The Ghost Crabs Of The Gulf

While it's true that Ghost Crabs, Ocypode quadrata, aren't birds, they are vitally important to the ecosystems in which shorebirds live, and are an important food source for many species. Anyone who has ever strolled an Atlantic beach is familiar with them, or at least the holes in which they live.  Beaches from Rhode Island south, through the Gulf of Mexico and all the way to South America are dotted with the circular openings of their cylindrical burrows.  They are gorgeous little creatures, and a major component of the diets of many beach going birds, including Wilson's Plover, American Oystercatcher, and just about anything that might happen upon them.  On a moonlit night, shoreline explorers can be dazzled by the iridescent eyes of these bejeweled little buggers.

A Ghost Crab on Grand Isle, Louisiana. 

As a conspicuous member of the food chain, they may have a story to tell as this situation unfolds along our coasts.  There is much speculation on the effects of this oil on invertebrates.  There is also growing concern about the various efforts of the response taking their own environmental toll.  By taking a close look at the populations of the ghost crab, we may be a able to paint a more detailed picture of what has happened to these near-shore ecosystems, and the birds that inhabit them.  We are asking that people here, in affected areas count ghost crabs, but also anyone else, even if the oil may never touch your shores.

A Ghost Crab Covered In Oil From the Deepwater Horizon Oil Spill.  Photo: Bridget Besaw

What can you do??  Much like the coastal bird surveys that LSU and Audubon have organized, I am trying to organize a citizen science project to monitor what happens to these crabs.  My good friend Sea Mckeon in the lab of Invertebrate Zoology at the University of Florida has helped design an easy study that anyone in the southeastern U.S. can help with.  If you like to walk the beach, you can help.  What we need is people to walk the same transect multiple times and count the ghost crab holes.  It's as easy as that, well sort of...  We need the counts to be repeatable, and to be repeated, so they have to begin and end in the same exact location, either physically marked (by a pier or other non-moving structure), or identified by GPS.  Either way, we request that the end points be GPS'd, but that doesn't need to happen right away, if you need to borrow one at a future date we can make that happen. We will count the number of active ghost crab holes within 2 meters of the high tide line, for the length of the 30 m. transect.  We also request that the diameter of the first ten holes be measured and recorded, and that notes be made as to the human influence of the area, accompanied by a photo.  The Ghost Crab holes need to be active, that is open and not caved in, they need not have active tracks coming in and out, just not filled with sand.

A Ghost Crab Hole Survives the ATV Onslaught OF Clean Up Crews on Grand Isle, Louisiana

That's that.  By taking a pen, paper and tape measure with you, you can help us quantify the effects of this spill on our beaches and our birds.  Please email me for any details and questions about methods at ghostcrabstudy@gmail.com.  All data will be sent here as well.  This could be pretty cool.

Specific Methods outlined below: (read if you're serious about helping, and email for data sheets, or just take good notes.)

You need:

A meter tape:  Each transect will be 30m long
A ruler:  To measure the width of crab holes at their widest point
A clipboard and pencil:  To write stuff down
A camera:  To take photos of the beach each day you do your transect.
A hat and sunscreen:  'cause we don't want you to get burned.
A GPS (or you can borrow one):  Cause we need to know exactly where your transects were.

How you do it:

Choose a time of day to start each time, best to be consistent:  I like morning because the sand is still moist and the crab tracks are still visible.

Go to the wrackline that is highest up the beach before the dunes start.   This should be the line that only gets wet during the highest tides of the month.

Mark your starting point with a noticeable piece of debris.  If it lasts through multiple transects, that is best, because you want to be able to find this exact location again.  Take a GPS point.

Lay out your 30m transect on the wrackline.   Mark the endpoint with debris, and with your GPS.

You are measuring 1m above and below the transect tape.  It is helpful to have a stick that you can hold out to see if a crabhole is in or out.   I walk the transect twice: once counting up-beach, once counting down-beach.   

The first 10 crab holes you encounter, please measure with your ruler.  You are measuring them at their widest point- it is a good indicator of how large the crab that lives there is.   Some of them are going to be very small.   

The reason we are doing this is because Ghost Crabs draw their water from the beach surrounding them in their holes, or run right into the water.   Either way, with sufficient sample size it'll tell us how toxic the beach is.  The size of the crab holes will let us know if new ghost crabs are colonizing from the ocean.

Comments

[Linda Foss]

You are the first I've heard worry about the crabs and other vital members of the food chain. In that part of the Gulf anyway. I mentioned it to Dr Healy, a member of WRANDE's team at the Oiled Wildlife Response training held in May and she said she knew of no studies on crabs and oil spills.

I wonder if they can be spawned and released like they do with salmon and sport fish.

[Jesse Vooz]

You are awesome Drew. Your relentless, borderless dedication to the wildlife is so inspiring. Keep up the good work. Thanks buddy.

[Alison]

Following everyday. Please take care of yourself.

[Angela]

Great suggestion. I know there are many down there that would like to make a positive contribution and this is a very easy way. It may not feel as immediately gratifying as releasing a rehabbed bird, but in the long run, it is much more important to collect this sort of data.

[Coby]

Drew,
I would like to build/host the web systems to accept and visualize your data. We have a bunch of lessons learned from running beakgeek.org et al and are very interested in helping solve emergent citizen science problems like this.

Please email me; would love to chat.
R,
Coby

[Marge Anderson]

Thank you so much for your posts. I'm sure you're exhausted and heartsick. But your work really matters to so many people - and creatures. I re-post a lot of your blogs on Facebook and lots of non-birders read and respond.

[Trish Dawson]

I've contacted the White House about the spill not being funneled through a hosed into a vessel instead of them trying to cap it after all this time and I got a generic letter from President Oboma. He thanked me for my perspective. I'm really disappointed because the White House staffers always address my concerns and suggestions personally. Well I'm screaming mad now because my beautiful ocean is being polluted more every day and they still haven't been able to figure out the simplest solution.

R&D Direct - Working to minimize the world's health and ecological burdens by creating simple solutions for complex concerns.

[dining table]

You are really concern about what is happening with the marine life especially the food crabs. There are more species out there that are affected by the oil spill.

[drew wheelan]

Coby, somehow I lost your email. I would love if you could help us develop an interactive site to make this project work more smoothly. In the process of getting a data sheet together. Please get in touch, @
ghostcrabstudy@gmail.com
Drew

[Crab People]

Drew.....eventually all the coastline will have infiltrated Correctix (why ultimately, this will obliterate all coastal life!)and those compounds don't bio-degrade (made for propylene glycol in cold oceans) and every creature probing (bird, turtle, invert) will have material absorbed......thanx for trying....this country sucks!

[Rickson]

You have written a very impressive post providing highly valuable information. You have a very good feel for getting the right information out to the people through blogs. I am also very impressed with the website as a whole. Keep up the good work

[Shawn Carlson]

Drew, the Society for Amateur Scientists (sas.org) has just launched the perfect platform for your work. It's called iDoScience, at it was designed to help people organize citizen science projects exactly like yours. Please go to iDoScience.org for info. To gain access to the Website you must register through LabRats.org. Go there an click the "Register" tab near the top of the page.

I will create this project for you there for your evaluation. If you like it, you can have your people register for free and upload their data directly to this site.

Let me know when you register so I can give you Project Manager status. That will enable you to create as many projects like this as you wish and collect data from people all over the planet.

Shawn Carlson, Ph.D.
Executive Director
Society for Amateur Scientists
LabRats Science Education Program
iDoScience