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Marine Conservation Science and Policy Service learning Program

Invasive Species are infiltrators that invade and cause harm to ecosystems beyond their historic range. Their invasion can threaten native ecosystems or commercial, agricultural, or recreational activities dependent on these ecosystems. They may even harm the health of humans. Human actions, both unintentional and intentional, are the primary means of invasive species introductions and spread to new locations.

Module 4: Marine Issues

Sunshine State Standards SC.912.L.17.8, SC.912.L.15.3, SC.L.17.4, SC.912.E.7.8, SC.912.L.17.20, SC.912.L.17.16

Objectives

Differentiate between exotic/non-native and invasive species

Collect information on a specific invasive species

Identify the pathways by which non-native species are transported

Vocabulary Native species- a species that normally lives and thrives in a particular ecosystem; usually its presence in that region is the result of only natural resources, with no human intervention Non-native species- species that do not originate in the area or region from which they are found growing; also known as introduced, alien or exotic species

Section 5: Invasive Species

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Exotic species- species that occur in a given place as a result of direct or indirect, deliberate or accidental actions by man. Invasive species- species that are not native to an area and whose introduction causes or is likely to cause economic or environmental harm or harm to human health; Non-native species of plants or animals that out-compete native species in a specific habitat

Ballast water- water taken up or released by a ship to stabilize it, or to raise/lower it in the water column; and then discharge when their cargo is loaded; ballast water pumped into a ship contains larvae, microscopic organisms, and sometimes adult fishes or crabs Pathway- The means by which a species is moved from place to place and introduced

Background Introduction All across the planet, the number and severity of outbreaks and infestations of invasive species (i.e. species purposefully or accidentally introduced in non-native environments) is growing, and invasions of marine habitats are now occurring at an alarming rate. Exotic and invasive species have been identified by scientists and policymakers as a major threat to marine ecosystems, with dramatic effects on biodiversity, biological productivity, habitat structure and fisheries.

The introduction of non-native species to an ecosystem is one of the major causes of decreased biodiversity. Termed alien species, they are also known as exotic, introduced, non-indigenous, or invasive species. As the names imply, these species do not belong to ecosystems in which they are either intentionally or unintentionally placed. They tend to disrupt the ecosystem's balance by multiplying rapidly. Additionally, the introduction of an alien species is often responsible for an increase in predation and competition, habitat reduction, a variety of diseases, extinction of native plants or animals and genetic change in populations. These species are often plants, fishes, mollusks, crustaceans, algae, bacteria or viruses.

Many alien species are transferred into marine ecosystems through the ballast water transported during commercial shipping operations. The organisms are taken in when ships attempt to balance their load by letting water into their holding tanks. When they

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reach their destination, the ballast water is released and with it any organisms picked up earlier. Ship ballast water may transport up to 3,000 species around the world every day. Mollusks and other organisms whose habitat includes marine substrate also attach to the surfaces of ocean-going vessels at the point of departure and then fall into the water at the destination. Alien species are often introduced into freshwater ecosystems such as estuaries, rivers, lakes and streams by humans discarding animals or plants formerly held in captivity. In some cases, species used as bait can invade freshwater ecosystems. Well-known invasive species include the Northern Snakehead fish, the Zebra mussel, the Sea Lamprey and the Asiatic Clam, Corbicula fluminea. Aquarium plants and animals, such as the invasive algae Caulerpa, as well as ornamental plants like the purple loosestrife are released innocently into waterways by humans. They quickly overgrow and eventually choke native plants and even interfere with the water flow of lakes, rivers, estuaries, and streams. Unwanted exotic fish, such as the red lionfish, Pterois volitans, have invaded the waters of the Southeastern United States. The introduction of this non-native species may cause problems because of its poisonous spines that divers or swimmers may be unaware of and it may also pose a risk to native species through predation or competition. New seaways or cross-basin connections provide a way for alien species to cross over into novel territories. The Great Lakes became significantly invaded by alien species following the creation of the St. Lawrence Seaway in 1959.

Seafood like shrimp, oysters, and Atlantic salmon is farmed in non-native areas like the Pacific Northwest. When juveniles escape into waterways, the potential for spread of disease and harm to the ecosystem is created. Animals like the northern snakehead fish and Asian swamp eel were introduced as a potential source of food, but they soon overwhelmed the ecosystem forcing local communities, scientists, and policy makers to

find ways to control them. Recreational fishermen have introduced alien species to their favorite fishing hole so that there are an abundance of fish available to catch. Fish bait, such as crayfish, minnows, and earthworms are often thrown overboard, introducing them to new ecosystems that cannot support them. Earthworms have depleted the topsoil in some northern U.S. forests reducing the organic matter available for native species.

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Invasive Species

"Invasive species", or Invasive Exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions.

The first definition, the most used, applies to non-indigenous species, or "non-native", plants or animals that adversely affect the habitats and bioregions they invade economically, environmentally, and/or ecologically. They disrupt by dominating a region, wilderness areas, particular habitats, and/or wildland-urban interface land from loss of natural controls (i.e.: predators or herbivores).

This includes non-native invasive plant species labeled as Exotic Pest Plants and Invasive Exotics, in restoration parlance, growing in native plant communities. It has been used in this sense by government organizations as well as conservation groups such as the International Union for Conservation of Nature (IUCN) and the California Native Plant Society. It is also used by land managers, botanists, researchers, horticulturalists, conservationists, and the public for noxious weeds. The Kudzu Vine (Pueraria lobata), Andean Pampas Grass (Cortaderia jubata), and Yellow Starthistle (Centaurea solstitialis) are examples.

The second definition includes the first, but broadens the boundaries to include indigenous or native species, with the non-native ones, that disrupt by a dominant colonization of a particular habitat or wildlands area from loss of natural controls (i.e.: predators or herbivores). Deer are an example, considered to be overpopulating their native zones and adjacent suburban gardens, by some in the Northeastern and Pacific Coast regions of the United States.

