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Upgrading Marine Ecosystem Restoration Using Ecological-Social Concepts
Abelson, Avigdor ; Halpern, Benjamin S. ; Reed, Daniel C. ; Orth, Robert J. ; Kendrick, Gary A. ; Beck, Michael W. ; Belmaker, Jonathan ; Krause, Gesche ; Edgar, Graham J. ; Airoldi, Laura ; Brokovich, Eran ; France, Robert ; Shashar, Nadav ; Blaeij, Arianne De; Stambler, Noga ; Salameh, Pierre ; Shechter, Mordechai ; Nelson, Peter A. - \ 2016
Bioscience 66 (2016)2. - ISSN 0006-3568 - p. 156 - 163.
conservation - marine ecosystems - marine spatial planning (MSP) - Ocean Health Index (OHI) - social-ecological restoration
Conservation and environmental management are principal countermeasures to the degradation of marine ecosystems and their services. However, in many cases, current practices are insufficient to reverse ecosystem declines. We suggest that restoration ecology, the science underlying the concepts and tools needed to restore ecosystems, must be recognized as an integral element for marine conservation and environmental management. Marine restoration ecology is a young scientific discipline, often with gaps between its application and the supporting science. Bridging these gaps is essential to using restoration as an effective management tool and reversing the decline of marine ecosystems and their services. Ecological restoration should address objectives that include improved ecosystem services, and it therefore should encompass social-ecological elements rather than focusing solely on ecological parameters. We recommend using existing management frameworks to identify clear restoration targets, to apply quantitative tools for assessment, and to make the re-establishment of ecosystem services a criterion for success.
An exposure-effect approach for evaluating ecosystem-wide risks from human activities
Knights, A.M. ; Piet, G.J. ; Jongbloed, R.H. ; Tamis, J.E. ; Robinson, L.A. - \ 2015
ICES Journal of Marine Science 72 (2015)3. - ISSN 1054-3139 - p. 1105 - 1115.
baltic sea - fisheries management - environmental-change - coastal ecosystems - marine ecosystems - human impact - new-zealand - food webs - support - climate
Ecosystem-based management (EBM) is promoted as the solution for sustainable use. An ecosystem-wide assessment methodology is therefore required. In this paper, we present an approach to assess the risk to ecosystem components from human activities common to marine and coastal ecosystems. We build on: (i) a linkage framework that describes how human activities can impact the ecosystem through pressures, and (ii) a qualitative expert judgement assessment of impact chains describing the exposure and sensitivity of ecological components to those activities. Using case study examples applied at European regional sea scale, we evaluate the risk of an adverse ecological impact from current human activities to a suite of ecological components and, once impacted, the time required for recovery to pre-impact conditions should those activities subside. Grouping impact chains by sectors, pressure type, or ecological components enabled impact risks and recovery times to be identified, supporting resource managers in their efforts to prioritize threats for management, identify most at-risk components, and generate time frames for ecosystem recovery.
Coastal eutrophication in Europe caused by production of energy crops
Wijnen, J. van; Ivens, W.P.M.F. ; Kroeze, C. ; Löhr, A.J. - \ 2015
Science of the Total Environment 511 (2015). - ISSN 0048-9697 - p. 101 - 111.
biomass production - marine ecosystems - future-trends - biofuels - land - rivers - export - agriculture - nitrogen - waters
In Europe, the use of biodiesel may increase rapidly in the coming decades as a result of policies aiming to increase the use of renewable fuels. Therefore, the production of biofuels from energy crops is expected to increase as well as the use of fertilisers to grow these crops. Since fertilisers are an important cause of eutrophication, the use of biodiesel may have an effect on the water quality in rivers and coastal seas. In this study we explored the possible effects of increased biodiesel use on coastal eutrophication in European seas in the year 2050. To this end, we defined a number of illustrative scenarios in which the biodiesel production increases to about 10–30% of the current diesel use. The scenarios differ with respect to the assumptions on where the energy crops are cultivated: either on land that is currently used for agriculture, or on land used for other purposes. We analysed these scenarios with the Global NEWS (Nutrient Export from WaterSheds) model. We used an existing Millennium Ecosystem Assessment Scenario for 2050, Global Orchestration (GO2050), as a baseline. In this baseline scenario the amount of nitrogen (N) and phosphorus (P) exported by European rivers to coastal seas decreases between 2000 and 2050 as a result of environmental and agricultural policies. In our scenarios with increased biodiesel production the river export of N and P increases between 2000 and 2050, indicating that energy crop production may more than counterbalance this decrease. Largest increases in nutrient export were calculated for the Mediterranean Sea and the Black Sea. Differences in nutrient export among river basins are large.
