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Posted 25 February 2009

IUCN sounds warning on weedy biofuels

A report commissioned by the International Union for Conservation of Nature has recommended that non-native plant species being touted as possible biofuels should be tested for their potential as weeds before being introduced.

The report warns that the threat of species invasion should be taken very seriously by any group planning biofuel production, not only due to the potentially severe environmental impacts, but also because the costs of an invasive species are likely to outweigh any potential economic benefit of developing biomass energy.

References:
Keam, S., and N. McCormick. 2008. Implementing Sustainable Bioenergy Production. A Compilation of Tools and Approaches. IUCN, Gland, Switzerland.

US report highlights risks of invasive species in warmer waters

A paper by Frank Rahel and Julian Olden documents myriad potential interactions of climate change and invasive species in US freshwater ecosystems.

They highlight risks associated with introducing non-native species for aquaculture and sports fishing. Fly peacock bass (Cichla ocellaris) were introduced into southern Florida canals largely on the rationale that cold winter temperatures would prevent them from spreading, but this may not be the case under warming.

They also note that some native aquatic species will behave like invasive species under climate change as they spread, increase in abundance and harm other native species.

References:
Rahel, F. J., and J. D. Olden. 2008. Assessing the Effects of Climate Change on Aquatic Invasive Species. Conservation Biology 22: 521-33.

The big question, how will pests and weeds behave under climate change?

Jessica Hellmann and colleagues have reviewed the numerous effects of climate change on invasive species in terms of consequences for transport and introduction, establishment, impacts, distribution and effectiveness of control strategies, with examples from the US.

They note that a key research question is whether climate change “will be a zero-sum game for invasive species”, with some invasive species declining and others emerging or expanding.

The answer based on anecdotal evidence so far seems to be no because many invasive species span a range of environmental conditions and won’t be substantially affected while new species will arrive due to climate change.

References:
Hellmann, J. J., J. E. Byers, G. Bierwagen, and J. S. Dukes. 2008. Five Potential Consequences of Climate Change for Invasive Species. Conservation Biology 22: 534-43.

Combination of environmental pressures can crash species populations

A case study looking at the collapse of anchovy populations in 1989-90 in the Black Sea has shown how invasive species, climate change, and other pressures can combine to cause major population crashes.

The invasive ctenophore Mnemiopsis leidyi is a gelatinous organism that competes with anchovies for plankton and preys on anchovy eggs and larvae.

Introduced to the Black Sea in the early 1980s, its numbers exploded in 1989-90 due to nitrogen enrichment and warmer seas in spring.  There had also been much heavier fishing pressure on the anchovy (Engraulis encrasicolus) and populations crashed.

Modelling by Temel Oguz and colleagues found that neither overfishing or the Mnemiopsis outbreak could explain the anchovy crash on their own, but in combination they could.

References
Oguz, T., B. Fach, and B. Salihoglu. 2008. Invasion Dynamics of the Alien Ctenophore Mnemiopsis Leidyi and Its Impact on Anchovy Collapse in the Black Sea. Journal of Plankton Research 30: 1385-97.

European tree disease may worsen under climate change

Tree fungal diseases in Europe may become more devastating under climate change, according to a recent review.

Potential contributing factors include stresses such as drought and floods, temperature and moisture impacts on reproduction and dispersal of fungi, climate-induced migration of pathogens, new vectors and new threats due to changes in tree species or invasive species.

Warming can lead to higher rates of infection for some pathogens, and southern pathogens may spread north and up mountains.

References
La Porta, N., P. Capretti, I. M. Thomsen, R. Kasanen, A. M. Hietala, and K. Von Weissenberg. 2008. Forest Pathogens with Higher Damage Potential Due to Clmate Change in Europe. Canadian Journal of Plant Pathology 30: 177-95.

Helping plants and animals migrate under climate change – damned if we do, damned if we don’t

Helping species threatened by climate change move to more climatically suitable areas carries a low risk of invasion but the consequences if invasion did result could be severe, recent research in the US shows.

Jillian Mueller and Jessica Hellmann compared invasive species originating from within North America and those from elsewhere and concluded that the small proportion that may become invasive are just as likely to cause harm as invasive species from elsewhere.

Because there are risks with assisted migration, the researchers recommend the activity be regulated and subject to risk analysis and impact evaluation. Risk exists on all sides, they say — “risk of inaction, risk of unsuccessful action, and risk of being too successful (i.e., creating novel invasive species).”

References
Mueller, J. M., and J. J. Hellmann. 2008. An Assessment of Invasion Risk from Assisted Migration. Conservation Biology 22: 562-67.