The third definition identifies invasive species as a widespread non-indigenous species. This one can be too broad as not every non-indigenous or "introduced" species has an adverse effect on a non-indigenous environment. An non-adverse example is the common goldfish (Carassius auratus), though common outside its native range globally, it is rarely in harmful densities to a native habitat.

Because of the variability of its definition, the phrase invasive species is often criticized as an imprecise term for the scientific field of ecology.

Conditions that lead to invasion

Scientists propose several mechanisms to explain invasive species, including species-based mechanisms and ecosystem-based mechanisms. It is most likely a combination of several mechanisms that cause an invasive situation to occur, since most introduced plants and animals do not become invasive.

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Species-based mechanisms

Species-based characteristics

focus on competition.

While all species

compete to survive, invasive

species appear to have specific traits

or combinations

of specific traits that allow them to

outcompete native species. Sometimes they just have the ability to grow and reproduce more rapidly than native species; other times it's more complex, involving a multiplex of traits and interactions.

Studies seem to indicate that certain traits mark a species as potentially invasive. One study found that of a list of invasive and noninvasive species, 86% of the invasive species could be identified from the traits alone. Another study found that invasive species tended only to have a small subset of the invasive traits and that many of these invasive traits were found in non-invasive species as well indicating that invasiveness involves complex interaction not easily categorized. Common invasive species traits include:

The ability to reproduce both asexually and sexually Fast growth Rapid reproduction High dispersal ability Phenotypic plasticity(the ability to alter one’s growth form to suit current

conditions) Tolerance of a wide range of environmental conditions (generalist) Ability to live off of a wide range of food types (generalist) Association with humans Other successful invasions

Typically an introduced species must survive at low population densities before it becomes invasive in a new location. At low population densities, it can be difficult for the introduced species to reproduce and maintain itself in a new location, so a species

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might be transported to a location a number of times before it become established. Repeated patterns of human movement from one location to another, such as ships sailing to and from ports or cars driving up and down highways, allow for species to have multiple opportunities for establishment (also known as a high propagule pressure).

An introduced species might become invasive if it can out-compete native species for resources such as nutrients, light, physical space, water or food. If these species evolved under great competition or predation, the new environment may allow them to proliferate quickly. Ecosystems in which all available resources are being used to their fullest capacity by native species can be modeled as zero-sum systems, where any gain for the invader is a loss for the native. However, such unilateral competitive superiority (and extinction of native species with increased populations of the invader) is not the rule. Invasive species often coexist with native species for an extended time, and gradually the superior competitive ability of an invasive species becomes apparent as its population grows larger and denser and it adapts to its new location.

An invasive species might be able to use resources previously unavailable to native species, such as deep water sources accessed by a long taproot, or an ability to live on previously uninhabited soil types. For example, Barbed Goatgrass (Aegilops triuncialis) was introduced to California on serpentine soils, which have low water-retention, low nutrient levels, a high Mg/Ca ratio, and possible heavy metal toxicity. Plant populations on these soils tend to show low density, but goatgrass can form dense stands on these soils crowding out native species that have not adapted well to growing on serpentine soils.

Facilitation is the mechanism by which some species can alter their environment using chemicals or manipulating abiotic factors, allowing the species to thrive while making the environment less favorable to other species with which it

competes. One such facilitative mechanism is allelopathy, also known as chemical competition or interference competition. In allelopathy a plant will secrete chemicals which make the surrounding soil uninhabitable, or at least inhibitory, to competing species.

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Changes in fire regimes are another form of facilitation. Bromus tectorum, originally from Eurasia, is highly fire-adapted. It not only spreads rapidly after burning, but actually increases the frequency and intensity (heat) of fires, by providing large amounts of dry detritus during the dry fire season in western North America. In areas where it is widespread, it has altered the local fire regime so much that native plants cannot survive the frequent fires, allowing B. tectorum to further extend and maintain dominance in its introduced range.

Facilitation also occurs when one species physically modifies a habitat and that modification is advantageous to other species. For example, zebra mussels increase habitat complexity on lake floors providing crevasses in which invertebrates live. This increase in complexity, together with the nutrition provided by the waste products of mussel filter-feeding increases the density and diversity of benthic invertebrate communities.

Ecosystem-based mechanisms

In ecosystems, the amount of available resources and the extent to which those resources are utilized by organisms determines the effects of additional species on the ecosystem. In stable ecosystems, equilibrium exists in the utilization of available

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resources. These mechanisms describe a situation in which the ecosystem has suffered a disturbance which changes the fundamental nature of the ecosystem. When changes occur in an ecosystem, like forest fires in an area, normal succession would favor certain native grasses and forbs. With the introduction of a species that can multiply and spread faster than the native species, the balance is changed and the resources that would have been used by the native species are now utilized by an invader. This impacts the ecosystem and changes its composition of organisms and their use of available resources. Nitrogen and phosphorus are often the limiting factors in these situations.

Every species has a role to play in its native ecosystem; some species fill large and varied roles while others are highly specialized. These roles are known as niches. Some invading species are able to fill niches that are not utilized by native species, and they also can create niches that did not exist.

When changes occur to ecosystems, conditions change that impact the dynamics of species interaction and niche development. This can cause once rare species to replace other species, because they now can utilize greater available resources that did not exist before, an example would be the edge effect. The changes can favor the expansion of a species that would not have been able to colonize areas and niches that did not exist before.

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Ecology

Although an invasive species is often defined as an introduced species that has spread widely and causes harm, some species native to a particular area can, under the influence of natural events such as long-term rainfall changes or human modifications to the habitat, increase in numbers and become invasive.

