invasive species final 2

stages of invasion

transport, introduction, establishment, spread, integration

transport

individuals in their native range that enter a transport vector or are in transit to a nonnative destination (propagule entrained into a vector)

introduction

viable propagules that have survived transit and reached a nonnative destination and have disembarked from the transport vector and are introduced to the nonnative destination

establishment

involved surviving the new environment and establishing a self-sustaining population through reproduction

spread

a self-sustaining population where individuals can disperse and establish beyond the origin location of introduction, may involve the individuals finding more optimal environmental locations/niches for themselves

integration

involves neutral, positive or negative interactions with the native environment

pathway

purpose or activity that leads to introduction, either intentional or not

vector

the physical means or mechanism that transport species

route

geographic locations of source and donor populations

primary pathways and vectors of aquatic introductions

international and domestic trade, aquarium pet trade, horticulture and ornamental plant trade, stocking, recreational boating, aquaculture, canals and artificial waterways, live seafood trade, scientific research activities, ritualistic release

transport vectors associated with shipping activities

ballast water and hull fouling

trans-shipment of aquarium organisms

when a seller in one country ships to another country with lax rules for receiving organisms, then the organisms are driven across borders into other countries to be sold

stock contamination

unintended species are stocked because of misidentification or contamination of stocking sources

reasons for fish stocking

for recreation, aesthetics, conservation, aquaculture/food, biocontrol

bait bucket transfer

the transport and subsequent release of aquatic biota through sportfishing activities, ex. unused live bait release

recreational boating vectors

boats become entrained with adults encrusted on hulls/engine propellers or larvae in live wells/accumulated water on the boat
fishing gear becomes entrained

aquaculture

farming of fish, shellfish, and aquatic plants

propagule pressure

composite measure of the number of individuals released into a region to which they are not native

propagule size

number of individuals involved in any one introduction event

propagule number

number of discrete release events

Allee effects

inverse density dependence where small populations experience reduced growth rates and decreased opportunities (social foraging behavior and mate detection impacted)

risk-release relationship

as propagule size increases, probability of establishment increases

likelihood of species establishment is a function of…

ecological attributes of the invader, characteristics of the environment (abiotic), ecological attributes of the recipient community (biotic)

characteristics associated with invasive species

high fecundity, high breeding frequency, rapid maturity, high tolerance for various environments, generalist feeding/lower trophic level, high dispersal ability, defensive mechanisms, high genetic variability, abundant and widely distributed in their native range

interspecific trait variability

how traits vary within a species

fluctuating resource availability hypothesis

predicts that a community will become more susceptible to invasion whenever there is an increase in unused resources

environmental change associated with aquatic invasions

land-use change (deforestation and urban development), physical habitat disturbance, pollution, dams and river regulation, climate change

enemy release hypothesis

the success of nonnative species is related to reduced rates of predation, competition, or parasitism in the introduced range compared with the native range

regulatory enemy release

an invasive species has a low resistance to the enemy and therefore is released from this regulation in the introduced range

compensatory enemy release

an invasive species is well-defended against the enemy and that cost of defense is reduced in the introduced range, energy used in defense can be allocated to other uses (happens over longer evolutionary time periods)

biotic resistance hypothesis

a robust native community, with more native richness, will have less established invasive species

invasional meltdown theory

describes the process by which facilitative interactions among invaders may promote establishment and amplify their effects on native communities

the invasion paradox

describes the both negative and positive relationship observed between native and nonnative species richness

dispersal pathway

refers to the combination of processes and opportunities resulting in the movement of propagules from one area to another

pathways differ with respect to…

frequency of dispersal events, propagule size, number of donor and recipient regions

short-distance dispersal

model based on reproduction (amount of available propagules) and dispersal (rate of spread), application of reaction-diffusion models

long-distance dispersal

or jump dispersal, ultimately governs invasion speed, natural jump or human-facilitated

gravity models

model with stratified diffusion involving both local and jump dispersal, relates “force of attraction” between an invaded site and a non-invaded site

directional dispersal

models that focus on the idea of differential probabilities in the direction of spread/dispersal

individual-based models

simulate animal population dynamics by accounting for environmental effects on the biology and individual behavior of organisms

boom and bust dynamics

instances where non-native populations increase dramatically in their numbers and geographic range after initial establishment and then suddenly crash down to extinction

sleeper population

an established population of a nonnative species that persists at low abundance and impact which has the potential to become invasive id triggered by an environmental factor

time lag

lag between initial colonization and onset of rapid population growth and range expansion, often due to needing time to reproduce

components of defining an impact

directionality (+ or -), classification and measurement of impact, ecological or socioeconomic, scale of impact

hybridization

can lead to decline of species through outbreeding depression, decreased fitness in offspring that arises whether hybrids survive or not

introgressive hybridization

alters genetic composition of the native population and can result in extinction of the native genotypes

ecosystem engineers

species that can create, destruct, or modify habitat

evolutionary trap

in environments that have rapidly altered, native organisms may become trapped by their evolutionary responses to formerly reliable cues (which are no longer reliable due to an invasive species)

evolutionary release

the interaction between two species that do not share an evolutionary history could also result in a positive outcome for one or both species

