Assessment Of Estuarine Trophic Status Research Articles

A comprehensive approach to assessing eutrophication for the Guangdong coastal waters in China

Eutrophication is a global issue associated with increasing anthropogenic activities. Previous studies have mainly focused on nutrients and phytoplankton biomass in some typical estuaries and bays along the Guangdong coast, while integrated evaluations of eutrophication status based on ecological symptoms is still rare in this area. To better understand the health of the Guangdong coastal waters, two comprehensive methods including the Assessment of Estuarine Trophic Status (ASSETS) and the Northwest Pacific Action Plan Common Procedure (NOWPAP CP) were employed with slight modifications. The study area was divided into eight coastal zones (Z1~Z8) based on multiple criteria including salinity, catchment range, and administrative division. The results of the modified NOWPAP CP method demonstrated a generally increasing trend in the degree and effects of nutrient enrichment along the Guangdong coast in the past 30 years mainly due to the increasing nutrients and chlorophyll a (Chl-a). The results of the modified ASSETS method revealed that the water quality was between moderate and high for most coastal zones during 2015-2018, with the highest score (0.83) in the northern part of the Pearl River Estuary (PRE). However, the ecological symptoms showed inconsistent spatial patterns with the water quality, being high or moderate high in Z2 (including Zhanjiang Harbor and Leizhou Bay), Z4~Z5 (representing the northern and southern parts of the PRE, respectively), and Z6 (containing Mirs Bay and Daya Bay) for severe ecological symptoms, such as high levels of Chl-a, frequent harmful algal blooms (HABs). Moreover, eutrophication in Z4~Z6 may further deteriorate due to the increasing nutrient loads driven by growing economy and population. Synthetically, Z2, Z4~Z6 were graded between poor and bad for the overall eutrophication conditions (OEC), while Z1 (including the western and southern parts of the Leizhou Peninsula) and Z7 (consisting of Honghai Bay and Jieshi Bay) had a good OEC. The application of the modified ASSETS method effectively identified areas of severe eutrophication problems and the prospect of nutrient load along the Guangdong coast. The assessment results revealed the spatiotemporal variations and potential trends in the eutrophication status, providing scientific basis for the coastal management related to nutrient problems.

Eutrophication assessment and environmental management perspectives of Tóbari: an arid subtropical coastal lagoon of the Gulf of California.

Coastal lagoons are vulnerable to eutrophication processes. In this study, we evaluate the eutrophication process in the restricted, arid subtropical Tóbari coastal lagoon, located in the eastern coast of the Gulf of California, where the main source of nutrient inputs and other pollutants is agricultural wastewater from the Yaqui Valley. The Assessment of Estuarine Trophic Status (ASSETS) model and the Trophic State Index (TRIX) were used to evaluate eutrophication. Overall, ASSETS showed that the Tóbari lagoon has a moderate eutrophication process, with seasonal symptoms of hypoxia, increased phytoplankton biomass, dominance of macroalgae (indicative of nutrient enrichment), and blooms development of potentially harmful algae species. The TRIX showed that the lagoon is mesotrophic most of the year. Challenges of environmental management detected correspond to reducing the input of nutrients and others contaminants from anthropic sources: agriculture, shrimp farming, livestock, and urban zones.

Evaluation of environmental impact of red tide around Pearl River Estuary, Guangdong, China

This paper presents a case study of red tide hazards around the Pearl River Estuary (PRE). Red tide hazards, meteorological data, and seawater monitoring data were collected from 1996 to 2020 at different locations around the PRE to investigate the internal and external factors influencing the occurrence of red tides. The enhancement of the assessment of estuarine trophic status (ASSETS) method enables us to evaluate the effects of meteorological factors and seawater eutrophication status on the red tide risk level. Using ASSETS, we established a framework for red tide risk assessment of the Pearl River Estuary. We analysed the external and internal factors causing the red tide based on meteorological data and seawater monitoring data in the PRE. The results show that the temperature was higher than the annual monthly average temperature of 1.265 °C, and east and north winds at velocities of 3–4 m/s could result in the formation of red tides. However, precipitation inhibits the formation of the red tide in PRE.