All species go through changes in population numbers, in many cases accompanied by expansion or contraction of range. Human alterations of the natural landscape are especially significant. This anthropogenic alteration of an environment may enable the expansion of a species into a geographical area where it had not been seen before and thus that species could be described as invasive. In essence, one must define "native" with care, as it refers to some natural geographic range of a species, and is not coincident with human political boundaries. Whether noticed increases in population numbers and expanding geographical ranges is sufficient reason to regard a native species as "invasive" requires a broad definition of the term but some native species in disrupted ecosystems can spread widely and cause harm and in that sense become invasive. For example, the Monterey Cypress is an endangered endemic naturally occurring only in two small stands in California. They are being exterminated as exotic invasive species less than 50 miles (80 km) from their native home.

Traits of invaded ecosystems

In 1958, Charles S. Elton argued that ecosystems with higher species diversity were less subject to invasive species because of fewer available niches. Since then, other ecologists have pointed to highly diverse, but heavily invaded ecosystems and have argued that ecosystems with high species diversity seem to be more susceptible to invasion. This debate seems largely to hinge on the spatial scale at which invasion studies are performed, and the issue of how diversity affects community susceptibility to invasion remains unresolved. Small-scale studies tend to show a negative relationship between diversity and invasion, while large-scale studies tend to show a positive relationship. The latter result may be an artifact of invasive or non-native species capitalizing on increased resource availability and weaker overall species interactions that are more common when larger samples are considered.

Invasion is more likely if an ecosystem is similar to the one in which the potential invader evolved. Island ecosystems may be prone to invasion because their species are “naïve” and have faced few strong competitors and predators throughout their existence, or because their distance from colonizing species populations makes them more likely to have “open” niches. An example of this phenomenon is the decimation of the native bird populations on Guam by the invasive brown tree snake. Alternately, invaded ecosystems may lack the natural competitors and predators that keep introduced species in check in their native ecosystems, a point that is also seen in the Guam example. Lastly, invaded ecosystems have often experienced disturbance, usually human-induced. This disturbance may give invasive species, which are not

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otherwise co-evolved with the ecosystem, a chance to establish themselves with less competition from more adapted species.

Vectors

Non-native species have many vectors, including many biogenic ones, but most species considered "invasive" are associated with human activity. Natural range extensions are common in many species, but the rate and magnitude of human-mediated extensions in these species tend to be much larger than natural extensions, and the distances that species can travel to colonize are also

often much greater with human agency.

Species have also been introduced intentionally. For example, to feel more "at home", American colonists formed "Acclimation Societies" that repeatedly released birds that were native to Europe until they finally established along the east coast of North America. In 2008 U.S. postal workers in Pennsylvania noticed noises coming from inside a box from Taiwan. It turns out that the box contained more than two dozen live beetles. U.S. Customs and Border Protection sent the beetles to the Agricultural Research Service (ARS) to be expertly identified. The ARS entomologists identified the beetles as rhinoceros beetle, hercules beetle, and king stag beetle. Because these beetles are not native to the U.S. they could pose a threat to native ecosystems, agriculture, and the environment. To prevent exotic species from becoming a problem in the U.S. special handling and permits when insects and other living materials are shipped from foreign countries. Programs such as Smuggling Interdiction and Trade Compliance (SITC) have also been set up by the United States Department of Agriculture in an effort to prevent exotic species outbreaks in America.

Economics play a major role in exotic species introduction. The scarcity and demand for the valuable Chinese mitten crab is one explanation for the possible intentional release of the species in foreign waters.

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Impacts of wildfire

Invasive species often exploit disturbances to an ecosystem (wildfires, roads, foot trails) to colonize an area. Large wildfires are capable of sterilizing soils and removing any trace of life from their path, while adding a variety of nutrients to the soil. In the resulting ecological free for all, invasive species can easily dominate native plants, and quickly become established.

Many invasive plant species have the ability to regenerate from their roots. This means that if a low intensity fire burns through an area and removes surface vegetation, native species will have to rely on seeds for propagation, while a well-established invasive species with intact roots can regrow as soon as the ecosystem recovers from the fire, often completely shade out any native vegetation.

Impact of wildfire suppression on spreading

Wildfires often occur in remote areas, requiring fire suppression crews to travel through pristine forest in order to reach the site. The crews can unwittingly be the bearers of invasive seeds. Should any of these stowaway seeds become established along the way, a new thriving concentration of invasive weeds can be present in as few as 6 weeks, at which point controlling the outbreak will require years of continued attention to prevent further spread. Also the disturbance of the soil surface such as firebreaks for fire prevention, destroying the native cover and exposing open soil, can accelerate 'invasive exotic' plants spreading. In suburban and wildland-urban interface areas the vegetation clearance and brush removal ordinances of municipalities for defensible space can result in excessive clear-cutting of native shrubs and perennials that exposes the soil to more light and less competition for invasive plant species.

Fire suppression vehicles are often the major culprits of such outbreaks, as the vehicles are frequently driven on back roads often overgrown with invasive plant species. The undercarriage of the vehicle becomes a prime vessel of transport. In response to this, on large fires vehicle washing stations are set up, and it is required that vehicles be "decontaminated" prior to engaging in suppression activities. In addition when suppressing large wild fires personnel from around the country are often utilized, further increasing the potential for transport of seeds across the country. Thus showing the importance of "cleaning stations".

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Ecological impacts

Land clearing and human habitation put significant pressure on local species. This disturbed habitat is prone to invasions that can have adverse effects on local ecosystems, changing ecosystem functions. A species of wetland plant known as

ʻaeʻae in Hawaiʻi (the indigenous Bacopa monnieri) is regarded as a pest species in artificially manipulated water bird refuges because it quickly covers shallow mudflats established for endangered Hawaiian stilt (Himantopus mexicanus knudseni), making these undesirable feeding areas for the birds.

Multiple successive introductions of different non-native species can have interactive effects; the introduction of a second non-native species can enable the first invasive species to flourish. Examples of this are the introductions of the amethyst gem clam (Gemma gemma) and the European green crab (Carcinus maenas). The gem clam was introduced into California's Bodega Harbor from the East Coast of the United States a century ago. It had been found in small quantities in the harbor but had never displaced the native clam species (Nutricola

spp.). In the mid 1990s, the introduction of the European green crab, found to prey preferentially on the native clams, resulted in a decline of the native clams and an increase of the introduced clam populations.

