| Contributors | Affiliation | Role |
|---|---|---|
| Steneck, Robert S. | University of Maine (U Maine DMC) | Principal Investigator |
| Estes, James A. | University of California-Santa Cruz (UCSC) | Co-Principal Investigator |
| Rasher, Douglas B. | Bigelow Laboratory for Ocean Sciences | Contact |
| Gerlach, Dana Stuart | Woods Hole Oceanographic Institution (WHOI BCO-DMO) | BCO-DMO Data Manager |
| Heyl, Taylor | Woods Hole Oceanographic Institution (WHOI BCO-DMO) | BCO-DMO Data Manager |
These data were published in Table S1 in Rasher et al., 2020 (see Related Publications section below).
At each island, visual counts of sea otters were made from a 4 m open boat as it circumnavigated the island perimeter at a speed of 18 to 25 km per hour, just outside of any existing kelp canopy and/or close enough to shore (50-150 m) to be able to easily see an animal swimming or resting on the surface. The perimeter of the island was divided into sectors, and these designations were utilized every year a survey was conducted. Survey teams consisted of a primary observer, data recorder, and boat operator (who also acted as a secondary observer). As the boat moved parallel to shore and around any offshore islets, observers visually scanned for sea otters both inshore and offshore of the boat trajectory and, in the case of larger sea otter groups or difficult-to-access locations, the boat was paused and binoculars were used to scan the area and obtain accurate counts. Whenever sea otters were observed and counted, we noted their geo-location, group size, reproductive status (single animals or females with pups), whether the animals were less than or greater than 20 m from the nearest point of land or emergent substrate, and whether each animal was within or outside a surface canopy of kelp. Here, we report only island-wide abundance estimates for independent (non-pup) individuals, as dependent pup counts were variable due to annual differences in the timing of reproduction. Because surveys varied from year to year in terms of the percentage of the island’s perimeter surveyed (ranging from ~50% to 100%), we standardized counts to linear density (independent sea otters per km of linear coastline surveyed).
NOTE: Surveys were conducted opportunistically, and thus intermittently, from 1991 to 2015 at each island. As such, some islands were surveyed more frequently than others.
BCO-DMO processing:
- Adjusted parameter names to comply with database requirements
- Added a conventional header with dataset name, PIs, and version date
- Converted longitude West values to degrees East
| File |
|---|
island_survey_sea_otter_density_historical.csv (Comma Separated Values (.csv), 7.42 KB) MD5:e92485e59abf23a1822fd843ac169111 Primary data file for dataset ID 838077 |
| Parameter | Description | Units |
| Year | Year of survey | Year |
| Island | Name of island surveyed | Unitless |
| Latitude | Latitude of island surveyed | Decimal degrees |
| Longitude | Longitude of island surveyed | Decimal degrees |
| Density | Number of individuals per linear km of coastline | Units |
| Dataset-specific Instrument Name | |
| Generic Instrument Name | Binoculars Handheld |
| Generic Instrument Description | Handheld binoculars, generally used for bird or mammal observations. |
| Website | |
| Platform | R/V Point Sur |
| Start Date | 2014-07-05 |
| End Date | 2014-07-22 |
| Description | Benthic community studies associated with project "Project: Ocean Acidification: Century Scale Impacts to Ecosystem Structure and Function of Aleutian Kelp Forests". |
Extracted from the NSF award abstract:
Marine calcifying organisms are most at risk to rapid ocean acidification (OA) in cold-water ecosystems. The investigators propose to determine if a globally unique and widespread calcareous alga in Alaska's Aleutian archipelago, Clathromorphum nereostratum, is threatened with extinction due to the combined effects of OA and food web alterations. C. nereostratum is a slow growing coralline alga that can live to at least 2000 years. It accretes massive 'bioherms' that dominate the regions' rocky substrate both under kelp forests and deforested sea urchin barrens. It develops growth bands (similar to tree rings) in its calcareous skeleton, which effectively record its annual calcification rate over centuries. Pilot data suggest the skeletal density of C. nereostratum began to decline precipitously in the 1990's in some parts of the Aleutian archipelago. The investigators now propose to use high-resolution microscopy and microCT imaging to examine how the growth and skeletal density of C. nereostratum has changed in the past 300 years (i.e., since the industrial revolution) across the western Aleutians. They will compare their records of algal skeletal densities and their variation through time with reconstructions of past climate to infer causes of change. In addition, the investigators will examine whether the alga's defense against grazing by sea urchins is compromised by ongoing ocean acidification. The investigators will survey the extent of C. nereostratum bioerosion occurring at 10 sites spanning the western Aleutians, both inside and outside of kelp forests. At each site they will compare these patterns to observed and monitored ecosystem trophic structure and recent C. nereostratum calcification rates. Field observations will be combined with laboratory experiments to determine if it is a decline in the alga's skeletal density (due to recent OA and warming), an increase in grazing intensity (due to recent trophic-level dysfunction), or their interactive effects that are likely responsible for bioerosion patterns inside vs. outside of forests. By sampling C. nereostratum inside and outside of forests, they will determine if kelp forests locally increase pH via photosynthesis, and thus buffer the effects of OA on coralline calcification. The combination of field observations with laboratory controlled experiments, manipulating CO2 and temperature, will help elucidate drivers of calcification and project how these species interactions will likely change in the near future. The project will provide the first in situ example of how ongoing ocean acidification is affecting the physiology of long-lived, carbonate producing organisms in the subarctic North Pacific. It will also be one of the first studies to document whether OA, ocean warming, and food web changes to ecological processes are interacting in complex ways to reshape the outcome of species interactions in nature.
NSF Climate Research Investment (CRI) activities that were initiated in 2010 are now included under Science, Engineering and Education for Sustainability NSF-Wide Investment (SEES). SEES is a portfolio of activities that highlights NSF's unique role in helping society address the challenge(s) of achieving sustainability. Detailed information about the SEES program is available from NSF (https://www.nsf.gov/funding/pgm_summ.jsp?pims_id=504707).
In recognition of the need for basic research concerning the nature, extent and impact of ocean acidification on oceanic environments in the past, present and future, the goal of the SEES: OA program is to understand (a) the chemistry and physical chemistry of ocean acidification; (b) how ocean acidification interacts with processes at the organismal level; and (c) how the earth system history informs our understanding of the effects of ocean acidification on the present day and future ocean.
Solicitations issued under this program:
NSF 10-530, FY 2010-FY2011
NSF 12-500, FY 2012
NSF 12-600, FY 2013
NSF 13-586, FY 2014
NSF 13-586 was the final solicitation that will be released for this program.
PI Meetings:
1st U.S. Ocean Acidification PI Meeting(March 22-24, 2011, Woods Hole, MA)
2nd U.S. Ocean Acidification PI Meeting(Sept. 18-20, 2013, Washington, DC)
3rd U.S. Ocean Acidification PI Meeting (June 9-11, 2015, Woods Hole, MA – Tentative)
NSF media releases for the Ocean Acidification Program:
Press Release 10-186 NSF Awards Grants to Study Effects of Ocean Acidification
Discovery Blue Mussels "Hang On" Along Rocky Shores: For How Long?
Press Release 13-102 World Oceans Month Brings Mixed News for Oysters
| Funding Source | Award |
|---|---|
| NSF Arctic Sciences (NSF ARC) |