Eutrophic Ecosystems Research Articles

Effects of supplementary feeding in carp ponds on discharge water quality: a review

Discharge of aquacultural wastewater can lead to eutrophication and disruption of natural ecosystems in receiving water bodies. A controlled waste production strategy is necessary, therefore, in order to maintain sustainable aquacultural growth. Along with fertilisation, supplementary feeding is the major source of allochthonous matter in aquaculture and management of aquacultural waste, therefore, should be approached through diet formulation and/or feeding strategy. The introduction of highly digestible feed has reduced solid waste excretion, and further reductions can be achieved through careful selection of ingredients and processing to improve nutrient availability. Dissolved nitrogen waste can be reduced by ensuring a balance between protein and energy, such that fish use non-protein sources as energy, while phosphorous waste can be reduced through careful ingredient selection and processing to improve digestibility. Thermal and mechanical treatment of feed cereals prior to application can also help decrease the amount of poorly or undigested feed. Finally, feeding practices that minimise wastage should also be explored as they have a significant impact, not only on waste output but also on the overall economy of carp pond farming.

Entropy generation as an environmental impact indicator and a sample application to freshwater ecosystems eutrophication

Generally speaking, an ecosystem is seen as a complex set, it is composed by different biotic and abiotic parts. Naturally, each part has specifics functions related with mass and energy, those functions have influence between the parts directly and indirectly, and these functions are subjected to the basic laws of thermodynamics. If each part of the ecosystem is taken as thermodynamics system its entropy generation could be evaluated, then the total entropy generation of the ecosystem must be sum of the entropy generation in each part, to be in accordance with the Gouy-Stodola theorem. With this in mind, in this work an environmental indicator, for any kind of ecosystems, can be determined as a function of the ratio of total entropy generation for reference state, for instance a healthy forest; and the entropy generation of new different state of the same ecosystem can take, for instance a deforestation. Thus, thermodynamics concepts are applied to study the eutrophication of freshwater ecosystems; the strategy is based on techniques that integrate assumptions of the methodology of entropy generation inside ecosystems. The results show that if the amount of entropy generation is small respect a reference state; the sustainability of the ecosystem will be greater.

Eutrophication impacts littoral biota in Lake Ohrid while water phosphorus concentrations are low

Eutrophication has traditionally been measured as increased phosphorus concentrations. In some lakes, however, such as transboundary Lake Ohrid situated between Macedonia and Albania, pelagic phosphorus concentrations are low, in spite of known sources of nutrient input. We assumed that littoral biota may be more responsive to phosphorus load than water chemistry, and studied nearshore water chemistry, macrophytes, diatoms and macroinvertebrates at 30 sites around the lake, analyzing functional groups as well as standard eutrophication metrics. We hypothesized that the incorporation of nutrients into benthic biomass will conceal correlations between water phosphorus concentrations and biological eutrophication metrics, but that analysis of functional groups in addition to eutrophication metrics may help draw a plausible picture of how phosphorus is transferred through the food web. Water total phosphorus concentrations in the Lake Ohrid littoral were generally low, while all three analyzed organism groups indicated at least some degree of eutrophication. This shows that littoral biota are more sensitive indicators of nutrient input than hydrochemistry. The abundance of the benthic alga Cladophora sp. correlated positively with water total phosphorus concentrations, indicating that P-loading at local scales may be an important driver of Cladophora biomass. In contrast, none of the biotic metrics (macrophyte index, diatom index, and macroinvertebrate ICM) correlated with ambient water P-concentrations. We argue that this is not a sign of poorly working biological metrics, but a consequence of ecosystem processes in the lake littoral. Analysis of macrophyte and benthic algae abundance, and macroinvertebrate feeding types together with the biotic metrics suggests a meso- to slightly eutrophic littoral ecosystem where nutrient supply is incorporated into macrophyte and benthic algae biomass, and transferred through the food web from benthic algae to grazers, and from macrophytes to shredders and gatherers. Macroinvertebrate filter feeders correlate negatively with water total phosphorus concentrations, suggesting they remove phosphorus from the water. Our results indicate that the combined use of classical biological eutrophication metrics and functional groups may be a way to not only distinguish between oligotrophic and eutrophic ecosystems, but in addition give information as to whether or not nutrient input and nutrient removal in an ecosystem are balanced. This may eventually also give information about ecosystem functioning and ecosystem stability, and thus provide a basis for the development of “second generation” metrics for ecosystem assessment.