Resilience indicators: Prospects and limitations for early warnings of regime shifts
Dakos, V. ; Carpenter, S.R. ; Nes, E.H. van; Scheffer, M. - \ 2015
Philosophical Transactions of the Royal Society B. Biological sciences 370 (2015)1659. - ISSN 0962-8436 - p. 1 - 10.
critical slowing-down - ecological-systems - critical transitions - marine ecosystems - stochastic resonance - catastrophic shifts - empirical-evidence - leading indicator - trophic cascades - tipping point
In the vicinity of tipping points—or more precisely bifurcation points— ecosystems recover slowly from small perturbations. Such slowness may be interpreted as a sign of low resilience in the sense that the ecosystem could easily be tipped through a critical transition into a contrasting state. Indicators of this phenomenon of ‘critical slowing down (CSD)’ include a rise in temporal correlation and variance. Such indicators of CSD can provide an early warning signal of a nearby tipping point. Or, they may offer a possibility to rank reefs, lakes or other ecosystems according to their resilience. The fact that CSD may happen across a wide range of complex ecosystems close to tipping points implies a powerful generality. However, indicators of CSD are not manifested in all cases where regime shifts occur. This is because not all regime shifts are associated with tipping points. Here, we review the exploding literature about this issue to provide guidance on what to expect and what not to expect when it comes to the CSD-based early warning signals for critical transitions.
Sustainable fishing of inland waters
Kolding, J. ; Zwieten, P.A.M. van - \ 2014
Journal of Limnology 73 (2014)s1. - ISSN 1129-5767 - p. 132 - 148.
size-based indicators - multispecies fisheries - marine ecosystems - celtic sea - body-size - exploitation - community - abundance - patterns - fluctuations
Sustainability in fisheries has over the past decades evolved from a single species maximization concept to covering ecosystem and biodiversity considerations. This expansion of the notion, together with increased evidence that the targeted removal of selected components of the fish community may have adverse ecological consequences, poses a serious dilemma to the conventional fisheries management approach of protecting juveniles and targeting adults. Recently, the idea of balanced harvest, harvesting all components in the ecosystem in proportion to their productivity, has been promoted as a unifying solution in accordance the ecosystem approach to fisheries, but this will require a fundamental change to management. In this paper, we review theoretical background, and practicalities of securing high yielding fisheries in inland waters, with empirical examples freshwater fisheries which satisfy the extended objectives of minimal impact on community and ecosystem structure. We propose framework of ecological indicators to assess these objectives.
Evaluating targets and trade-offs among fisheries and conservation objectives using a multispecies size spectrum model
Blanchard, J.L. ; Andersen, K.H. ; Scott, F. ; Hintzen, N.T. ; Piet, G.J. ; Jennings, S. - \ 2014
Journal of Applied Ecology 51 (2014)3. - ISSN 0021-8901 - p. 612 - 622.
