Exotic Plant and Animal Control Projects

SUMMARY OF DOI SCIENCE NEEDS RELATED TO EXOTIC PLANT AND ANIMAL CONTROL PROJECTS

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Implementing an Exotic Plant Management Strategy

Project Purpose and Major DOI Interest
Invasive exotic species pose serious threats to the South Florida restoration efforts. They replace native plants and animals, including threatened and endangered species, alter ecosystem functions like soil formation, hydrology, and nutrient processes, and form monocultures of exotic plants where species-rich and diverse natural communities once flourished. Recognizing the seriousness of this threat, the Task Force and Working Group authorized the Noxious Exotic Weed Task Team (NEWTT) to address invasive exotics concurrently with other work being directed by the CERP and the MSRP. This team produced a report called Weeds Won't Wait that documents the problems caused by invasive exotic plants throughout Florida and the Everglades and outlines a comprehensive strategy for their management.

The purpose of this strategic implementation project is to identify and address the invasive exotic plant species in the Greater Everglades that directly affect USDI lands, and to articulate the associated activities that require USDI input and involvement, recognizing that effective control activities must be interagency in scope. The major approaches to managing invasive exotic species include (1) reducing the impact and distribution of existing exotics identified as most critical, (2) preventing new exotic weeds from being introduced and becoming established, (3) generating public awareness of the threats posed by invasive exotic plants, and (4) marshalling interagency resources to better integrate and coordinate common activities and resources related to the management of invasive exotic plants. Coordination with the national invasive species strategies and programs is also a component of invasive exotic plant management in the Greater Everglades.

Serious environmental threats to USDI lands have focused USDI scientists on developing a strategy for managing invasive exotic species holistically as well as managing the impacts of individual species at specific locations. Defining the USDI role in exotic plant management is important for USDI science program planning. However, it is crucial that USDI science be coordinated with other agency and interagency activities to manage and control invasive exotic plants.

Currently the USACE is preparing two reports. The first is a special reconnaissance-type report based on Weeds Won't Wait that will further describe the overall problem and make recommendations regarding the federal interest, potential federal sponsors, and integration of the invasive species control and management actions of all the federal Task Force agencies. The second report is a PIR for biological control of melaleuca and other exotic species. This PIR will guide the federal agencies and the CERP sponsor (SFWMD) regarding use of CERP funding for the biological control program at the new Davie quarantine facility.

What Is Known
Scientists have identified and prioritized 50 different species of invasive exotic plants that pose the greatest threat to South Florida ecosystem restoration. They are ranked into three categories: A (most pressing for management), B (critical but not as pressing as category A), and C (least pressing, but species that must be addressed and monitored because of their potential threat). An example of how species are ranked is provided by melaleuca: It is included in category C for South Florida because (1) a great deal is known of its biology and ecological effects, (2) a comprehensive and extremely effective management plan has been in operation for 15 years, and because of effective control and management, it is decreasing in extent and rate of invasion, but (3) because of its abilities to proliferate quickly, it remains a focus for management.

Scientists have developed management plans for six key invasive exotic species that are now in various stages of implementation. These species are melaleuca, Old World climbing fern, Brazilian pepper, water hyacinth, water lettuce, and hydrilla. These management plans outline numerous tasks and activities considered essential for managing invasive exotic plants, including strong coordination among all the affected agencies. NEWTT also identifies the numerous tasks and activities that are part of carrying out the four major approaches outlined previously, along with the individual agencies that are either taking a lead role or would consider taking a lead role should adequate resources become available.

What Is Needed
DOI support and participation in developing an implementation Plan for an interagency invasive exotic plant management program for South Florida restoration. DOI science now needs to focus activities and attention on the problem of invasive exotics in a way that enhances control and management of these intrusive and damaging plants on DOI lands and also supports the broader interagency ecosystem approach. An implementation plan for the exotic plant management strategy is needed. The plan will help identify individual agency roles in invasive exotic plant management for this ecosystem and help integrate and coordinate resources and actions.

Risk assessment model to determine the potential threat posed by existing species and possible future invaders of DOI lands

Research into the best control methods for species by life form. Research at the life form level will help determine if there are control methods that might be useful across life forms or if independent research into control methods by species is necessary.