Multiple stressors influencing the general eutrophication status of transitional waters of the Brazilian tropical coast: An approach utilizing the pressure, state, and response (PSR) framework

Modeling approaches are useful tools for assessing the general state of eutrophication and understanding the effects of multiple stressors on coastal ecosystems. Thus, we hypothesized that anthropogenic pressures and multiple stressors would increase the trophic state of macrotidal estuaries. Datasets from long-term (2012−2020) environmental and biological monitoring in the Itapecuru River estuary (IRE) were analyzed using the pressure-state-response (PSR) approach and nonlinear methods. Our results indicated a low dilution of nutrients and a moderate flushing potential of urban effluent (2150.94 ton year−1) in the estuary. The estuary was consequently classified as being in a high trophic state, being susceptible to and suffering high estuarine pressure to develop eutrophic symptoms. The Assessment of estuarine trophic status (ASSETS) model indicates that eutrophication is seasonal and depends on climatic variation. La Niña events (2019–2020) contributed to chlorophyll-a (>40 μg L−1) and orthophosphate (0.04 mg L−1) concentrations, principally during periods of low river discharge. According to the GAM's model, brackish waters (salinity>10) with high temperatures (> 30 °C) and high dissolved oxygen (>4 mg L−1) have more intense trophic conditions, especially in the mixing zone. The low dissolved oxygen (DO) levels (DO<3 mg L−1) and high concentrations of chlorophyll-a in the seawater zone indicate that the lower portion of the estuary was the most susceptible. In addition, the random forest model selected salinity, DIP and Chl-a as the principal stressors that intensified eutrophication in the macrotidal systems. According to the ASSETS final ranking (worsen-high) for the next decade (2021−2031), the primary planned strategies should be to reduce anthropogenic contributions and improve trophic conditions in the IRE. From these results, the interactions and predictions of eco-hydrological effects could facilitate the characterization of future risks and the management of macrotidal estuarine systems.

Assessment of red tide risk by integrating CRITIC weight method, TOPSIS-ASSETS method, and Monte Carlo simulation

This study proposes a red tide risk assessment method based on intercriteria correlation (CRITIC), technique for order preference by similarity to an ideal solution (TOPSIS), assessment of estuarine trophic status (ASSETS) methods and Monte Carlo simulation (MCS) to calculate the probability of each risk level. The integrated TOPSIS-ASSETS method is used to calculate the risk levels of each year, where index weight is determined by CRITIC method. MCS method is employed to calculate the probability of each risk level. The results showed that level III to level V indicates high possibility of red tides in the case study area (Tolo Harbor). The highest risk rating was level V in 1988. The change of the risk level of red tide is consistent with the real situation of the occurrence of red tide. Another case of the east part of Skagerrak Strait shows that the results of this method are consistent with field situation. When there is an error between the evaluation results and the real situation, MCS can further suggest the probability of error in the evaluation results. Meanwhile, sensitivity analysis was used to test the performance of the evaluation model and two comparative methods. The results show that the proposed risk assessment method has better performance than other methods and can provide an effective risk evaluation for red tide management.

Compound eutrophication index: An integrated approach for assessing ecological risk and identifying the critical element controlling harmful algal blooms in coastal seas.

Current ecological risk assessment and controlling element identification methods of harmful algal blooms (HABs) are not connected. Here, we identified the controlling elements by correlation and principal component analyses, and the analytic hierarchy process. A compound eutrophication index (CEI) integrating risk assessment with controlling element identification was constructed and verified using data collected from Jiaozhou Bay, China. The CEI results agreed with the chlorophyll-a concentration and the main eutrophication assessment results. The HAB risk assessment of the CEI was more efficient than that of the nutrient quality index and Assessment of Estuarine Trophic Status. The contribution ratio of the loads and concentrations of nutrients (nitrogen, phosphorus, and chemical oxygen demand) to HABs in Jiaozhou Bay was 70%. In the high-risk areas, the contribution ratio of nutrients to HABs was 77%. Therefore, terrestrial nutrient inputs must be reduced to prevent and control HABs in the north-eastern areas of Jiaozhou Bay.

