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Spotlight on Sandy

USGS Scientist Examines Foraminifera Collected from Remote Clipperton Island

[revised January 2017]
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Clipperton Island is an uninhabited French island in the Pacific Ocean, approximately 1,300 kilometers (800 miles) from the Central American mainland. Abyssal ocean depths lie between Clipperton Island, the mainland, and the other four island groups of the tropical eastern Pacific Ocean (the Revillagigedo Islands of Mexico, Cocos Island of Costa Rica, Malpelo Island of Colombia, and the Galápagos Islands of Ecuador). Clipperton Island’s remoteness attracts DXers—amateur (“ham”) radio operators seeking to achieve radio communications over long distances and in exotic locales. (“DX” comes from an abbreviation for “distance” used by Morse code operators.) It also attracts biologists interested in the nature, origin, and distribution of its organisms.

Location of Clipperton Island and other islands in the tropical eastern Pacific Ocean.
Above: Location of Clipperton Island and other islands in the tropical eastern Pacific Ocean. [larger version]

In February–March 2013, the 2013 Cordell Expedition (TX5K) to Clipperton Island combined ham radio operations with science. While most of the group exchanged radio communications with ham operators around the world, other expedition members made wildlife observations and collected samples of sand from around the island. After the expedition, the sand samples were transferred to Mary McGann, a micropaleontologist with the U.S. Geological Survey (USGS), who examined them for microscopic one-celled organisms called foraminifera.

Map of Clipperton Island
Above: Map of Clipperton Island, showing site of 2013 Cordell Expedition (TX5K) camp (orange circle) and locations of sand samples collected for analysis of foraminifera (yellow dots). LP, samples collected by Louis-Philippe Loncke; R, samples collected by Robert W. Schmieder; km, kilometers; mi, miles. [larger version]

Foraminifera from Clipperton Island.
Above: Foraminifera from Clipperton Island. A, Amphisorus hemprichii Ehrenberg, 1.2 millimeters in diameter. B, Pseudohauerina orientalis, 0.3 millimeters high by 0.4 millimeters wide. USGS photographs by Mary McGann. [larger version]

The summary of a 1958 scientific expedition to Clipperton Island (1.6 MB PDF) mentions collecting foraminifera and states that they would be housed at the University of California Museum of Paleontology in Berkeley, but those collections could not be found in 2013. McGann’s study, therefore, is the first detailed examination of foraminifera from the island. It was prompted by some of the scientific questions raised by Clipperton Island’s isolation: 

  • Does the island host organisms from both the tropical eastern Pacific Ocean along the Pacific coast of the Americas (the Panamic Province) as well as tropical waters from the Indian Ocean and the western and central Pacific Ocean (the Indo-Pacific Province)?
  • How do these organisms disperse to Clipperton Island?
  • How large a role do endemic organisms—those that live only in the immediate area of Clipperton Island or the islands nearby—play in local ecosystems?

Clipperton Island is the only atoll (ring-shaped coral reef encircling a lagoon) in the tropical eastern Pacific Ocean. Most tropical islands have many habitats where organisms can live—such as muddy, silty, and sandy bottoms; rocky shorelines; and extensive plant life near the water, including mangrove forests and algal mats. These habitats are lacking on Clipperton Island. Instead, coral covers extensive areas, making biodiversity far lower than for most tropical islands. 

Because of Clipperton Island’s unique environmental conditions, one goal of the 2013 Cordell Expedition was to document the distribution of an element of the island’s biota: foraminifera, organisms about the size of a sand grain that produce a hard shell and are abundant in brackish to marine waters. These tiny animals are of particular interest to scientists because they are extremely sensitive to climate change and environmental pollution. To sample the island’s foraminifera, expedition member Louis-Philippe Loncke, with some help from expedition leader Robert Schmieder, collected beach sand from 17 sites in the surf zone around the perimeter of the island and three sites on the margin of the inner brackish-water lagoon. This is the first known detailed collection of these organisms in the vicinity of Clipperton Island.