large fish indicator - north-sea - ecosystem models - marine ecosystems - trophic cascades - celtic sea - community - management - abundance - climate
Marine environmental management policies seek to ensure that fishing impacts on fished populations and other components of the ecosystem are sustainable, to simultaneously meet objectives for fisheries and conservation. For example, in Europe, targets for (i) biodiversity, (ii) food web structure as indicated by the proportion of large fish and (iii) fishing mortality rates for exploited species that lead to maximum sustainable yield, F-MSY,F- are being proposed to support implementation of the Marine Strategy Framework Directive. Efforts to reconcile any trade-offs among objectives need to be informed by knowledge on the consequences of alternate management actions. We develop, calibrate and apply a multispecies size spectrum model of the North Sea fish community to assess the response of populations and the community to fishing. The model predicts species' size distributions, abundance, productivity and interactions and therefore provides a single framework for evaluating trade-offs between population status, community and food web structure, biodiversity and fisheries yield. We show that the model can replicate realistic fish population and community structure and past responses to fishing. We assess whether meeting management targets for exploited North Sea populations (fishing species at F-MSY) will be sufficient to meet proposed targets for biodiversity and food web indicators under two management scenarios (status quo and F-MSY). The recovery in biodiversity indicators is 60% greater when fishing populations at F-MSY than if status quo (2010) fishing rates are maintained. The probability of achieving a food web target was 60% under both scenarios in spite of major community restructuring revealed by other indicators of community size structure. Synthesis and applications. Our model can be applied to evaluate indicator targets and trade-offs among fisheries and conservation objectives. There is a significant probability that reductions in fishing mortality below F-MSY would be needed in Europe if managers make a binding commitment to a proposed large fish indicator target, with concomitant reductions in fisheries yield.
Beyond net deficits: new priorities for an aquacultural geography
Belton, B. ; Bush, S.R. - \ 2014
Geographical Journal 180 (2014)1. - ISSN 0016-7398 - p. 3 - 14.
political ecology - environmental-change - shrimp aquaculture - marine ecosystems - blue revolution - mekong delta - fish - food - globalization - certification
Geographers first identified aquaculture as an important field of study during the 1990s, pointing to a ‘net deficit’ in geographical knowledge about the activity. This paper examines how far geographers have come in bridging this knowledge deficit in the last 20 years. While increasing attention has focused on the political economy of export products consumed in the global North, ‘everyday’ geographies of aquaculture production and consumption in the global South have been neglected. We argue that paying greater attention to everyday aquaculture in the global South provides opportunities for geographers to engage with wider questions around development and change that extend far beyond aquaculture. By focusing on changing patterns of aquaculture production for Southern domestic markets, geographers can provide a counterpoint to Northern dominated agro-food studies by re-emphasising the importance of consumption, urbanisation and agrarian transitions from a more place-based perspective and, in doing so, support the development of theory that reflects Southern realties.
Multiscale regime shifts and planetary boundaries
Hughes, T.P. ; Carpenter, S. ; Rockstrom, J. ; Scheffer, M. ; Walker, B. - \ 2013
Trends in Ecology and Evolution 28 (2013)7. - ISSN 0169-5347 - p. 389 - 395.
safe operating space - climate-change - critical transitions - ocean acidification - marine ecosystems - stable states - time - resilience - impacts - system
Life on Earth has repeatedly displayed abrupt and massive changes in the past, and there is no reason to expect that comparable planetary-scale regime shifts will not continue in the future. Different lines of evidence indicate that regime shifts occur when the climate or biosphere transgresses a tipping point. Whether human activities will trigger such a global event in the near future is uncertain, due to critical knowledge gaps. In particular, we lack understanding of how regime shifts propagate across scales, and whether local or regional tipping points can lead to global transitions. The ongoing disruption of ecosystems and climate, combined with unprecedented breakdown of isolation by human migration and trade, highlights the need to operate within safe planetary boundaries. © 2013 Elsevier Ltd.
Nutrient Discharge from aquaculture operations in function of system design and production enviorment
Verdegem, M.C.J. - \ 2013
Reviews in Aquaculture 5 (2013)3. - ISSN 1753-5123 - p. 158 - 171.
