Project Title

Nova Southeastern University Assistance with Area-Wide Project for Integrated Management Addressing Waterhyacinth (Pontederia Crassipes)

Principal Investigator/Project Director

Jeffrey Matthew Hoch

Colleges / Centers

Halmos College of Arts and Sciences

Funder

U.S. Department of Agriculture

Start Date

7-2021

Abstract

Since its introduction in the late 19th century, waterhyacinth (Pontederia crassipes) has become arguably the worst aquatic weed in the southern United States, blocking commercial shipping channels and causing ecological collapse in one of America’s largest freshwater lakes. Lake Okeechobee is centrally located in Florida and historically was the primary source of water for the Everglades. Throughout the 20th century though, water was dammed and diverted to support development in south Florida. Development, combined with agricultural run-off from upstream sources, resulted in a physically and biologically altered lake. While these factors produced catastrophically spectacular algal blooms that resulted in massive fish and mammal die-offs, they also encouraged the growth of waterhyacinth and other invasive aquatic weeds in Lake Okeechobee’s eutrophic conditions.

Waterhyacinth is a floating plant that reproduces through vegetative and sexual means, forming a nearly impenetrable mat of vegetation. Millions of dollars are spent annually to manage waterhyacinth and water lettuce (Pistia stratiotes). For example, in FY2019-2020, the Florida Fish and Wildlife Conservation Commission (FWC) spent $4.19 million in public (federal and state) money to manage floating weeds in Florida, with $2.8 million of that spent in south Florida (mostly on Lake Okeechobee). As public perception of herbicides has soured due to high-profile lawsuits, there is renewed interest in developing sustainable integrated management techniques that lower the amount of herbicide needed to control waterhyacinth and other aquatic weeds on Lake Okeechobee. The FWC enacted a statewide “herbicide moratorium” for several months in 2019, but mechanical harvesters were unable to keep up with plant growth, and waterhyacinth coverage on Lake Okeechobee and elsewhere exploded to numbers not seen for 35 years.

This project aims to develop integrative weed management methods for waterhyacinth and other floating aquatic weeds that apply a systems approach. This work will build on foundational experiments completed with University of Florida and USDA researchers that demonstrated in mesocosms that herbicide could be drastically reduced if integrated with biological control. In addition to specifically investigating improved control methods, we also aim to facilitate community restoration by determining how the native community responds to changes in invasive cover and if this can be improved through active restoration. Over the course of the proposed Areawide Project, we plan to demonstrate better ways to control waterhyacinth while reducing herbicide input into sensitive aquatic environments.

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