I just thought I would write a post expanding on the last topic I mentioned yesterday about scientists finding unexpected changes in fish and marine organisms' behaviour due to ocean acidification.
I've been reading an article entitled 'Near-future carbon dioxide levels alter fish behaviour by interfering with neurotransmitter function' by Nilsson et al. (2012). It starts by proposing an explanation for why fish are affected in this manner by high levels of CO2. When fish are exposed to the high levels of CO2, fish increase the concentration of HCO3 - ions in their bodies and decrease the concentration of Cl - ions. They do this in order to regulate the amount of acid in their body, as too much can cause acidosis, in which there is too much acid in the fish's body fluids. This causes some neurons (nerve cells) to shift from being inhibitory (not likely to send a nerve impulse) to become excitatory (more likely to send nerve impulses). This is turns causes changes in a fish's sense of smell and its turning preferences, thereby affecting the fish's behaviour.
This hypothesis was tested using Clownfish larvae.Their study found that Clownfish raised in water that was similar to natural seawater were more likely to move away from predatory cues while Clownfish raised in acidified conditions were strongly attracted towards the predatory cue.
The study goes on to show how the effect of acidified seawater can be reversed in Damselfish using a drug that reverses the change in the neurons and makes them inhibitory again.
I just felt that this study really helps to explain how ocean acidification can cause seemingly unrelated changes to fish. The impacts of the change in behaviour could lead to changes in predation patterns, which would then cause changes at other trophic levels.
If you want to find out more, but don't fancy the whole article, this Journal of Experimental Biology update contains an excellent briefing on its second page. I personally just find it incredibly interesting that CO2 has the ability to cause changes in fish physiology which could then have further impacts along the food chain.
Finally, I just want to add a quick message to say that if you want to make a comment about anything on my blog, please do! If there is something you would like me to discuss further, if you have interpreted something differently, have a burning question or just love debating, please comment below, or tweet me @bethevans11 with whatever it is you have on your mind!
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