In the Waterberg region of South Africa, cattle grazing over the past six centuries has allowed invasive scrub and small trees to displace much of the original grassland, resulting in a massive reduction in forage for native bovids and other grazers. Since the 1970s large scale efforts have been underway to reduce invasive species; partial success has led to re-establishment of many species that had dwindled or left the region. Examples of these species are giraffe, Blue Wildebeest, impala, kudu and White Rhino.

Invasive species can change the functions of ecosystems. For example invasive plants can alter the fire regime (cheatgrass, Bromus tectorum), nutrient cycling (smooth cordgrass Spartina alterniflora), and hydrology (Tamarix) in native ecosystems. Invasive species that are closely related with rare native species have the potential to hybridize with the native species. Harmful effects of hybridization have led to a decline and even extinction of native species. For example, hybridization with introduced cordgrass, Spartina alterniflora, threatens the existence of California cordgrass (Spartina foliosa) in San Francisco Bay.

Genetic pollution

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Natural, wild species can be threatened with extinction through the process of genetic pollution. Genetic pollution is uncontrolled hybridization and introgression which leads to homogenization or replacement of local genotypes as a result of either a numerical or fitness advantage of the introduced species. Genetic pollution can bring about a form of extinction either through purposeful introduction or through habitat modification, bringing previously isolated species into contact. These phenomena can be especially detrimental for rare species coming into contact with more abundant ones where the abundant ones can interbreed with them, creating hybrids and swamping the entire rarer gene pool, thus driving the native species to extinction. Attention has to be focused on the extent of this problem, it is not always apparent from morphological observations alone. Some degree of gene flow may be a normal, evolutionarily constructive process, and all constellations of genes and genotypes cannot be preserved. However, hybridization with or without introgression may, nevertheless, threaten a rare species' existence. An example of this is the interbreeding of immigrating coyotes (left) with the red wolf (right), in areas of eastern North Carolina where the red wolf has been reintroduced.

Economic impacts

Benefits

Often overlooked, economic benefits from "invasive" species should also be accounted. The wide range of benefits from many "invasive species" is both well-documented and under-reported. (In most cases invasive species have benefits, but the negative effects are generally perceived to outweigh the positive, at least initially.) Asian oysters, for example, are better at filtering out water pollutants than native oysters. They also grow

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faster and withstand disease better than natives. Biologists are currently considering releasing the mollusk in the Chesapeake Bay to help restore oyster stocks and clean up the bay's pollution. A recent study by the Johns Hopkins School of Public Health found the Asian oyster could significantly benefit the bay's deteriorating water quality.

Economic opportunities

For many invasive species there are commercial benefits, either existent or capable of being developed. For instance, Silver Carp (left) and Common Carp where heavy metals are not excessive in their flesh can be harvested for human food and exported to markets already familiar with the product, or into pet foods, or mink food. Numerous vegetative 'invasives' like Water Hyacinth can, when in sufficient quantities to be harvestable, be turned into methane digesters if no other better use can be determined. The depletion or exploitation of any unwanted species is dependent on officials who recognize the need for a solution. Commercial enterprises need assurances

that the exploitation can continue long enough for a reasonable profit to be generated and that taxation of the 'resource' is given a sufficiently long period of grace that an enterprise is attracted to the proposition.

Agriculture

Weeds cause an overall reduction in yield, though they often provide essential nutrients for sustenance farmers. Weeds can have other useful purposes: some deep-rooted weeds can "mine" nutrients from the subsoil and bring them to the topsoil, while others provide habitat for beneficial insects and/or provide alternative foods for pest species. Many weed species are accidental introductions with crop seeds and imported plant material. Many introduced weeds in pastures compete with native forage plants, are toxic (e.g., Leafy Spurge, Euphorbia esula) to young cattle (older animals will avoid them) or non-palatable because of thorns and spines (e.g., Yellow Starthistle, Centaurea solstitialis). Forage loss from invasive weeds on pastures amounts to nearly $1 billion in the U.S. alone. A decline in pollinator services and loss of fruit production has been observed to cause the infection of honey bees (Apis mellifera another invasive species to the Americas) by the invasive varroa mite. Introduced rodents (rats, Rattus rattus and R. norvegicus) have become serious pests on farms destroying stored grains.

In many cases, one could consider the over-abundant invasive plant species as a ready source of biomass in the perspective of biogas production.

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Forestry

The unintentional introduction of forest pest species and plant pathogens can change forest ecology and negatively impact timber industry. The Asian long-horned beetle (Anoplophora glabripennis) was first introduced into the U.S. in 1996 and is expected to infect and damage millions of acres of hardwood trees. Thirty million dollars have already been spent in attempts to eradicate this pest and protect millions of trees in the affected regions.

The woolly adelgid inflicts damage on old growth spruce fir forests and negatively impacts the Christmas tree industry. The chestnut blight fungus (Cryphonectria parasitica) and Dutch elm disease (Ophiostoma novo-ulmi) are two plant pathogens with serious impacts on forest health.

Tourism and recreation

Invasive species can have impacts on recreational activities such as fishing, hunting, hiking, wildlife viewing, and water-based recreation. They negatively affect a wide array of environmental attributes that are important to support recreation, including but not limited to water quality and quantity, plant and animal diversity, and species abundance. Eiswerth goes on to say that "very little research has been performed to estimate the corresponding economic losses at spatial scales such as regions, states, and watersheds." Eurasian Watermilfoil (Myriophyllum spicatum) in parts of the US, fill lakes with plants making fishing and boating difficult.

