H1 East Transect – July 2017

Permanent Site: H1 East Transect; Depth: 5.2 Meters (16.9 Feet); Distance from river mouth: 2.4 Kilometers (1.5 Miles) east; Pre/Post Dam Removal: 6 years post-dam removal; Lat/Long: 48.1479177,-123.53472865; Site Description: This is a shallow site and one of the farthest removed from the effects of the sediment plume outside of the control sites. Substrate remains mainly gravel with some sand, cobble and an occasional boulder. In 2017 surveys were conducted monthly for 6 months (Feb-July) to observe seaweed growth throughout the main growing season. During this month the seaweed growth is profuse, covering 94% of the sea floor. Visibility was poor this day, a frequent occurrence at this site due to shallow depths and wave surges. Five species of brown seaweeds were present. Two species were very abundant; Alaria marginata (0:37, 1:27 seconds) and three-ribbed kelp Cymathere triplicata (1:09 seconds). The perennial seaweed Pterygophora californica (1:41 seconds) was also present. The large, white patch seen on the seaweed frond at 2:03 seconds is the kelp-encrusting bryozoan Membranipora serrilamella. Horse clams (Tresus capax) were still abundant. No invertebrates are seen on video due to the dense seaweed cover.