ecosystems. Inherent problems of measuring spatially and temporally heterogeneous N2 production under an N2-rich atmosphere account for much of this slow progress, but lack of interdisciplinary communication of research results and methodological developments has also impeded denitrification research. An integrated multidisciplinary approach to denitrification research, from upland terrestrial ecosystems, to small streams, river systems, estuaries, and continental shelf ecosystems, and to the open ocean, may yield new insights into denitrification across landscapes and waterscapes.

POSITIVE FEEDBACK AND THE DEVELOPMENT AND PERSISTENCE OF ECOSYSTEM DISRUPTIVE ALGAL BLOOMS1

Harmful algal blooms (HABs) have occurred with increasing frequency in recent years with eutrophication and other anthropogenic alterations of coastal ecosystems. Many of these blooms severely alter or degrade ecosystem function, and are referred to here as ecosystem disruptive algal blooms (EDABs). These blooms are often caused by toxic or unpalatable species that decrease grazing rates by planktonic and benthic herbivores, and thereby disrupt the transfer of nutrients and energy to higher trophic levels, and decrease nutrient recycling. Many factors, such as nutrient availability and herbivore grazing have been proposed to separately influence EDAB dynamics, but interactions among these factors have rarely been considered. Here we discuss positive feedback interactions among nutrient availability, herbivore grazing, and nutrient regeneration, which have the potential to substantially influence the dynamics of EDAB events. The positive feedbacks result from a reduction of grazing rates on EDAB species caused by toxicity or unpalatability of these algae, which promotes the proliferation of the EDAB species. The decreased rates also lower grazer‐mediated recycling of nutrients and thereby decrease nutrient availability. Since many EDAB species are well‐adapted to nutrient‐stressed environments and many exhibit increased toxin production and toxicity under nutrient limitation, positive feedbacks are established which can greatly increase the rate of bloom development and the adverse effects on the ecosystem. An understanding of how these feedbacks interact with other regulating factors, such as benthic/pelagic nutrient coupling, physical forcing, and life cycles of EDAB species provides a substantial future challenge.

Prognosis of the state (eutrophication and pollution) of freshwater ecosystems on the example of longterm research into Lake Baikal

porewaters were AN 20.61 mg/L, Nitr-N 12.72 mg/L, org-N 3.65 mg/L, and TN 36.98 mg/L in the Fu River; 27.54 mg/L, Nitr-N 27.54 mg/L, org-N 5.26 mg/L, and TN 42.24 mg/L in the Nan River. In the Fu River, the org-N was relatively scarce and maintained a smooth pattern fluctuating between 6.04 mg/L to 0.86 mg/L. In comparison with marine and lake systems, urban river suffered from direct municipal and industrial wastewater discharges. In porewaters and overlying waters of the two rivers, it was found that AN was the predominant form, followed by nitrate-nitrite and the organic (in minimal). As to the high concentration in overlying water and correlation coefficients between AN, Nitr-N, org-N in porewaters, it was demonstrated that the AN was mainly derived ~om the overlying water penetration but from the ammonification by bacterial activities, which indicated the river sediment acts as an important reservoir for excess inputs of nutrients, Secondly, it seems that ammonification and nitrification were restricted owing to high diffusion to the fluvial sediment and the sediment characteristics may also affect the transformations of nitrogen species.

Nitrogen as the limiting nutrient for eutrophication in coastal marine ecosystems: Evolving views over three decades

The first special volume of Limnology and Oceanography, published in 1972, focused on whether phosphorus (P) or carbon (C) is the major agent causing eutrophication in aquatic ecosystems. Only slight mention was made that estuaries may behave differently from lakes and that nitrogen (N) may cause eutrophication in estuaries. In the following decade, an understanding of eutrophication in estuaries proceeded in relative isolation from the community of scientists studying lakes. National water quality policy in the United States was directed almost solely toward P control for both lakes and estuaries, and similarly, European nations tended to focus on P control in lakes. Although bioassay data indicated N control of eutrophication in estuaries as early as the 1970s, this body of knowledge was treated with skepticism by many freshwater scientists and water‐quality managers, because bioassay data in lakes often did not properly indicate the importance of P relative to C in those ecosystems. Hence, the bioassay data in estuaries had little influence on water‐quality management. Over the past two decades, a strong consensus has evolved among the scientific community that N is the primary cause of eutrophication in many coastal ecosystems. The development of this consensus was based in part on data from whole‐ecosystem studies and on a growing body of evidence that presented convincing mechanistic reasons why the controls of eutrophication in lakes and coastal marine ecosystems may differ. Even though N is probably the major cause of eutrophication in most coastal systems in the temperate zone, optimal management of coastal eutrophication suggests controlling both N and P, in part because P can limit primary production in some systems. In addition, excess P in estuaries can interact with the availability of N and silica (Si) to adversely affect ecological structure. Reduction of P to upstream freshwater ecosystems can also benefit coastal marine ecosystems through mechanisms such as increased Si fluxes.

An investigation of the potential to use street trees and their root zone soils to remove nitrogen from urban stormwater

Eutrophication in coastal ecosystems is often attributed to elevated nitrogen levels. Reducing the amount of nitrogen entering Port Phillip Bay is therefore an important objective for Melbournians. This article details the performance of a pilot scale street tree bioretention system in reducing nitrogen loads in urban stormwater. Three tree species (Eucalyptus polyanthemos, Lophostemon confertus and Platanus orientalis) and three sandy soils of different hydraulic conductivity (4, 95 and 170 mm/hr) were tested in a randomised block design. Over the course of the experiment, all species displayed seasonal height growth patterns with maximum growth rates occurring in late Spring and Summer. Applications of stormwater increased height growth and root length density compared with tapwater applications. Tree growth was similar in the three soils studied. During the warmer months, leachate volumes from the planted systems were significantly less than the unplanted systems due to transpirational drying. Leached nitrogen loads were significantly reduced in systems with a tree. Whilst there were some statistically significant differences in ammonium, oxidised nitrogen and organic nitrogen removal between species, these were not large in practical terms. In December, total nitrogen load removal from stormwater was 82 to 95% in planted systems (L. confertus), compared to 36 to -7% in the unplanted systems

Eutrophication of freshwater and marine ecosystems

Initial understanding of the links between nutrients and aquatic productivity originated in Europe in the early 1900s, and our knowledge base has expanded greatly during the past 40 yr. This explosion of eutrophication‐related research has made it unequivocally clear that a comprehensive strategy to prevent excessive amounts of nitrogen and phosphorus from entering our waterways is needed to protect our lakes, rivers, and coasts from water quality deterioration. However, despite these very significant advances, cultural eutrophication remains one of the foremost problems for protecting our valuable surface water resources. The papers in this special issue provide a valuable cross section and synthesis of our current understanding of both freshwater and marine eutrophication science. They also serve to identify gaps in our knowledge and will help to guide future research.