Maybe you have already seen this paper of Morabito et al. 2013, they found that ocean acidification affected the osmotic swelling etc of nematocysts. That would hamper their capacity for food capture. This is a really interesting, and devastating, effect that has received very little attention.
Morabito et al. 2013. Sea Water Acidification Affects Osmotic Swelling, Regulatory Volume Decrease and Discharge in Nematocytes of the Jellyfish. Cellular Physiology and Biochemistry 32(suppl 1): 77-85.
Article Ocean acidification reduces feeding rates in the scleractini...
I read that just now. I recognize that it was difficult to understand because I am stranger to that specialty.
I found an interesting job because I'm on the subject of the jellyfish. And I just finished a research dealing with feeding and changing the in situ diet of a species of jellyfish.
We discuss some of the pobables causes of change in diet, but do not consider the acidity because the seawater pH was slightly alkaline and stable during the study. However, we can not discard it, but in order to test this hypothesis we should do another experimental approach.
In my opinion, it would be difficult to test this hypothesis with field sampling, because there are several more determining factors (temperature, salinity, ontogeny) that may alter the functioning of the nematocytes. The pH varies little at sea, even in coastal areas. Instead, in the experiments described by Morabito et al. 2013, they used solutions with very low pH values, hard to find in the sea, if any, would be unlikely to find jellyfish (or other animal).
That is an interesting question and worth of further investigation. I only read the Morabito et al. (2013) paper. The results clearly show differences in preparations of tentacles and oral arms exposed to different pHs. But I think that animals will become used with the slight variations in water acidification and can respond to that by some regulatory mechanism. Or eventually, in the case of the jellyfishes, they can 'swim away' from the areas in which the water properties are not the most adequate for them.
Maybe additional experiments can be performed with the whole animals and check how they react.
And what about the effect of the acidification over the jellyfish prey body surface and behaviour?
But surely it is something to be in our mind.
It’s an incredibly interesting question, Susanna. We’ve known for many decades and across a fairly wide body of literature that pH affects the discharge of nematocysts: in some cases, this is inhibitory, while in other cases this is stimulatory. Most of this work has been done in the context of first aid for things that sting us, rather than on the subtler shifts that could alter an organism’s ability to survive. But given everything we know about nematocysts, it seems completely plausible to me that yes, OA could conceivably alter the discharge of nematocysts. In fact, I would go so far as to say it would be surprising if it didn’t. It’s just an educated guess – certainly the research needs to be performed! Man, this is exciting!
Nice to see that there are others out there that find this issue intriguing! I'm working on a re-description of the cnidae of Lophelia pertusa, but haven't gotten into the function of cnidae yet. But I'm getting interested in that aspect. Especially considering the larval cnidae, and possible effects of OA would be very exciting to investigate.
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