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Health impacts

An increasing threat of exotic diseases exists because of increased transportation and encroachment of humans into previously remote ecosystems. This can lead to new associations between a disease and a human host (e.g., AIDS virus). Introduced birds (e.g. pigeons), rodents and insects (e.g. mosquitoes, fleas, lice and tsetse fly) can serve as vectors and reservoirs of human diseases. The introduced Chinese mitten crabs are carriers of the Asian lung fluke. Throughout recorded history epidemics of human diseases such as malaria, yellow fever, typhus, and bubonic plague have been associated with these vectors. A recent example of an introduced disease is the spread of the West Nile virus across North America resulting in the deaths of humans, birds, mammals, and reptiles. Waterborne disease agents, such as Cholera bacteria (Vibrio cholerae), and causative agents of harmful algal blooms are often transported via ballast water. The full range of impacts of invasive species and their control goes beyond immediate effects and can have long term public health implications. For instance, pesticides applied to treat a particular pest species could pollute soil and surface water.

Threat to global biodiversity

Biotic invasion is one of the five top drivers for global biodiversity loss and is increasing because of tourism and globalization. It poses a particular risk to inadequately regulated fresh water systems, though quarantines and ballast water rules have improved the situation

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Activity: The Invaders

Students explore how invasive species arrive in Florida.

Duration: 1 hour, plus research time Materials

Books or internet resources on invasive species Copies of species fact sheet

Procedure

1. Place students into groups of 3. Distribute one of the species fact sheets to each group

2. Instruct each group to perform research on the invader. Students should pay special attention to:

Where the organism originated from

The organism’s special characteristics

How it travelled to Florida

Where it can be found in Florida

The first reported sightings

How it affects the environment it inhabits; what plants, animals, or other environmental features are the most susceptible to this species

How the species is being controlled or eradicated 3. Inform groups that when they have gathered sufficient research, they must create

a story outlining the way the first individual of that organism arrived. Students should be sure to include the information above as well as:

The common and scientific name

Descriptions of the organism

Any interesting or cool facts

An introduction to any human characters (if any) involved in its transport, including their jobs or role in the story

A depiction of the trip

A description of the arrival in Florida 4. Students can write their stories or create a visual presentation (PowerPoint, skit,

video, etc.) 5. Ask each group to present their final projects to the class 6. Lead a class discussion, using the following as guiding questions:

Were the non-native species introduced intentionally or unintentionally? Why or why not?

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Non-native species are not necessarily invasive. How are these 2 types of organisms different? Is your species considered “invasive”? Why or why not?

What are some ways that introductions of these species could have been prevented?

Have we been successful in controlling this species? Why or why not?

Can you think of any additional pathways that might bring a species to Florida that you haven’t heard presented?

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Nutria Myocastor coypus Order: Rodentia Family: Myocastoridae Description: Nutria are large semi-aquatic rodents, smaller than a beaver but larger than a muskrat. Unlike beavers or muskrats, they have round, scaly tails with some hair. The muzzle and chin are white and the ears and eyes are small. The incisors are large and dark orange, protruding beyond the lips. The four inner toes of the hind feet are webbed. Nutrias may be 3 feet long and weigh up to 35 pounds. Range and Habitat: Nutria are native to South America. Their original range includes Argentina, Chile, Bolivia, Uruguay, Paraguay and southern Brazil, where they are called coypu. After escaping from captivity in the U.S. and elsewhere, they now inhabit a much greater area. Nutria were first imported into the United States between 1899 and 1930 in an attempt to establish a fur farm industry. Many of the fur farms failed in the late 1940s because fur prices fell and nutria did not reproduce well in captivity. Many nutria were released into the wild. Nutria are now reported throughout the Chesapeake Bay system and in every Gulf state, including Florida. They have caused widespread damage to wetlands in Texas, Louisiana and the Chesapeake. In Florida, possession of nutria requires a license. Nutria spend their lives in or near water, especially marshes and ponds. Wild Diet: Favorite foods include rushes, reeds, cattails, arrowhead and sawgrass. They will also eat sugarcane. Reproduction: Nutria breed year-round and are extremely prolific. Males reach sexual maturity at 4-9 months, and females are sexually mature at 3-9 months. With a gestation period of only 130 days, in one year, an adult nutria can produce two litters and be pregnant with a third! The number of young in a litter ranges from 1-13. Females can breed within a day of having a litter. At birth, young nutria are fully furred and the eyes are open. Newborn nutria feed on vegetation within hours, and they will nurse for 7-8 weeks. Special Features:

Life Span – A nutria’s lifespan is about 6 years.

Behavior – Nutria feed on the roots of plants, severely damaging wetlands by digging underneath and overturning plants to feed on the root mat. Nutria are excellent swimmers, and typically swim with their food to a feeding platform for eating.

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Habitat Use – Although they are generally found in freshwater habitats, some populations inhabit brackish and salt waters.

Nutritious Nutria? – Although Louisiana officials have attempted to market nutria as a restaurant entrée, it hasn’t yet caught on as a popular dinner item.

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Marine Toad Bufo marinus Order: Anura (or Salienta) Family: Bufonidae Description: Known as the cane or giant toad, marine toads have flat heads. Typically, 4-6 inches long but can reach 9 inches – female is usually larger. Dry skin that is brown with lighter spots and a cream underbelly. Very large eyes and large, triangular parotoid glands. Known to live 40 years in captivity. Nocturnal. Special Features:

Warts – Collections of poison glands. When the toad is attacked, warts exude milky fluid that irritates the attacker’s mucus membranes (snakes and birds don’t appear to be affected).

Parotoid Glands – Two sets of poisonous glands behind each eye and extending along the body. When stressed, a marine toad can release enough toxin (milky white fluid) to kill a large dog.

Tympanic Membranes – In addition to their use in hearing, these membranes, found on just behind the eyes, have been correlated with the ability of the toad to produce sound.

Call – The Peterson Field Guide (Reptiles and Amphibians, 1991) describes the call of the marine toad as a slow, low-pitched trill, like the exhaust noise of a distant tractor. The mating call is produced by pumping air back and forth over vocal chords.

