Microscopic Life in a Louisiana Crawfish Pond

Driving through the small town of Roberts Cove, Louisiana, you would be hard pressed to find a stretch of highway not lined by commercial crawfish ponds this time of year. And as any southerner knows, you will see more than crawfish in these waters. The ponds provide habitat for many frogs, snakes, turtles, wading birds, and insects. What you may not know is these waters are teeming with tiny plants and animals, called plankton, that can’t be seen with the naked eye. Plankton make up the base of the aquatic food chain and play a vital role in the pond ecosystem. 

Crawfish_Pond.jpgCrawfish ponds in Roberts Cove, Louisiana. May 2015.

 You might be wondering how we know the plankton are there if we can’t see them. Well, studying these microscopic organisms is one of the many things we do at the LSU Plankton Lab, and we do this with the help of our FlowCam®. The FlowCam is an imaging system that can detect, image, count, and measure each of the organisms in a water sample as the water flows past the system’s camera. The camera is equipped with a 4x, 10x, or 20x objective, which magnifies the tiny organisms so they can be seen. We use the FlowCam data to determine the abundance (how many organisms) and composition (what types of organisms) of the plankton community at our study site. 

FlowCam_small.jpgFlowCam® VS Series with portable housing

While our typical study sites are in estuaries or the open ocean, occasionally our curiosity gets the best of us and we take a sample from whatever body of water we find ourselves in. Recently, one of our research associates collected water from a crawfish pond in Roberts Cove and brought it back to the lab to study the microscopic plankton community. This crawfish pond sample contained over 125,000 organisms in just 1 milliliter of water!

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You can see what 1 mL of water looks like in the picture to the right. The vial with the orange cap contains 1 mL of colored water, and the Expo marker is there for scale. Imagine this: if the 125,000 organisms in this small volume of water were people, they would not all fit in Tiger Stadium! Among these organisms were numerous species of cyanobacteria, chlorophytes, diatoms, ciliates, rotifers, and many more. You can see the diverse plankton community in the images below from our FlowCam analysis.

 

 

 

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For more information about plankton ecology, visit: Teach Ocean Science - Plankton, National Geographic - Ocean Photosynthesis, or Estuary Education - Plankton

 For more information about the FlowCam®, visit: Fluid Imagine Technologies, Inc.