Historical and present day records on the distribution of marshes, eelgrass meadows and kelp forests are compiled and compared to evaluate historical changes in these nearshore habitats. The findings of the study are as follows: The most comprehensive records were for tidal marshes, which have decreased 71 percent in area since records made in the 1800s. Much of the loss is due to diking, filling and dredging; Records of eelgrass meadows from before the major influx of humans in the late 1800s were not comprehensive. However, eelgrass losses of 30 percent and 15 percent were estimated for Bellingham Bay and the Snohomish River delta, respectively. Eelgrass cover may have increased by approximately fivefold in Padilla Bay. Kelp has apparently increased approximately 58 percent in Puget Sound and the Straits. The greatest increase in kelp distribution was documented in the most populated areas including the Main Basin and south Puget Sound. Invading species of algae and flowering plants have had a major impact on the distribution of eelgrass and kelp, tideflat and estuarine marsh in some subregions. Recommendations are: Monitor habitats in a quantitative manner; investigate causal factors related to dramatic changes in kelp distribution; develop methods to quantify subtidal eelgrass distribution; investigate factors affecting eelgrass distribution, especially subtidal meadows; incorporate only new quantitative habitat records into a Geographic Information System (GIS) which includes information on water quality and physical site conditions.

"Final report to Office of Puget Sound, Region 10, U.S. Environmental Protection Agency." "June 1990." "EPA 910/9-91-005." "FRI-UW-9008." Includes bibliographical references (p. 52-55).