Similar Species: Large size and distinctive appearance distinguishes adults from other toads. Range and Habitat: Diverse. Native from northern South America to Central America and Texas. Introduced to Haiti, Hawaii, the Philippines, Puerto Rico and Australia for pest control. However, occurrence in southern Florida is the result of accidental releases at Miami International Airport and further sales as pets. Prefers open, damp, leaf-littered fields where insect food is plentiful. Able to flourish in conditions from arid to tropical rainforests. Wild Diet: Having large appetites and being voracious feeders, they will eat just about anything they can catch and fit in their mouths. Use persistence, energy and speed to catch prey. They often feed on worms and insects. Reproduction: In early spring, toads move to a breeding pond where males attract females with their calls. Males call while pushing themselves up on their front legs in

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shallow water. The male clasps the female behind the arms and the pair swims together (referred to as “amplexus”) typically until the female comes into contact with some water weed. The female extrudes eggs as a long string while the male ejects sperm over them. This continues for several hours. The female then swims around so the long string of eggs (which is usually 7-10 ft. long) gets wrapped around the water weed. The female can lay up to 35,000 eggs. The tadpoles hatch after 12 days. Time to maturity varies with temperature, usually taking about 3 months. Predators: Dogs, snakes, larger frogs and toads, and birds. Dragonfly nymphs and other water insects feed on toad larvae. A small percentage of babies actually reach maturity due to predation. Notes:

Class Amphibia (from the Greek for “both lives”) – Along with frogs and salamanders, toads are classified as amphibians.

Frogs vs. Toads – Frogs usually have moist, smooth skin and are good leapers. Toads have dry, warty skin and usually hop.

Invasive Species? – Introduced to certain areas, marine toads are beginning to out-compete native species.

Movie Stars – A documentary about the marine toads’ introduction and success in Australia is called Cane Toads: An Unnatural History. Be sure to rent it.

“Toad Licking” – The secretions of this toad can be made into a hallucinogenic drug. Improper preparation of this drug, including “toad licking,” has resulted in deaths.

NOTE – A person does not get warts from touching toads, but their skin-gland secretions can be irritating to mucus membranes. After handling, remember to keep your fingers away from your eyes and mouth until you wash your hands.

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Lionfish Pterois sp. Order: Scorpaeniformes Family: Scorpaenidae Size: May reach 14-17 inches. Description: Lionfish are easily recognized by their elongated venomous dorsal spines and bright stripes. Appendages on the head and around the eyes mask the mouth and eyes. Lionfish appear to hover in the water column. They have been observed hanging motionless at the crest of a reef or ledge waiting for prey to approach. Range and Habitat: Temperate and tropical Indo-Pacific Ocean. Commonly seen in openings of coral or around pilings in harbors and bays. Wild Diet: Crustaceans, worms, smaller fish. Usually prefers live prey. Notes:

There are more than 300 species in the Scorpaenidae family.

Due to their striking appearance and venomous sting, lionfish are also known as dragonfish, turkeyfish, zebrafish, scorpionfish and firefish.

Lionfish are primarily nocturnal hunters. These voracious feeders will try to swallow anything they can get into their mouths.

Lionfish often use their large pectoral fins to trap and corner smaller fish. When feeding on benthic (bottom-dwelling) prey, these fins spread like a net to trap prey.

The venomous dorsal spines of lionfish are used as a defense mechanism. Lionfish often point these spines toward a predator.

The sting of a lionfish can be painful, but it is rarely fatal to humans unless multiple stings are inflicted and help is not sought immediately. For immediate treatment, apply very hot water to the afflicted area.

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Green Mussel Perna viridis Order: Mytiloida Family: Mytilidae Description: The Green Mussel is a bivalve that can grow to 6 or 7 inches. Shell length is approximately twice the height. Young mussels are a brilliant green and adults are darker green to brown. Special Features:

Size – Florida’s native mussels are nearly as large as green mussels, but none of them act as fouling organisms like the green mussel.

Density – It is not uncommon to find as many as 1,000 adult green mussels per square foot.

Distinguishing Characteristics – The green mussel can be distinguished from other mussels because it has both a green lip on the inside of the shell and an indented curve on the bottom edge of the shell.

Similar Species: Green lipped mussel and brown edible mussel Range and Habitat: The green mussel is native to the tropical marine and estuarine waters of the Indo-Pacific region of Asia, from the Persian Gulf to the South China Sea. They live in waters where the salinity ranges from 27-33 PSU, and their optimal temperature range is 26-32oC (78.8oF to 89.6oF). The first known occurrence of the green mussel in the United States was in Tampa Bay, Florida, in the summer of 1999, where they were discovered clogging the inside of cooling water intake tunnels at a local power plant. Wild Diet: Phytoplankton, zooplankton and detritus filtered from the water

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Australian Pine Casuarina equisetifolia Order: Casuarinaceae Family: Casuarinales Description: The Australian Pine is not a pine tree at all. In fact, it is not even related to the pines. A straight, up-right tree capable of reaching 70 to 90 feet or more in height, the Australian pine has escaped cultivation and become naturalized. Propagating itself on barrier beaches, road sides, and in woods as if wild, the Australian pine tree is now outlawed in many parts of Florida due to its invasive nature and rapid growth rate. Special Features:

Leaves – The Australian Pine appears to have long, soft, graygreen needles, but these needles are actually multi-jointed branchlets. The true leaves are small, inconspicuous, tooth-like scales whorled at joints on the tree’s slender, drooping branches. Branchlet length ranges from 4-8 inches.

Fruit – The fruit is tiny, one-seeded and forms in woody cone-like clusters.

Bark – The wood is reddish brown to gray, rough and peeling.

Flowers – Flowers are unisexual and inconspicuous, with female flowers in small axillaries clusters and male flowers in small terminal spikes.

Similar Species: There are 45 species of the genus Casuarina, variously known as Australian pine, beefwood, forest oak, horsetail tree and iron wood. All are large evergreen trees resembling conifers, with a thin crown of drooping branches and leaves reduced to scales. Range and Habitat: Originating in Australia, South Pacific Islands and Southeast Asia, the Australian pine was introduced to Florida in the late 1800s. By the early 1900s, it was planted extensively in the southern half of the USA. It can also be found in the West Indies, Mexico and elsewhere in tropical America. In particular, the Australian pine flourishes in the warmest areas in South Florida on pine land and along exposed shores. Reproduction: The Australian pine reproduces with seeds, as many as 300,000 per pound, which are dispersed by birds, wind and water. Flowers are unisexual and inconspicuous with female flowers in small axillary clusters and male flowers in small terminal spikes.

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Notes:

Ecological Significance – With rapid growth, dense shade, dense accumulation of plant litter, and other competitive advantages, the Australian pine is displacing and extremely destructive to native vegetation.

Erosion – Originally planted extensively in the Southern United States to provide shade and protect against wind and erosion, the Australian pine can encourage beach erosion by displacing deep-rooted native vegetation.

Endangered Species – Interferes with nesting of endangered sea turtles and the American crocodile.

Life History – Not freeze tolerant; sensitive to fire. The Australian pine loses branches easily and topples in high winds because of its shallow roots. It can colonize nutrient-poor soils easily by using nitrogen-fixing microbial associations.

Allelopathy (suppression of growth of one plant species by another due to the release of toxic substances) – The Australian pine produces compounds that inhibit the growth of native vegetation.

Related Exotics – May be confused with other related exotics including C. glauca, which has 10-17 leaf scales per whorl, and C. cunninghamiana, which has 8-10 scales per whorl (the Australian pine has 6-8 scales per whorl).

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Oscar Astronotus ocellatus (Astronotus – marked with star on back; ocellatus - spotted with little eyes) Order: Perciformes Family: Cichlidae Description: Coloration is usually very dark, olive-brown to deep blue-black with pale yellow or orange markings. The base of the caudal fin has a large spot or ocellus bordered with red. Fin coloration varies, usually they are very dark, and occasionally they have ocelli (eyelike colored spots). Eyes are red. Special Features:

Eye Spot - The eyespot on the tail is a common feature among Oscars. The spot is believed to provide a diversion to misdirect the attack of a potential predator toward the tail.

Growth – Oscars grow very rapidly in a short period of time, and can reach lengths of 14 inches.

Range and Habitat: Over its native range this species is found in the Amazon, Orinoco and La Plata River systems in South America. Due to temperature limitations, their range in Florida is as far north as Tampa Bay. High densities of Oscars are associated with extensive marsh-type and modified habitats (e.g. Everglades basin). Reproduction: Oscars are sexually mature once they reach a length of approximately 5 inches. Fish pair off and often stay together to breed several times. Females lay up to 2000 eggs, which hatch in just a few days. In Florida, spawning occurs from June to October. Notes:

Introduction - This South American cichlid has been established in Florida waters since the late 1950s when it was first released from a fish farm and spread by anglers who released them in new sites.

Limitations – Oscars do not tolerate cold temperatures.

Feeding Habits - Oscars are mainly carnivorous, but they are known to eat plant matter as well. The main components of their diet include fish and insects, with other items such as reptiles taken opportunistically.

Interest to Fisheries – Oscars are frequently taken by sport fishermen, and they are presently one of the most popular sport fish in southern Florida. In the early 1980s, there was an unexplained increase in numbers, especially in the water

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conservation areas of the Everglades. With this increase, Oscars grew in popularity as a sport fish. In 1991-1992 the number of Oscars harvested in Everglades water conservation areas was about 53,286.

Potential Impacts - The impact of this species on native fishes is unclear. There is no concrete evidence of displacement of native fishes by Oscars. However, this species is renowned for its aggressiveness. It may have a significant impact on native fishes through direct predation and competition for breeding areas.

Pike Killifish Belonesox belizanus Order: Cyprinofontiformes Family: Poeciliidae Description: Pike killifish can easily be identified by their long jaws and large teeth. The origin of the dorsal fin is posterior to the origin of the anal fin. Dorsally, they appear dark olive in color, fading to white at the belly. Several rows of black spots are present on their sides and a black spot is present on the tail fin. Special Features:

Feeding - Pike killifish are ambush predators; they lurk behind plants, roots, and rocks until they strike violently at their prey. Within one day of their birth, young begin feeding on small crustaceans and newborn fish.

Size – Pike killifish are the largest fish in the family Poeciliidae, and they grow to about 8 inches total length in Florida.

Range and Habitat: Native to Central America, pike killifish were introduced into a canal in Dade County, Florida in November of 1957, after termination of a research project. Over their native range, pike killifish are found along the banks and in the upper water levels of slow moving fresh water streams, in the brackish waters of mangrove and reed swamps, and around inlets of salty bays. In Florida, pike killifish are typically found in shallow waters rich in vegetation or in mangrove swamps. They are seldom present in open waters. Reproduction: Pike killifish are live-bearers that breed throughout the year. They are capable of storing sperm for at least 47-56 days, and may produce one brood about every 40 days. Gestation takes between 30 and 50 days. Among mature fish, females are larger than males and significantly more numerous. Notes:

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Potential Impacts - Pike killifish exert strong pressure on small native fish through direct predation.

Mosquitoes – Pike killifish like to eat the native eastern mosquitofish, which are predators on mosquito larvae.

Interest to Fisheries - Pike killifish are of no value as a food fish.

Predator or Prey? – Due to its torpedo-shaped body and preference for swimming near the surface, the pike killifish is often a preferred prey for larger fish.

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Walking Catfish Clarias batrachus Order: Siluriformes Family: Clariidae Description: Walking catfish may appear dark brown, gray, or olive with white specks on the latter half of the flanks. Fins are gray-green and there may be red borders on the median fins and some yellow on the dorsal fin. Although all Florida imports were originally albinos (which are tinted yellow at the outer margins of dorsal fins), albinos in the wild are now rare and descendants have reverted to the dominant, dark-color phase, probably a result of natural selection by predators. Special Features:

Locomotion – Snakelike

Breathing – The gills of the walking catfish are stiffened to prevent collapse while out of water. On land, they keep their gills closed and in the water the gills remain open. On land, they breathe most efficiently using a special part of the gill chamber consisting of spongy organs that grow from the upper ends of the gill arches. These organs are well supplied with blood vessels and operate efficiently on land as well as in low oxygen waters.