Monitoring and assessment of the overall invasive exotic plant problem on DOI lands, sharing information with other agencies

Monitoring and assessment to determine the responses of native species to management activities designed to control invasive exotics

Invasive Exotic Plant Detection and Monitoring

Project Purpose and Major DOI Interest
The purpose of this project is to identify a set of detection and monitoring methods that can be used by the various agencies across Florida to develop a comprehensive understanding of the magnitude of infestations by invasive exotic plant species and the success (or failure) of existing management programs. Agencies currently use a variety of methods of varying quality and accuracy to locate, map, and monitor invasive exotic plants and to assess the success of control programs. The lack of uniformity and consistency among these methods has made it impossible to create a spatially precise, consistent geographical reference system that all agencies can use to locate invasive exotic plants and document the effects of management actions.

What Is Known
Multiple techniques for vegetation mapping and community or species classification are available.

Remote sensing using imaging systems (photographs, thematic imagers, etc.) is generally not applicable or practical in instances where both very detailed and high resolution results are required, or where extremely large areas are being covered. In the case of extremely large areas of coverage, modeling seems to be a practical alternative for locating the most probable locations of exotics both for control and budget planning.

Simple, low-tech and low-cost tools are essential to field managers who are on the ground trying to find and control invasive exotic species. Existing low-tech field remote sensing methods are practical, cost-effective, and achieve basic agency aims; however, the results of these methods are not sufficient to meet other critical information needs, such as consistency and repeatability of data collection, precision of species location data, retreatment information, ecological and landscape use relationships, and more rigorous aerial extent and invasion rate calculations. In particular, more precision is needed in spatial coordinates for species locations.

What Is Needed
Prototype development of remote sensing field system. With numerous technologies available for locating invasive exotic plants, a priority is to combine and use the existing technologies (including hardware and software) to create an affordable, field applicable (ground or aircraft), user friendly, data rigorous tool for accurately detecting and monitoring invasive exotic plants. A prototype will be developed by first evaluating all the field detection programs currently in use by Florida agencies. From this evaluation a single system or small number of systems will be configured for use by both field managers, for whom the data collection system (especially of spatial data) will be transparent, and researchers, who may use the spatial data in their studies.

Invasive Exotic Plant Management on the Arthur R. Marshall Loxahatchee National Wildlife Refuge

Project Purpose and Major DOI Interest
The Arthur R. Marshall Loxahatchee National Wildlife Refuge Comprehensive Conservation Plan identifies invasive pest plant management as the highest priority and proposes that populations of several of the more aggressive exotic pest plants be reduced to maintenance control levels within the next 15 years (2015). In addition, reduction of exotics to maintenance control by 2017 is a performance measure agreed to by the SFWMD and the FWS in conjunction with the renewal of the refuge license agreement in 2002.

Two invasive exotics, melaleuca and Old World climbing fern (Lygodium), cover more than 90,000 acres (60%) of the refuge. Lygodium alone covers nearly 25,000 acres (15%) of the refuge. Research on the biology and control technologies for melaleuca has been underway for at least 10 years. Because Lygodium is a fairly recent invader, much less is known about its biology and methods of control.

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Managers will not be able to determine when they have reached maintenance control until they can express maintenance control in measurable terms. Florida legislation (§ 369.22 (1) (d)) defines maintenance control as "applying management techniques on a continuous basis to keep non-indigenous plant populations at the lowest feasible levels. Under maintenance control there is a reduction in: navigation restrictions, irrigation and flooding problems, sedimentation and lake aging, management costs, competition with native plants, loss of fish and wildlife habitat, and use of herbicides." This objective standard needs to be quantified in order to measure the success in meeting it.

What Is Known
The Florida Exotic Pest Plant Council Lygodium Task Force has prepared a Lygodium Management Plan for Florida that discusses the current, rather limited knowledge about the species and summarizes strategies and needs for future management. Efforts have been underway since 1993 to map the distribution of Lygodium within South Florida via aerial surveys. Identification of dense concentrations and outlier populations is a first step in developing a treatment strategy.

Initial research on methods using fire and herbicides to control Lygodium is available, and the SFWMD has conducted aerial applications of herbicides in Dupuis Reserve and the refuge. The effectiveness of these treatments, and the nontarget effects, are being evaluated.

