Tag: Wildlife

Cold snaps curtail invasions

ResearchBlogging.orgClimate change not only causes shifts in the distributions of native species, but also allow invasive species to establish new populations. For example, many Caribbean species are taking advantages of warming temperatures, expanding polewards and invading into the south-eastern United States.

Green porcelian crabHaving established themselves, however, it’s not unknown for the invaders to come to pain. For example, in early 2010, the south-eastern United States experienced a particularly cold winter, which came to be known as “Snowmageddon”. After Snowmageddon, scientists found that the populations of several established invaders had crashed, in some cases been entirely wiped out.

Kaplan-Meyer survival curves for the experimental crabsCurious, Dr. João Canning-Clode and his colleagues collected a number of invasive green porcelain crabs (Petrolisthes armatus) to study. They had three groups: one control group would be held at what would be a fairly mild winter temperature at the collection site, one group would go through a cold snap similar to that experienced in January 2010, and one would experience a cold snap which was a couple of degrees even more extreme.

The results were striking. In the control group, 83% of the crabs survived the winter. In the Snowmageddon group, however, only 39% of the crabs survived – and the population that experienced an even colder snap was entirely wiped out. They also noted that cold temperatures caused the crabs to move around less – which, in the wild, would have probably caused them to be more vulnerable to predators and also make it harder for them to find their own food.

The researchers figure that the occasional cold snap may have the effect of stopping invasive species in their tracks – devastating, if not wiping out the populations. However, as the globe warms, extreme cold snaps have been getting less frequent, a trend which is expected to continue.

References

Canning-Clode, J., Fowler, A., Byers, J., Carlton, J., & Ruiz, G. (2011). ‘Caribbean Creep’ Chills Out: Climate Change and Marine Invasive Species PLoS ONE, 6 (12) DOI: 10.1371/journal.pone.0029657

DeGaetano, A., & Allen, R. (2002) Trends in Twentieth-Century Temperature Extremes across the United States. Journal of Climate, 15(22), 3188-3205.

Kodra, E., Steinhaeuser, K., & Ganguly, A. (2011) Persisting cold extremes under 21st-century warming scenarios. Geophysical Research Letters, 38(8).

Photo #17 – Longfin grouper

Longfin grouper

Longfin grouper (Epinephelus quoyanus), photographed in the waters off Pelorus Island, Queensland.

I love these fellows. Their habit of finding a bit of sand or a bit of rock and sitting around on it, instead of darting all over the place like most fish, makes them terribly easy to photograph.

Photo #16 – Phyllidia ocellata

Phyllidia ocellata, a species of nudibranch

Phyllidia ocellata, photographed in the waters off Pelorus Island, Queensland.

Nudibranchs (including Phyllidia ocellata) form a “clade” (meaning that all species of nudibranch descend from a common ancestor that no non-nudibranch descends from) of predatory sea slugs. Nudibranchs tend to be vibrantly coloured, and there is a great deal of variation between species in not only the colour patterns but even in the anatomy – which makes them great photography subjects!

Photo #13 – Great Eggfly

Great Eggfly
Hypolimnas bolina, photographed in Townsville, Queensland. This species is sexually dimorphic (that is, the different genders look very different to each other) – this is a male.

At this point, I think we can all agree that I’m rather bad at blogging. I recently moved to Townsville, and have more or less settled in by now – so hopefully I can get something a bit more regular going here!