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4: Wildlife and Human Health

Jacoby Carter, Jill Jenkins, and Clint Jeske

U.S. Geological Survey, National Wetlands Research Center, Lafayette, Louisiana

Invasive species are threats to ecosystem integrity, disrupting communities by replacing native species and altering flows of energy and materials. However, invasive species can also be disease organisms and vectors. This talk will focus on invasive species with an emphasis on disease and disease vectors in the Gulf of Mexico region.

For the last two years, southern Louisiana crawfish operations have experienced significant mortalities due to white spot syndrome virus (WSSV) infection impacting Procambarus clarkii (red swamp crawfish). First seen in 1999, WSSV epizootics devastated Pacific coastal Latin American countries. Other emerging diseases with some level of regional monitoring include West Nile Virus, chytrid fungus (affecting frogs) and equine encephalitis.

Island applesnails (Pomacea insularum) are popular aquarium pets. In Asia they were introduced for the escargot industry but escaped and now are major pests in rice fields. In Southeast Asia they have disrupted tropical swamp ecosystems. Furthermore, applesnails are carriers for the nematode Angiostrongylus cantonensis, the rat lungworm, the most common cause of human eosinophilic meningitis. Recently breeding populations of Island applesnails were discovered in southeast Louisiana. Applesnails have the potential to disrupt Gulf Coast freshwater marsh and swamp ecosystems, and to damage the rice industry and spread disease.

Nutria (Myocastor coypus), imported in the 1930’s, established feral populations throughout the Gulf Coast and elsewhere. Nutria herbivory can cause marsh loss and undermine coastal recovery efforts. Coastal marshes are the most cost-effective way to protect human lives and property against hurricane impacts. In addition to causing direct environmental damage, nutria can act as host for several parasites that affect people and livestock including Strongyloides myopotami, the roundworm that causes “nutria itch.”

The USGS-NWRC in partnership with the Louisiana Department of Wildlife and Fisheries is sampling shorebirds and waterfowl for avian influenza as part of a USGS effort to identify and map influenza strains. While most of the focus has been on avian flu in the Pacific Flyway, the transmission of other highly pathogenic strains from South America by migrating wild birds is also a possibility and the Gulf Coast would be the first region affected. A better understanding of invasion and disease occurrence patterns will facilitate assessments of spatio-temporal vulnerability of humans and ecosystems.

Contact Information: Jacoby Carter, U.S. Geological Survey, National Wetlands Research Center, 700 Cajundome Blvd., Lafayette, Louisiana 70506; phone: 337-266-8620; fax: 337-266-8664; email: carterj@usgs.gov

Jill A. Jenkins1, Steve Hartley1, and Charles R. Demas2

1 U.S. Geological Survey, National Wetlands Research Center, Lafayette, Louisiana
2 U.S. Geological Survey, Louisiana Water Science Center, Baton Rouge, Louisiana

Integrated, quantitative measures of anthropogenic stress over large geographic regions can be valuable for environmental research and management. In order to develop regional stress measures, pre-existing spatial datasets of variables can be categorized into classes of anthropogenic stress based on measures such as agricultural use, human population levels, point source pollution, and land cover type. By mapping these stress measures, spatial patterns may become apparent, whereby gradients of stressors can be chosen along which hypotheses may tested according to management needs.

Historic, accurate, and detailed images are a cornerstone for reconstructing scenarios that can be used to analyze, model, and predict the status and conditions of natural resources within river basins, such as the Lower Mississippi River Basin (LMRB). In the LMRB, constructed data sets include the National Gap Analysis Program (GAP) land use/land cover, the USGS GIRAS land use/land cover, and the National Land Cover Data (NLCD). These data sets have been converted to a common projection and datum, and reclassified according to a crosswalk by which categories can be compared through USGS interactive map servers. These land use/cover classifications can be further manipulated and useful for environmental assessments of patterns with respect to water quality analysis, growth management, and other environmental impact assessments.

Temporal spatial analysis can provide patterns of change as a basis for which organismal data can be collected. Because artifacts due to classification methods, scale, and projection directly impact temporal change analyses, rigorous quality control measures must be considered. Data needs may be either immediate or long-term, and are dependent on factors that may include acute or hazardous incidences, invasive species encroachment in ecosystems, human and development impacts, and water quality changes. Geospatial data overlays can be used to delineate impact severity patterns. Hence, hypothesis testing for site differences in water quality and consequent biomarkers can be performed using appropriate aquatic species.