Seasonal δ13C and δ15N isoscapes of fish populations along a continental shelf trophic gradient

The West Florida Shelf, located in the eastern Gulf of Mexico, transitions from a eutrophic ecosystem dominated by the Mississippi River plume to mesotrophic and oligotrophic ecosystems off the coast of peninsular Florida. Three extensive trawl surveys in this region were used to acquire samples of fish muscle, benthic algae from sea urchin stomach contents, and filtered particulate organic matter (POM) to create δ13C and δ15N isoscapes. Muscle δ15N from three widely distributed fish species, Synodus foetens (inshore lizardfish), Calamus proridens (littlehead porgy), and Syacium papillosum (dusky flounder), exhibited strong longitudinal correlations (Pearson′s r=−0.67 to −0.90, p<0.001) that coincided with the principal trophic gradient, whereas δ13C values of fish muscle and benthic algae were correlated with depth (Pearson′s r=−0.34 to −0.73, p<0.05). Correlations between isotopic values and surface concentrations of chlorophyll and particulate organic carbon (POC) imply linkages between the isotopic baseline and transitions from eutrophic to oligotrophic waters. The δ13C depth gradient and the δ15N longitudinal gradient were consistent between seasons and years, providing a foundation for future stable isotope studies of animal migration in the Gulf of Mexico.

The fate of phosphorus fertilizer in Amazon soya bean fields

Fertilizer-intensive soya bean agriculture has recently expanded in southeastern Amazonia, and whereas intensive fertilizer use in the temperate zone has led to widespread eutrophication of freshwater ecosystems, the effects in tropical systems are less well understood. We examined the fate of fertilizer phosphorus (P) by comparing P forms and budgets across a chronosequence of soya bean fields (converted to soya beans between 2003 and 2008) and forests on an 800 km(2) soya bean farm in Mato Grosso, Brazil. Soya bean fields were fertilized with 50 kg P ha(-1) yr(-1) (30 kg P ha(-1) yr(-1) above what is removed in crops). We used modified Hedley fractionation to quantify soil P pools and found increases in less-plant-available inorganic pools and decreases in organic pools in agricultural soils compared with forest. Fertilizer P did not move below 20 cm. Measurements of P sorption capacity suggest that while fertilizer inputs quench close to half of the sorption capacity of fast-reacting pools, most added P is bound in more slowly reacting pools. Our data suggest that this agricultural system currently has a low risk of P losses to waterways and that long time-scales are required to reach critical soil thresholds that would allow continued high yields with reduced fertilizer inputs.

Winter and summer vertical distribution of epipelagic copepods in the Gulf of California

Summary The finding that most copepod species in the central andnorthern Gulf of California do not exhibit DVM (con-centrating in the upper 75 m) is relevant in a regionaltropho-dynamics perspective as it results in similar day–night copepod availability for their epipelagic planktivor-ous predators. The absence of copepod DVM, but notother planktonic organisms, such as euphausiids, seemsto be regulated by the combination of vertical and sea-sonal environmental conditions. Copepod distributionand abundance was positively associated with tempera-ture, depth of the thermocline, chl-a, zooplanktonbiomass and concentration of dissolved oxygen. Largeconnectivity rates are known to exist along the easternside of the Gulf and relatively high rates of retentionalong the western side (Marinone, 2012; Soria et al.,2012), causing a coast-ocean-coast ecosystem that con-trasts with cross-shelf-oceanic conditions that prevail incoastal upwelling regions (Peterson et al., 1979; Peterson,1998). All factors combined seem to favor copepodspecies that live under mesotrophic conditions in theupper 50 m and are transported across poor and richtrophic habitats in relativelyshort periods within their lifespan, as suggested by recent three-dimensional models ofparticulates tracked in surface waters. Although most ofthe copepod assemblage is of tropical zoogeographic af-finity, we found shifts in winter–summer relative abun-dance (!19% of all species) in dominant species havingdifferent body sizes. However, seasonal changes incopepod assemblages do not seem to significantly modifythe day–night copepod biomass stock for predators inthe epipelagic ecosystem of the Gulf. It is important tostudychanges in sizewithin the zooplankton assemblagesto measure biomass and vital rates (molt, growth and re-production) of at least the numerically-dominant speciesto estimate secondary production to conceptually scalethe actual productivity of the Gulf of California(Go´mez-Gutie´rrez et al., 2012; Palomares-Garci´a et al.,2013). Until this study, there were no data on which tobase such an approach in this species-diverse and eu-trophic ecosystem.