Barbels – Walking catfish possess 4 pairs of barbels: one pair of nasal, one pair of maxillary and two pairs of mandibular barbels.

Male or Female? - The male of this species is usually more colorful than the female. The most distinguishing feature however, is a dark spot on the rear of the male’s dorsal fin.

Range and Habitat: The native range of the walking catfish spans Southeast Asia and includes eastern India, Sri Lanka, Bangladesh, Burma, Indonesia, Singapore and Borneo. They are commonly found in freshwater and brackish water. They can exist in cloudy, low-oxygen waters. Wild Diet: Omnivore. Walking catfish are mainly active at night and prey on items such as insect larvae, fish eggs, fish and occasionally plant material. Reproduction: It is reported that walking catfish engage in mass spawning migrations in late spring and early summer. Adhesive eggs are laid in a nest or in submerged vegetation and the males guard the eggs. Juveniles appear in late summer and sexual maturity is attained by the end of the first year.

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Notes:

Introduction - In the early 1960s, walking catfish were imported to Florida from Thailand for the aquarium trade.

Movement – In Florida, dispersal apparently has occurred by way of the interconnected network of canals. However, spread was accelerated by overland migration, typically during rainy nights.

Impact of Introduction - Largely unknown. In Florida, walking catfish are known to invade aquaculture farms, entering ponds where these predators prey on fish stocks. In response, fish farmers erect fences to protect ponds, though they are inefficient in floods.

Threats – Cold weather is believed to be the major threat in the introduced range.

Status - In 1967, the importation or possession of the walking catfish without a permit was outlawed in the state of Florida.

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Hydrilla Hydrilla verticallata Order: Hydrocharitales Family: Hydrocharitaceae Description: Sometimes called “water thyme,” Hydrilla is a submerged plant found in all types of freshwater. It can grow to the surface and form dense mats. Hydrilla stems are slender and branched. Its small leaves are strap-like, pointed and grow in whorls of four to eight around the stem. Tiny white flowers are visible on long stalks, and potato-like tubers form along the roots that are found in the mud. Hydrilla is a prohibited plant in Florida. Special Features:

Leaves – Hydrilla leaves are small, pointed and arranged in whorls of 4 to 8. They have serrated margins and one or more sharp teeth under the midrib. Development of the leaves may vary with location, age and water quality.

Growth Rate – Hydrilla can grow extremely rapidly, up to one inch per day, until it reaches the surface of the water and forms a thick mat that effectively shades any plants below it.

Length – Plants have been known to reach lengths of up to 50 feet and produce a biomass of more than 130 tons per acre.

Range and Habitat: Historical reports indicate Hydrilla may have originated on the island of Sri Lanka, and DNA analysis points to India’s southern mainland. Hydrilla can grow in almost any fresh water including springs, lakes, marshes, rivers and tidal zones of over 20 states. Reproduction: Hydrilla reproduces mainly by regrowth of stem fragments, but also by means of axillary buds and subterranean tubers. Tubers can remain viable for more than 4 years and a single tuber can produce as many as 6,000 new tubers/m2. Notes:

How did it get here? - The dioecious (having male reproductive parts in one individual and female in another) strain was imported to the U.S. in the 1950s for use in aquariums. It entered Florida’s inland water system after plants were discarded into canals in Tampa and Miami. The monecious (having both male and female flowers on the same plant) strain was a separate introduction, first found decades later in the Potomac Basin.

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Distribution of Populations - Southern populations are predominantly dioecious female (plants having only female flowers) that overwinter as perennials. Populations north of

South Carolina are essentially monoecious.

Stats - The most abundant aquatic plant in Florida public waters, 70% of Florida’s freshwater drainage basins contain water bodies infested with Hydrilla.

Limiting Factors - Very few factors limit Hydrilla because it can grow in shallow and deep water, high and low nutrient concentrations, low or very intense sunlight, and it can withstand cool temperatures.

Why the Concern - Intakes for drinking water, power generation and irrigation are easily clogged. Shoreline access and boating traffic can be restricted.

Impacts – Hydrilla grows aggressively and competitively forming thick mats that block sunlight penetration to native plants. It has been shown to alter the chemical and physical components of lakes. Stratification of the water column, decreased oxygen levels, and fish kills have all been documented.

Money – Florida officials estimate they will spend $100 million in a decade to control Hydrilla and water hyacinth.

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Activity: Stop the Invasion (Invasive Sampling post)

Further examine the impacts of invasive species.

Duration: Homework assignment or In-class timed writing Materials

Writing prompts

Procedure

1. Have students select one of the following prompts to write an essay/paper on:

Prompt 2 Explain the difference between native, exotic, and invasive plants. Discuss the pros and cons of the various methods used to eradicate the non-native species?

Prompt 1 Describe the ways that invasive species enter our communities and how we can prevent this invasion.

Prompt 3 Are there any instances when it would be best to leave an invasive alone? Why or why not? Please remember to use appropriate evidence to support your ideas.

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Resources http://www.fws.gov/contaminants/issues/invasivespecies.cfm http://en.wikipedia.org/wiki/Invasive_species http://www.invasivespeciesinfo.gov/ http://www.invasive.org/ http://www.invasivespecies.gov/ http://www.nbii.gov/portal/server.pt?open=512&objID=221&mode=2&in_hi_userid=2&cached=true http://www.fws.gov/contaminants/issues/invasivespecies.cfm http://www.issg.org/database/welcome/ http://www.wisegeek.com/what-are-invasive-species.htm http://www.fl-dof.com/forest_management/fh_invasives_index.html