Determining the Differences in Aquatic Community Structure Between Invasive Waterhyacinth and Native Pennywort in the Everglades and Lake Okeechobee

Determining the Differences in Aquatic Community Structure Between Invasive Waterhyacinth and Native Pennywort in the Everglades and Lake Okeechobee

Alvin Sherman Library

Waterhyacinth is an invasive floating plant that rapidly grows across aquatic environments, creating dense mats that disrupt ecosystems like the Everglades and Lake Okeechobee. Our prior observations showcased that waterhyacinth supports different fish and invertebrate species assemblages than the native plant species. More invertebrates, especially amphipods, are found in the roots of waterhyacinth than its native equivalent, pennywort. To determine what causes these patterns, we asked four different questions: whether waterhyacinth has a greater root surface area than pennywort, whether fish preferred native plant environments, whether dissolved oxygen (DO) levels were comparable, and whether predation rates were similar. Surface area was established by collecting root samples of both species and measuring them. Fish preference was determined by a behavioral choice experiment. The hypothesis that predation rates were greater under native plants was tested by using tethered baits and documenting consumption. DO levels were compared in the field to determine if lowered oxygen might explain differences between the two communities. We found that waterhyacinth plants had a greater root surface area than native plants, providing more space and refuge for epiphytic invertebrates. Fish, especially those naïve to waterhyacinth, showed slight preference for native plants, but predation rates and DO levels were similar between the plant types. These results will assist in waterhyacinth management strategies and their long-term ecological implications in Florida’s Everglades.