Ecosystem services of geoduck farming in South Puget Sound, USA: a modeling analysis

Provisioning and regulatory ecosystem services of Pacific geoduck clam (Panopea generosa) culture were simulated for an intertidal shellfish farm in Eld Inlet, South Puget Sound, Washington, USA. An individual geoduck clam growth model was developed, based on a well-established framework for modeling bivalve growth and environmental effects (AquaShell™). Geoduck growth performance was then validated and calibrated for the commercial farm. The individual model was incorporated into the Farm Aquaculture Resource Management (FARM) model to simulate the production cycle, economic performance, and environmental effects of intertidal geoduck culture. Both the individual and farm-scale models were implemented using object-oriented programming. The FARM model was then used to evaluate the test farm with respect to its role in reducing eutrophication symptoms, by applying the Assessment of Estuarine Trophic Status (ASSETS) model. Farm production of 17.3 t of clams per 5-year culture cycle is well reproduced by the model (14.4 t). At the current culture density of 21 ind m−2, geoduck farming at the Eld Inlet farm (area: 2684 m2) provides an annual ecosystem service corresponding to 45 Population-Equivalents (PEQ, i.e. loading from humans or equivalent loading from agriculture or industry) in top-down control of eutrophication symptoms. This represents a potential nutrient-credit trading value of over USD 1850 per year, which would add 1.48% to the annual profit (USD 124,900) from the clam sales (i.e. the provisioning service). A scaling exercise applied to the whole of Puget Sound estimated that cultured geoducks provide a significant ecosystem service, of the order of 11,462 PEQ per year (about USD 470,600) in removing primary symptoms of eutrophication, at the level of the whole water body. The modeling tools applied in this study can be used to address both the positive and negative externalities/impacts of shellfish aquaculture practices in the ecosystem and thus the trade-offs of the activity.

Detecting Eutrophication Symptoms in a Subtropical Semi-Arid Coastal Lagoon by Means of Three Different Methods

Excess supply of nutrients of anthropogenic origin is one of the main drivers of global change that is affecting the ecological function and provision of ecosystem services by coastal wetlands. This study examines the response of a subtropical semi-arid coastal lagoon to anthropogenic nutrient input, through the use and comparison of eutrophication indices and models, and compares the usefulness of such methods to identify eutrophication symptoms. The Lobos Lagoon is located on the eastern coast of the Gulf of California and receives agricultural and urban wastewater discharges. To identify potential eutrophication symptoms, the Trophic IndeX (TRIX), the Arid Zone Coastal Water Quality Index (AZCI) along with the Assessment of Estuarine Trophic Status (ASSETS) model were used. Lobos Lagoon was found to have good environmental condition; however eutrophication symptoms were identified in the zone where untreated urban and agricultural wastewaters are discharged. Results obtained using the three methods were consistent and, thus, their performance can be considered as good and complementary, and can be used to evaluate the extent of eutrophication in subtropical semi-arid coastal lagoons.

Seasonal and spatial variations of water quality and trophic status in Daya Bay, South China Sea

Coastal water quality and trophic status are subject to intensive environmental stress induced by human activities and climate change. Quarterly cruises were conducted to identify environmental characteristics in Daya Bay in 2013. Water quality is spatially and temporally dynamic in the bay. Cluster analysis (CA) groups 12 monitoring stations into two clusters. Cluster I consists of stations (S1, S2, S4–S7, S9, and S12) located in the central, eastern, and southern parts of the bay, representing less polluted regions. Cluster II includes stations (S3, S8, S10, and S11) located in the western and northern parts of the bay, indicating the highly polluted regions receiving a high amount of wastewater and freshwater discharge. Principal component analysis (PCA) identified that water quality experience seasonal change (summer, winter, and spring–autumn seasons) because of two monsoons in the study area. Eutrophication in the bay is graded as high by Assessment of Estuarine Trophic Status (ASSETS).

Ecosystem goods and services from Manila clam culture in Puget Sound: a modelling analysis