Calculation of Sulphur and Nitrogen Deposition with the Frame Model and Assessment of the Exceedance of Critical Loads in Poland

Abstract Sulphur and nitrogen deposition were calculated with the FRAME model and used to assess the exceedances of the critical loads for acidification and eutrophication of natural ecosystems in Poland. For the first time two tools: the FRAME and SONOX models were used jointly to provide information on ecosystems at risk. The FRAME model obtained close agreement with available sulphur and nitrogen wet deposition measurements. The total mass of sulphur deposited in Poland in year 2008 was estimated as 292 Gg S. Total deposition of nitrogen (oxidized + reduced) is 389 Gg N. 11% of the ecosystems in Poland were calculated to be at risk of acidification due to deposition of sulphur and nitrogen. In the case of eutrophication, over 95% of terrestrial ecosystems are at risk due to the large deposition of nitrogen compounds.

Assessing the impact of land abandonment, nitrogen enrichment and fairy-ring fungi on plant diversity of Mediterranean grasslands

Semi-natural calcareous grasslands are of great conservation interest because of their high species richness, but they are threatened by land abandonment and nitrogen eutrophication. These plant communities evolved as a result of a long history of human activity, which generated and maintained these habitats by extensive grazing and mowing. Calcareous grasslands are listed as a priority for conservation in the EC Habitats Directive. However, the effects of different management regimes, nitrogen enrichment, and soil-borne pathogens on plant species diversity are less clear for grasslands of the Mediterranean Basin, compared to meadows in Northern and Central Europe. In this study, we assessed the impact of land abandonment, nitrogen enrichment, and fairy-ring fungi on species diversity in semi-natural grasslands found in the Mediterranean Basin by comparing the available literature with findings from recent studies carried out in Central Italy. In a series of field experiments, the cutting of abandoned grassland consistently reduced the living biomass of the dominant perennial grasses, such as Brachypodium rupestre and Bromus erectus, and promoted a rapid increase in species richness and diversity by allowing the establishment of rare species. There was a similar, but less effective, restoration of species diversity and composition in mowed grassland after litter removal. We also show that nitrogen enrichment at levels comparable to atmospheric deposition depresses species diversity, which also hampers the positive effects of litter removal. Our findings are consistent with previous results achieved in Northern and Central Europe, which however, mainly focused on grasslands with intermediate to high primary productivity levels. The limited availability of data from low-productivity, drought-prone Mediterranean grasslands requires further studies to assess the impact of land abandonment and nitrogen eutrophication in such ecosystems. Finally, we discuss the role of fairy-ring fungi in the maintenance of plant diversity in species-rich grassland. We show that fairy-ring fungi (e.g. Agaricus campestris) critically affect the spatial distribution and diversity of coexisting plant species. By killing the dominant perennial herbs, these radially growing plant pathogens produce empty niches for rare, short-lived species, thus affecting the vegetation pattern. Overall, our results are of interest for environmental managers, as they provide guidelines for the restoration of abandoned areas and the conservation of these species-rich habitats.

Composition of Heterotrophic Flagellates in Coastal Waters of Different Trophic Status

Heterotrophic flagellates (HFs) are important members of the aquatic microbial food web. However, information on their spatial patterns in relation to eutrophication is limited. Here, we examined the composition and spatial distributions of HFs (<3μm) in subtropical coastal waters of different trophic status by re-analyzing two previously published small subunit rDNA pyrosequence datasets using information from the newly launched Protist Ribosomal Reference database (PR(2)). Whereas the contributions of different major clades composing the Marine Stramenopiles (MASTs), picobiliphytes and Chrysophyceae were found relatively comparable between the stations, contrasting compositions of the Marine Alveolates (MALV) groups I and II were observed. The high and relatively stable contribution of MAST-1, -3 and -7 among the MASTs in both stations suggest their importance as bacterial grazers in coastal waters, irrespective of trophic status. By contrast, the dominance of clades 3, 5 and 14 of MALV II in the eutrophic station implies their importance in regulating the dinoflagellate population at the site. Our study provides insights into the ecological importance of different HF groups in eutrophic coastal ecosystems.

