Sanctuary Integrated Monitoring Network
Monitoring Project

Kelp Watch 2014

Principal Investigator(s)

  • Steven Manley
    California State University, Long Beach
  • Kai Vetter
    University of California, Berkeley
Start Date: February 03, 2014

Dr. Steven Manley (CSU Long Beach) and Dr. Kai Vetter (UC Berkeley) are organizing a group of marine biologists participating in a research effort called Kelp Watch 2014. The purpose is to monitor potential radiation absorbed by our California beds of giant kelp Macrocystis pyrifera and bull kelp Nereocystis luetkeana, two species of canopy forming kelp that form important habitat along the coast of the eastern Pacific. The major isotopes in seawater arriving from the damaged Japanese Fukushima reactor are Cs-134 and Cs-137, and may reach the shores of the eastern Pacific by mid-2014 and be incorporated by kelp into its tissue. Drs. Kai Vetter and Mark Bandstra, Department of Nuclear Physics, UC-Berkeley, have agreed to analyze the kelp tissue samples as part of the Berkeley Radiological Air and Water Monitoring Team.

To collect kelp samples, Kelp Watch 2014 is partnering with multiple academic and agency institutions, including Monterey Bay National Marine Sanctuary and the West Coast Regional office of ONMS. Other partners in central California include UC Santa Cruz, Stanford's Hopkins Marine Station, and Moss Landing Marine Lab. These partners will collect kelp at a particular area 3x a year in 2014. The samples will be dried (70 C) and milled to 20 mesh powder, a process that is being handled by Dr. Mike Graham at Moss Landing Marine Laboratory.

Kelp Watch 2014 could be the beginning of a California monitoring program to track the presence of anthropogenic radionuclides in our kelp beds. It could eventually expand to cover other contaminants.

All data will be shared and posted on the web. If you are interested in organizing collecting in your region (e.g., southern, central, or northern California coastline) please let Dr. Manley know. He would like to involve faculty from community colleges and high schools also. If you have colleagues that are not in California but are on the west coast (e.g. OR, WA, BC, AK, Baja) but may want to participate please let him know. You can contact him at "Steven.Manley 'at'" for more information.

Summary to Date

Update October 7, 2014:
Results from Round 2 of sampling will be available on the KW14 web site, very soon. So far, all results for Fukushima radioactivity have been negative. I-131 continues to be found in southern California samples, especially from the Port of Los Angeles-Long Beach, where all samples have high levels. The outer breakwall location, that has been previously sampled, is not the site with the highest amount.

Presently, KW14 is in a holding pattern because of finances. Partners are going to maximize the use of our remaining dollars, and are waiting for spatial data from Dr. Ken Buesseler of WHOI as to where the plume is located. Once that determination is made, KW14 can adjust its sampling focus both spatially and temporally. We hope to know that by November 2014. Therefore, the third scheduled sampling period is on hold.

Dr. Steven Manley is continuing to pursue funding so that Kelp Watch can continue into 2015. LBNL and Dr. Vetter continue to be strong supporters of KW14 and will continue to analyze samples at no charge.

Samples from giant and bull kelp will be collected by partners up and down the coast of the eastern Pacific, including throughout California, on three separate occasions. The collection dates in 2014 are:
Sample #1: Feb 24 through Mar 5 (completed, results available May 7, 2014)
Sample #2: Jul 1 through Jul 10 (dropped)
Sample #3: Oct 13 through Oct 22 (postponed as of October 7, 2014)

NOAA through the Office of National Marine Sanctuaries (ONMS) West Coast Region (WCR) and the Monterey Bay National Marine Sanctuary (MBNMS) are involved with the Kelp Watch 2014 monitoring program in two ways. First, Dr. Steve Lonhart is helping coordinate the sampling efforts on the coast of central California, all sites within MBNMS. Partners include Dr. Mark Carr at UC Santa Cruz, Dr. Mike Graham at Moss Landing Marine Lab, Dr. Mark Denny at Stanford's Hopkins Marine Station, and at two sites in the UC Natural Reserve System: Dr. Mark Readdie at the Landels-Hill Big Creek Reserve (Big Sur) and Don Canestro at the Ken Norris Rancho Marino Reserve (Cambria). Second, WCR vessel support will help with the collection of kelp samples along with staff researchers from MBNMS. NOAA is assisting with the collection of kelp samples beyond Monterey Bay itself, which is facilitated by use of NOAA small boats to sample in areas difficult to access from shore.

This program quickly grew from a California-centric campaign to include Canada and Mexico. A few areas are sill not that well covered (see map), including Del Norte County, central Alaska, Aleutian Islands, central British Columbia, or even Korea. Some tropical locations have been added recently, where Sargassum will be collected.

