Temperature
can be described as the single most influential limiting factor to any organism
on the planet. If the temperature can be altered so that it is habitable then
the species can persist. Humans are able to live in every habitat on the planet
due to technological advances such as insulating layers like coats worn by
eskimo’s in the Arctic. This is not possible for single celled microbiota and
because of this their species abundance is greatly influenced by the areas of
the planet that they can live in. The paper I am reviewing describes the
dramatic increase in abundance a species shows once the habitable area it can
live in increases.
Due to
global warming, sea temperatures are rising, causing the widening of the
equatorial band of hot water called the tropic/sub-tropic region. Due to this,
many bacterial species’ habitats are expanding polewards, one of which is Amphistegina; a large, symbiont-bearing
Foraminfera.
The study used both newly obtained and historical data of
range shifts and ecological niche constraints of Amphistegina spp. during global climate change events to generate a
Species Distribution Model. Using this model, the authors measure and forecast
the southwest advance of Amphistegina through
the Mediterranean Sea. The authors predict that, with the current level of
global warming, the warm front is advancing at a rate of 2.7-8km per year, with
a projected total expansion of 267km by the year 2100.
The paper describes this worrisome concept well and states
that the encroachment of Amphistegina will
cause competition to the extant microbiota for space, nutrients and resources.
Other speculation from the authors suggest that the global-level shift in microbial
abundance will have massive effects on other ecosystems and carbonate
concentrations (as Amphistegina produces
Calcium Carbonate), but the authors fail to follow this up with any explanation
of how or what effect this will be. Nonetheless
this study is provides a novel and interesting assessment of the impact of
human activity on the planet and offers further evidence of global warming. Evidence
like this is undisputable and should be presented to climate change sceptics (Americans)
in the hope that we can save our planet before we reach an irreversible tipping
point.
Langer MR,
Weinmann AE, Lötters S, Bernhard JM, Rödder D (2013) Climate-Driven Range
Extension of Amphistegina (Protista,
Foraminiferida): Models of Current and Predicted Future Ranges. PLoS ONE 8(2):
e54443. doi:10.1371/journal.pone.0054443
Accessed from: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0054443
Hi Harri,
ReplyDeleteI was especially interested to read about the poleward expansion of Amphistegina in your post (nice title!), as your mention of a global-level shift in microbial abundance due to climate change is absolutely relevant to what Craig Baker-Austin of Cefas was presenting at PML a couple of days ago.
Craig illustrated how rising temperatures in temperate regions are creating an increase in ‘heat wave’ events, and thus preferential conditions for vibrios (i.e. ≥16oC). Recorded incidence of elevated temperatures and decreased salinity (also preferential for vibrios) were used to model the risk of vibriosis outbreaks, which were mapped onto actual reported outbreaks (in humans, mostly very serious wound infections), in real-time.
Despite the inability to rule out human behaviour as a contributing factor (“hey, it’s warm – lets go for a swim in the sea!”), I thought the correlation made a good case for the data collection on the actual abundance of vibrios at the time of predicted ‘high risk’ conditions (which is not presently available). If the ‘vibriosis risk’ model is found to predict actual Vibrio abundance, I wonder if it could perhaps serve as a model for predicting other changes in marine microbe abundance (as well as a warning system for swimmers!).
Did Langer et al. (2013) mention anything about Amphistegina expansion in connection with ocean currents? Craig Baker-Austin talked about potential ‘corridors of disease’ (e.g. the Gulf Stream), which might carry Vibrio strains across oceans. I imagine this could potentially happen with planktonic larvae also. Was anything like that discussed?
Jo
Hi all
ReplyDeleteThat temperature strongly affects organism distribution is clear, so is that climate is not constant and will cause distribution range shifts. However, climate is defined per se as variable and we tend to take the current ranges of organisms as reference of where these species should be found and speculate about the huge impacts changes in this distribution could have on other ecosystems. Only because we don't find Amphistegina in parts of the Mediterranean Sea today, doesn't mean that those regions haven't been habitable to them before the last ice age. OK humans might be speeding up the process, but I think even without humans a similar range shift would be observed, just on a different temporal scale.
Jo, I was slightly confused by this concept, because Craig Baker-Austin mentioned the spread through ocean currents could explain the occurrence of the same Vibrio strain in Spain as in the US east coast. But when someone asked about the increase in Vibrios in the North Sea, he said that an increase from the local vibrio community was likely the source for this outbreak, following the 'everything is everywhere' model. I will review his paper soon, so look out for that blog!
Anna
Hi Anna,
ReplyDeleteAlthough I agree with you that Amphistegina range must change over time with innate climate variability, I believe that concerns over recent poleward expansion of organismal ranges with increasing SST are sparked by their temporal aspect (as Vicky mentioned on your blog). Surely the worry is that such anthropogenically driven changes are happening too quickly for many species to adapt, and as such biodiversity appears to be threatened by the impossibility of exponential northward emigration for more temperate species.
I am not entirely sure about how the ‘everything is everywhere’ model fits into the ‘corridors of disease’ concept, but perhaps what we are really talking about is the number of organisms transported. Maybe a few of any OTUs of an organism generally get transported elsewhere by chance anyway (everything is everywhere), but when the numbers of those OTUs are high in a particular place due to favourable conditions, then the numbers transported from that place by ocean currents are far greater. If conditions at the ‘destination’ are favourable, then an OTU can take hold in that new place. Perhaps this is what is meant by a corridor of disease?
Jo
Hi Jo,
ReplyDeleteIt would be interesting to know the mechanism that facilitates range shifts. Because if ocean currents transport OTUs then some regions may be more affected than others by changes in temperature.
As to the global warming comment, not every region on the planet is warming at the same rate, some areas have even be reported cooling down. So I think range shifts will be not be homogeneously polewards, but much more complex and dynamic and will be influenced by differential temperature thresholds, competition and plasticity. A lot of potential for future studies!
Anna
Hi Anna,
ReplyDeleteGood point re: the factors affecting the heterogeneity of range shifts. I'm definately of the opinion that there is a lot of evdience out there for the poleward shift of certain marine groups (e.g. species of copepods), but there will no doubt be a lot of different factors involved in the outcome of any such changes.
Concerning the possibility of ocean currents transporting OTUs, I wonder if it would be possible to use 'risk' models(for example, vibrios), combined with current knowledge of ocean currents between areas (that are thought to be at risk), in order to predict when and where certain OTUs might turn up? Then surveys could be carried out to test these predictions. Sounds like a project for a microbiologist-oceanographer team!
Jo
Hey Jo and Anna,sorry about the late reply, I’ve been bogged down with other work.
ReplyDeleteAnna I agree that natural range shifts are a tendency among any species in any domain, however the startling thing about the trend seen with Amphistegina is, as you said, the speed at which its spreading, which is far more rapid.
As to the global cooling comment, yes parts of the world are cooling, but as far as I can tell Amphistegina is not connected to those areas and therefore not receding at all, only expanding.
The mechanism that facilitates this range shift is not described in the paper and therefore I just assumed expansion from growth of the population. I would be interested to know the answer to this too! Colin? The thought of a predicative model is interesting, if enough advance notice is given about, say, vibrio cholerae turning up on a populated shoreline, then health guidelines or some pre-emptive therapy or prophylaxis could be applied! Also this could apply to coastal aquaculture farms where livestock could be vaccinated against pathogens known to be approaching. Sounds like a great idea! However with the amount of weather variables and other influencing factors I doubt solid, dependable predictions would ever be reached...
Harri