What kinds of crayfish might you expect to find in the Ogeechee?

What kinds of crayfish might you expect to find in the Ogeechee?  With so much aquatic diversity in the basin, what you might see in the upper part of the basin can be completely different from what you might see near the coast. That’s because, even though the river is well connected from top to bottom, the habitats found in the upper part of the basin are completely different from the coastal habitats.

The headwaters of the Ogeechee form on the far extent of the Piedmont (the geographic region separating the coastal plain from the Appalachian mountains) making for clearer and swifter flowing water. But as the Ogeechee slowly snakes its way towards the coast, the water starts to move slower and slower, becoming much darker due to the leaching of tannins. Understandably, these stark differences result in differing crayfish fauna.

Procambarus pygmaeus

In the upper part of the basin, the Variable crayfish (Cambarus latimanus) and the Brushnose crayfish (Procambarus pubsecens) are two commonly found species that are strongly associated with this part of the basin, and are rarely if ever found downstream of Millen, Georgia. The Variable crayfish is one of only a couple of species within the genus Cambarus found within the Ogeechee basin, with the vast majority of other species belonging to the genus Procambarus. This is because, in general, Cambarus species are strongly associated with more rocky streams, like those found in the Piedmont. The Brushnose Crayfish is very similar to other Procambarus species found throughout the basin, with the namesake difference being dense hairs along the rostrum (nose area) of the crayfish.

Cambarus latimanus

Some species that can be found in both the upper and lower sections of the basin are the Ogeechee crayfish (Procambarus petersi), Blackwater crayfish (Procambarus litosternum) and Red Swamp crayfish (Procambarus troglodytes). The Ogeechee crayfish, though not common, can be found from the headwaters almost to Savannah. The Blackwater crayfish is incredibly common, and can be found in small streams all over. Chances are, if you’ve seen a small crayfish poking around in a stream in the basin, it was a Blackwater crayfish. The Red Swamp crayfish is one most people are familiar with – it is what people commonly catch for food, and they are easily distinguishable by their large, tubercle-covered red claws.

Procambarus troglodytes

Lastly, you might see as the Ogeechee is flowing into the ocean would be the Hummock crayfish (Procambarus lunzi), and the Christmas Tree crayfish (Procambarus pygmaeus). Both of these species are more associated with slower, stagnant water; but the Christmas Tree crayfish has one particularly interesting adaptation. The bright colors of the Christmas Tree crayfish are thought to be used as camouflage, as it is almost always found in dense mats of lush aquatic vegetation. 

Hopefully this brief introduction to some of the crayfish found within our basin encourages you to get out and explore some of the novelties that make this basin a special place!

(All photos courtesy of Chris Lukhaup and Chris Skelton)

Why should we care about freshwater organisms?

Why should we care about freshwater organisms? This is an incredibly common question directed towards freshwater ecologists like myself, and it’s completely valid. Why spend all the time and effort to study things that appear to have little to no impact on human welfare? While the ultimate answer to this question is nuanced, one of the most important reasons why we as scientists care about them is their use as bioindicators.

The concept of a bioindicator is fairly straightforward, generally referring to the use of a living thing (bio-) as an indicator for the health of the ecosystem it lives in. For example, let’s say that there’s a rare crayfish species that is known to only occur in pristine habitat with very clean water, and has no tolerance for pollution of any kind. Therefore, if that species is found, scientists can use it as evidence that the stream it was found in is very healthy. On the flip side, if the only species that are found in a specific stream are fairly common and can tolerate a large range of conditions, then these species might indicate that that stream has poor water quality.

Female Red Swamp Crayfish from 15 Mile Creek, with young on the abdomen. Image by Ray Chandler.

Beyond being good “tools” for humans to assess the health of our ecosystems, different freshwater organisms serve distinct purposes in the aquatic food web. This is especially true of crayfishes, which are commonly viewed as “keystone” species. A keystone species is one that performs such an important role in an ecosystem that without it, there would be a large-scale detrimental effect on the rest of the ecosystem.

The crayfish is a keystone species for a variety of reasons. Firstly, crayfish are omnivorous, eating all kinds of different things in stream ecosystems, from other smaller insects to plant matter. Secondly, crayfish are important food sources for larger predators, like sport fish and amphibians. This combination of  eating and being eaten by so many different things make crayfish an integral part of aquatic food webs. 

Thirdly, crayfish act as “ecosystem engineers” through the creation of burrows. Many of you may be familiar with crayfish burrows that you see on land (check out this article), but what many people don’t realize is that all crayfish burrow to some extent. In stream ecosystems, these underwater burrows act as key habitat for other freshwater organisms, and therefore harbor the diversity of life that is important for healthy streams.