baltic sea consideration - recirculating aquaculture - fresh-water - coagulation/flocculation aids - antibiotic-resistance - biogeochemical cycles - constructed wetlands - marine ecosystems - reduction measure - farm effluent
In aquaculture, nutrient loading is defined as the difference between nutrients supplied with fertilizers and feed and nutrients harvested in the form of finfish, crustaceans, molluscs and seaweeds. On average, the production of finfish and crustaceans results in a net nutrient loading, while for the production of molluscs and seaweeds the nutrient loading is negative. In marine and brackish water aquaculture, on a global scale, more nutrients are extracted than added to the environment. However, in freshwater, more nutrients are loaded than extracted. In 2008, the global aquaculture production of finfish and crustaceans resulted in an environmental loading of 1.7 million metric tonnes of nitrogen (N) and 0.46 million metric tonnes of phosphorus (P). This nitrogen loading represents 0.9% of the human input to the N-cycle and 0.4% of the global N-cycle. For phosphorus, the loading from finfish and crustacean aquaculture represents 2.3% of the global annual fertilizer supply. With cage aquaculture, nutrients are directly discharged to the environment. Mitigation measures should be shared equally between all polluters involved. For land-based aquaculture, the development of water re-use systems is still in its infancy. Although still a minor contributor to global aquaculture production, recirculation technology shows that control and mitigation of pollution from aquaculture is possible. A 15–20 year goal should be to have all inland aquaculture operations applying water re-use and purification technology and generating useful (waste) outputs in addition to standard aquaculture products
Estimating spatial and temporal variability of juvenile North Sea plaice from opportunistic data
Poos, J.J. ; Aarts, G.M. ; Vandemaele, S. ; Willems, W. ; Bolle, L.J. ; Helmond, A.T.M. van - \ 2013
Journal of Sea Research 75 (2013). - ISSN 1385-1101 - p. 118 - 128.
pleuronectes-platessa l - dutch wadden sea - marine ecosystems - climate-change - trawl fishery - flatfish - temperature - ecology - discard - growth
Surveys are often insufficient to accurately capture the distribution of a species in both space and time. Complementary to the use of research vessel data, platforms of opportunity can be a powerful strategy to monitor species distributions at high temporal and spatial resolution. In this study we use data from commercial fishing vessels, collecting – under the European Union data collection framework – biological data on all species that are caught and subsequently discarded. Using such discard data in combination with a systematic trawl survey, we model the spatial and temporal distribution of juvenile plaice (Pleuronectes platessa) in the central North Sea. There is a clear age-dependent difference between the commercial fishing vessel data and the research vessel data, with age 1 being the dominating age in the survey catches, while age 2 is the dominating age in the discards. The results show how immature plaice, slowly migrate from the nursery areas, westwards into the deeper regions of the North Sea. Also, the results show that during the study period, juvenile plaice gradually moved to deeper waters at an earlier age. Finally we discuss how the framework can be applied to similar opportunistic data to monitor seasonal and inter-annual migration of marine organisms, and to quantify how they may be influenced by biotic and abiotic gradients, such as temperature.
Early Detection of Ecosystem Regime Shifts: A Multiple Method Evaluation for Management Application
Lindegren, M. ; Dakos, V. ; Groger, J.P. ; Gardmark, A. ; Kornilovs, G. ; Otto, S.A. ; Mollmann, C. - \ 2012
PLoS One 7 (2012)7. - ISSN 1932-6203
central baltic sea - early-warning signals - catastrophic shifts - marine ecosystems - leading indicator - slowing-down - climate - dynamics - time - reorganization
Critical transitions between alternative stable states have been shown to occur across an array of complex systems. While our ability to identify abrupt regime shifts in natural ecosystems has improved, detection of potential early-warning signals previous to such shifts is still very limited. Using real monitoring data of a key ecosystem component, we here apply multiple early-warning indicators in order to assess their ability to forewarn a major ecosystem regime shift in the Central Baltic Sea. We show that some indicators and methods can result in clear early-warning signals, while other methods may have limited utility in ecosystem-based management as they show no or weak potential for early-warning. We therefore propose a multiple method approach for early detection of ecosystem regime shifts in monitoring data that may be useful in informing timely management actions in the face of ecosystem change.
Does predator interference cause alternative stable states in multispecies communities?
