PHYSICAL REGIONALIZATION OF 

 COASTAL ECOSYSTEMS OF THE UNITED STATES AND ITS TERRITORIES 



INTRODUCTION 

 OBJECTIVES AND PURPOSES 



The objective of this project is to formulate a 

 hierarchical regional classification scheme for 

 partitioning coastal ecosystems of the United 

 States and its territories, based on the physical 

 (mainly hydrological and geological) charac- 

 teristics of those areas. The geographical area 

 covered by this classification is the continental 

 United States, Alaska, Hawaii, and all other 

 United States claimed, governed, and adminis- 

 tered territories and areas. The classification is 

 based on physical criteria rather than biotic 

 criteria because the objective is to define whole 

 ecosystems, which are constrained by their physi- 

 cal components, rather than to define the distri- 

 bution of one or a few species. (See the discussion 

 of the differences between biogeographical and 

 physical regional classifications in the following 

 subsection, Review of Existing Coastal Classifica- 

 tions). 



This classification should serve two purposes. 

 It should first provide a data collection structure 

 for organizing the storage of data and for demon- 

 strating areas where additional data should be 

 collected. Second, and perhaps more important, 

 it should delineate geographical zones about 

 which predictions on the structure and function- 

 ing of ecosystems within these zones may be 

 made at various levels of resolution. These geo- 

 graphical areas are analogous to the ecological 

 land and ecological water units of the Wildland 

 Planning Glossary (Schwartz et al. 1976) and 

 should be regarded as operational definitions of 

 the boundaries of ecosystems or clusters of 

 similarly functioning ecosystems. Thus, predic- 

 tions within any given division* of the regional 

 classification should be more reliable than predic- 

 tions spanning divisions (ecosystems or clusters 

 of ecosystems). 



The term division is used in the same sense as the word 

 taxonomy; i.e., any one of the categories such as Level I, 

 Level II, etc., into which coastal ecosystems are classified. 



This classification system should be useful to 

 a broad range of users for the above reasons. Two 

 primary users are the National Coastal Eco- 

 systems Team and Ecological Services, both 

 within the U.S. Fish and Wildlife Service (FWS), 

 for the delineation of study boundaries of their 

 Ecological Characterization Studies, and Profiles 

 (see Glossary). 



REVIEW OF EXISTING COASTAL CLASSIFI- 

 CATIONS 



It is appropriate to review several existing 

 coastal classifications, and to explain why these 

 were not suitable to answer the stated objective 

 of this work. It should be noted, however, that 

 numerous ideas and pieces of information used in 

 this classification were borrowed from many of 

 those classifications reviewed. 



There are a number of existing classifications 

 of coastal areas, each serving a different purpose. 

 They fall into three categories: structural, func- 

 tional, and regional (geographical). While these 

 may not be totally mutually exclusive types of 

 classification, each has very specific characteris- 

 tics. Following are descriptions of each category 

 of classification, and several examples of each. 



Structural classification schemes classify the 

 coastline on the basis of the structural compo- 

 nents of the area; for example, geological struc- 

 ture (rocky beach, sandy beach) or surface cover 

 or structure (seagrass beds, kelp beds). Examples 

 of this type of classification are the main body 

 of the Cowardin et al. (1977) wetlands classifi- 

 cation system (exclusive of the regional por- 

 tion), as it applies to estuarine and marine sys- 

 tems, Ray's (1975) classification by habitat, 

 and Hedgpeth's (1957) discussion of classifica- 

 tions. The Cowardin et al. (1977) system is a 

 structural classification because it classifies sub- 

 strate type, bottom cover, and/or surface cover. 

 An example of a unit in this classification would 

 be a marine, subtidal bedrock bottom dominated 

 by Strongylocentrotus. Ray's (1975) classifica- 

 tion deals mainly with geological structure. An 

 example of a unit in this classification would be 



