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     data   graph     files  public [Island grazing history] - Historical reconstruction of sea urchin grazing events in Aleutian
Island ecosystem from grazing scars, 1965-2004 (Ocean Acidification: Century Scale Impacts to
Ecosystem Structure and Function of Aleutian Kelp Forests)
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The Dataset's Variables and Attributes

Row Type Variable Name Attribute Name Data Type Value
attribute NC_GLOBAL access_formats String .htmlTable,.csv,.json,.mat,.nc,.tsv,.esriCsv,.geoJson,.odvTxt
attribute NC_GLOBAL acquisition_description String Clathromorphum species produce annual growth increments (hereafter \"year
bands\") in their skeleton (Adey et al. 2013), which contain elemental and
isotopic signatures that can be used to reconstruct past oceanographic
conditions (e.g., Fietzke et al. 2015). We discovered that such year bands
also archive urchin grazing scars, allowing us to measure the timing and
frequency of past urchin grazing events on C. nereostratum. Wild specimens of
C. nereostratum were thus collected and analyzed in order to reconstruct
grazing events in the ecosystem.

At each site studied with respect to bioerosion, we collected C. nereostratum
specimens (n = 10/site) with hammer and chisel, focusing on individuals
without visible signs of grazing on the epithallus. Ship-side, samples were
sectioned with a diamond lapidary saw and examined for quality; high quality
samples were placed in an oven (50\u00b0C) until dry, then archived for
subsequent analysis. Samples collected from Amchitka were of poor quality.
Hence for Amchitka, we used specimens collected previously (2004) for this
exercise. We also augmented our 2014 collections from Attu with samples
previously collected (2008) from the same locale, because many of the 2014
samples did not meet our criteria for reconstruction (see below).

Each C. nereostratum specimen (n = 5/island) was mounted to a glass slide,
sectioned parallel to the growth axis with a diamond lapidary saw, and
polished to 3 microns resolution following established methods (Hetzinger et
al. 2009). Each section was then imaged with a camera coupled to a reflected
light microscope (GeoTS, Olympus Inc.), which obtains a mosaic of overlapping
images and stitches them together to produce a single high-resolution image of
the cross-section. This photomosaic was used to carefully identify, age, and
count grazing scars that occurred along a transect oriented parallel to the
alga's growth axis in the plane of the section. We scored multiple (n = 2-3)
transects per sample, given that grazing events do not span the entirety of a
year band. The origin of each transect was randomly plotted, then moved to the
nearest location on the epithallus that was living and that displayed a flat
or convex shape. The transect was then plotted through sequentially older year
bands, so long as it: (i) did not cross a fusion between two individual algae;
(ii) spanned at least 30 years of growth; and (iii) intercepted year bands
that were clearly visible. If any of these criteria were violated, the
transect was relocated.

Along each transect, we aged and measured the growth (vertical extension) of
year bands in 5-year intervals, repeating this process so long as dating could
be rigorously performed and end-dates aligned for all transects within a
sample. Within each 5-year interval, we assessed the annual frequency of
grazing scars - which manifest as a jagged interruption of the growth margin
coupled with serial pitting of the reproductive conceptacles - found 5 mm to
either side of the transect. Straight growth lines that lacked conceptacles or
the occasional empty conceptacle within an otherwise clean growth band was not
considered evidence of grazing. In instances where one side of the transect
entered an area that violated the above criteria (e.g., passed under an area
that had a concave epithallial surface), we analyzed only one side of the
transect (10 mm). With this methodology remains the possibility that urchin
grazing may have removed entire years of growth, thus obscuring our estimates
of grazing frequency and the timing of each grazing event. To address this
issue, we compared (double blind) our age models for a subset of samples from
Alaid and Ogliuga to ages produced using Uranium series dating (Fietzke et al.
2005). Our age estimates were very similar to those produced by Uranium series
dating, indicating we did not lose entire years to grazing.