Feng, J. ; Dakos, V. ; Nes, E.H. van - \ 2012
Theoretical Population Biology 82 (2012)3. - ISSN 0040-5809 - p. 170 - 176.
mutual interference - marine ecosystems - shallow lakes - regime shifts - thresholds - enrichment - paradox - stabilization - resilience - stability
Whereas it is well known that simple ecological mechanisms may promote stability in simple species models, their consequences for stability and resilience in multispecies communities are largely unexplored. Here, we studied the effect of predator interference on the occurrence of alternative attractors and complex dynamics in randomly constructed multispecies predator-prey communities. We studied three types of interference: random interference ("asymmetric"), random interference but symmetrical between pairs of predators ("symmetric"), and interference among only the same species ("conspecific"). In all cases predator interference increased the average number of alternative attractors, whereas at the same time it reduced the emergence of oscillatory or chaotic dynamics. Our findings demonstrate a contrasting effect of predator interference on the stability of a community: on the one hand it reduces cycles and chaos in the dynamics, on the other hand predator interference increases the likelihood that communities may undergo critical transitions between multiple stable states.
Spatial dimension and exploitation dynamics of local fishing grounds by fishers targeting several flatfish species
Rijnsdorp, A.D. ; Poos, J.J. ; Quirijns, F.J. - \ 2011
Canadian Journal of Fisheries and Aquatic Sciences 68 (2011)6. - ISSN 0706-652X - p. 1064 - 1076.
marginal value theorem - individual transferable quotas - multispecies trawl fishery - ideal free distribution - north-sea - fleet dynamics - competitive interactions - marine ecosystems - effort allocation - tac management
Patch exploitation dynamics, based on individual tow data, provided new insights into the fishing behavior of mixed fisheries. Fishing grounds were determined and their geometry quantified based on the proximity of tow positions. Tows were classified as being part of either searching, sampling, or exploitation behavior based on the intertow distance. Fishers can detect patches of flatfish on a scale of 25 nautical miles2. Catch rate during exploitation was 24%–36% above the catch rate while searching, and decreased at a rate of 20%·day–1. Once a patch was found, exploitation occurred until the catch rate dropped below a threshold level. The optimal giving-up catch rate was estimated based on the observed search time, catch rate decline, and range of fishing ground quality. The observed giving-up catch rate was 6%–11% higher than predicted by the marginal value theorem. The discrepancy between the observed and predicted patch leaving decision was consistent with the bias expected in an individual transferable quota (ITQ) management system. Our results provide a basis for interpreting vessel monitoring system (VMS) data and studying the interaction among fishers and between fishers and their resources at the appropriate time and spatial scale
Long-term divergent tidal flat benthic community recovery following hypoxia-induced mortality
Colen, C. van; Montserrat, F. ; Vincx, M. ; Herman, P.M.J. ; Ysebaert, T. ; Degraer, S. - \ 2010
Marine Pollution Bulletin 60 (2010)2. - ISSN 0025-326X - p. 178 - 186.
cerastoderma-edule - marine ecosystems - wadden sea - polydora-ligni - sediment - dynamics - recolonization - invertebrates - consequences - bioturbation
Macrobenthos recovery after hypoxia-induced mass mortality was assessed in an estuarine tidal mudflat during 3 years. During the first 2 years, a Pearson-Rosenberg type of community recovery took place along with the improving bottom water oxygen conditions. After 3 months, spionid polychaetes became superabundant (i.e. opportunistic peak), followed rapidly by a steep decline (i.e. ecotone point). Subsequently, a moderate increase in species richness and a steep increase in biomass, related to the growth of long-lived species occurred (i.e. transition region). Afterwards, however, the recovering community diverged again from the ambient, undisturbed, sediments due to enhanced recruitment success of long-lived species presumably resulting from the lowered interference from bioturbation during early recovery stages in the disturbed plots. Hence, despite early community recovery may be more or less deterministic, lagged divergent community reassembling may occur at the longer-term, thereby contributing to benthos patchiness in areas which are frequently subjected to disturbances.