The SFWMD and the USDA Agricultural Research Service are conducting limited biological control research to develop possible biological control agents. Because of the nature and rate of spread of Lygodium, some experts think that biological control will be the only long-term effective management tool. However, this program is not adequately funded, and physical control agents are needed while the biological control agents are being developed, to prevent Lygodium from invading large areas of South Florida.

Little is known about the ecological requirements of Lygodium in Florida. Lygodium is documented to grow in both wetland and upland habitats and to reproduce throughout the year. Ongoing research on the reproductive ecology of Lygodium may discover possible weaknesses in its life cycle and help determine more effective control approaches.

Efforts are underway to integrate what is known about Lygodium at the refuge, the available control technologies, and costs into a decision tool that the refuge manager will use to evaluate alternative control strategies and optimize the use of existing resources for Lygodium management.

What Is Needed
Measurable targets for maintenance control of Lygodium. Quantitative definitions of "ecologically acceptable" will be required in order to establish measurable targets for maintenance control. Ecologically acceptable levels can be determined through field studies. Research shows, for example, that in tree islands with almost 100% cover of Lygodium there is a significant reduction in the abundance of native plant species. Determining what percent cover of Lygodium begins to alter the flora and fauna will help quantify management targets and prioritize control efforts.

Research to identify effective control methods for Lygodium. Developing effective Lygodium control methods and approaches will require continued partnerships among agencies and universities. Efforts to develop biological control methods need increased priority and funding. Additional study will identify the most cost-effective and ecologically beneficial chemical and physical control treatment for Lygodium in refuge habitats. Ongoing studies of the effectiveness of various control methods should continue while biological control programs are in the development phase. A better understanding of weaknesses in the life cycle of Lygodium, and factors that inhibit Lygodium growth, may enhance the ability to effectively control this species.

Aquatic Exotic Animals

Project Purpose and Major DOI Interest
Unintentional introductions of aquatic exotic animals have generally been harmful, in some cases catastrophic. Although control has been successful in some cases, such as in the early stages of colonization by nonnative fish species, complete eradication is often not economically feasible once the populations have become well established. Because eradication of established introduced species is often of limited success, the best strategy may be to avoid operations that are likely to facilitate the introduction of nonnative species from canals, borrow pits, and water detention ponds into natural areas of the Everglades.

The purpose of this project is to provide DOI managers working in partnership with the USACE and the SFWMD with the scientific information they need to ensure that the potential for introduction of aquatic exotic animals is adequately considered during planning for restoration projects and water management operations. For example, canals are documented to serve as corridors for the movement of nonnative animals, and as deepwater thermal and dry-season refuges for both native and introduced aquatic species. The extensive canal system is typically dominated by nonnative fishes in South Florida. Because the canals act as pathways for dispersal, their filling would slow the colonization of introduced aquatic organisms that occur east of the Everglades. Some canals will be filled under the CERP, but a new set will be excavated. Therefore, it is critical to understand the consequences of this artificial aquatic habitat with regard to introduced species.

Other structures also need to be evaluated. For example, pumps and other structures at points of inflow to natural areas in the Everglades are typically not designed to prevent the movement of aquatic animals through them, as they are at many water control structures throughout the United States.

Additionally, some of the water management actions being used to achieve hydrological restoration (such as overflow of water from canals) may pose an increased threat of introducing nonnative species to natural areas. Also, hydrological operations designed for other purposes, such as flood control or even protection of endangered species, have the potential to introduce nonnative species to natural areas if not properly planned. Water management actions and operations that limit direct connections of canal and marsh surface habitats will help prevent the dispersal of exotic animals.

What Is Known
South Florida supports greater numbers of exotic fishes than most other states, owing to the subtropical climate, and the vast network of inter-connecting canals. Most invasions of introduced fishes and gastropods occur in proximity to pump stations and canals, which allow for the persistence and dispersal of these species.

Canals and water detention areas along the northern and eastern boundaries of natural areas provide a source of exotics to Everglades marsh habitats. Although all the exotic fishes established in the area are tropically derived, and many are sensitive to cold temperatures, canal and borrow pond habitats provide a refuge from cold temperatures. Seven species of exotic fishes were reported as established in Everglades National Park in 2000. Since the summer of 2000 three new exotic species have been collected. Exotic fishes are now a large component of deep solution hole habitats in the Rocky Glades in the eastern marl prairies of Everglades National Park.

