Advanced Search Abstract The abundance of birds recorded in the North American Breeding Bird Survey decreased by up to 18 percent between and The abundance of US and Canadian resident species decreased by 30 percent, and that of migrants within the United States and Canada decreased by 19 percent.
Joao Ferreira Ecological Modelling 1 — 15 www. The development of salt marsh vegetation was simulated separately for C3 and C4 plants, using a combined biogeochemical and demographic model. This simulation, which provided small-scale m2 results of annual above-ground primary production, was upscaled to the whole salt marsh area, using bathymetry data, remote sensing and Geographic Information System GIS for assessing vegetation cover and determining areal distribution of C3 and C4 vegetation.
Based on IPCC data, several sea-level rise scenarios were considered, and the coupled ecological model-GIS were applied to these in order to determine changes in global salt marsh productivity. The results indicate that the salt marshes of the mesotidal estuaries such as the Tagus are susceptible to sea-level rise only in a worst case scenario, which is more likely to occur if the terms set out by the Kyoto protocol are not met by several industrialised nations.
The low vulnerability of salt marshes supports the suggestion that areas with high tidal ranges are less vulnerable to sea level change, due to greater sediment transport and accretion. Nevertheless, the precautionary principle should always be applied by coastal planners, due to the great uncertainty surrounding forecasts of sea-level rise.
Introduction atmospheric concentration of the main green- house gases, carbon dioxide; methane and nitrous The enhanced greenhouse effect is well docu- oxide.
This change has a Human origin — during mented e. It is the result of a recent increase in the increasing and with it the combustion of fossil fuels such as coal, oil, and gaswhich produce these gases Houghton, Ecologically, complex General Circulation Models GCMsas- salt marshes are characterised by their high pri- suming the doubling of the pre-industrial atmo- mary productivity and species diversity, represent- spheric CO2 concentration the main greenhouse ing habitat for migratory waterfowl, transient fish gas.
According to the reports of the Intergovern- species and indigenous flora and fauna. Commer- mental Panel on Climate Change IPCC incially, these ecosystems provide important re- confirmed inthe global average temperature sources as nursery grounds for several fish and will rise by about 2.
Salt marsh vege- the natural temperature variability from place-to- tation is located in areas receiving both inunda- place, day-to-day, and season-to-season, as well tion by sea water and exposure to air, as well as as to uncertainties with modelling Gates, ; having an adequate soil salinity and chemistry Houghton, Eleuterius and Eleuterius, A rise in average sea-level is another expected Since salt marshes are described as transition consequence of the enhanced greenhouse effect, zones between land and sea, they are also particu- both because of oceanic thermal expansion, and larly vulnerable to sea-level rise — as the sea the melting of Arctic and Antarctic glaciers Titus rises, the outer salt marsh boundary will erode et al.
The uncertainties in estimates about and new salt marsh will form inland. According future global sea-level rise are substantial.
The to Reedthe response of coastal marshes to estimates for sea-level rise bymade since relative sea-level rise depends upon their ability to by several authors, range from 0 to cm maintain their relative elevation through sedimen- Titus and Narayanan, This could be due tation, areas where the sedimentation rate is in to the uncertain amount of temperature rise, as excess of sea-level rise are considered areas of well as due to the different model estimates given positive balance.
These areas are frequently asso- for the amount of sea level rise due to the melting ciated with estuarine marshes of rivers with high of glaciers and small ice caps. However, according sediment discharge. Examples of these systems are have important impacts on aquatic ecosystems.
Finally, tidal range is considered by estuaries, barrier islands and lagoons, benthic sys- Stevenson et al. However, rapid sea-level rise in temperate zones, mainly occupied by halo- can counteract this negative feedback with a posi- T.
Methodology Allen, a,b ; mineralogic sedimentation is de- pendent, not only on greater submersion periods, The relationship between the different compo- but also on available sediment in the system, nents of this work is shown in Fig.
Although data described in the literature, and by remote these two feedback processes are understood, sensing of the study area.
Firstly, a coupled bio- their modelling is still qualitative and exploratory, geochemical and population-dynamics model was with little quantitative reliability Nyman et al.
Sedimentation of organic mat- salt marsh vegetation per unit of area. In parallel, ter is considered constant Allen, b,an initial spatial analysis of the salt marsh areacorrelated with mineralogic deposition was conducted using Geographic Information Woolnough et al.
This information calibration with field data Day et al. The model was then upscaled using the consequences of sea-level rise in salt marsh areas, spatial analysis data, in order to give results for using an approach combining ecological mod- the full salt marsh area.
Finally, the model results elling, remote sensing, and geographical informa- were further analysed with GIS, giving them a tion analysis.
The methodology developed in this spatial dimension. Study area The Tagus estuary is one of the largest in Europe, covering an area of about km2 Fig. This ecosystem forms the major part of the Tagus Estuary Natural Reserve; only the salt marshes belonging to the Reserve were object of this study.
Table 1 compares the study area with other estuarine salt marshes. This area was chosen because it can represent a wide range of different estuarine salt marshes.
An average-sized salt marsh area thrives under mesotidal conditions tidal range of 1—4 m. Halophytic succession is similar to other salt marshes — lower areas are dominated by Spartina species while the upper areas are domi- Fig.Climate change may impact the unique bird assemblage found in tidal marshes by increasing the frequency (Resio and Hayden , Hayden ) and intensity (Emanuel , Knutson , Bacon and Carter ) of storm surges.
Additionally, sea-level rise is projected to result in a loss of high marsh habitat on the Atlantic Coast. THE EFFECTS OF GLOBAL CLIMATE CHANGE ON THE FISHES OF THE SOUTHEASTERN UNITED STATES given rise to the most diverse fish community in North America (Warren et al.
For example, a square quadrat ( miles on a side) containing eastern Tennessee and western fisheries of the southeastern United . Smooth cordgrass Spartina alterniflora Loisel., a perennial rhizomatous grass native to the Atlantic and Gulf coasts of North America, spreads rapidly in estuaries and coastal salt marshes in the.
Ecological Modelling () 1–15 Effects of global climate change on coastal salt marshes T. Simas, J.P. Nunes, J.G.
Ferreira * IMAR — Center for Ecological Modelling, Departmento de Cieˆncias e Engenharia do Ambiente, Faculdade de Cieˆncias e Tecnologia, Uni ersidade No a de Lisboa-Qta.
da Torre, Monte de Caparica, . Here are 9 species that are already being impacted by climate change. 9 animals that are feeling the impacts of climate change | U.S. Department of the Interior Skip to .
Global warming can affect saltmarshes in two broad ways, through change in the climate and by sea-level rise. Climate change Bertness and Pennings () argued that the zonation of saltmarsh plants might be influenced by nutrient enrichment (eutrophication) and by climate.