Global ecosystem typology

Alternative site for the Global ecosystem typology with additional information for ecosystem profiles and indicative maps.

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MFT1.1 Coastal river deltas

Biome: MFT1. Brackish tidal biome

Contributors:
(texts)

At the convergence of terrestrial, freshwater and marine realms, coastal river deltas are shaped by river inflows that deposit sediment and ocean tides and currents that disperse it. Gradients of salinity and submergence and dynamic substrates create shifting mosaics of channels, islands, floodplains, intertidal and subtidal mud plains and sand beds that may be regarded as embedded patches of other functional groups. The dynamic mosaics support complex foodwebs. Planktonic algae, aquatic plants and river inflows contribute detritus for in-sediment fauna. Fish and zooplankton are diverse and abundant in the water column, providing food for wading and fishing birds and marine and terrestrial predators.

Key Features

Depositional, mosaic systems with strong gradients between terrestrial, freshwater and marine elements. Productive with diverse plankton, fish, birds and mammals..

Overview of distribution

Continental margins of high rainfall catchments globally.

Profile versions

Main references

Selected references for this functional group:

  • Bianchi TS, Allison MA (2009) Large-river delta-front estuaries as natural “recorders” of global environmental change Proceedings of the National Academy of Sciences of the USA 106:8085-8092 DOI:10.1073/pnas.0812878106

  • Orton GJ, Reading G (1993) Variability of deltaic processes in terms of sediment supply, with particular emphasis on grain-size Sedimentology 40:475-512 DOI:10.1111/j.1365-3091.1993.tb01347.x

Diagrammatic assembly model

Diagrammatic assembly model of MFT1.1 Coastal river deltas. See general notes on diagrams. Open image full size.

Maps

Maps are indicative of global distribution patterns are not intended to represent fine-scale patterns. The maps show areas of the world containing major (coloured red) or minor occurrences (coloured yellow) of each ecosystem functional group. See general notes on maps.

Information about the current valid indicative map for this functional group is shown below.

MFT1.1.WM.nwx_v1.0

The extent of major coastal deltas was taken directly from Nienhuis et al. (2020). The data are based on polygons that encompass the lowest reaches of deltaic floodplains and a marine buffer approximating the extent of subtidal deltaic sediments. We checked the data for completeness against point locations shown in Fig. 1 of Goodbred & Saito (2012) and maps of Tessler et al. (2015) and found them to be inclusive of major occurrences. The latter included fewer deltas and olygons that extended some distance up freshwater floodplains into the Freshwater-Terrestrial (FT) transition biome. Open image full size.

Datasets

  • Deltas-at-Risk
  • Global-Delta-Data

Map references

  • Z.D. Tessler, C.J. Vörösmarty, M. Grossberg, I. Gladkova, H. Aizenman, J.P.M. Syvitski, E. Foufoula-Georgiou (2015) Profiling Risk and Sustainability in Coastal Deltas of the World Science 349(6248), 638-643 DOI:10.1126/science.aab3574

  • Nienhuis, J.H., Ashton, A.D., Edmonds, D.A. et al. (2020) Global-scale human impact on delta morphology has led to net land area gain Nature 577, 514–518 DOI:10.1038/s41586-019-1905-9

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