Scenarios for global biodiversity in the 21st century
Pereira, H.M. ; Leadley, P.W. ; Proenca, V. ; Alkemade, J.R.M. ; Scharlemann, J.P.W. ; Fernandez-Manjarres, J.F. ; Araujo, M.B. ; Balvanera, P. ; Biggs, R. ; Cheung, W.W.L. ; Chini, L. ; Cooper, H.D. ; Gilman, E.L. ; Guenette, S. ; Hurtt, G.C. ; Huntington, H.P. ; Mace, G.M. ; Oberdorff, T. ; Revenga, C. ; Rodrigues, P. ; Scholes, R.J. ; Sumaila, U.R. ; Walpole, M. - \ 2010
Science 330 (2010)6010. - ISSN 0036-8075 - p. 1496 - 1501.
climate-change - land-use - marine ecosystems - changing climate - range shifts - future - models - extinctions - distributions - vulnerability
Quantitative scenarios are coming of age as a tool for evaluating the impact of future socioeconomic development pathways on biodiversity and ecosystem services. We analyze global terrestrial, freshwater, and marine biodiversity scenarios using a range of measures including extinctions, changes in species abundance, habitat loss, and distribution shifts, as well as comparing model projections to observations. Scenarios consistently indicate that biodiversity will continue to decline over the 21st century. However, the range of projected changes is much broader than most studies suggest, partly because there are significant opportunities to intervene through better policies, but also because of large uncertainties in projections
Nutrients Export by Rivers to the Coastal Waters of Africa: Past and Future trends
Yasin, J.A. ; Kroeze, C. ; Mayorga, E. - \ 2010
Global Biogeochemical Cycles 24 (2010)4. - ISSN 0886-6236
west-africa - marine ecosystems - cabora bassa - world rivers - nitrogen - consequences - management - pollution - eutrophication - phosphorus
We analyze past and future trends in nitrogen (N), phosphorus (P), and carbon (C) export by rivers to the coastal waters of Africa as calculated by the Global Nutrient Export to WaterShed (NEWS) models for the period 1970–2050. Between 1970 and 2000 the total nutrient export by African rivers increased by 10–80%. For future years (2000–2050) we calculate an increase in the total loads of dissolved forms of N and P, but decreasing trends for dissolved organic C and particulate forms of N and P. There are large regions that deviate from these pan-African trends. We explore the regional patterns and the underlying processes, in particular for the Nile, Zaire, Niger, and Zambezi. In the future, anthropogenic sources may, in large parts of Africa, become larger contributors to riverine nutrient loads than natural sources
Future Trends in Nutrient Export to the Coastal Waters of South America: Implications for Occurrence of Eutrophication
Struijk, F. ; Kroeze, C. - \ 2010
Global Biogeochemical Cycles 24 (2010). - ISSN 0886-6236 - 14 p.
anthropogenic nitrogen - marine ecosystems - global system - algal blooms - rivers - pollution - inputs - ocean - sea
We analyze future trends in nutrient export to the coastal waters of South America, with a special focus on the causes of nutrient export and their potential effects. Nutrient Export from Watersheds (NEWS) model results for South America are presented, including trends in human activities and the associated river export of nutrients for the period 1970–2050. For 25 areas in coastal waters of South America where eutrophication or hypoxia has been observed, we investigate how these relate to NEWS model output. For selected watersheds we discuss the causes of increased nutrient loadings of rivers and future trends as projected by the NEWS models
Global River Nutrient Export: A Scenario Analysis of Past and Future Trends
Seitzinger, S.P. ; Mayorga, E. ; Bouwman, A.F. ; Kroeze, C. ; Beusen, A.H.W. ; Billen, G. ; Drecht, G. van; Dumont, E.L. ; Fekete, B.M. ; Garnier, J. ; Harrison, J. - \ 2010
Global Biogeochemical Cycles 24 (2010). - ISSN 0886-6236 - 16 p.
