We collected replicate samples of each species from a variety of stations with known gradients of nutrients, when possible. Collections on the West Coast of the United States were both from within estuaries and from rocky intertidal habitats. Our results demonstrate both Acanthophora spicifera and Hypnea musciformis are good candidates as indicators within tropical marine habitats. They are able to sequester both N and P in proportion to supply. This is based on results of collections in Puerto Rico and both coasts of Panama.
Data have yet to be analyzed for Honduras and Hawaii.
Since A. spicifera was not found as commonly in the Pacific as in the Caribbean, it will be useful to use it in conjunction with Hypnea musciformis at all locations. For the West Coast of the United States, Ulva spp and Enteromorpha spp were identified as good candidate species. They are both common and collections demonstrate tissue N and P reflecting varying nutrient regimes. Ulva may be more useful than Enteromorpha in the Pacific Northwest as it is more common. In this region, Enteromorpha is largely restricted to freshwater seeps.