TX5K campsite

Above: TX5K campsite on an open, flat sand deposit in front of a palm grove, with lagoon in background. Photograph courtesy of Robert W. Schmieder, Cordell Expeditions, 2013 Expedition to Clipperton Island. [larger version]

As expected, McGann’s preliminary observations show that the diversity of foraminifera is extremely low on Clipperton Island. Whereas hundreds of species are typically found on tropical Pacific islands, the samples from Clipperton Island contain only 21 species representing 11 genera: Amphisorus, Quinqueloculina, Spirillina, Peneroplis, Pseudohauerina, Elphidium, Massilina, Cibicides, Planorbulina, Rectobolivina, and Globigerinoides. The low diversity may result from several factors, including the scarcity of habitats where these tiny organisms can live, difficulty finding food, and a pounding surf that smashes shells and other biological remains deposited in the surf zone and along the beach. No endemic foraminifera were discovered, but foraminifera from both the tropical eastern Pacific Ocean and the Indo-Pacific region were observed. How these foraminifera reach the island is a topic for further investigation.

Kite Aerial photograph of TX5K camp
Above Left: Kite used for taking aerial photographs of the island. Photograph courtesy of Robert W. Schmieder, Cordell Expeditions, 2013 Expedition to Clipperton Island. [larger version]

Above Right: Aerial photograph of TX5K camp. Photograph courtesy of Robert W. Schmieder, Cordell Expeditions, 2013 Expedition to Clipperton Island. [larger version]

In addition to the tiny foraminifera, remains of other organisms were found in the sand samples. The surf and beach samples included tiny clams, bryozoans (minute colonial filter feeders also known as “moss animals”), crab claws, sea urchin spines, snails, worm tubes, and ostracods (tiny crustaceans sometimes called “seed shrimp”). Samples from the inner lagoon contained fish bones and teeth, clams, snails, ostracods, insects, and seeds of aquatic plants.

Currently, the sand samples are being analyzed more thoroughly in an effort to find other foraminiferal species. McGann is also attempting to obtain fine sediment collected offshore by benthic grabs and scuba dives during a 2007 expedition to Clipperton Island to study molluscs—a diverse group that includes snails, octopuses, clams, squid, and oysters. (The 2007 expedition is described by Kirstie L. Kaiser in “The recent molluscan fauna of Île Clipperton…,” published September 9, 2007, in volume 39 of The Festivus, 20.6 MB PDF.) McGann hopes to discover a more pristine and diverse foraminiferal fauna in the offshore samples.

To learn more about the 2013 expedition, visit the Cordell Expedition website.

Related Sound Waves Stories
Calibrating Proxies for the Study of Holocene Climate Change in the Northern Gulf of Mexico
April 2008
Getting Warmer? Prehistoric Climate Can Help Forecast Future Changes
Jan. / Feb. 2009
Whale Falls
Oct. / Nov. 2010

Related Websites
The 2013 Cordell Expedition (TX5K) to Clipperton Island
The Cordell Organization
1959 Field Report: IGY Clipperton Island Expedition (1.6 MB PDF)
UC Scripps Institute of Oceanography
The Recent Molluscan Fauna Of Île Clipperton (Tropical Eastern Pacific) (20.6 MB PDF)
Smithsonian Tropical Research Institute

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in this issue:

Spotlight on Sandy
cover story:
Decade of Fire Island Research Available

Using Scenarios to Improve Resilience to Major Storms

USGS Deploys Oceanographic Gear Offshore of Fire Island

Research New Geologic Explanation for the Florida Middle Ground

Deep-Sea Corals Record Human Impact on Mississippi River Basin

Nitrate Levels in the Mississippi River, Illinois River

USGS Scientist Examines Foraminifera Collected from Remote Clipperton Island

3rd Annual St. Petersburg (Florida) Science Festival

Deepwater Canyon Study Given Prestigious DOI Award

Barbara Lidz Retires after Long Career with the USGS in Florida

Publications Jan. / Feb. Publications

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