Introduction to Wildlife & Fisheries Conservation

WFSC 304Lecture 13: Introduced Species

“Invasive species may displace native species through competition for limiting resources, they may prey upon native species to the point of extinction, or they may alter the habitat so that natives are no longer able to persist” —Primack

How are introduced species introduced? Trade and travel (e.g. bark beetles) Species hitchhike on any type of human transport Water ballast Intentional introductions (e.g. to control other

invasives)

Annotate this yourself—be ready to answer questions on the general result, not specific details.

Purple loosestrife originally introduced as an ornamental; now dominate wetlands. It spreads across 1 million acres every year. Cost of controlling loosestrife is about $45 million per year.

Success story:

Another: Mass citizen efforts in California go after Scotch Broom

Kudzu was introduced from Japan into the US in 1876. In 1930s, millions of seedlings planted to fight soil loss during the Dust Bowl era. The vine prevented so much erosion that villages across the U.S. southeast had Kudzu festivals and harvested it.In 1950’s, people realized that kudzu was out of control & choking native vegetation and human infrastructure. It has roots so deep the vine can be

nearly impossible to remove. Kudzu has been spreading at the rate of 150,000 acres (61,000 ha) annually. 1996 estimate: kudzu covered 7 million acres.

Aquatic invasive plants in TX

Background• Invasive plants cause severe ecologic and economic damage• 33% of most damaging invasive aquatic species originate from releases from

the ornamental trade• Texas is home to some of the largest distributors of aquatic ornamentals in

the world, with online sale, because of its convenience, being among the most popular sources

• As availability of non-native plants and interest in water gardening and aquarium-keeping grows, so does the threat of new, potentially devastating invasive species, so we need methods to predict “invasive potential”

Impacts observed• Change in water chemistry and hydrologic cycle• Decrease in biodiversity• Millions spent annually in control efforts• Increased transportation costs• Decrease in fishing and recreational opportunities• Decreased land value

Approach Designed questionnaire—asks about species’ traits New analytical method

Result

Fig. x. Canonical ordination of 100 plant species based on 40 imputed question responses. Circles give multivariate centroids (95% confidence region for class means). Vectors indicate large response loadings (structure coefficients ≥ 0.7 for the horizontal axis; ≥ 0.3 for the vertical axis). The vertical dashed line indicates the threshold bounding major invaders from minor and non-invaders. Major invaders are distinct in their response profile from other classes by vectors projecting to the right in this space; minor invaders are distinct from other classes by vectors projecting upward in this space.