Kelp Counts and Bottom Cover Estimates Obtained by SCUBA at Shallow Nearshore Sites along the North Pacific Rim from Bering Island to Southeast Alaska during 1987-2021
Dates
Publication Date
2023-12-14
Start Date
1987-06-24
End Date
2021-08-26
Citation
Kenner, M.C., Weitzman, B.P., Konar, B.H., Edwards, M.S., and Estes, J.A., 2023, Kelp and sea urchin data obtained by SCUBA at shallow nearshore sites along the north Pacific Rim from Bering Island to Southeast Alaska obtained over multiple decades beginning in 1987: U.S. Geological Survey data release, https://doi.org/10.5066/P9N9Z1IC.
Summary
The data consist of counts of kelps and estimated percent cover of fleshy red algae, other benthic algal cover, and non-motile invertebrates in quadrats from over 600 nearshore rocky bottom sites that were sampled by scuba between 1987 and 2021. The sites are from 38 locations on the north Pacific Rim ranging from Bering Island, along the Aleutian Island chain and the Alaska Peninsula to southeast Alaska. At each site, divers counted kelps and estimated percent cover of other algae and encrusting invertebrates in 20 quadrats along 20-25-foot depth contour. At a subset of sites, 40-foot depths were targeted. Quadrat size is specified in the data table but was 0.25 m2 at almost all sites. At the same sites where kelps were counted, divers [...]
Summary
The data consist of counts of kelps and estimated percent cover of fleshy red algae, other benthic algal cover, and non-motile invertebrates in quadrats from over 600 nearshore rocky bottom sites that were sampled by scuba between 1987 and 2021. The sites are from 38 locations on the north Pacific Rim ranging from Bering Island, along the Aleutian Island chain and the Alaska Peninsula to southeast Alaska. At each site, divers counted kelps and estimated percent cover of other algae and encrusting invertebrates in 20 quadrats along 20-25-foot depth contour. At a subset of sites, 40-foot depths were targeted. Quadrat size is specified in the data table but was 0.25 m2 at almost all sites. At the same sites where kelps were counted, divers counted and collected sea urchins from quadrats placed at random distances along the same depth profile. Sites were plotted at random from along the coasts of islands or areas designated. Hard substrate was targeted. Sites included here are at Adak Island, Agattu Island, Akutan Island, Alaid Island, Amchitka Island, Anangula Island, Atka Island, Attu Island, Bering Island, Chiachi Island, Chuginadak Island, Hawadax (formerly Rat) Island, Kiska Island, Kodiak Island, Mitrofania Island, Nizki Island, Ogliuga Island, Sanak Island, Seguam Island, the Semidi Islands, Shemya Island, Sitkalidak Island, Skagul Island, Tanaga Island, Umnak Island, Unalaska Island, Unga Island, Yunaska Island; Amalik Bay, Kukak Bay, and Pavlov Bay on the Alaska Peninsula; Kachemak Bay on the Kenai Peninsula; and Torch Bay, Surge Bay, and Sitka Sound in southeast Alaska. Sea urchin counts data, sea urchin size data, and site locations are presented in other tables.
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Purpose
The data were collected opportunistically over several decades and under several different funded projects as a means of assessing the impact of sea otters on community structure in the shallow, rocky nearshore environment along the north Pacific Rim. Across the geographical and temporal range of these data collections, sea otter populations have varied with population expansions in some areas and dramatic declines in others. In conjunction with data on local sea otter abundance, these data illustrate sea otters' powerful top-down influence on these communities. The tight ecological linkages between sea otters and benthic habitats can be used to assess the functional role of sea otters in the ecosystem and was incorporated in the 2014 USFWS Sea Otter Recovery Plan as an Ecological Recovery Criterion for the depleted Southwest Stock of northern sea otters.