Water chemistry and biology in a shallow lake (Lake Pamvotis - Greece). Present state and perspectives

Lake Pamvotis is a shallow lake, located in NW Greece, which during last decades has influenced by a lot of man-made impacts such as sewage discharge, water level fluctuation, e.t.c. Water quality for physicochemical and biological parameters was monitored seasonally in five sampling-stations from April 1998 to March 1999. Lake Pamvotis is an eutrophic ecosystem which has been influenced by the nutrients input, rates of nutrient cycling and plankton-fish dynamics. According to the nitrogen: phosphorus ratio, the limiting factor is phosphorous during spring while a nitrogen limitation is switched on during the warm season. Restoration management strategy requires reduction of external organic load, control of non-point pollution from the surrounding agricultural area and establishment of biomanipulation techniques.

Native plant restoration combats environmental change: development of carbon and nitrogen sequestration capacity using small cordgrass in European salt marshes

Restoration of salt marshes is critical in the context of climate change and eutrophication of coastal waters because their vegetation and sediments may act as carbon and nitrogen sinks. Our primary objectives were to quantify carbon (C) and nitrogen (N) stocks and sequestration rates in restored marshes dominated by Spartina maritima to provide support for restoration and management strategies that may offset negative aspects of eutrophication and climate change in estuarine ecosystems. Sediment C content was between ca. 13mgCg(-1)and sediment N content was ca. 1.8mgNg(-1). The highest C content for S. maritima was recorded in leaves and stems (ca. 420mgCg(-1)) and the lowest in roots (361 ± 4mgCg(-1)). S. maritima also concentrated more N in its leaves (31 ± 1mgNg(-1)) than in other organs. C stock in the restored marshes was 29.6tCha(-1); ca. 16% was stored in S. maritima tissues. N stock was 3.6tNha(-1), with 8.3% stored in S. maritima. Our results showed that the S. maritima restored marshes, 2.5years after planting, were sequestering atmospheric C and, therefore, provide some mitigation for global warming. Stands are also capturing nitrogen and reducing eutrophication. The concentrations of C and N contents in sediments, and cordgrass relative cover of 62%, and low below-ground biomass (BGB) suggest restored marshes can sequester more C and N. S. maritima plantations in low marshes replace bare sediments and invasive populations of exotic Spartina densiflora and increase the C and N sequestration capacity of the marsh by increasing biomass production and accumulation.

Real-time estimation of TP load in a Mississippi Delta stream using a dynamic data driven application system

Elevated phosphorus (P) in surface waters can cause eutrophication of aquatic ecosystems and can impair water for drinking, industry, agriculture, and recreation. Currently, no effort has been devoted to estimating real-time variation and load of total P (TP) in surface waters due to the lack of suitable and/or cost-effective wireless sensors. However, when considering human health, drinking water supply, and rapidly developing events such as algal blooms, the availability of timely P information is very critical. In this study, we developed a new approach in the form of a dynamic data driven application system (DDDAS) for monitoring the real-time variation and load of TP in surface water. This DDDAS consisted of the following three major components: (1) a User Control that interacts with Schedule Run to implement the DDDAS with starting and ending times; (2) a Schedule Run that activates the Hydstra model; and (3) a Hydstra model that downloads the real-time data from a US Geological Survey (USGS) website that is updated every 15 min with data from USGS monitoring stations, predicts real-time variation and load of TP, graphs the variables in real-time on a computer screen, and sends email alerts when the TP exceeds a certain value. The DDDAS was applied to monitor real-time variation and load of TP for 30 days in Deer Creek, a stream located east of Leland, Mississippi, USA. Results showed that the TP concentrations in the stream ranged from 0.24 to 0.48 mg L−1 with an average of 0.30 mg L−1 for a 30-day monitoring period, whereas the cumulative load of TP from the stream was about 2.8 kg for the same monitoring period. Our study suggests that the DDDAS developed in this study was useful for estimating the real-time variation and load of TP in surface water ecosystems.

Influence of low levels of water salinity on toxicity of nitrite to anuran larvae