AEI Aquaculture Environment Interactions Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AEI 5:255-270 (2014) - DOI: https://doi.org/10.3354/aei00109 Ecosystem goods and services from Manila clam culture in Puget Sound: a modelling analysis Camille Saurel1, João G. Ferreira2,*, Dan Cheney3, Andy Suhrbier3, Bill Dewey4, Jonathan Davis5, Jeff Cordell6 1Danish Shellfish Center, DTUAqua, Øroddevej 80, 7900 Nykøbing Mors, Denmark 2Dept. Environmental Science and Engineering, Faculty of Sciences and Technology, New University of Lisbon, 2829-516 Monte de Caparica, Portugal 3Pacific Shellfish Institute, 509 12th Ave SE, Olympia, WA 98501, USA 4Chuckanut Shellfish Inc., 704 E. Hiawatha Blvd., Shelton, WA 98584, USA 5Baywater Inc, 15425 Smoland Lane NE, Bainbridge Island, WA, 98110-1040 USA 6University of Washington, School of Aquatic and Fisheries Sciences (SAFS), Box 355020, Seattle, WA 98195-5020, USA *Corresponding author: joao@hoomi.com ABSTRACT: The carrying capacity of a 2.4 ha Manila clam Venerupis philippinarum farm, using mechanised harvesting in North Puget Sound, WA, USA, was determined by means of an ecological model; the results were also scaled to Puget Sound as a whole. An individual Manila clam growth model was developed, calibrated and validated for the commercial farm, together with a macro- algal model to simulate fouling of the predator nets by seaweeds. Both models are based on our previously developed generic frameworks for bivalves (AquaShell) and seaweeds (AquaFrond). For the most part, equations are taken or adapted from the literature and parameterised for the studied site. The individual models were incorporated into the Farm Aquaculture Resource Man- agement (FARM) model to simulate the production cycle, environmental effects and economic optimisation of culture. Both the individual and farm-scale models are built using object-oriented programming. Potential effects of clam production on seaweed growth were analysed and found to be about 10% above background. The FARM model was also used to classify the farm area with respect to its eutrophication status, by applying the Assessment of Estuarine Trophic Status (ASSETS) model. Farm production ranging from 32 to 45 t of clams per year is well reproduced by the model. Harvest yield is very sensitive to mortality, and profitability is very sensitive to seed costs. Manila clam culture provides a potential nutrient credit trading value of over US $41000 per year, over 1000 Population-Equivalents (PEQ, i.e. loading from humans or equivalent loading from agriculture or industry) with respect to eutrophication control. The potential income would add 21% to the annual profit ($194900) from clam sales. A scaling exercise to the whole of Puget Sound is in reasonable agreement with declared production (difference of 16%), and suggests that clams provide a significant ecosystem service, of the order of 90000 PEQ per year. KEY WORDS: Manila clam · Aquaculture · Sustainability · Ecological model · Culture practice · FARM model Full text in pdf format PreviousCite this article as: Saurel C, Ferreira JG, Cheney D, Suhrbier A, Dewey B, Davis J, Cordell J (2014) Ecosystem goods and services from Manila clam culture in Puget Sound: a modelling analysis. Aquacult Environ Interact 5:255-270. https://doi.org/10.3354/aei00109 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AEI Vol. 5, No. 3. Online publication date: October 23, 2014 Print ISSN: 1869-215X; Online ISSN: 1869-7534 Copyright © 2014 Inter-Research.

Nutrients distribution and trophic status assessment in the northern Beibu Gulf, China

Using historical and 2010 field data, the distribution of nutrients in the northern Beibu Gulf of China is described. There was a decreasing trend in the concentration of nutrients from the north coast to offshore waters of the northern Beibu Gulf, reflecting the influence of inputs from land-based sources. High concentrations of dissolved inorganic nitrogen (DIN) and phosphate (PO4-P) occurred mainly at Fangchenggang Bay, Qinzhou Bay, and Lianzhou Bay. Four different methods were used to assess eutrophication. The trophic status of the Beibu Gulf was characterized using the single factor, Eutrophication index (EI), Trophic index (TRIX) and Assessment of Estuarine Trophic Status (ASSETS) methods. Based on nutrient concentrations, 73.9% of DIN and 26.7% of PO4-P samples exceeded the fourth grade Seawater Quality Standard of China. Eutrophication index values varied widely, but higher levels of eutrophication were generally found in bays and estuaries. TRIX values ranged from 2.61 to 7.27, with an average of 4.98, indicating a mesotrophic and moderately productive system. A positive correlation between TRIX and harmful algal species richness and abundance was observed. The ASSETS model evaluates eutrophication status based on a Pressure-State-Response approach, including three main indices: influencing factors, overall eutrophic condition, and future outlook. The Beibu Gulf was graded as moderate using ASSETS. The single factor and Chinese nutrient index methods were considered inadequate for the assessment of trophic status. TRIX can be used as an indicator of trophic state and ASSETS showed good potential to assess eutrophication. The results of TRIX and ASSETS depend on threshold values. To establish these values, further research is required within the northern Beibu Gulf.