A targeted bioindicator/biomarker approach based on the geospatial database of known anthropogenic variables can be used to develop hypotheses specific for management needs. Bioindicators are measures of variables that respond in quantifiable ways to changes in the environment. The choice of bioindicators at specific biological levels of organization (such as genetic, cellular, tissue, hormonal, and organismal levels) is dependent on the resource management need. Applying geospatial data sets to quantify anthropogenic impacts has the potential for simplifying complexities of interacting biological and environmental effects.

Contact Information: Jill Jenkins, U.S. Geological Survey, National Wetlands Research Center, 700 Cajundome Blvd., Lafayette, Louisiana 70506; phone: 337-266-8607; fax: 337-266-8664; email: jenkinsj@usgs.gov

Thomas W. Doyle and Randy G. Westbrooks

U.S. Geological Survey, National Wetlands Research Center, Lafayette, Louisiana

A landscape simulation model of Federal lands across the southeastern United States has been developed to foster early detection and rapid response of the translocation and movement of invasive species. The model documents known population loci of invasive plants and insects and predicts their potential spread by generational patterns and rates combined with probabilities for rapid relocation of viable progeny by tropical storms making landfall. The counterclockwise circulation of tropical storms and hurricanes in the northern hemisphere may hasten the western and northern spread of spores, seeds, and reproducing adults across the Gulf coastal plain. The landscape model works in concert with another physical model (HURASIM) that tracks hurricane paths, historical and hypothetical, to investigate the role tropical storms may have on invasive spread. The ultimate goal is to monitor the paths of tropical storms across coastal areas where particular invaders are known to occur, and to simulate translocation across impacted inland areas. In this project, we modeled the potential spread of the South American Cactus Moth (Cactoblastis cactorum) by Hurricane Dennis in July 2005, from infested areas along the Gulf Coast of Alabama to inland areas where prickly pear cacti (Opuntia spp. – the only host of Cactus Moth) are known to occur. With such a system, conservation land managers in impacted areas could be alerted soon after a storm event, and thus be able to implement appropriate actions to prevent the establishment and spread of target species. In the future, the system will be expanded by adding distribution information on high profile invasive plants of concern such as cogongrass (Imperata cylindrica) and old world climbing fern (Lygodium microphyllum).

Contact Information: Tom Doyle, U.S. Geological Survey, National Wetlands Research Center, 700 Cajundome Blvd., Lafayette, Louisiana 70506; phone: 337-266-8647; fax: 337-266-8586; email: doylet@usgs.gov

Michael R. Rochford1, Michael S. Cherkiss1, Matthew L. Brien1, Skip Snow2, Kenneth Rice3, Michael E. Dorcas4, Alexander Wolf1, Brian Greeves1, Laurie Wilkins5, Gordon Rodda6, Robert Reed6, Kristen Hart3, and Frank Mazzotti1

1 University of Florida, Fort Lauderdale Research & Education Center, Davie, Florida, USA
2 South Florida Natural Resources Center, Everglades National Park, Homestead, Florida, USA
3 U.S. Geological Survey, Florida Integrated Science Center, Gainesville, Florida, USA
4 Department of Biology, Davidson College, Davidson, North Carolina, USA
5 Florida Museum of Natural History, Gainesville, Florida, USA
6 U.S. Geological Survey, Fort Collins Science Center, Fort Collins, Colorado, USA

Native to Southeast Asia, Burmese pythons (Python molurus bivittatus) are a recently established invasive species in South Florida. Burmese pythons have the potential to adversely affect their new environment. The release of Burmese pythons in South Florida is especially troublesome because they appear to thrive in both disturbed and undisturbed habitats within the Everglades. The purpose of this project is to provide science support to develop control measures for Burmese pythons and to evaluate impacts of pythons on native biological diversity. We are using radio telemetry to determine habitat use, extent and timing of movements, and find aggregations of pythons during the breeding season. Since December 2005, 17 adult pythons have been captured and surgically implanted with VHF radio transmitters in Everglades National Park and on lands owned by South Florida Water Management District. Distances traveled by the pythons varied from shorter movements of several hundred meters associated with breeding, to distances greater than 78 kilometers for pythons that had been relocated. The unique dispersal capabilities of Burmese pythons and affiliation with water indicate that effective management of the rapidly expanding python population in south Florida requires cooperation and involvement of all land managers and relevant agencies.

