Human output of CO2 is the highest it has ever
been, so high that it is starting to affect our planet in a rather drastic way.
Whether you believe in it being human induced or not, climate change is a thing
and most evidence points towards human activity being the cause. The CO2
we produced is absorbed in “sinks” and the largest of them is the world’s
oceans, which can naturally buffer against the increase in CO2 to an
extent, but past that then ocean acidification occurs. Increased atmospheric
levels of CO2 are also contributing (along with other factors) to an
increase in the average temperature of the Earth.
In a paper by Tatters et
al. (2013) investigate the effects that temperature, CO2
concentration and phosphate concentration have on the toxicity of the
dinoflagellate Alexandrium catenella.
It was collected of the coast of America and a strain was isolated (A-11c) and
cultured. A-11c was then subjected to
a high and a low of each variable for example warm temperature being 19⁰C
and low temperature being 15⁰C leading to eight treatments overall.
The toxins were extracted and detected using liquid chromatography, these were
then compared to the standards from the National Research Council of Canada.
The results showed that the highest toxicity levels were
found in the samples kept in high CO2, low phosphate and low
temperate treatment, and the least toxic was found in the low CO2,
high phosphate and warm temperature. The general trend found was that increased
CO2 lead to an increased potency.
With the increase in the number of harmful algal blooms it
raises the question of whether more shellfish are harbouring toxins such as
saxitoxin and if this is leading towards more cases of Paralytic Shellfish Poisoning,
or if the shellfish are becoming more toxic/potent due to the results showed in
the paper. One thing I have to criticize in the range of temperatures used as
seasonal variation can fluctuate more than the range, if they really wanted to
see the effect of increased temperature and to relate it to climate change then
surely they should have gone higher.
Tatters
A.O., Flewelling L.J., Fu F., Granholm A.A. and Hutchins D.A., (2013). High CO2
promotes the production of paralytic shellfish poisoning toxins by Alexandrium
catenella from Southern California waters. Harmful
Algae. 30. pp.37-43.
Hi Evan,
ReplyDeleteThanks for your post. I really enjoyed your review. I was wondering, you mention that you disagree with the range of temperatures used. What range of temperatures do you suggest would be more suitable? I notice from the paper that the samples were collected in Northport, NY and the Bay of Fundy, Canada. The temperature ranges here are 5 – 23 degrees and 1 – 12 degrees respectively. Whilst I agree with your criticism of the temperature ranges used. How would you conduct the experiment whilst having two overlapping temperature ranges?
Regards
Scott
Thanks for your question Scott.
DeleteI could see your point if that was the case, but the samples in this paper were collected from Jalama Beach, California, USA, where the seasonal variation in sea surface temperature ranges from a minimum of 12⁰C in February to a maximum of 19⁰C in September. The point I'm trying to get across in my post is that their chosen temperature range of 15-19⁰C is within seasonal variation and I think that a larger range of temperatures (even if just expanded to the seasonal range) would show a more significant range of results.
-Evan
Evan,
DeleteThank you for your reply. It appears there has been some confusion in the sources of our information on my part. I agree with your criticism of the temperature range in that it is too small. However, looking at the paper it shows that the samples were collected from the beach. Do you think that the temperature range would be more extreme in the shallows on a beach and that the range should adjusted rather than mimic that of the water temperature collected away from the beach?
Regards
Scott
Hi Scott,
DeleteThe temperature data I used was for that beach itself, as that beach is monitored and a surf forecast is given each day. So the range I said is for the shallows.
-Evan
Hi Evan,
ReplyDeleteI found your review very interesting, as you mentioned there is a trend between carbon dioxide levels and the dinoflagellates toxicity, i am interested in the reason this occurs. Does the paper suggest any mechanisms that may be causing the increased toxicity, or do you have any possible suggestions?
It is interesting thinking when considering the possible effects on shell fish leading to human diseases, i think this could possibly a secondary effect of elevated carbon dioxide levels which is not as highly studied.
Thanks
Natasha-lea
Hello Natasha,
DeleteIn the discussion they go on to briefly hypothesize why that it is due to a shunting of ‘excess’ fixed carbon into a secondary metabolic pathway under conditions of high CO2 availability. But in the referenced paper by Fu et al. (2012) they go on to talk about how photosynthesis is important in toxin production and how under normal conditions saxitoxin production is proportional to hours of daylight.
Having a knock on effect on humans was purely me speculating, yes there is currently an increasing concentration of CO2 in the atmosphere and oceans but there is also an increase in global temperature which may balance out the effects when it comes to toxin production/toxicity.
Thanks,
Evan
Referenced papers:
DeleteFu F.X., Tatters A.O. and Hutchins D.A., (2012). Global change and the future of harmful algal blooms in the ocean. Marine Ecology Progress Series. 470. pp.207-233.
Thanks Evan,
DeleteI will read this paper to try understand this area more.
Thanks
Natasha
Hello Evan,
ReplyDeleteI was wondering how abundant A.catenella is and therefore how important from a global point of view?
However, I find this an interesting study and I would like to see a similar study being conducted on the effect of methane. There are some scientists that support the theory that CO2 leads to the increasing temperature but methane is even worse.
Thanks,
Eleni
Hi Eleni,
DeleteThe distribution of A. catenella is fairly wide spread, it has been found in Japan, parts of South America, Australia, South Africa and the west coast of North America. A paper by Vila et al. (2001) also found the species occurring in the Mediterranean. I do have to question that with climate change will we see this species in new locations due to changing habitats?
An increasing temperature actually helped decrease the toxicity in the presence of high CO2 concentrations, and with methane being a more ‘potent’ greenhouse gas it is contributing to the overall temperature rise. As for methane effecting toxicity I doubt it would as methane is not used in any metabolic processes that I am aware of.
Thanks for your question,
Evan
Referenced papers:
Vila M., Garcés E., Masó M. and Camp J., (2001). Is the distribution of the toxic dinoflagellate Alexandrium catenella expanding along the NW Mediterranean coast?. Marine Ecology Progress Series. 222. pp.73-83.