Aquatic Invasive Species
Laura Fogt
EEES 4730
Objective: To discuss the ecological impacts of aquatic invasive species and propose some possible
solutions
Definitions
-Invasive species (aka exotic, non-native, alien)- species which is non-native, or alien, to the ecosystem
under consideration and whose introduction causes or is likely to cause economic or environmental
harm (NISIC, 2011).
-Ballast water-Water taken from a port or other location that is taken on board a ship and stored in
tanks to add weight and maintain ships stability
-Biotic homogenization - Occurs when non-native species become established in many places, increasing
the compositional similarity among those places.
-Zoogeographic pollution – Occurs when organisms are moved out of their known home range and
introduced into new areas by humans. Loss of genetic integrity can occur if organisms from both
habitats are closely related.
-Hybridization-Interbreeding of individuals from what are believed to be genetically distinct populations,
regardless of their taxonomic status (Rhymer et al, 1996)
-Introgression-Gene flow between populations whose individuals hybridize, achieved when hybrids
backcross to one or both parental populations (Rhymer et al, 1996)
-Extirpated-Local extinction
Problem-invasive species dispersed across globe through human interaction
Causes
-Intentional man-made pathways
-Unintentional man-made pathways
-Attachment of organisms to ships and boats
-Canal construction
-Intentional release
-Shipping
-Aquaculture
-Ornamental fish trade
Consequences
-Extinctions through competitive exclusion
-Threat to aquatic biodiversity conservation
-Hybridization and introgression
-Predation
-Diseases and parasites
Solutions
-Strict penalties for violations
-Ballast-water exchange
-Follow guidelines set forth by experts
Research paper-“Impacts of alien invasive species on freshwater fauna at risk in Canada”
-Alan Dextrase and Nicholas Mandrak, 2003
-Study examines threat factors contributing to the endangerment of freshwater fishes and molluscs in
Canada and the nature of alien invasive species introductions affecting aquatic species at risk
-Status designations of extinct, extirpated, endangered, threatened and special concern assigned by the
Committee on the Status of Species at Risk in Canada (COSEWIC)
-Found that alien invasive species was second only to habitat loss as a threat factor for at risk fish
species
-Alien invasive species primary threat factor for about half of mollusc species, all due to impact of zebra
mussels
-Seven pathways determined for invasive species: sport fishing, ballast discharge, aquarium fish release,
canals, movement of recreational boats, aquaculture and horticulture escapes
References
Anonymous. 2011. What is an invasive species? Referenced from
http://www.invasivespeciesinfo.gov/whatis.shtml. Accessed on October 29, 2011.
Dextrase, A. and N. Mandrak. 2004. Impacts of alien invasive species on freshwater fauna at risk in
canada. Biological invasions. 8: 13-24
Rhymer, J. and Simberloff, D. 1996. Extinction by hybridization and introgression. Ecology, evolution, and
systematics. 27: 83-109. Referenced from
http://www.annualreviews.org/doi/pdf/10.1146/annurev.ecolsys.27.1.83. Accessed on October
29, 2011.