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Peter R F Bell - One of the best experts on this subject based on the ideXlab platform.
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the demise of the fringing coral reefs of barbados and of regions in the great barrier reef gbr lagoon impacts of Eutrophication
1994Co-Authors: Peter R F Bell, T TomascikAbstract:Historical data from Barbados demonstrate a close correspondence between the demise of the coral reefs with increased tourist and industrial development and the resulting degradation in water quality and associated Eutrophication. Chronic low levels of Eutrophication can restrict coral growth and reproduction and in doing so inhibit the recovery of damaged reefs. The virtual extinction of Acropora palmata in recent times indicates that it could be particularly sensitive to Eutrophication. Data suggest a Eutrophication threshold of 0.3 mg chlorophyll a m if the demise of A. palmata is relevant which is low in comparison with the 0.5 mg chlorophyll a m previously suggested for the Great Barrier Reef (GBR) lagoon. Data for the lagoon off Townsville show that the status of Eutrophication or fertility of the waters is equivalent to or greater than that which was associated with the demise of reefs in Barbados and Hawaii. The fertility (as measured by total diatom counts) of the lagoon water near to Low Isles is far higher than that measured in 1928-29. The increased fertility in both GBR regions is attributed mainly to agricultural runoff. -from Authors
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Eutrophication and coral reefs some examples in the great barrier reef lagoon
1992Co-Authors: Peter R F BellAbstract:Eutrophication or “nuisance” algal growth causes negative impacts on coral reefs via a number of routes and can eventually lead to the replacement of the coral community with various flora and fauna (e.g. attached algae, seagrasses and detrital/filter feeders). Chlorophyll a appears to be the best water quality indicator of Eutrophication and a Eutrophication threshold value at or below an annual mean of 0.5 mg m−3 is suggested. The concentrations of nutrients N and P associated with the onset Eutrophication in coral reef communities are less well defined (annual mean DIN ∼ 1 μM; P-PO4 ∼ 0.1–0.2 μM) but are in accord with Eutrophication threshold levels for sensitive freshwater ecosystems. The proliferation of nitrogen fixing algae in pristine coral reef regions highlights the importance of phosphorus and trace components such as Mo and Fe and even soluble organic matter to the overall primary production. The concentration of nutrients and levels of chlorophyll a in some regions of the Great Barrier Reef (GBR) lagoon are comparable to those that would be classed as eutrophic in other coral reef regions of the world. The available evidence points to riverine run-off as the cause of elevated P-PO4 levels in the inner lagoon. Historical evidence indicates that the levels of P-PO4 and phytoplankton growth, and particularly that of Trichodesmium spp, are relatively high in the river affected areas and that the levels may have significantly increased in the inner lagoon over the past 50–60 years. The nitrogen-fixing ability of Trichodesmium suggests that increased levels of P alone may be driving increased levels of primary productivity in the lagoon. It is hypothesized that the riverine-promoted Eutrophication is a significant factor in the demise of fringing reefs in the inner GBR lagoon. The recorded levels of nano plankton growth in some river-affected regions of the GBR lagoon are sufficient to promote the survival of Acanthaster planci (crown of thorns starfish) larvae and as such Eutrophication could well be a principal causative factor of the crown of thorns outbreaks. Elevated levels of nutrients and algal growth occur in some outer regions of the GBR but these appear to be due to natural phenomena. The high background concentrations of nutrients and phytoplankton in both the inner and outer GBR, whether they are natural or not, demands that special precautions be exercised in the control of sewage effluents and run-of in the vicinity of coral reefs.
Jesper H Andersen - One of the best experts on this subject based on the ideXlab platform.
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long term temporal and spatial trends in Eutrophication status of the baltic sea
2017Co-Authors: Jesper H Andersen, Jacob Carstensen, Daniel J Conley, Karsten M Dromph, Vivi Fleminglehtinen, Bo G Gustafsson, Alf B Josefson, Alf NorkkoAbstract:Much of the Baltic Sea is currently classified as 'affected by Eutrophication'. The causes for this are twofold. First, current levels of nutrient inputs (nitrogen and phosphorus) from human activities exceed the natural processing capacity with an accumulation of nutrients in the Baltic Sea over the last 50-100 years. Secondly, the Baltic Sea is naturally susceptible to nutrient enrichment due to a combination of long retention times and stratification restricting ventilation of deep waters. Here, based on a unique data set collated from research activities and long-term monitoring programs, we report on the temporal and spatial trends of Eutrophication status for the open Baltic Sea over a 112-year period using the HELCOM Eutrophication Assessment Tool (HEAT 3.0). Further, we analyse variation in the confidence of the Eutrophication status assessment based on a systematic quantitative approach using coefficients of variation in the observations. The classifications in our assessment indicate that the first signs of Eutrophication emerged in the mid-1950s and the central parts of the Baltic Sea changed from being unaffected by Eutrophication to being affected. We document improvements in Eutrophication status that are direct consequences of long-term efforts to reduce the inputs of nutrients. The reductions in both nitrogen and phosphorus loads have led to large-scale alleviation of Eutrophication and to a healthier Baltic Sea. Reduced confidence in our assessment is seen more recently due to reductions in the scope of monitoring programs. Our study sets a baseline for implementation of the ecosystem-based management strategies and policies currently in place including the EU Marine Strategy Framework Directives and the HELCOM Baltic Sea Action Plan.
