A Better Understanding of Coral Reef Ecosystems

Pelagic predators such as these barracuda, Sphyraena qenie, are part of the coral reef ecosystem in the U.S. Line Islands (NOAA Photo by Kevin Lino).
A team of scientists have embarked from Hawai'i on a three-month survey of coral reef ecosystems at Johnston Atoll, the U.S. Phoenix Islands, the islands of American Samoa, and the U.S. Line Islands in the tropical Pacific Ocean. The overarching objective is to better understand the coral reef ecosystems of these areas, many of which are seldom explored. The research expedition is part of a regular monitoring program, conducted by the Coral Reef Ecosystem Division (CRED), headquartered in Honolulu, Hawai'i. The expedition is supported by NOAA's Coral Reef Conservation Program and involves extensive cooperation among NOAA scientists and research partners, including the University of Hawaii Joint Institute for Marine and Atmospheric Research (JIMAR), the U.S. Fish and Wildlife Service, San Diego State University, and the Papahānaumaokuākea Marine National Monument.

The research expedition will be carried out from February 27 to May 24, 2012 aboard the NOAA ship Hi'ialakai. Under the leadership of Chief Scientists Dr. Jill Zamzow, Dr. Bernardo Vargas-Angél, and Jamison Gove, a diverse team of researchers will be conducting multidisciplinary coral reef ecosystem surveys, assessing the status of fishes, corals, algae, marine invertebrates, and the oceanographic conditions in which these organisms exist. The scientific data collected during the three-month research expedition will enable informed and effective implementation of ecosystem-based management and conservation strategies for coral reef ecosystems, helping to ensure their protection for generations to come.

Sunday, April 24, 2011

Creature Feature: The Mosaic Boxer Crab Lybia tesselata

by Kerry Grimshaw and Annette DesRochers

One of the participants on this cruise is Steve McKagan, a fisheries biologist and NOAA partner from the Pacific Islands Regional Office (PIRO) located in Saipan. While Steve's role on this mission is with the Fish REA team, he has also taken an interest in the ARMS project. He is working with local agencies in Saipan to start up a Biosecurity (i.e., marine invasive species) project and is considering using ARMS methods and materials to establish a baseline for the harbors of Saipan, Tinian, and Rota. As such, he spent a day at Maug with the ARMS team to learn how ARMS are deployed in the field and how they are processed, which was a win-win situation for both sides as he captured some excellent photographs while observing the activities.

Taking advantage of the opportunity, following are some of Steve's photos capturing a bit of the ARMS recovery process followed by Kerry's writeup on one of the creatures that he found most intriguing. As an honorary ARMS team member—Data Managers serve dual roles on RAMP missions by helping to process the ARMS once they have been recovered—I too am enamored with these critters.

ARMS team member Russell Reardon recovering an ARMS unit at Maug. NOAA photo by Steve McKagan.
Transiting a recovered ARMS unit on the small boat back to the ship to be processed. NOAA photo by Steve McKagan.
Russell Reardon, hard at work in the ARMS "office". NOAA photo by Steve McKagan.

ARMS team members Kerry Grimshaw and Russell Reardon begin processing an ARMS unit. NOAA photo by Steve McKagan.
As the ARMS are processed, crabs are separated out to be photo documented and for taxonomic identification. NOAA photo by Steve McKagan.
As Kerry explains, one of the characters we have seen often in the ARMS on this cruise has been the Mosaic Boxer Crab, Lybia tesselata.  While many of the crabs that are collected are unique and dare I say beautiful, this little guy highlighted below tends to stand out from the others.
Mosaic Boxer Crab, Lybia tesselataNOAA photo by Kerry Grimshaw.
These small crabs, commonly known as pom-pom crabs for the small anemones they hold in their pincers, have a mutualistic symbiotic relationship with anemones.  The boxer crab’s pincers are small and are so well adapted to holding their anemones that they are rendered nearly useless for defense, yet they are able to take advantage of the anemones to serve this purpose. The stinging anemones act as a deterrent to predators by giving an extra punch to the crab's defense tactics; it advertises its weapons by waving its pincers with the anemones in the direction of any potential predator as if it’s shadowboxing.

The Boxer Crab versus the fish. Source: YouTube.  

Possessing such a pair of specialized pincers can be beneficial and has proven useful as there are a number of different species of Lybia that carry anemones; however, there are disadvantages too. Having such small pincers with only a few grippers unfortunately means the crab's pincers aren’t strong enough to tear up food as other crabs do. To overcome this boxer crabs have adapted to using their second pair of legs for this purpose by tearing food into small pieces and then moving it towards its mouth.  Another way that boxer crabs have been observed to feed is by using the anemones as “mops” which are swiped along the substrate to collect food particles on the tentacles of the anemone which can then be removed by the crab’s mouthparts.
The Mosaic Boxer Crab in action. Source: YouTube.
The boxer crabs can put their anemones down, but doing this would make them very vulnerable to predation. However they must do such a risky thing when molting their exoskeleton.  The crabs will place each anemone in turn in a safe place and then as quickly as possible free itself of its old exoskeleton. Then it quickly grasps its anemones in its pincers before quickly retreating to a safe place where it can allow its new body to harden.

There's even a YouTube video showing a Boxer Crab molting. This one takes a little more patience, it's not quite 5 minutes long, though it's not really worthwhile to watch until about 3:30.

And yet another video showing the Boxer Crab that just molted recovering its pom poms!

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