Lecture 20- Community change: Introduced marine species Flashcards
What is the definition of an introduced species?
-species transported by human activities into region in which they did not occur in historical time and are now reproducing in the wild; not native to the area -also called non-indigenous, exotic, alien
What is the definition of a cryptogenic species?
-species not demonstrably native or introduced -suspected of being introduced but cannot prove it as there isn’t a record of their presence/absence in the past
What is the definition of an invasive species?
-species that spread from their point of introduction and cause environmental damage -have negative effect on the environment -can be introduced or not
What is the definition of a weed?
-plant growing in an area where it is not wanted
What is the definition of a pest?
-organism considered harmful to human activities (including plants)
What is Port Philip Bay full of?
-introduced species -2003=99 introduced =61 cryptogenic (suspected introductions) -in 2010- 1 more introduction and 2 more possible
How many introduced marine species are there in Australia? (roughly)
-300
What are the four most damaging introduced species in Port Philip Bay?
- Northern Pacific Seastar 2. Green alga Codium fragile 3. Polychaete worm= feed by filtering larvae, impact on reproduction of other species 4. Brown alga Unidaria pinnatifida= outcompetes native species for light and substrate
Why should we be concerned about the introduced species?
-Human-mediated biological invasions a major threat to native biodiversity -Threat to habitats, ecosystem function -Economic impacts -there is a high biodiversity in Australia, lot of endemism, would be a shame to lose it
Are the introduced species a global problem?
- yes
- eg. Unidaria pinnatifida
- japanese kelp
- worldwide problem
- native in Japan, Korea
- initially in Tasmania (from vessels probably),then spread more
What are the impacts of the Northern Pacific Seastar? (Asterias amurensis)
-voracious predator - In Derwent Estuary 1986 –now dominant benthic invertebrate predator -Northern hemisphere = damage to commercial shellfish including oysters, cockles, scallops -tube feeding -eats bivalves -generalist predator -will change habits depending on what is available -firts in Derwen Estuary a -keystone species -now problematic -australia
What are the impacts of the green alga Caulerpa taxifolia? (aqarium caulerpa)
-In Mediterranean Sea –large monospecific meadows – reduced commercial fish catches –accumulation of toxins in fish flesh –entangling of nets and boat propellers -grows incredibly fast -outcompetes everything else -produces toxin that affects fish -toxin has flow on effects= ends up in fish flesh -a guy knew it was there and was reported = could have been prevented
What are the impacts of the comb jelly?
-Mnemiopsis ledyi –predator of zooplankton including fish eggs and larvae –native to Atlantic coast of N and S America -In Black Sea, early 1980s –ballast water introduction –no predators/competitors – anchovy fishery collapsed problematic when billions of them -extremely abundant, feed on larvae= kill off the other species as cannot grow
What is ballast water?
- water in a ship to keep the boat stable when it is traveling without load
What is the process of invasion?
-
What is the tens rule?
- all of these filter
- only about 10% of the propagules that end up on a vector will survive to get to a place
- only 10% of those will establish
- of those only 10% will have a serious impact on the assemblages
- only 1 in 1000 species transported from A to B will end up as a problem
- just a statistic
- may differ
- more transport then more species transported
What are the most important vectors?
-biofouling and ballast water are the most important vectors
