A natural conclusion

While some of you may agree that species will be able to adapt to the future climate changes that are predicted as has occurred in the past. I believe that we cannot take this risk and allow ourselves to take the easy option, with our head stuck in the sand.

The effects that behavioural impairments in reef fish larvae will increased mortality rate, thus jeopardizing future populations have been discussed throughout this blog. Such a reduction in future fish populations  will result in serious implications not just for reef ecosystems, but also to humans due to the services that reef fish provide. With future predictions strongly suggesting that ocean acidification will increase in the future, as a result of anthropogenic CO2 being released into the atmosphere, it would appear to stop such effects requires a reduction in carbon dioxide emissions.

Recently a news article by the BBC highlighted the outcomes of the recent IPCC report, providing a more user-friendly summary than the report  (http://www.bbc.co.uk/news/science-environment-29855884).  Stating that the IPCC recommend a complete reduction of fossil fuels by the end of this century, and that though this would be costly, the implications that climate change would have, would be even more so.

In addition the have been improvements between countries in the attempts to reduce climate change. With America and China, two of the largest industrial countries agreeing on a reduction in their emissions, something which they have previously tried to avoid. This was discussed by a BBC news article http://www.bbc.co.uk/news/world-asia-china-30015545

This proves that the further reductions in CO2 emissions are being considered perhaps more importantly than in the past, and as a result a reduction in ocean acidification would follow.

In my personal opinion, this is probably the only  solution to stop anthropogenic sources impacting the behavioural in reef fish  larvae. A reduction in emissions, would not just benefit reef ecosystems, but also reduce flooding, droughts, extreme weather and pollution. Benefiting and reducing a variety of other problems at the same time.

Rather nicely, this blog appears to have completed its own life cycle, starting off with the implications of released CO2 into the atmosphere, and concluding that that is where a solution can be found.

Evolution Fast Forward

The possibility of reef fish species to adapt is discussed in a pod-cast by the BBC with Philip Munday, who has led and been part of numerous papers in this area of research. This pod cast is a nice brief sum up of what has been discussed in this blog. In addition it discusses the observations of fish found  in naturally high CO2 ocean environments, which are caused by CO2 gas released from volcanic vents. These high CO2 environments produce levels similar to those expected to occur in the future, and so can be used as a way to predict the future of reef fish communities.

http://www.bbc.co.uk/programmes/p01xd9fs/player

This paper based on this pod-cast led by Philip Munday was published this year and aimed to see whether behavioural impairment can improve during the life time exposure of reef fish to CO2. The study looked at these naturally high CO2 ocean environments and found that reef fish brought up in these environments still showed impaired risky behaviour including attraction towards predators. Of interest to note, results found that the fish communities in these high CO2 environments were not greatly different from those found in normal CO2 conditions. This lack of difference expected was thought to be due to lack of reef predators and differences in coral present. Additionally, it was thought that a constant supply of young fish to these communities regenerated and sustained the current population. Munday went on to conclude that more research is required to see if species can adapt to high CO2 conditions and reduce behaviour impairments over generations.

Such research into adaptation over generation has only recently been conducted, with one of the only studies published this October.

Acanthochromis polyacanthus young fish. Taken from: http://www.casc.it/photogallerynew.asp?Page=0&P=1&S=4241&F=974
Acanthochromis polyacanthus young fish. Taken from: http://www.casc.it/photogallerynew.asp?Page=0&P=1&S=4241&F=974

This ground breaking research was led by Megan Welch and studied the possibility of transgenerational acclimatization (the ability to adapt over generations) as a solution which would enable reef fish to adapt and reduce their behaviour impairment over generations in high CO2 oceans. The research focussed on the reduced behavioural lateralization and attraction to conspecific alarm cues (CAC) that occurred when Acanthochromis polyacanthus (spiny damselfish) larvae were raised in elevated CO2 concentrations, to see if these impairments could be reduced. Results found no reduction of attraction to CAC cues in offspring from parents raised in identical conditions. Behavioural lateralization did increase and improve significantly in larvae, when their parents had been raised in identical elevated CO2 concentrations, however lateralization was not fully restored to the level found in reef larvae in normal CO2 conditions. Such research suggests that fish will be unable to adapt rapidly to modify and correct behaviour to their changing environment.

But not all hope should be lost for future reef fish, with M. Welch suggesting genetic adaptation may be the way forward enabling such species to adapt and survive successfully. Such varied levels of impaired behaviour within species was observed in the results of this study by Welch, providing evidence that genetic adaptation may be possible. