Seasonal variations in and observations of landslide impacts on the algal composition of a puget sound nearshore kelp forest

A medium scale landslide (2153 m 3 ) deposited sediment on to a intertidal beach on the north side of Point Williams, Seattle, Washington on 4 April 1991. Within 23 days of the slide, high tides and rain carried 77% of the sediment to nearshore waters and north through a seasonal kelp bed immediately adjacent to the slide area. Transects were placed in north and unimpacted south kelp beds and monitored seasonally for algal community and densities. Significant differences in north and south kelp bed Costaria costata, Laminaria sp., and Nereocystis luetkeana densities occurred during spring. No other community or density differences were found. Irradiance values for the two beds differed during winter months but were similar for the rest of the year