Burmese pythons are generalist predators that consume a wide variety of mammal and bird species, as well as reptiles, amphibians, and fish. Prey species in the digestive tracts of Burmese pythons were identified by examining hair, bone, and teeth. Fourteen species of mammals, five species of birds, and one species of reptile have been found in the digestive tracts of pythons collected and examined in Florida, including several federally endangered Key Largo woodrats (Neotoma floridana smalli); one threatened species, the American alligator (Alligator mississippiensis); and two species of special concern, the limpkin (Aramus guarauna) and the white ibis (Endocemus albus).

Because temperature affects nearly all aspects of the biology of ectotherms, examining patterns of body temperature variation can often provide insight into their activity and behavior. To better understand the ecology of introduced Burmese pythons in ENP, we initiated a radiotelemetry study of pythons within and adjacent to the ENP and monitored their temperatures using surgically implanted micro-dataloggers. We simultaneously monitored environmental temperatures. Using these data, we hope to provide information on python thermal biology, behavior, and activity that will assist in a better understanding of their overall ecology and development of effective population controls.

Trapping is one control method currently under development. The purpose of trapping is to remove pythons from the Everglades system. We are currently testing various trap and trap door designs. We intend to synthesize the knowledge gained from radio-telemetry, diet, and thermal studies to increase trapping success. This multi-faceted approach should increase success in reaching our primary goal of developing control methods for Burmese pythons.

Contact Information: Kristen Hart, United States Geological Survey, Florida Integrated Science Center, 3205 College Ave., Fort Lauderdale, FL 33314 USA, Phone: 954-577-6304; Fax: 954-475-4125, Email: Kristen_hart@usgs.gov

Thomas C. Michot1, Marc C. Woodin2, Stephen E. Adair3, E. Barry Moser4

1 U.S. Geological Survey, National Wetlands Research Center, Lafayette, Louisiana
2 U.S. Geological Survey, Environmental and Contaminants Research Center, Corpus Christi, Texas
3 Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station Texas
4 Department of Experimental Statistics, Louisiana State University, Baton Rouge, Louisiana

ABSTRACT: Diurnal time-activity budgets were determined for wintering redheads (Aythya americana) from estuarine seagrass beds in Louisiana (Chandeleur Sound) and Texas (Laguna Madre), and from ponds adjacent to the Laguna Madre. Activities differed significantly (P < 0.0001) by location, month, and diurnal time period. Resting and feeding were the most frequent activities of redheads at the two estuarine sites, while drinking there was almost nonexistent. Birds on ponds in Texas engaged most frequently in resting and drinking, but feeding was very infrequent. Redheads from the Louisiana estuarine site rested less than birds in Texas at either the Laguna Madre or freshwater ponds. Redheads in Louisiana fed more than birds in Texas; this was partially due to weather differences (colder temperatures in Louisiana), but the location effect was still significant even when weather effects were adjusted for in the model. Redheads in Louisiana showed increased resting and decreased feeding as the winter progressed, but redheads in Texas did not exhibit a seasonal trend in either resting or feeding. Males and females at both Chandeleur Sound and Laguna Madre showed statistical differences in their activities, but the absolute difference seldom exceeded 2% for any single activity. Diurnal time-activity budgets of redheads on the wintering grounds may have been influenced by water salinities and the use of fresh water, and by weather conditions, tides, and vegetation differences (patch size) between sites.

Contact Information: Tommy Michot, U.S. Geological Survey, National Wetlands Research Center, 700 Cajundome Blvd., Lafayette, Louisiana 70506; phone: 337-266-8882; fax: 337-266-8664; email: michott@usgs.gov

Ikuko Fujisaki1, Frank J. Mazzotti2, Kenneth G. Rice3, Skip Snow4, Kristen M. Hart5, and Michael Rochford2

1 Texas A&M University, College Station, Texas
2 University of Florida, Ft. Lauderdale Research and Education Center, Davie, Florida
3 U.S. Geological Survey, Florida Integrated Science Center, Gainesville, Florida
4 U.S. National Park Service, Everglades National Park, Homestead, Florida
5 U.S. Geological Survey, Florida Integrated Science Center, St. Petersburg, Florida

Global trade of live reptiles has facilitated introduction and establishment of exotic reptiles in many locations around the world. In south Florida, a subtropical climate and frequent import of exotic reptiles as pets have contributed to successful establishment of numerous taxa of reptiles. In this risk assessment project, we developed quantitative models to predict the successful establishment of exotic reptiles in south Florida. To identify which biotic, abiotic, and human-induced factors may be the best predictors of successful establishment for exotic reptiles, we used discriminant analysis, logistic regression, and recursive partition and regression trees.

Significant variables in the models included taxonomic group, maximum temperature match between native range and Florida, animal price, and manageability. We applied the models to predict establishment success of the 33 reptiles that were most frequently imported through Miami and St. Petersburg ports in Florida from 2000-2005. Among the assessed reptiles, we identified eight lizards and two snakes as potentially successful invaders. We further assessed risks associated with  potential invaders should they become established by identifying species that are (1) dangerous to humans; (2) upper trophic-level predators in an ecosystem; (3) have the potential to spread rapidly; and (4) particularly difficult to manage or control.

Once exotic reptiles become established, managing them is expensive and labor intensive, thus prevention of establishment is the ideal management goal. Our study provides a foundation to develop screening tools that identify potentially problematic species among imported reptiles.

This project has relevance to Everglades restoration. If restoration activities alter microhabitat features of the landscape to be more favorable for exotic reptiles, the probability of establishment may increase. In addition, restoration of native and endangered species habitats may be negated by release and establishment of exotic reptiles in south Florida. Management tools that screen potential invaders and assess risk of establishment must be integrated into restoration goals and future modeling scenarios.

Contact Information: Kristen M. Hart, U.S Geological Survey, Florida Integrated Science Center, 600 4th Street South, St. Petersburg, Florida, 33701 USA; Phone: (727) 803-8747 x3035; Email: kristen_hart@usgs.gov

Barry H. Rosen, U.S. Geological Survey, Florida Integrated Science Center

Harmful algal blooms (HABs) in the Gulf of Mexico (GOM) have a long history of causing fish kills, shellfish poisonings and other health hazards. Their toxins cause a variety of impacts to humans, wildlife, shellfish and fish that range from irritation to mortality. Ingestion of contaminated shellfish and breathing of aerosolized toxins are the most common exposure routes. Among the phytoplankton species that are present in the GOM, there are approximately 300 species that form blooms and 100 species that produce algal toxins. Although these organisms are microscopic, when they are at high concentrations in the water they impart color to the water and their pigments can be detected by satellite imagery.

One of the most common toxins, paralytic shellfish poison (PSP), is produced by the dinoflagellate Karenia and there are at least 7 species of this organism in the GOM. In Florida, Karenia blooms are initiated offshore (18-64 km) and then winds and currents move the blooms toward shore. Karenia population growth is a result of nutrients, such as nitrogen and phosphorus. These nutrients are more readily available near shore due to upwelling as well as surface-water and ground -water sources in the coastal marine habitats. Blooms of Karenia, which only occur above the salinity of 24 ppt and in the temperature range of 17-32OC, typically last three to five months during late summer through the fall. Between 1994 and 1996, a Karenia bloom lasted 21 months in Florida. When the population density is above 5000 cell/mL, shellfish beds are closed due to the likelihood of PSP accumulation. In 1996, the death of 151 endangered Florida manatees was attributed to a Karenia bloom on the Southwest coast of Florida and over 650 fish kills were reported.

Other genera are also known to form blooms in the GOM. In 2008, Dinophysis acuminata bloomed in Port Aransas, Texas, which led to the closure of Corpus Christi, Aransas and Copano bays to the harvest of oysters, clams and mussels. This was the first time the Texas shellfishing was closed due to okadaic acid. Okadaic acid accumulates in bivalves and causes diarrhetic shellfish poisoning. Over the next month, the population of Dinophysis declined and the toxin rapidly decreased and allowed subsequent reopening of the shellfish beds.

Techniques for the detection of HABs have been deployed from Texas to Florida and are mostly in the experimental stage. Satellite imagery of phytoplankton pigments is widely used to detect and track HABs. Molecular and optical probes attached to fixed locations or mobile units are showing some measures of success. New instruments under development are smaller, less expensive, faster, more accurate, and will be equipped to provide integrated and automated simultaneous measurements.

Contact Information: Barry H. Rosen, U.S. Geological Survey, Florida Integrated Science Center, 12703 Research Parkway, Orlando, Florida 32826; phone: 407-803-5508; fax: 407-803-5501; email: brosen@usgs.gov