A crayfish burrow found in the field in southern Georgia.

With spring already in full swing, I’m sure many of you will be seeing crayfish a lot more often, and I’m excited to write more about what you may see out in the watershed.

Why freshwater critters like crayfish are so fascinating

Hi everyone! I’m incredibly excited and I figured I would use this first post to provide a bit of background on myself, what I’m hoping to get out of this research project, and why freshwater critters like crayfish are so fascinating!

Brian trying to ID a tiny juvenile

I was born and raised in Ohio, and have been interested in the natural world my entire life. I grew up hiking, kayaking, and climbing, and knew that I wanted to have a career that would allow me to explore nature and to help conserve the land that I was recreating in. This led me to pursue a degree in environmental science at Ohio State, but it wasn’t until I lucked into a lab research job studying stream ecology that I found my passion for the animals that call the freshwater their home. 

Of course, like every little kid, I had spent time growing up playing in creeks and knew about some of the weird things that you could find in streams. But it wasn’t until I started really spending time doing biological surveys that I discovered how much beauty and diversity lies under the water. That’s why I decided to come all the way down to the southeast for graduate school; I wanted to be in an area that harbored a large diversity of organisms, and that’s exactly what Georgia has.

While Ohio is home to roughly 20 crayfish species, Georgia is home to over 70 (!), the 4th most in the U.S. behind Alabama, Mississippi, and Tennessee. This incredibly high diversity is due to a lot of different things, but one of the main reasons is that crayfish often have very specific and restricted ranges, whether due to geographic barriers or very specific life history traits that allow them to only occupy very specific areas. If you’re interested in learning more about some of the biodiversity of Georgia crayfishes, Georgia DNR has amazing resources for experts and amateurs alike.

Procambarus pubescens (Brushnose Crayfish) from Magnolia Springs

One of these species that has a very specific range is the Ogeechee Crayfish, or Procambarus petersi. Found only in the Ogeechee and Canoochee basins, very little is known about P. petersi beyond the fact that it is a stream-dwelling crayfish. What I hope to do with this project is to better understand this species range within the basin, what its habitat preferences are, and how it interacts with other species within its habitat. 

Next month, we will start doing some of our first surveys of the basin, and hopefully start catching some petersi to show everyone! I’ll also dive into why conservation of aquatic organisms matters in the first place, and what specific roles crayfish play within aquatic ecosystems. 

– Brian Bush, ORK Fellow

RELEASE: First research fellow at ORK starts crayfish project

Ogeechee Riverkeeper
Contact: Meaghan Gerard, Communications and Administrative Director

The annual fellowship will provide research opportunities in the watershed

Ogeechee Riverkeeper (ORK) has launched a new research fellowship to be filled each year. In 2022, the ORK Research Fellow is Brian Bush, a first-year graduate student at Georgia Southern University, pursuing a master’s degree in biology. The fellowship is underwritten by investments secured from the 2011 fish kill settlement. 

“We are excited to launch this annual fellowship,” said Damon Mullis, executive director and riverkeeper of ORK. “Research is important to our mission to protect the waterways in our basin. This fellowship will spur more interest in our basin and result in more academic research projects.  We are excited to have this initiative to further our mission.”

Photo by Chris Lukhaup

The Ogeechee River Basin is home to 16 different native crayfish species, including Procambarus petersi, an endemic species commonly called the Ogeechee Crayfish. The project aims to document riverine crayfish populations and distribution, with a focus on P. petersi, and provide education and outreach opportunities throughout the watershed. Throughout the fellowship, Bush will be sharing blog posts and photos of his time in the field and in the lab.

Brian Bush

Bush will lead the research project with the supervision of Checo Colón-Gaud, Ph.D., professor of biology and associate dean of the Jack N. Averitt College of Graduate Studies at Georgia Southern University. Bush earned a bachelor’s degree in environmental science from The Ohio State University, with Honors Research Distinction from the School of Environment and Natural Resources. During his time at Ohio State, Bush conducted research with Dr. Mažeika Sullivan in the stream and river ecology laboratory. After graduation, Bush worked for the Nevada Bureau of Land Management, conducting stream surveys in northern Nevada and southern Idaho.

About Ogeechee Riverkeeper: Ogeechee Riverkeeper 501(c)(3) works to protect, preserve, and improve the water quality of the Ogeechee River basin, which includes all of the streams flowing out to Ossabaw Sound and St. Catherine’s Sound. The Canoochee River is about 108 miles long and the Ogeechee River itself is approximately 245 miles long. The Ogeechee River system drains more than 5,500 square miles across 22 counties in Georgia. More at ogeecheeriverkeeper.org.


PDF – Press Release – 2022 Research Fellowship