aquatic ecosystems - marine ecosystems - nitrogen - world - eutrophication - terrestrial - phosphorus - inputs - ocean - water
An integrated modeling approach was used to connect socioeconomic factors and nutrient management to river export of nitrogen, phosphorus, silica and carbon based on an updated Global NEWS model. Past trends (1970–2000) and four future scenarios were analyzed. Differences among the scenarios for nutrient management in agriculture were a key factor affecting the magnitude and direction of change of future DIN river export. In contrast, connectivity and level of sewage treatment and P detergent use were more important for differences in DIP river export. Global particulate nutrient export was calculated to decrease for all scenarios, in part due to increases in dams for hydropower. Small changes in dissolved silica and dissolved organics were calculated for all scenarios at the global scale. Population changes were an important underlying factor for river export of all nutrients in all scenarios. Substantial regional differences were calculated for all nutrient elements and forms. South Asia alone accounted for over half of the global increase in DIN and DIP river export between 1970 and 2000 and in the subsequent 30 years under the Global Orchestration scenario (globally connected with reactive approach to environmental problems); DIN river export decreased in the Adapting Mosaic (globally connected with proactive approach) scenario by 2030, although DIP continued to increase. Risks for coastal eutrophication will likely continue to increase in many world regions for the foreseeable future due to both increases in magnitude and changes in nutrient ratios in river export
Global Nutrient Export from WaterSheds 2 (NEWS 2): Model development and implementation
Mayorga, E. ; Seitzinger, S.P. ; Harrison, J.A. ; Dumont, E.L. ; Beusen, A.H.W. ; Bouwman, A.F. ; Fekete, B.M. ; Kroeze, C. ; Drecht, G. van - \ 2010
Environmental Modelling & Software 25 (2010)7. - ISSN 1364-8152 - p. 837 - 853.
land-use change - marine ecosystems - river discharge - world rivers - nitrogen - impact - ocean - sediment - forests - climate
Global NEWS is a global, spatially explicit, multi-element and multi-form model of nutrient exports by rivers. Here we present NEWS 2, the new version of Global NEWS developed as part of a Millennium Ecosystem Assessment scenario implementation from hindcast (1970) to contemporary (2000) and future scenario trajectories (2030 & 2050). We provide a detailed model description and present an overview of enhancements to input datasets, emphasizing an integrated view of nutrient form sub-models and contrasts with previous NEWS models (NEWS 1). An important difference with NEWS 1 is our unified model framework (multi-element, multi-form) that facilitates detailed watershed comparisons regionally and by element or form. NEWS 2 performs approximately as well as NEWS 1 while incorporating previously uncharacterized factors. Although contemporary global river export estimates for dissolved inorganic nitrogen (DIN) and particulates show notable reductions, they are within the range of previous studies; global exports for other nutrient forms are comparable to NEWS 1. NEWS 2 can be used as an effective tool to examine the impact of polices to reduce coastal eutrophication at regional to global scales. Continued enhancements will focus on the incorporation of other forms and sub-basin spatial variability in drivers and retention processes
Resolving the effect of climate change on fish populations
Rijnsdorp, A.D. ; Peck, M.A. ; Engelhard, G.H. ; Moellmann, C. ; Pinnegar, J.K. - \ 2009
ICES Journal of Marine Science 66 (2009)7. - ISSN 1054-3139 - p. 1570 - 1583.
vissen - migratie - mariene gebieden - atlantische oceaan - lichaamsgewicht - fishes - migration - marine areas - atlantic ocean - body weight - cod gadus-morhua - plaice pleuronectes-platessa - haddock melanogrammus-aeglefinus - individual-based models - north-sea plaice - sole solea-solea - marine ecosystems - trophic cascades - regime shifts - baltic sea
This paper develops a framework for the study of climate on fish populations based on first principles of physiology, ecology, and available observations. Environmental variables and oceanographic features that are relevant to fish and that are likely to be affected by climate change are reviewed. Working hypotheses are derived from the differences in the expected response of different species groups. A review of published data on Northeast Atlantic fish species representing different biogeographic affinities, habitats, and body size lends support to the hypothesis that global warming results in a shift in abundance and distribution (in patterns of occurrence with latitude and depth) of fish species. Pelagic species exhibit clear changes in seasonal migration patterns related to climate-induced changes in zooplankton productivity. Lusitanian species have increased in recent decades (sprat, anchovy, and horse mackerel), especially at the northern limit of their distribution areas, while Boreal species decreased at the southern limit of their distribution range (cod and plaice), but increased at the northern limit (cod). Although the underlying mechanisms remain uncertain, available evidence suggests climate-related changes in recruitment success to be the key process, stemming from either higher production or survival in the pelagic egg or larval stage, or owing to changes in the quality/quantity of nursery habitats