Publications and technical reports describing South Florida vertebrates, including the growing number of nonnative species, are available, particularly for Everglades National Park and Big Cypress National Preserve. A complete fish and amphibian inventory is underway in the Big Cypress National Preserve. Nonnative invertebrates are only partly inventoried in Everglades National Park because of sampling and identification difficulties and lack of funding, but data are available for some taxa.

What Is Needed
Research into the ecological impacts of invasive exotic species on native species, created habitats (filter marshes, reservoirs, etc.), and natural habitats. Research will support a better understanding of the magnitude of predation on native aquatic populations and the indirect effects on consumer groups, such as wading birds. Populations of native and introduced predatory fishes (e.g., the outstanding largemouth bass fishery in Everglades canals) may be sustained by energy subsidies from adjacent wetlands. A comparison of community patterns and seasonal dynamics in canals that cut through natural wetlands and canals that are isolated from wetlands will indicate the extent to which this occurs.

Research to develop effective control methods for exotic aquatic animals. Research and development of control methods will provide the tools managers need to reduce or eradicate introduced animals.

Studies to support water project designs. Analyses of canals as habitats and movement corridors for exotic fishes will support engineering designs for canals and pumps that avoid or mitigate the effects of aquatic invasive exotic species on wetlands, while allowing these structures to function as needed for ecosystem restoration. Wetlands adjacent to filled canals will be compared before and after filling, and those conditions will be compared to the conditions in wetlands adjacent to operating canals. Movement patterns by fishes will be studied using tagging and radio tracking.

Systemwide monitoring program to document the changes in invasive species resulting from project modifications, and modeling to assist in predicting possible future changes resulting from project management and operations. An effective early detection monitoring program for nonnative aquatic animals will allow for management action when it has the greatest chance of success, before populations and distributions have expanded. The monitoring program should track the dispersal of exotic fishes from canal and water detention ponds into Everglades marshes. In addition, Model characteristics of existing pests will be developed to screen for potential future pests and to prevent introductions.

Better monitoring for future detection. All non-indigenous fish species presently found in the Everglades have entered the ecosystem via canals. Further monitoring of canals (both in urban and more pristine areas) needs to be conducted to identify sources of future invasions, as early detection is key to control efforts.

Research into life history and ecology of non-indigenous species. A better understanding of the life history and ecology of non-indigenous aquatic species in both their native and introduced habitats is key to understanding their potential for expansion and the subsequent ecological impact in their new habitat. Comparisons of these factors with those of native fishes (novel functions vs. functional redundancy) will aid in determining the magnitude of impact they have on native organisms. Experiments assessing their direct impact on native species (i.e., predation, competition) are key– gut content analysis and studies utilizing stable isotopes for diet and trophic position will be particularly insightful. Furthermore, understanding the conditions that cause greatest stress to the non-indigenous species at various life stages will aid in the development of control methods.

Non-indigenous species risk assessment. Risk assessment methods (empirical comparisons of ecological, behavioral, physiological and life history traits) should be applied to increase our ability to screen and identify potentially harmful species prior to extensive invasions. Identification of which species may be more likely to spread and impact the system will allow for better prioritization of control efforts.

Better understanding of the role of canals. An understanding is needed of the role of canals as sources of colonists after the dry-season, and/or sinks for wetland production at the end of the wet-season. It is important to differentiate these scenarios for different fish species, as they may vary. It is also important to analyze canals as habitats and movement corridors for exotic fishes, and determine if they result in higher colonization rates by exotic animals into wetlands, and how far into wetlands native and non-native fishes move from these artificial habitats.

Better understanding of the extent and role of deep solution holes. In the Rocky Glades, deep solution holes (holes that retain water throughout the dry season) often primarily contain communities of non-indigenous fishes. Extensive surveys should be conducted to determine how many of these dry-season refuges exist and their potential role as sources of non-indigenous colonists as marshes re-flood. Research describing the physiological limitations of both native and non-native fishes will aid in understanding each species' ability to survive the dry-season in these refuges and reemerge as potential marsh colonists in the wet season. Identification of primary dry-season refuges may allow for systematic removal to manage populations.