Jacksonville area residents are generally pretty proud of their lawns and many do whatever it takes to have the greenest grass in the neighborhood. This means spreading weed killers, pesticides, fertilizers and other chemicals on yards and following up with heavy dousing to make sure the powerful agents soak into the ground to work their magic.
Unfortunately, those chemicals end up making their way from lawns to storm-water drains and eventually to the St. Johns River via retention ponds and tributaries. Each time it rains, additional pollutants from the roadways — crash debris, dirt, motor oil, gasoline, cigarette butts and trash — are also washed into the St. Johns, where they make up a “chemical soup” that wreaks havoc on the river’s ecosystem.
In response to growing pollution problems in local waterways, the St. Johns River Water Management District (SJRWMD) elicited the help of a team of faculty and student researchers from UNF’s Biology Department to conduct a two-year study that may help significantly reduce the level of pollutants in the St. Johns River and its tributaries. Drs. Dale Casamatta, Daniel Moon, Anthony Rossi and Kelly Smith, along with a number of grad students, each play very specific roles in the project, which is being funded through a $175,000 SJRWMD grant and is scheduled to be completed this fall.
The name of the study is “Establishment and Use of Native Vegetative Riparian Buffer Zones for Nutrient Reduction in the Lower St. Johns River,” but unless you’re a biologist that probably doesn’t mean much. In a nutshell, UNF’s research team has been working together to study the effects of the introduction of a variety of native vegetation, which was planted along the banks of five tributaries of the St. Johns River, hypothetically to filter pollutants and impurities in the water before it flows into the river.
After identifying a handful of easy-access, mostly urban test sites and assessing the existing native plant communities there, the researchers cleared the banks of trash and removed any exotic plants that may have found their way to the area. Next, the team sectioned off areas along the banks and planted native plants, all which would be under water at various times depending upon the amount of rainfall. Rossi, who specializes in the ecology of plant-insect interactions, headed this part of the study.
“We planted five plant species at each site, including river birch, golden Canna, pickerelweed, summer sweet and maidencane, and four of the five plant choices ended up being excellent choices with a high rate of survivability,” said Rossi, associate professor of biology at UNF. “The idea was to try to increase the native biodiversity at each site to filter down runoff from the surrounding land before it gets into the creeks and eventually ends up in the St. Johns.”
In order to quantify the data collected at the garden sites, the researchers identified an additional five sites to serve as a control group. But because one of the control sites was on private property and the researchers discovered the owners of the land had been polluting the water, the team decided to abandon that site. “They were apparently doing some illegal things and getting in trouble with some of the state agencies, so every time we showed up to do our research, they’d start freaking out and wouldn’t give us permission to go through,” Rossi said. “It also looked like they were running an unapproved sewage line right into the creek, which of course is not only illegal, but dumping human waste right into our field site would definitely affect the results of the study.”
The team collected water and soil samples before introducing the native plants, and then continued to do so at least twice a month over the two-year period to measure such things as oxygen, chlorophyll, nitrate, phosphate and pH levels. They also collected and counted samples of fish and invertebrates and studied their health throughout the project.
“My part is to study the algae and aquatic bacteria and such, so I monitor how the algal community changes, Tony [Rossi] does the plant-insect interactions so he monitors how the plants are changing, Dan [Moon] monitors the insects as an entomologist, and Kelly [Smith] is our fish biologist,” said Casamatta, an assistant biology professor. “The nice thing is between all of us, we can get a really great view of how the ecosystem changes and whether or not these buffers will help clean up the St. Johns River.”
Moon, who is also an assistant biology professor, uses dip nets to sweep along the bottom of each creek to collect whatever’s there. “The dip net stirs up the top layer of sediment and it gets all your little critters, your aquatic inverts, in your net bag,” he said. “And then you can collect them and identify them and count how many you’ve got. Depending upon the species you find, you can use the diversity — the types and numbers of aquatic insects — as an indicator of water quality.”
Smith, an associate biology professor whose research interests focus on juvenile fish ecology in estuarine environments, studies and compares the health of fish that have been placed in cages both upstream and downstream from the garden plots.
“One thing that affects fish growth is water quality, so the idea is that we compare the growth of fishes in cages that are set above the garden to cages set below the garden,” Smith said. “If we’re seeing differences in the water quality related to the location of the garden, perhaps we’ll start seeing a response in the fish.”
Unfortunately, many of the fish were washed out of the cages at one of the sites after a major storm event — and at another site a pollution event killed all the fish — so Smith has had to be flexible in her research. “Last year I wasn’t able to do the caging study because a lot of the tributaries were dry with the drought, so we held off on the fish study until this year, but now we’re having problems with too much rain,” she said. “So what we’re going to be doing now is looking at changing our study to a short-term feeding and seeing if they’re feeding on different types of invertebrates depending on where we cage them, and we’re collecting samples of the various fish in the creeks just to see what’s living there.”
Smith said it’s typical in field biology that research adaptations need to be made in reaction to various environmental factors. “These are highly changeable habitats, and I think a lot of the story’s going to be told in the vegetation and their response,” she said. “The data we’re able to collect on the fish populations will provide additional bits of information about the community that we’ll be able to include in the study.”
The data-collecting phase of the project ends this month, but it will take another three or four months to analyze the data and generate a report to submit to SJRWMD.
According to SJRWMD Technical Program Manager Dr. Dean Dobberfuhl, who came up with the idea for this project and formulated its objectives, there will be several uses for the data. The results will be published in scientific literature for other scientists to use; surveys of intact riparian areas will provide a better understanding of that community; and results will be used to improve restoration efforts in projects that may be conducive to riparian restoration.
“The data will also allow planning and permitting staff to improve their activities with respect to preserving and maintaining riparian habitat and function in the face of ongoing development,” Dobberfuhl said.
“Just between our four labs, we’ve generated so much data that we’ll also end up with a number of publications about this study, and our grad students are already presenting papers on it,” Casamatta said.
Grad student Jason McGregor said since his involvement in this project he’s learned several new scientific methods and techniques to use in the field. “I have also acquired a large database of plant species, both native and non-native, that are present in Florida,” he said. “This will be useful in my future career pursuits as well as any research I may pursue.”
“Almost nobody does projects that are this inclusive with this many researchers, so it’s just been a really neat project,” Casamatta said. “We’re all looking forward to finding out whether what we’ve been doing is going to help clean up our river.”