PAR measurements from kelp forests and urchin barrens on the Aleutian Islands, Alaska from R/V Oceanus cruises OC1606A and OC1707A during 2016-2017

Data Type: Cruise Results, Other Field Results
Version: 1
Version Date: 2019-11-19

» Collaborative Research: Changes in ecosystem production and benthic biodiversity following the widespread loss of an ecosystem engineer (Kelp Forest Ecosystem Engineer Loss)
Edwards, MatthewSan Diego State University (SDSU)Principal Investigator
Konar, BrendaUniversity of Alaska Fairbanks (UAF)Co-Principal Investigator
Rauch, ShannonWoods Hole Oceanographic Institution (WHOI BCO-DMO)BCO-DMO Data Manager


Spatial Extent: N:53.38962 E:-179.30663 S:51.41008 W:177.60144
Temporal Extent: 2016-06-17 - 2017-07-23

Dataset Description

Estimates of benthic primary production and respiration in kelp forests and urchin barrens in the Aleutian Archipelago, Alaska (Attu, Nizki, Kiska, Atka, Adak, Chuginadak, Tanaga, Amchitka, Yunaska, Unmak, and Unalaska).

Acquisition Description

We deployed 3 benthic chambers in each of three habitats (kelp forests, urchin barrens, and transition zones) at each of 10 islands in the Aleutian Archipelago. Each chamber was equipped with a data logger for dissolved oxygen (PME Minidot) and light (Odyssey PAR) and were left on the benthos for 36 hours. These data are hourly totals for light irradiance data for each habitat type at each island.

Data were collected each minute while deployed. Data were ultimately summed for each hour. Data are presented in different tabs for each island.

Processing Description

We used MS Excel and R-Studio to summarize and QA the data.

BCO-DMO Processing:
- inserted latitude and longitude for each site;
- added column with date formatted as yyyymmdd for clarity;
- added date to Nizki site.

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IslandIsland name unitless
latLatitude of measurement; positive values = North decimal degrees
lonLongitude of measurement; positive values = East decimal degrees
DateDate; format: dd/mm/yyyy unitless
TimeTime of day; 24-hr clock; format: HH:MM:SS unitless
Sensor_numSensor number unitless
SerialSensor serial number unitless
HabitatHabitat type unitless
umol_photon_m2_hourIrrandiance measurement micromoles photons per square meter per hour (umol photons/m2/hr)
Date_yyyymmddDate formatted as yyyymmdd unitless

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Dataset-specific Instrument Name
Odyssey PAR Logger
Generic Instrument Name
Photosynthetically Available Radiation Sensor
Generic Instrument Description
A PAR sensor measures photosynthetically available (or active) radiation. The sensor measures photon flux density (photons per second per square meter) within the visible wavelength range (typically 400 to 700 nanometers). PAR gives an indication of the total energy available to plants for photosynthesis. This instrument name is used when specific type, make and model are not known.

Dataset-specific Instrument Name
PME Minidot Oxygen loggers
Generic Instrument Name
Dissolved Oxygen Sensor
Generic Instrument Description
An electronic device that measures the proportion of oxygen (O2) in the gas or liquid being analyzed

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R/V Oceanus
Start Date
End Date
Project: Changes in Ecosystem Production and Benthic Biodiversity


R/V Oceanus
Start Date
End Date
Project: Changes in Ecosystem Production and Benthic Biodiversity

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Project Information

Collaborative Research: Changes in ecosystem production and benthic biodiversity following the widespread loss of an ecosystem engineer (Kelp Forest Ecosystem Engineer Loss)

Coverage: Aleutian Islands Alaska (Attu Island to Unalaska)

NSF abstract:

In many ecosystems the presence of a single dominant species can modify the physical conditions of the environment and alter patterns of biodiversity, nutrient cycling, and primary production. Losses of these "ecosystem engineers" can have profound impacts to how ecosystems function. Coastal kelps provide excellent examples of organisms whose structure modifies the physical characteristics of their habitats (light, nutrients, water motion) and supports enhanced biodiversity. The kelp forests in the coastal waters of the Aleutian Archipelago have suffered large-scale declines over the past several decades. This project will examine how these losses impact patterns of ecosystem production and biodiversity using a combination of techniques ranging from in situ benthic chambers and shipboard incubations to remote sensing using satellite imagery. The results will provide an understanding of how such events may impact this and other ecosystems. This project will support graduate students and will introduce the public to the Aleutian ecosystems in a series of videos. The investigators will also work with a San Diego high school teacher to integrate project findings into classroom activities, and they expect to involve a teacher in their field program.

The investigators will ask two highly integrated questions: 1) How do the widespread losses of kelp forests impact benthic productivity across the Aleutian Archipelago? 2) How do the widespread losses of kelp forests impact benthic biodiversity and community structure across the archipelago? To address these, the investigators will estimate changes to productivity at ten islands where they have historic data on seaweed community composition and estimates of kelp canopy cover. They will use in situ benthic chambers placed in both kelp forests and urchin barrens to measure plot-scale patterns of net ecosystem productivity (NEP), and shipboard incubations to examine net primary productivity (NPP) for the dominant macroalgae. Data for individual species rates of NPP will be scaled by their biomass and combined with in situ plot-scale benthic chamber experiments of whole communities to estimate NEP at the islands visited. These estimates will be scaled up to calculate NEP across the entire archipelago by first extrapolating results from the study sites to entire islands, and then across the archipelago. They will also estimate broad-scale patterns in production by characterizing water column irradiances across the archipelago and modeling NPP using species-level relationships between irradiance and photosynthesis. Coupling these with estimates of water column irradiance and community respiration will allow modeling of NEP across this region. Benthic biodiversity will be assessed using diver surveys and shipboard benthic trawls. Following these activities, satellite remote sensing of the kelp canopies dating back to the 1980s and the investigators' own historical data on benthic macroalgal abundances at these and other islands will be used to estimate the temporal and spatial patterns of change across the archipelago.

For more information see:

Project blog:
Project website:

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Funding SourceAward
NSF Division of Ocean Sciences (NSF OCE)

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