Reactive nitrogen compounds such as nitrite (NO2-) are highly toxic to aquatic animals and are partly responsible for the global decline of amphibians. On some fish and Caudata amphibian species low levels of sodium chloride significantly reduce the toxicity of nitrite. However, the nitrite–salinity interaction has not been properly studied in anuran amphibians. To verify if chloride (Cl−) attenuates NO2- toxicity, eggs and larvae of three anuran species were subjected to a series of NO2- solutions combined with three salt concentrations (0, 0.4 and 2 or 0, 0.052 and 0.2gL−1NaCl). One of the species tested originated from two different populations inhabiting highly contrasted nutrient richness environments: lowland Doñana Natural Park and Sierra de Gredos Mountain. In general, the presence of Cl− increased survival and growth of lowland Pelophylax perezi and activity of mountain P. perezi larvae exposed to NO2-, thus attenuating the toxicity of NO2- to developing amphibians. Mountain amphibian populations appeared to be much more sensitive to the concentrations of NO2- and Cl− used in this experiment than coastal conspecifics, suggesting possible adaptation of populations to local conditions. Nitrogen pollution in coastal wetlands poses a serious threat to aquatic organisms, causing direct toxicity or indirect effects via ecosystem eutrophication. The presence of low to medium levels of salinity that would be common in coastal wetlands may attenuate the direct effects of increasing concentrations of nitrogenous compounds in water bodies. Furthermore, treating cultures of endangered anurans with small amounts of NaCl may provide an additional protective measure.

Sustainable Management of Algae in Eutrophic Ecosystems

The accelerated eutrophication of the world’s freshwater and marine ecosystems is a complex problem that results in decreased productivity, loss of biodiversity, and various economic woes. Controlling algae populations in a eutrophic water body has values in mitigating some of these negative effects. This paper reviews a number of strategies for algae management, with a focus on sustainable practices that have minimal environmental impact. The information in the literature is then used to propose a design for an integrated algae-aquaculture system to be used for the dual purposes of nutrient assimilation and production of fish and algal biomass. Effectiveness of the proposed system and possible revenue streams to offset capital costs are examined; other solutions that utilize the techniques in the literature are also explored.

The Limnology of Ohana Lake, a Potential Manmade Aquaculture System in Nigeria

The concentrations of heavy metals (Fe > Zn > Cu > Pb > Ag) in bottom sediments and fish gills in Ohana Lake, were found to be significantly high and far exceeded FEPA and WHO environmental standards for water quality by 1.5 to 18 times, respectively. Six classes of each of phytoplankton and zooplankton with a total of 35 phytoplankton taxa comprising 46 species i.e. 35(46) and 22(28) faunal were observed. The class Chlorophyceae dominated the phytoplankton community with 18(22) followed by Cyanobacteria 6(10). The aquatic fauna was dominated by the Rotifera 8(11), followed by the Copepoda 6(9). The benthic flora community consisted of five classes of phytoplankton made up of 28(36). The class Bacillariophyceae 11(15) dominated the group followed by Chlorophyceae 10(11). Benthic fauna were made up of seven classes of 13(13). The dominant class Nemata 4(4) was followed closely by Protozoa 2(3). Ohana Lake is fast turning to a eutrophic ecosystem with accompanied algal bloom due to very high nutrient contents. The equitability or evenness indices (J) for both phytoplankton and zooplankton were lowly indicating generally low species diversities as well as predominantly unstable ecosystem. The aquacultural implications of these parameters are discussed.

Does microbial stoichiometry modulate eutrophication of aquatic ecosystems?

The stoichiometry of prokaryotes (Bacteria and Archaea) can control benthic phosphorus (P) fluxes relative to carbon (C) and nitrogen (N) during organic matter remineralization. This paper presents the first experimental data on benthic microbial stoichiometry. We used X-ray microanalysis to determine C : N : P ratios of individual prokaryotes from C-limited Baltic Sea sediments incubated under oxic or anoxic conditions. At approximately 400:1, C : P ratios of prokaryotes from both oxic and anoxic incubations were higher than the Redfield ratio for marine organic matter (106:1), whereas prokaryotic C : N ratios (6.4:1) were close to the Redfield ratio. We conclude that high microbial C : P ratios contribute to the enhanced remineralization of P from organic matter relative to C and N observed in many low oxygen marine settings.

Sediment flux modeling: Calibration and application for coastal systems

Benthic–pelagic coupling in shallow estuarine and coastal environments is an important mode of particle and solute exchange and can influence lag times in the recovery of eutrophic ecosystems. Links between the water column and sediments are mediated by particulate organic matter (POM) deposition to the sediment and its subsequent decomposition. Some fraction of the regenerated nutrients are returned to the water column. A critical component in modeling sediment fluxes is the organic matter flux to the sediment. A method is presented for estimating POM deposition, which is especially difficult to measure, by using a combination of long term time series of measured inorganic nutrient fluxes and a mechanistic sediment flux model (SFM). A Hooke–Jeeves pattern search algorithm is used to adjust organic matter deposition to fit ammonium (NH4+) flux at 12 stations in Chesapeake Bay for up to 17 years.POM deposition estimates matched reasonably well with sediment trap estimates on average (within 10%) and were strongly correlated with previously published estimates based upon sediment chlorophyll-a (chl-a) distribution and degradation. Model versus field data comparisons of NH4+ flux, sediment oxygen demand (SOD), sulfate (SO42−) reduction rate, porewater NH4+, and sedimentary labile carbon concentrations further validated model results and demonstrated that SFM is a powerful tool to analyze solute fluxes. Monthly model-field data comparisons clearly revealed that POM decomposition in the original SFM calibration was too rapid, which has implications for lagged ecosystem responses to nutrient management efforts. Finally, parameter adjustments have been made that significantly improve model-field data comparisons and underscore the importance of revisiting and recalibrating models as long time series (>5 years) become available.

