Habitat change in the lower Columbia River estuary, 1870–2009

Anthropogenic changes beginning in the 1860s including agriculture, dike building, and dam construction altered water quality and habitat conditions, resulting in loss of 68-70% of vegetated tidal wetlands.

“anthropogenic changes beginning in the 1860s including agriculture, dike building, and dam construction for the hydropower system, altered water quality and habitat conditions [23–25], resulting in loss of 68–70% of vegetated tidal wetlands [26].”

Since the 1870s, herbaceous wetland area decreased from 35,466 to 11,381 acres (68%), while forested and shrubscrub decreased from 39,439 to 12,289 acres (69%).

“Since the 1870s, herbaceous wetland area decreased from 35,466 to 11,381 acres (68%), while forested and shrubscrub decreased from 39,439 to 12,289 acres (69%; Marcoe and Pilson 2017).”

Virtually all of this wetland loss is due to the levee system, filling, and urban development.

“Virtually all of this loss is due to the levee system, filling, and urban development.”

The Columbia River estuary has lost 70% of its historic tidal wetlands, primarily to diking.

“Like most West Coast estuaries, the CRE has been highly modified by anthropogenic activities over nearly 150 years and has lost 70% of its historic tidal wetlands, primarily to diking (Marcoe and Pilson 2017).”

Greater similarity in diet composition for salmon at the lower three sites was expected given the similarity in habitat mosaics in the lower estuary and given the relatively short travel time (~1 d) in which the fish migrate through the lower estuary.

“Greater similarity in diet composition for salmon at the lower three sites was expected given the similarity in habitat mosaics in the lower estuary (Marcoe and Pilson 2017) and given the relatively short travel time (∼1 d) in which the fish migrate through the lower estuary (Harnish et al. 2012;Morrice et al. 2020).”