Monitoring Trends

  • MAY 7, 2014: Kelp samples were dried and milled into a powder and then sent to LBNL to be measured with a high-purity germanium detector. As expected, all kelp samples contained significant amounts of naturally occurring radioactivity, primarily due to potassium-40 (K-40) since dried kelp has a high potassium content. Also found were smaller amounts of other naturally occurring radioactive isotopes, including Beryllium-7 which is a cosmogenic nuclide present in air and rain, and portions of the Uranium-238 and Thorium-232 radioactive decay chains.
  • Cesium-137 was detected in all West Coast samples at very low levels. This isotope is still detectable in the marine environment due to above-ground nuclear weapons testing that took place mostly in the 1950s and 1960s. The very low limits set on the shorter-lived Cesium-134 mean that the Cs-137 cannot be directly tied to the Fukushima releases and is more likely due to these legacy sources.
  • For a sense of scale, the K-40 activities ranged from 2500 to 4500 Becquerels per kilogram dry weight (Bq/kg dwt), where one Becquerel is one nuclear decay per second, while the Cs-137 was detected in all samples at levels ranging from 0.08 to 0.44 Bq/kg, or about 10,000 times lower than K-40. The upper limits set for Cs-134 are approximately 0.04 Bq/kg, or 100,000 times lower than some of the K-40 levels.
  • A kelp sample obtained from Chile was similarly analyzed and had no detectable Cs-137. This is consistent with the lower levels of Cs-137 known to be in the southern oceans. Because kelps are not found in the tropics, related brown seaweeds, Sargassum spp. were sampled from Hawaii and Guam. The samples from Hawaii and Guam were consistent with the North American samples, showing no signs of Fukushima radioactivity.


The project includes the participation of 19 academic and government institutions and three other organizations/businesses. These participants will sample kelp from the entire California coastline as far north as Del Norte County and as far south as Baja California. The sampling will begin in mid-February and will end in late winter. There are ongoing efforts to expand sampling into Oregon, Washington and Alaska.

Sampling will take place several times in 2014, and processed kelp samples will be sent to the Lawrence Berkeley National Lab’s Low Background Facility for detailed radionuclide analysis. As data becomes available it will be posted for public access. Dr. Vetter and his group have extensive experience in measuring radioactivity in a variety of biological samples, including seaweeds. If the kelp takes up the radioactive material, the Dr. Vetter's group should detect it. Vetter, who is also a professor of nuclear engineering at UC Berkeley, pointed out that UC Berkeley and Berkeley Lab’s analysis within the new Kelp Watch initiative is part of a larger, ongoing, effort to measure Fukushima related radionuclides in a large variety of objects. There are two main objectives—to learn more about the distribution and transport of these materials in our world, and to make the results and explanations available to the public.

Making the results publicly available is a critical aspect of Kelp Watch 2014, and it allows research scientists to address concerns about Fukushima radiation levels and to explain the meaning and potential impact of these levels, particularly in the context of the natural radiation background people are exposed to daily.

Study Parameters

  • Radioactivity
  • Other pollutants

Study Methods

Collection Protocols:
The tissue required is canopy blade tissue, juvenile and mature without pneumatocysts. Macrocystis blades will be considered mature and acceptable if they show less than 40% erosion and are not diseased. The presence of bryozoans, although not desirable, is acceptable. Please visually estimate and report % bryozoan coverage on mature blades. Complete apical scimitars can also be included.

The amount of tissue needed is 6.5 kg fresh.

Many of you will be in the water to collect; others may prefer to collect from a boat. It appears that for Macrocystis 6.5 kg can be obtained by collecting all blades (defined above) from 16-20 canopy fronds cut 3.7 m from the apex. For Nereocystis blade size can vary dramatically depending on the season so no standard number can be delineated; cut off and discard severely eroded portions of the blade tips; ship the rest.

Please record your GPS coordinates, date and time for each sample.

Drying and milling kelp samples:
1. Dry the blade tissue at 70 – 80 C for 2 days. Drying time should actually be determined by achieving a constant weight for sample or subsample; two days should be sufficient.
2. For ease of milling, grind (crush) the dried tissue in a Waring® Blender (or equivalent). Wear a shop mask to avoid inhaling kelp dust!
3. Mill dried material to #18-20 Mesh (Wiley Mill® or equivalent; 1 – 0.84 mm; shop mask advised).

Figures and Images

Figure 1. Map indicating kelp sampling sites in California, as of December 18, 2013.

Figure 2. Growing edge of the giant kelp Macrocystis pyrifera off the coast of Big Sur.

Figure 3. Sampling sites as of February 4, 2014.


  • Kelp Watch 2014 Spring Results
    Table of radioactivity measured in kelp samples.
    47 KB PDF
  • Kelp Watch 2014 handout
    Informational flyer on how to participate.
  • Manley & Lowe (2012)
    Canopy-Forming Kelps as California’s Coastal Dosimeter: 131 Iodine from Damaged Japanese Reactor Measured in Macrocystis pyrifera. Environmental Science and Technology, 46:3731-3736.