301Environmental Analysis Tools
services, such as primary production or plant density if the habitat is relatively
uniform, such as a mangrove swamp or Spartina spp. salt marsh.
Selecting a currency that is indicative of the health of a habitat is another
approach that can be useful for some habitats. For example, the density of
grass shrimp (Palaemonetes pugio), considered a key species by local experts,
is highly correlated with many and diverse services provided by marsh
habitats (NOAA 1997). Thus, grass shrimp population density can serve as
thecurrency in HEA because it is indicative of the services provided by the
environmental resource under consideration and can ultimately be used to
calculate ecological debit and credit ...