2005 Loftus Introduced Fish

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Introduced-Fish Studies in Southern Florida Natural Areas William F. Loftus USGS-Florida Integrated Science Center Everglades National Park Field Station Homestead, FL

Collaborators: 

Collaborators NPS Jeff Kline – Everglades N.P. University Joel Trexler; Tim Collins - FIU NGO Jerry Lorenz; Jenn Rehage; Krissy Dunker – National Audubon Society USGS Leo Nico; Shawn Smith – Florida Integrated Science Center ____________________ FUNDING: NPS, USGS, US FWS, ACOE

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ISSUE: Dozens of Tropical Freshwater Fishes Have been Introduced into South Florida What are they? How did they arrive here? What are their effects? Why are they successful here? Can anything be done about them?

Introduced Fishes in South FL: 

Introduced Fishes in South FL 15 introduced species in So. FL natural areas; most in family Cichlidae. Most are from tropical Asia, South America, and Africa. 31 introduced species reproducing in Florida's waters (Shafland 2002); most are freshwater. Native freshwater fishes originate from temperate North America (35 spp.).

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Planned Introductions Major Sources of Introductions Illegal or Accidental Introductions Food-fish Introductions Unknown Source

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Inventory and Monitoring Studies

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Sampling Methods

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2001 Jewel cichlid Jaguar cichlid

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2004 Jewel cichlid Jaguar cichlid

Temporal Colonizations of the Everglades Region: 

Temporal Colonizations of the Everglades Region 1960s: Black acara. 1970s: Oscar, walking catfish, spotted tilapia, blue tilapia. Mid-1980s: Mayan cichlid, pike killifish, peacock bass, Mozambique tilapia. Late 90s-00s: Jewel cichlid, jaguar cichlid, brown hoplo, banded cichlid, spotfinned spiny eel.

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First-record Locations in ENP Clarias Acara Jewel Mayan Tilapia Jaguar Cichla Hoplo Pike Spinyeel Heros

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Drift-fence – 2000 % introduced/total # introduced species 3 6 7 3 10 4 10 4 Taylor 0.38 Interior 0.04 Edge Areas 0.24 Throw traps-1996-2001 % introduced/total 4 2 0.7 2 0.7 2

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Canals are sites of introduction, dispersal, and refuge for non-indigenous biota

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Canal inhabitants that are potential future colonizers of the Everglades. C. salvini C. citrinellum Monopterus sp. O. mossambicus C. marulius Photo Credit: Florida FWC

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CERP Project features affecting the southern Everglades

Risk Assessment: 

Preventing future introductions rests in identifying potential problems in advance Perform taxonomic/life-history/ecology research to understand risks and vulnerabilities. Model biology of existing pests to screen future introductions Identify new introduction vectors. Risk Assessment

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Single-species Studies Monopterus albus – Asian Swamp Eel Genetics and life-history studies of diet, salinity tolerance, and reproduction.

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Swamp-eel Cladogram (Collins et al. 2002)

Eel Diet Results - % Volume: 

Eel Diet Results - % Volume

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Eel Life History – Food-Web Simulation

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Community Effects Problem: Difficult to demonstrate effects in field with highly variable native fish populations. Effects may be lost in system “noise”. Field and mesocosm experiments will help understand mechanisms that give rise to patterns seen in field collections.

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Nesting Patterns Following Introductions

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Inverse Relationship of Native and Introduced Fish Catch, Indicating Predation Effects

Introduced Fishes in Short-hydroperiod Wetlands: Evaluation of Sampling, Status, and Potential Effects: 

Introduced Fishes in Short-hydroperiod Wetlands: Evaluation of Sampling, Status, and Potential Effects Use field studies and mesocosm experiments to test the effects of introduced fishes on native fauna. Tests for predation, nesting disturbance, and indirect effects of introduced species in disrupting native fish behavior.

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Fish CPUE in Rocky Glades Solution Holes

Experimental Design: Hemichromis Predation: 

Experimental Design: Hemichromis Predation B. Experimental Set-up A. Cage Design 1 m 18 cm Abiotic Stress Experiment Predation Trial (predator + prey) Predation Trial (prey only) 3 cm plastic mesh solid canvas bottom Water level artificial vegetation

Control: 

Control Existing control methods are ineffective in the open Everglades wetlands with connections to “reservoirs” of colonists. Eradication is presently impossible except in isolated water bodies. Research on innovative control methods is needed!

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Original wetland system a seasonal savanna or forested wetland, with shallow sloughs and strands that held water much of the year. Deepest habitats were alligator holes

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ENP Marsh Water Temperatures

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Winter Kill of Jaguar Cichlids

Pro-active Measures : 

Pro-active Measures Educate public to discourage releases. Fund effective, coordinated monitoring. Engineer delivery structures that impede access to wetlands. Research innovative control methods, as with plants/insects. Understand biotic interactions and ecology by experimentation. Model existing pests to screen future introductions.