misleading habitat cues

invasive species attracted to structure for habitat, which may be poor in their introduced range

decoupled foraging behavior

cued in on a particular prey, but is of poor food quality in the new range

maladaptive reproductive site selection

may be cued into sites that appear suitable, but result in lower reproduction

vulnerability to native predators/disease

may be cued to choose to enter an area they believe is good, but actually has a lot of predators or disease

market impacts

refers to changes in prices due to reduced productivity of commodities sold within the marketplace

non-market impacts

refers to economic losses associated with changes in human capital, social capital and ecosystem services

direct costs

costs incurred directly by the invasive species

indirect costs

costs mediated through effects on other species or through ecosystem changes

external costs

expenses incurred to parties that were not involved with the transaction responsible for the species introduction, vast majority of costs fall into this category

internal costs

expenses are incurred to the same party who was responsible for the establishment of the nonnative species, typically associated with deliberate introductions

early detection and rapid response

process of observing and documenting an invasive species and then reacting to the detection once the organism has been authoritatively identified and response options have been assessed

types of detection

monitoring programs (visual), monitoring programs (chemical), monitoring programs (canine detection), citizen science/public awareness, surveillance

risk assessment

broadly trying to understand the ecological and economic risks of an invasion for a given species at a given time

risk

probability/likelihood of an adverse effect, ex. a species getting introduced, risk of it spreading broadly, the risk of having an impact

risk analysis framework involves…

risk assessment (scientific process by which risk is determined/quantified), risk management (policy based, mitigation/avoiding/tolerating risk), risk communication (articulate risks associated with an invasive species)

integrated vector management

targeting all species transported by a specific vector/pathway, comprised of analysis (which species), strength (importance of different vectors within a pathway), interruption (what management actions could reduce invasive species), effectiveness (how effective are management strategies)

ecological niche monitoring (or species distribution monitoring)

approach to invasive species risk assessment based on the concept of ecological niches as a constraint on the distributional potential of a species, niche modeled based on occurrence patterns of species within their native distribution

quantitative risk assessments focus on…

identifying potential donor regions and dispersal pathways, select potential invaders using biological criteria, forecast the potential geographic range of the invader

eradication

removal of every potentially reproducing individual of a species or the reduction of their population density below a level that all individuals are eventually lost

requirements for a successful eradication program

sufficient economic resources for the project to be completed, clear lines of authority and cooperation, biology of target organism must make it susceptible to control measures, re-invasion must be prevented, invasive species must be detectable at low levels, strong public outreach and stakeholder engagement to prevent re-introductions

approaches to eradication

chemical eradication, physical removal, biocontrol agents

containment

refers to strategies and actions aimed at preventing invasive species from expanding its current range

permanent physical barriers

aimed to stop the flow and movement of a target species completely, always enacted, often infrastructure to block movement

temporary physical barriers

barriers that go up during certain times of the year, ex. gated-structure barriers that can be opened and closed

non-physical deterrent barriers

passage of invasive species can be reduced by exploiting differences in sensory sensitivities like fluid dynamics, acoustics, and visual (ex. bubble curtains, pheromones, electric barriers)

control

reducing population numbers over a large area provides an opportunity to control invasive species density

benthic mats or barriers

form of mechanical control, portable panels of porous synthetic weed fabric placed on the bottom of ponds/nearshore areas, often used temporarily

harvesting

form of mechanical control, weeds clipped at the base or completely removed (including roots) by hand

classical biological control

uses non-native or native agents that are host-specific to control invasive species

general biological control

uses control agents that are not host specific and will not target specific species, ex. grass carp control of aquatic nuisance species in general

bounty programs

a financial incentive program in which money is paid to an individual upon satisfactory evidence of collection of a specific organism

contract operation

a program that provides direct payment to the public or service provider to remove or harvest a species

recreational harvest

actions that enhance or encourage recreational fishing, hunting, or trapping of invasive species such as conducting outreach, modifying seasons, or changing license requirements or bag limits, not necessarily a financial incentive

Lacey Act (1990)

The Secretary of the Interior is authorized to regulate the importation and transport of species determined to be injurious to the health of humans, the interests of agriculture, horticulture or forestry, and the welfare and survival of wildlife resources, amendments in 1949 transferred this to a “black list” law

Nonindigenous Aquatic Nuisance Prevention and Control Act (NANPCA, 1990)

“To prevent and control infestations of the costal inland waters of the United States by the zebra mussel and other nonindigenous aquatic nuisance species, to reauthorize the National Sea Grant College Program, and for other purposes” (including minimizing impacts and monitoring species, prevent introduction and spread through ballast water management)

National Invasive Species Act (NISA, 1996)

Reauthorized and amended NANPCA, federal law intended to prevent invasive species from entering inland waters through ballast water carried by ships and unintentional introductions by recreational boating activities

Asian Carp Prevention and Control Act (2010)

prohibiting the transportation and importation of Asian carp without a permit from the U.S. Fish and Wildlife Services, also added bighead carp to the list of injurious species

WA Invasive Species Policy

a blacklist policy that is much broader than the Lacey Act, includes prohibited, regulated, and unlisted aquatic invasive specie