Local researchers begin fish surveys in the coastal dune lakes by Challen Hyman and Erika Zambello
The hot summer sun bounces off the water’s surface on Western Lake in Walton County. Challen Hyman, joint environmental research scientist with the Choctawhatchee Basin Alliance (CBA) and Mattie M. Kelly Environmental Institute at Northwest Florida State College (MKEI), readies a seine net, as Brandy Foley, CBA monitoring coordinator, checks their location. Richie Gray, MKEI environmental technician, throws a cast net and intern Cheslee Mathis wades into the water with a data clipboard. With both Gray and Hyman taking up one side of the long net, they shift onto the shoreline to walk in the warm, muddy shallows, scooping up small fish as they move. They turn around and retrace their steps three to five times at this site, then move on to the nine other pre-selected spots on the lake. Over the course of about three weeks, Gray and Hyman will hit the coastal dune lakes every good-weather day to collect valuable data.
CBA and MEKI are surveying fish species living in four of the coastal dune lakes — Western, Morris, Oyster and Eastern Lake — found in the southern coast of Walton County. The goal of this project is to gain a better understanding of which species of fish live in the Coastal Dune Lakes, and how large the populations of each species are within each lake.
Once the seined nets are brought ashore, Foley and Hyman identify as many of the fish species as possible, marking each one down on a data sheet after measuring length and weight and taking a photo.
“I’m really excited to see what we identify,” Brandy says. “You never know what you’re going to find in a coastal dune lake because they are so biodiverse.”
Coastal dune lakes are unique bodies of water that periodically open to the Gulf of Mexico. These lakes fluctuate in salinity (salt content), depending on how recently they have experienced an outflow event. However, some lakes open to the gulf more often than others, or stay open for longer periods of time. As a result, the coastal dune lakes have different average salinity values.
For example, Morris Lake in Topsail Hill Preserve State Park outfalls very rarely, therefore it is mostly fresh. On the other hand, Western and Eastern Lakes open quite regularly, and thus are brackish (a mix of fresh and saltwater).
As CBA and MKEI staff collect data, they are looking to see if the varying lakes have different communities of fish species and/or have different population sizes of each fish species, depending on how salty each lake becomes on average. Between July 23 and Aug. 8, the team sampled all four lakes to begin initial data collection. Once the group has community assessments from each lake, they hope to compare the communities to average salinity, and determine what, if any, patterns are present.
The summer surveys are just the beginning. Salinity and other coastal dune lake conditions change throughout the year along with weather patterns, and CBA and MKEI hope to sample every month and expand to all the dune lakes in order to track these alterations in fish populations. While the coastal dune lakes have been studied for vegetation, sediments, water quality, and algal blooms, this is the first long-term study of fish done for all the dune lakes, an ecosystem only found in a few places on earth.
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