Stephen R Carpenter - One of the best experts on this subject based on the ideXlab platform.
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aquatic Eutrophication promotes pathogenic infection in amphibians
2007Co-Authors: Pieter T J Johnson, Jonathan M Chase, Katherine L Dosch, Richard B Hartson, Jackson A Gross, Don J Larson, Daniel R Sutherland, Stephen R CarpenterAbstract: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.
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Eutrophication of aquatic ecosystems bistability and soil phosphorus
2005Co-Authors: Stephen R CarpenterAbstract:Eutrophication (the overenrichment of aquatic ecosystems with nutrients leading to algal blooms and anoxic events) is a persistent condition of surface waters and a widespread environmental problem. Some lakes have recovered after sources of nutrients were reduced. In others, recycling of phosphorus from sediments enriched by years of high nutrient inputs causes lakes to remain eutrophic even after external inputs of phosphorus are decreased. Slow flux of phosphorus from overfertilized soils may be even more important for maintaining Eutrophication of lakes in agricultural regions. This type of Eutrophication is not reversible unless there are substantial changes in soil management. Technologies for rapidly reducing phosphorus content of overenriched soils, or reducing erosion rates, are needed to improve water quality.
Robert W Howarth - One of the best experts on this subject based on the ideXlab platform.
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controlling Eutrophication nitrogen and phosphorus
2009Co-Authors: Daniel J Conley, Hans W. Paerl, Robert W Howarth, Donald F Boesch, Sybil P Seitzinger, Karl E Havens, Christiane Lancelot, Gene E LikensAbstract:Improvements in the water quality of many freshwater and most coastal marine ecosystems requires reductions in both nitrogen and phosphorus inputs.
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nitrogen as the limiting nutrient for Eutrophication in coastal marine ecosystems evolving views over three decades
2006Co-Authors: Robert W Howarth, Roxanne MarinoAbstract: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.
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Eutrophication of freshwater and marine ecosystems
2006Co-Authors: Val H Smith, Samantha B Joye, Robert W HowarthAbstract: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. Knowledge of the links between nutrients and aquatic productivity began with the pioneering work of Weber (1907) on German peat bogs and with Johnstone’s (1908) studies of the North Sea. A crystallization of freshwater Eutrophication concepts took place soon thereafter in Northern Europe, where the first trophic classification systems for surface waters were developed. These early classification systems were based on the intensity of aquatic organic matter production, as well as nutrient supply conditions and ecosystemlevel consequences of increased production (e.g., hypolimnetic oxygen depletion; Rodhe 1969). There was a lot of uncertainty in the subsequent 50 yr about the physical, chemical, and ecological details of the Eutrophication process, and hot debates raged about the relative roles of different mineral nutrients as constraints on, or regulators of, primary productivity, especially the macronutrients nitrogen (N), phosphorus (P), and carbon (C). Work on the Eutrophication process accelerated in the 1960s and 1970s. Particularly important was the landmark 1971 American Society of Limnology and Oceanography (ASLO) Eutrophication symposium that culminated in the publication of the first special issue of Limnology and Oceanography (L&O) on nutrients and Eutrophication, edited by G. E. Likens (Likens 1972a). This special issue was similarly stimulated by a symposium that the three of us 1
Michael Karydis - One of the best experts on this subject based on the ideXlab platform.
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coastal marine Eutrophication assessment a review on data analysis
2011Co-Authors: Dimitra Kitsiou, Michael KarydisAbstract:A wide variety of data analysis techniques have been applied for quantitative assessment of coastal marine Eutrophication. Indicators for assessing Eutrophication and frequency distributions have been used to develop scales for characterizing oligotrophy and Eutrophication. Numerical classification has also contributed to the assessment of eutrophic trends by grouping sampling sites of similar trophic conditions. Applications of Eutrophication assessment based on Principal Component Analysis and Multidimensional Scaling have also been carried out. In addition, the rapid development of Geographical Information Systems has provided the framework for applications of spatial methods and mapping techniques on Eutrophication studies. Satellite data have also contributed to Eutrophication assessment especially at large scale. Multiple criteria analysis methods can integrate Eutrophication variables together with socio-economic parameters providing a holistic approach particularly useful to policy makers. As the current concept of Eutrophication problems is to be examined as part of a coastal management approach, more complex quantitative procedures are needed to provide a platform useful for implementation of environmental policy. The present work reviews methods of data analysis used for the assessment of coastal marine Eutrophication. The difficulties in applying these methods on data collected from the marine environment are discussed as well as the future perspectives of spatial and multiple criteria choice methods.