We selected the year 1965 as the cutoff for our reconstruction because
ecological records are scant prior to this period (Estes et al. 2010). For C.
nereostratum samples collected in 2014, we excluded the 10 most recent years
of growth (2014-2005) from our analyses due to a known bias in our collection
method; since we collected non-grazed specimens from the wild and retained
only the highest quality samples, we biased ourselves against finding evidence
of grazing in recent years. For samples collected in 2004 and 2008, such a
bias was not evident, at least for those records that met our criteria and
were used in the study. For the three 2008 samples used, we excluded the first
four years to align chronologies with all other specimens.
attribute NC_GLOBAL awards_0_award_nid String 526658
attribute NC_GLOBAL awards_0_award_number String PLR-1316141
attribute NC_GLOBAL awards_0_data_url String http://nsf.gov/awardsearch/showAward?AWD_ID=1316141 (external link)
attribute NC_GLOBAL awards_0_funder_name String NSF Arctic Sciences
attribute NC_GLOBAL awards_0_funding_acronym String NSF ARC
attribute NC_GLOBAL awards_0_funding_source_nid String 390
attribute NC_GLOBAL awards_0_program_manager String Henrietta N Edmonds
attribute NC_GLOBAL awards_0_program_manager_nid String 51517
attribute NC_GLOBAL cdm_data_type String Other
attribute NC_GLOBAL comment String Historical reconstruction of sea urchin grazing events in the Aleutian Islands, 1965-2004
PI's: Steneck (Umaine), J.Estes (UCSC), D. Rasher (BLOS)
version: 2019-02-013
attribute NC_GLOBAL Conventions String COARDS, CF-1.6, ACDD-1.3
attribute NC_GLOBAL creator_email String info at bco-dmo.org
attribute NC_GLOBAL creator_name String BCO-DMO
attribute NC_GLOBAL creator_type String institution
attribute NC_GLOBAL creator_url String https://www.bco-dmo.org/ (external link)
attribute NC_GLOBAL data_source String extract_data_as_tsv version 2.3 19 Dec 2019
attribute NC_GLOBAL date_created String 2019-02-13T20:13:05Z
attribute NC_GLOBAL date_modified String 2019-02-25T20:18:35Z
attribute NC_GLOBAL defaultDataQuery String &time<now
attribute NC_GLOBAL doi String 10.1575/1912/bco-dmo.755687.1
attribute NC_GLOBAL Easternmost_Easting double 179.38346
attribute NC_GLOBAL geospatial_lat_max double 52.9336
attribute NC_GLOBAL geospatial_lat_min double 51.40901
attribute NC_GLOBAL geospatial_lat_units String degrees_north
attribute NC_GLOBAL geospatial_lon_max double 179.38346
attribute NC_GLOBAL geospatial_lon_min double -178.66258
attribute NC_GLOBAL geospatial_lon_units String degrees_east
attribute NC_GLOBAL infoUrl String https://www.bco-dmo.org/dataset/755687 (external link)
attribute NC_GLOBAL institution String BCO-DMO
attribute NC_GLOBAL keywords String bco, bco-dmo, biological, chemical, collection, data, dataset, date, depth, depth_feet, dmo, end, end_period, erddap, events, grazing, grazing_events, growth, growth_increment_um, increment, island, latitude, longitude, management, name, oceanography, office, period, preliminary, replicate, sample, sample_ID, site, site_name, start, start_period, time, time_period, transect
attribute NC_GLOBAL license String https://www.bco-dmo.org/dataset/755687/license (external link)
attribute NC_GLOBAL metadata_source String https://www.bco-dmo.org/api/dataset/755687 (external link)
attribute NC_GLOBAL Northernmost_Northing double 52.9336
attribute NC_GLOBAL param_mapping String {'755687': {'collection_date': 'flag - time', 'depth_feet': 'flag - depth', 'longitude': 'flag - longitude', 'latitude': 'flag - latitude'}}
attribute NC_GLOBAL parameter_source String https://www.bco-dmo.org/mapserver/dataset/755687/parameters (external link)
attribute NC_GLOBAL people_0_affiliation String University of Maine
attribute NC_GLOBAL people_0_affiliation_acronym String U Maine DMC
attribute NC_GLOBAL people_0_person_name String Robert S. Steneck
attribute NC_GLOBAL people_0_person_nid String 526659
attribute NC_GLOBAL people_0_role String Principal Investigator
attribute NC_GLOBAL people_0_role_type String originator
attribute NC_GLOBAL people_1_affiliation String University of California-Santa Cruz
attribute NC_GLOBAL people_1_affiliation_acronym String UC Santa Cruz
attribute NC_GLOBAL people_1_person_name String James Estes
attribute NC_GLOBAL people_1_person_nid String 51389
attribute NC_GLOBAL people_1_role String Co-Principal Investigator
attribute NC_GLOBAL people_1_role_type String originator
