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Lecture 9

ENSC 320 Lecture 9: Invasive Species

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Department
Environmental Studies
Course
ENSC 320
Professor
Ryan K Danby
Semester
Winter

Description
Invasive Species Wednesday, February 15, 2017 1:14 PM Invasive Species • Variety of analogous terms, including non-indigenous, non-native, exotic, introduced, alien, feral • Non-native species that have survived, reproduced and spread to the point of causing adverse ecological or economic effects • Generally defined as species proliferating outside their native range Some Invasive Traits • Specific traits that allow them to out -compete native species • Ability to reproduce both asexually as well as sexually • Fast growth and rapid reproduction • High dispersal ability • Phenotypic plasticity • Tolerance of a wide range of environmental conditions (generalist) • Ability to live off a wide range of food types • Association with humans Modes of Introduction: Intentional: 1. Potential commodity or resource a. Ex. Fur, food, timber etc. i. Ex. American mink ou- tcompetes European Mink ii. Brown trout outcompetes native fish in New Zealand streams 2. Control measure introduced to reduce certain species, even exotics a. Ex. Cane toad or cane beetle in Australia 3. Exotic pet release a. Gold fish in Sifton Bog, London ON 4. Domestic animal/cultivar released a. Feral goats in Galapagos Unintentional: 1. Ballast Water release (regulations poorly enforced) 2. Shipping and commercial products a. Ex. Emerald as borer, Asian lon-ghorned beetle 3. Removal of natural barriers Unintentional: 1. Ballast Water release (regulations poorly enforced) 2. Shipping and commercial products a. Ex. Emerald as borer, Asian lon-horned beetle 3. Removal of natural barriers a. Ex. Sea lamprey native to Atlantic ocean, moved into great lakes with construction of shipping canals Ecological impacts • Ecosystem modification • Resource competition • Aggression (and analogs) • Predation • Herbivory • Pathogens and parasites • Hybridization • Chain reactions and "invasion-al melt down" Economic Impacts Difficult to accurately quantify, but estimates do exist: • Invasive species cost the US $120 -140 billion annually in direct cost • Includes costs related to: ○ Crop or commodity loss/damage ○ Cost of eradication/control • Related to all species (vertebrate, arthropods, mullusks, plants, fungi, microbial pathogens) Examples (US FWS) • Nonnative species borne in ballast or hulls of ships cost Great lakes region >$200 million annually in direct control • Black and Norway rats consume stored grain and cause property damage >19 Billion • >$ 13 billion lost in agricultural production due to invasive insect species • Eurasian watermilfoil (invasive aquatic plant) • If zebra and quagga mussels invade Columbia river, direct maintenance cost to hydroelectric facilities would be $250 -$300 million annually Why they're a problem.. • Generalist predators considered to pose greater threats as invaders; always able to locate suitable prey • Giant constrictors particularly because they: ○ Grow rapidly and mature rapidly ○ Are habitat generalists Why they're a problem.. • Generalist predators considered to pose greater threats as invaders; always able to locate suitable prey • Giant constrictors particularly because they: ○ Grow rapidly and mature rapidly
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