Effects of nitrogen oxides on ground vegetation, Pleurozium schreberi and the soil beneath it in urban forests

Nitrogen oxides (NOx) are among the key phytotoxic components in many urban areas and contribute to acidification and eutrophication of ecosystems. This study looked at the composition of ground layer vegetation, dry biomass and shoot length of Pleurozium schreberi ((Brid.) Mitt.), and moss and soil total carbon (C) and nitrogen (N) concentrations and ratios in relation to modelled NO, NO2 and NOx concentrations in the Helsinki Metropolitan Area, southern Finland, in September 2010. The aim was to assess the use of P. schreberi as a bioindicator of atmospheric NOx concentrations and N deposition. The modelled annual mean of NO and NO2 concentrations, and consequently NOx concentrations, were 1–20, 8–27, and 9–48μgm−3, respectively, at the sites in the Helsinki Metropolitan Area. Samples from Kevo in Finnish Lapland, where the measured annual mean NO2 concentration was 0.8μgm−3, were used as references for moss C and N. The results indicate NOx-related decreases in moss shoot length, moss total C concentration, and soil C:N ratio. The moss total N concentration of 1.23±0.13% and the soil C:N ratio of 21±4 suggest N saturation in urban forests. The composition of ground layer vegetation varied depending on the relative sensitivity of functional groups and species to total N deposition, which was estimated to range from 0.8 to 1.5gm−2a−1. P. schreberi seems to acclimatise well to open and dry urban sites by forming a more dense carpet. The results challenge the use of total N concentration of P. schreberi as a bioindicator of NOx deposition.

Rethinking the Role of Nitrogen and Phosphorus in the Eutrophication of Aquatic Ecosystems

For many years, environmental agencies have sought to improve the water quality of lakes and estuaries by reducing inputs of phosphorus. New research indicates that we must reduce both phosphorus and nitrogen to reverse eutrophication symptoms. This 3-page fact sheet was written by Karl Havens and Thomas Frazer, and published by the UF Department of Sea Grant, June 2012. SGEF190/SG118: Rethinking the Role of Nitrogen and Phosphorus in the Eutrophication of Aquatic Ecosystems (ufl.edu)

Assessment of the trophic status of four coastal lagoons and one estuarine delta, eastern Brazil

Anthropogenic eutrophication of aquatic ecosystems continues to be one of the major environmental issues worldwide and also of Brazil. Over the last five decades, several approaches have been proposed to discern the trophic state and the natural and cultural processes involved in eutrophication, including the multi-parameter Assessment of Estuarine Trophic Status (ASSETS) index model. This study applies ASSETS to four Brazilian lagoons (Mundaú, Manguaba, Guarapina, and Piratininga) and one estuarine delta (Paraíba do Sul River), set along the eastern Brazilian coast. The model combines three indices based on the pressure-state-response (PSR) approach to rank the trophic status and forecast the potential eutrophication of a system, to which a final ASSETS grade is established. The lagoons were classified as being eutrophic and highly susceptible to eutrophication, due primarily to their longer residence times but also their high nutrient input index. ASSETS classified the estuary of the Paraíba do Sul river with a low to moderate trophic state (e.g., largely mesotrophic) and low susceptibility to eutrophication. Its nutrient input index was high, but the natural high dilution and flushing potential driven by river flow mitigated the susceptibility to eutrophication. Eutrophication forecasting provided more favorable trends for the Mundaú and Manguaba lagoons and the Paraíba do Sul estuary, in view of the larger investments in wastewater treatment and remediation plans. The final ASSETS ranking system established the lagoons of Mundaú as "moderate," Manguaba as "bad," Guarapina as "poor," and Piratininga as "bad," whereas the Paraíba do Sul River Estuary was "good."