attribute NC_GLOBAL people_2_affiliation String Bigelow Laboratory for Ocean Sciences
attribute NC_GLOBAL people_2_person_name String Douglas B. Rasher
attribute NC_GLOBAL people_2_person_nid String 480721
attribute NC_GLOBAL people_2_role String Co-Principal Investigator
attribute NC_GLOBAL people_2_role_type String originator
attribute NC_GLOBAL people_3_affiliation String Woods Hole Oceanographic Institution
attribute NC_GLOBAL people_3_affiliation_acronym String WHOI BCO-DMO
attribute NC_GLOBAL people_3_person_name String Nancy Copley
attribute NC_GLOBAL people_3_person_nid String 50396
attribute NC_GLOBAL people_3_role String BCO-DMO Data Manager
attribute NC_GLOBAL people_3_role_type String related
attribute NC_GLOBAL project String OA Kelp Forest Function
attribute NC_GLOBAL projects_0_acronym String OA Kelp Forest Function
attribute NC_GLOBAL projects_0_description String 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.
attribute NC_GLOBAL projects_0_end_date String 2016-08
attribute NC_GLOBAL projects_0_name String Ocean Acidification: Century Scale Impacts to Ecosystem Structure and Function of Aleutian Kelp Forests
attribute NC_GLOBAL projects_0_project_nid String 526660
attribute NC_GLOBAL projects_0_start_date String 2013-09
attribute NC_GLOBAL publisher_name String Biological and Chemical Oceanographic Data Management Office (BCO-DMO)
attribute NC_GLOBAL publisher_type String institution
attribute NC_GLOBAL sourceUrl String (local files)
attribute NC_GLOBAL Southernmost_Northing double 51.40901
attribute NC_GLOBAL standard_name_vocabulary String CF Standard Name Table v55
attribute NC_GLOBAL summary String Historical reconstruction of sea urchin grazing events in the ecosystem, achieved via enumerating the annual frequency of grazing scars that are archived in the calcified matrix of Clathromorphum nereostratum. Intact colonies of C. nereostratum were collected via SCUBA. Reconstructions were performed on polished and imaged sample cross-sections.
attribute NC_GLOBAL time_coverage_end String 2014-07-21
attribute NC_GLOBAL time_coverage_start String 2004-08-14
attribute NC_GLOBAL title String [Island grazing history] - Historical reconstruction of sea urchin grazing events in Aleutian Island ecosystem from grazing scars, 1965-2004 (Ocean Acidification: Century Scale Impacts to Ecosystem Structure and Function of Aleutian Kelp Forests)
attribute NC_GLOBAL version String 1
attribute NC_GLOBAL Westernmost_Easting double -178.66258
attribute NC_GLOBAL xml_source String osprey2erddap.update_xml() v1.3
variable time   double  
attribute time _CoordinateAxisType String Time
attribute time actual_range double 1.0924416E9, 1.4059008E9
attribute time axis String T
attribute time bcodmo_name String date
attribute time description String date of collection; formatted as yyyy-mm-dd
attribute time ioos_category String Time
attribute time long_name String Collection Date
attribute time nerc_identifier String https://vocab.nerc.ac.uk/collection/P01/current/ADATAA01/ (external link)
attribute time source_name String collection_date
attribute time standard_name String time
attribute time time_origin String 01-JAN-1970 00:00:00
attribute time time_precision String 1970-01-01
attribute time units String seconds since 1970-01-01T00:00:00Z
variable island   String  
attribute island bcodmo_name String site
attribute island description String name of island
attribute island long_name String Island
attribute island units String unitless
variable site_name   String  
attribute site_name bcodmo_name String site
attribute site_name description String name of collection site
attribute site_name long_name String Site Name
attribute site_name units String unitless
variable latitude   double  
attribute latitude _CoordinateAxisType String Lat
attribute latitude _FillValue double NaN
attribute latitude actual_range double 51.40901, 52.9336
attribute latitude axis String Y
attribute latitude bcodmo_name String latitude
attribute latitude colorBarMaximum double 90.0
attribute latitude colorBarMinimum double -90.0
attribute latitude description String latitude of collection site
attribute latitude ioos_category String Location
attribute latitude long_name String Latitude
attribute latitude nerc_identifier String https://vocab.nerc.ac.uk/collection/P09/current/LATX/ (external link)
attribute latitude standard_name String latitude
