Invasive plants like water hyacinth (Eichhornia crassipes) and hydrilla (Hydrilla verticillata) cause major problems in Florida’s aquatic environments. Clogging waterways, reducing native plant biodiversity, and altering water chemistry are all real effects these plants have in the ecosystem. Thankfully, tools are available to mitigate impacts caused by invasive plant populations.
There are several different management strategies for practitioners to use for controlling invasive plants. Aquatic herbicides are one of these strategies. The EPA has registered 15 herbicides for use in Florida, and they all have strict standards for practitioners to follow. You can read more about Florida’s registered herbicides here.
At the UF/IFAS Center for Aquatic and Invasive Plants (CAIP), we conduct research on herbicides to provide technical recommendations for invasive plant managers. This research contributes to safe and effective herbicide use on operational scales.
Researchers design a lengthy, well‑planned process for studying aquatic herbicides. This process is replicated across multiple studies before recommending a product for environmental use. The studies often start small with plant clippings in beakers. Eventually, researchers will work up to studying the effects of herbicides on fully grown plants at field scales.
The progression of aquatic plant management research from small scale to operational treatment is vital in making informed decisions about herbicide use in Florida’s waterbodies.” – Jonathan Glueckert, UF/IFAS CAIP Research Biologist
Starting Small – Beakers & Mesocosms
Before UF/IFAS CAIP researchers recommend an aquatic herbicide for environmental use (even if it is already registered), they conduct studies at several scales. At the smallest scale, they grow plant cuttings in beakers under controlled laboratory conditions. These small-scale studies are great for quick evaluation of herbicide behavior. However, long‑term herbicide action or plant growth cannot be observed at this scale.
Indoor and outdoor mesocosms provide a solution to this issue. Mesocosms are tanks or other containers of various sizes that replicate real world conditions. Mesocosms are highly controlled environments, allowing researchers to standardize conditions to isolate and identify the effects of different variables, such as herbicide concentrations, exposure times, species specific response to treatment, and application techniques. The size and complexity of the mesocosm depends on the research question being tested. Mesocosms can be as simple as plastic garbage cans in an indoor space to large outdoor tanks capable of holding thousands of gallons of water positioned under shade cloths. Researchers at UF/IFAS CAIP often test their large-scale experiments in our tank farm. This facility is one of few in the country! Using the tank farm allows researchers to observe herbicide behavior and effects in a larger simulated environment.
Moving On Up – Pond Trials to Operational Scales
After the mesocosms have served their purpose, researchers test the herbicides in pond trials. Man-made ponds are dug and filled with water to further simulate the natural world. These ponds are similar in size, depth, volume, and physical characteristics. Pond trials are an important step in the herbicide testing process to observe fate, dissipation, and efficacy. Essentially, the ponds allow researchers to observe how herbicides may act in the natural environment.
However, these trials come with their own drawbacks. Because the artificial ponds support biological communities, each pond will often develop its own “personality”. One pond may support a macrophyte community, while another may encourage algae growth. The invertebrate and fish populations of each pond can also vary. The differences between pond personalities make replication difficult. To combat this issue, researchers conduct pond trials at similar times all around the country, making some replication possible despite differences in biological communities.
Then, after the beakers, mesocosms, and pond trials, herbicides are tested at an operational scale. Researchers go to the ecosystem of interest and conduct tests on small plots. Doing this allows them to test and observe herbicides with site specific characteristics. Herbicides are never applied to a whole system without knowing how it will interact with and move through the environment.
Research for Management
Jonathan Glueckert, a research biologist at UF/IFAS CAIP, states, “The progression of aquatic plant management research from small scale to operational treatment is vital in making informed decisions about herbicide use in Florida’s waterbodies. Conversations with different stakeholder groups frequently sparks research ideas. The opinions of recreational lake-goers to plant management agencies all play a part in this process.”
“While we have a general understanding of the use cases for aquatic herbicides, site specific conditions and variables often play a vital role in the success of the treatment. Therefore, research at multiple scales allows us to identify possible successes or failures before applicators commit the time and resources to large-scale operational treatments,” says Glueckert.
Before we use herbicides at operational levels, we need to research them across multiple variables and scales so we can carefully observe how they interact with both target and non‑target plants. Even after operational adoption, post-treatment monitoring is essential to continue verification of techniques and identify challenges to address with future research. The herbicide research process is a never ending cycle of testing, treatment, observation, and testing all over again. At UF/IFAS CAIP, we work with practitioners to communicate our research findings to inform best management practices and promote responsible aquatic plant management.
References
Netherland, M. D., & Getsinger, K. D. (2018). Scaling studies for submersed aquatic plant management research. Journal of Aquatic Plant Management, 56(s), 10–16.
Subscribe for more blogs like this one. Questions or comments can be sent to the UF/IFAS CAIP communications manager at caip@ifas.ufl.edu.
UF/IFAS Center for Aquatic and Invasive Plants. Turning Science Into Solutions.
Did you find this post helpful or interesting? Click the heart below!
2
