Estuaries and Coasts

, Volume 37, Issue 1, pp 160–176 | Cite as

An Estuarine Habitat Classification for a Complex Fjordal Island Archipelago

  • G. Carl SchochEmail author
  • David M. Albert
  • Colin S. Shanley


Spatial patterns of estuarine biota suggest that some nearshore ecosystems are functionally linked to interacting processes of the ocean, watershed, and coastal geomorphology. The classification of estuaries can therefore provide important information for distribution studies of nearshore biodiversity. However, many existing classifications are too coarse-scaled to resolve subtle environmental differences that may significantly alter biological structure. We developed an objective three-tier spatially nested classification, then conducted a case study in the Alexander Archipelago of Southeast Alaska, USA, and tested the statistical association of observed biota to changes in estuarine classes. At level 1, the coarsest scale (100–1000’s km2), we used patterns of sea surface temperature and salinity to identify marine domains. At level 2, within each marine domain, fjordal land masses were subdivided into coastal watersheds (10–100’s km2), and 17 estuary classes were identified based on similar marine exposure, river discharge, glacier volume, and snow accumulation. At level 3, the finest scale (1–10’s km2), homogeneous nearshore (depths <10 m) segments were characterized by one of 35 benthic habitat types of the ShoreZone mapping system. The aerial ShoreZone surveys and imagery also provided spatially comprehensive inventories of 19 benthic taxa. These were combined with six anadromous species for a relative measure of estuarine biodiversity. Results suggest that (1) estuaries with similar environmental attributes have similar biological communities, and (2) relative biodiversity increases predictably with increasing habitat complexity, marine exposure, and decreasing freshwater. These results have important implications for the management of ecologically sensitive estuaries.


Marine spatial planning Conservation Nearshore ecosystems 



Funding for this project was provided by the Alaska Department of Fish and Game, Coastal Impact Assessment Program, Gordon and Betty Moore Foundation, NOAA National Marine Fisheries Service, Royal Caribbean Cruises Ltd., Ocean Fund, and the Skaggs Foundation. We are grateful for the efforts of project manager Laura Baker and for constructive review comments from M. Dethier and J. Harper. We greatly appreciate the efforts of the two anonymous reviewers for edits and suggestions that improved an earlier version of this manuscript.


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Copyright information

© Coastal and Estuarine Research Federation 2013

Authors and Affiliations

  • G. Carl Schoch
    • 1
    Email author
  • David M. Albert
    • 2
  • Colin S. Shanley
    • 2
  1. 1.Coastwise ServicesHomerUSA
  2. 2.The Nature ConservancyJuneauUSA

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