attribute latitude units String degrees_north
variable longitude   double  
attribute longitude _CoordinateAxisType String Lon
attribute longitude _FillValue double NaN
attribute longitude actual_range double -178.66258, 179.38346
attribute longitude axis String X
attribute longitude bcodmo_name String longitude
attribute longitude colorBarMaximum double 180.0
attribute longitude colorBarMinimum double -180.0
attribute longitude description String longitude of collection site
attribute longitude ioos_category String Location
attribute longitude long_name String Longitude
attribute longitude nerc_identifier String https://vocab.nerc.ac.uk/collection/P09/current/LONX/ (external link)
attribute longitude standard_name String longitude
attribute longitude units String degrees_east
variable depth_feet   double  
attribute depth_feet _FillValue double NaN
attribute depth_feet actual_range double 30.0, 33.0
attribute depth_feet bcodmo_name String depth
attribute depth_feet colorBarMaximum double 8000.0
attribute depth_feet colorBarMinimum double -8000.0
attribute depth_feet colorBarPalette String TopographyDepth
attribute depth_feet description String depth of sample collection
attribute depth_feet long_name String Depth
attribute depth_feet nerc_identifier String https://vocab.nerc.ac.uk/collection/P09/current/DEPH/ (external link)
attribute depth_feet standard_name String depth
attribute depth_feet units String feet
variable replicate   byte  
attribute replicate _FillValue byte 127
attribute replicate actual_range byte 1, 5
attribute replicate bcodmo_name String replicate
attribute replicate description String replicate individual alga studied
attribute replicate long_name String Replicate
attribute replicate units String unitless
variable sample_ID   String  
attribute sample_ID bcodmo_name String sample
attribute sample_ID description String unique sample identifier
attribute sample_ID long_name String Sample ID
attribute sample_ID nerc_identifier String https://vocab.nerc.ac.uk/collection/P02/current/ACYC/ (external link)
attribute sample_ID units String unitless
variable transect   byte  
attribute transect _FillValue byte 127
attribute transect actual_range byte 1, 3
attribute transect bcodmo_name String transect
attribute transect description String replicate transect within individual
attribute transect long_name String Transect
attribute transect units String unitless
variable end_period   short  
attribute end_period _FillValue short 32767
attribute end_period actual_range short 1969, 2004
attribute end_period bcodmo_name String year_end
attribute end_period description String upper bound of 5-year period scored
attribute end_period long_name String End Period
attribute end_period units String year
variable start_period   short  
attribute start_period _FillValue short 32767
attribute start_period actual_range short 1965, 2000
attribute start_period bcodmo_name String year_start
attribute start_period description String lower bound of 5-year period scored
attribute start_period long_name String Start Period
attribute start_period units String year
variable time_period   String  
attribute time_period bcodmo_name String date_range
attribute time_period description String discrete 5-year time interval scored
attribute time_period long_name String Time Period
attribute time_period units String years
variable growth_increment_um   short  
attribute growth_increment_um _FillValue short 32767
attribute growth_increment_um actual_range short 423, 3227
attribute growth_increment_um bcodmo_name String growth
attribute growth_increment_um description String net algal growth incurred over 5-year period
attribute growth_increment_um long_name String Growth Increment Um
attribute growth_increment_um units String micrometers
variable grazing_events   byte  
attribute grazing_events _FillValue byte 127
attribute grazing_events actual_range byte 0, 5
attribute grazing_events bcodmo_name String number
attribute grazing_events description String number of grazing events observed within 5-year period
attribute grazing_events long_name String Grazing Events
attribute grazing_events units String unitless

The information in the table above is also available in other file formats (.csv, .htmlTable, .itx, .json, .jsonlCSV1, .jsonlCSV, .jsonlKVP, .mat, .nc, .nccsv, .tsv, .xhtml) via a RESTful web service.


 
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