OOS 5-9 - Restoring an iconic ecosystem? Non-native fish and everglades restoration

Monday, August 8, 2016: 4:00 PM
Grand Floridian Blrm H, Ft Lauderdale Convention Center
Joel C. Trexler, Department of Biological Sciences, Florida International University, Miami, FL

Everglades aquatic communities support apex predators that define its iconic status.  Wading bird abundance is greatly reduced in the modern ecosystem and they often experience years of low nesting success because of food limitation. Everglades restoration assumes that water delivery is the source of these losses and that apex predators will rebound if historical hydropatterns are recovered.  The Everglades is experiencing marked invasion by non-native plants and animals, and in aquatic habitats a diversity of fishes have become established and at times reach high numbers. The impact of these invasions on proposed benefits of hydrological restoration is unclear. The objective of this presentation will be to evaluate if these invaded aquatic communities still provide historical function of providing high-quality prey resources for apex predators.  I will use long-term data records to evaluate the impacts of invasive species on fish biomass and community dynamics at the landscape scale. I have developed statistical models that predict fish biomass and community structure as a function of hydrological conditions, parameterized with data collected before the invasions of African Jewelfish (Hemichromis letourneuxi), Asian Swamp Eels (Monopterus albus), and Spotfin Spiny Eels (Macrognathus siamensis).  I will use these predictions to evaluate community structure since the invasions and document their impacts on community function.      


African Jewelfish increased in numbers in the Shark River Slough (SRS) following a 2010 cold snap and were present at ~50% of monitoring sites by 2012; their relative abundance exceeded 15% of all fishes collected at 70% of study sites in 2014.  Asian Swamp Eels and Spotfin Spiny Eels also increased in numbers over the same period in Taylor Slough (TSL) but were absent or incidental elsewhere through 2015.  In 2012, the density of native fish in SRS was less than expected based on hydrology in pre-invasion models, though the density of all fish (native plus non-native) was similar to predicted.  In TSL, there is no evidence of decreased density of native fishes linked to the two invasive species that are now common there.  The current data do not indicate that fish invasions have altered the food production system that underlies major features of the Everglades in the public’s view, though community structure has been altered in irreversible ways.  Continuing research is needed to determine if this new community can be managed in a way to sustain iconic values of the Everglades.