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."

Eutrophication Assessment in Basque Estuaries: Comparing a North American and a European Method

Eutrophication in marine ecosystems is an important problem that requires an accurate assessment. Although Basque estuaries (northern Spain) have historically been under high anthropogenic pressure, no specific eutrophication assessment method had been applied in these waters. In this study, a method employed in the Basque Country (BC) to assess the “risk of failing to achieve good ecological status” under the requirements of the Water Framework Directive (WFD) was adapted to exclusively assess the risk of eutrophication. This method is based on the driver–pressure–state–impact–response approach. The results from this method (called WFD-BC method) were compared to the results from Assessment of Estuarine Trophic Status (ASSETS; a specific method developed in the US to assess estuarine trophic status in a pressure–state–response approach). The nutrient pressure was better characterized with the WFD-BC method due to the local hydrographic conditions (i.e., small and river-influenced estuaries) that were not well accommodated by the ASSETS method. In contrast, the WFD-BC results for assessment of state generally reflected worse conditions than the results from the ASSETS method due to the different indicators employed and the way these are integrated in the WFD-BC method. Overall, the WFD-BC method showed a good potential to assess eutrophication. However, to improve it, a lower weight for the benthos and macroalgae is recommended for evaluating state.

Integrated Environmental Modeling and Assessment of Coastal Ecosystems: Application for Aquaculture Management

This article presents an approach that couples coastal ecosystem modeling with integrated environmental assessment methodologies to support coastal management. The focus is to support the development of an ecosystem approach to aquaculture management including interactions with watershed substance loading. A Chinese bay, with intense aquaculture and multiple catchment uses, and where significant modeling efforts were undertaken is used as a case study. The ecosystem model developed for this bay is used to run scenarios that test the local management strategy for nutrient reduction. The corresponding ecological and economic impacts of the managers’ scenarios are analyzed by means of the Differential Drivers-Pressure-State-Impact-Response (ΔDPSIR) analysis. Emphasis is given to the analysis of the eutrophication process in the bay including present eutrophic condition and the expected changes due to the simulated scenarios. For this purpose, the Assessment of Estuarine Trophic Status (ASSETS) screening model is a valuable tool to interpret and classify the data and model outputs regarding eutrophication condition and to evaluate the manageable level of the nutrient loading entering in the bay.

Trophic Assessment in Chinese coastal systems-review of methods and application to the Changjiang (Yangtze) Estuary and Jiaozhou Bay

Coastal eutrophication has become one of the main threats to Chinese coastal areas during the last two decades. High nutrient loads from human activities have modified the natural background water quality in coastal water bodies, resulting in a range of undesirable effects. There is a need to assess the eutrophic level in coastal systems and to identify the extent of this impact to guide development of appropriate management efforts. Traditional Chinese assessment methods are discussed and compared with other currently-used methods, such as the Oslo-Paris Convention for the Protection of the North Sea (OSPAR) Comprehensive Procedure and Assessment of Estuarine Trophic Status (ASSETS). The ASSETS method and two Chinese methods were tested on two Chinese systems: the Changjiang (Yangtze) Estuary and Jiaozhou Bay. ASSETS is process based, and uses a pressure-state-response model based on three main indices: Influencing Factors, Overall Eutrophic Condition, and Future Outlook. The traditional methods are based on a nutrient index. ASSETS was successfully applied to both systems, classifying the Changjiang Estuary as Bad (high eutrophication) and Jiaozhou Bay as High (low eutrophication). The traditional methods led to ambiguous results, particularly for Jiaozhou Bay, due to the high spatial variability of data and a failure to assess the role of shellfish aquaculture in nutrient control. An overview of the Chinese coastal zone identifies 50 estuaries and bays that should form part of a national assessment. A comparison of methods and results suggests that ASSETS is a promising tool for evaluating the eutrophication status of these systems.

Assessment of trophic status in Changjiang (Yangtze) River estuary

The integrated methodology for the assessment of estuarine trophic status (ASSETS), which was extended and refined from the United States National Estuarine Eutrophication Assessment (NEEA), is a multi-parameter assessment system and has been widely used in eutrophication assessment in estuarine and coastal waters. The ASSETS was applied to evaluate the trophic status of the Changjiang (Yangtze) River estuary, one of the largest estuaries in the world. The following main results were obtained: (i) The estuarine export potential is "moderate susceptibility" due to the "moderate" dilution potential and "moderate" flushing potential; (ii) The overall human influence (OHI) index classified the impact of nutrients in the system as "high" due to the high level of nutrient discharge by the river which channels anthropogenic impacts in the catchments to the estuarine system; (iii) The overall eutrophic condition (OEC) in the estuary was classified into the "high" category due to frequent occurrence of nuisance and toxic algal blooms in the mixing and seawater zones; (iv) Since the nutrient loadings (e.g., DIN) in the river is expected to continue to increase in the near future following the population increase and rapid economic growth throughout the drainage basin, the nutrient-related symptoms in the estuary are likely to substantially worsen, which leads to the "worsen high" category for the definition of future outlook (DFO). The combinations of the three components (i.e., OHI, OEC, and DFO) lead to an overall grade as "bad" for the trophic status in the Changjiang River estuary.

Eutrophication Status of Marine Environment of Mumbai and Jawaharlal Nehru Ports

The marine environment of Mumbai and Jawaharlal Nehru ports was monitored for some environmental and biological parameters during three different periods between 2001 and 2002. The results are compared with the records available since 1960s. With the passage of time the environmental status underwent changes, probably due to the increase in anthropogenic activities in the metropolis. The nutrient level especially the nitrate concentration has increased gradually over the years with a simultaneous decrease in dissolved oxygen, indicating increase in the biological activity. Characterization of this environment based on Assessment of Estuarine Trophic Status (ASSETS) model indicates that the current status is poor and may get worsen in future if no appropriate management policies are put into place.

Application and sensitivity testing of a eutrophication assessment method on coastal systems in the United States and European Union

The Assessment of Estuarine Trophic Status (ASSETS) screening model has been extended to allow its application to both estuarine and coastal systems. The model, which combines elements of pressure, state and response, was tested on four systems: Maryland Coastal Bays and Long Island Sound in the United States and The Firth of Clyde (Scotland) and Tagus Estuary (Portugal) in the European Union. The overall scores were: Maryland Coastal Bays: Bad; Firth of Clyde: Poor; Tagus Estuary: Good. Long Island Sound was modelled along a timeline, using 1991 data (score: Bad) and 2002 data (score: Moderate). The improvement registered for Long Island Sound is a consequence of the reduction in nutrient loading, and the ASSETS score changed accordingly. The two main areas where developments are needed are (a) In the definition of type-specific ranges for eutrophication parameters, due to the recognition that natural or pristine conditions may vary widely, and the use of a uniform set of thresholds artificially penalizes some systems and potentially leads to misclassification; (b) In the definition and quantification of measures which will result in an improved state through a change in pressures, as well as in the definition of appropriate metrics through which response may be assessed. One possibility is the use of detailed research models where different response scenarios potentially produce changes in pressure and state. These outputs may be used to drive screening models and analyze the suitability of candidate metrics for evaluating management options.

An integrated methodology for assessment of estuarine trophic status

This paper describes an integrated methodology for the Assessment of Estuarine Trophic Status (ASSETS), which may be applied comparatively to rank the eutrophication status of estuaries and coastal areas, and to address management options. It includes quantitative and semi-quantitative components, and uses field data, models and expert knowledge to provide Pressure-State-Response (PSR) indicators. A substantial part of the concepts underlying the approach were developed as the United States National Estuarine Eutrophication Assessment (NEEA), which was applied to 138 estuaries in the continental United States. The core methodology relies on three diagnostic tools: a heuristic index of pressure ( Overall Human Influence), a symptoms-based evaluation of state ( Overall Eutrophic Conditions), and an indicator of management response ( Definition of Future Outlook). Recently, the methodology has been extended and refined in its application to European estuaries, and a more quantitative approach to some of the metrics has been implemented. In particular, the assessment of pressure is carried out by means of simple modeling techniques, comparing anthropogenic nutrient loading with natural background concentrations, and the quantitative criteria for classification of system state based on different symptoms have been refined to improve comparability. The present approach has been intercalibrated with the original NEEA work, for five widely different U.S. estuaries (Long Island Sound, Neuse River, Savannah River, Florida Bay and West Mississippi Sound) with good results. ASSETS additionally aims to contribute to the EU Water Framework Directive classification system, as regards a subset of water quality and ecological parameters in transitional and coastal waters.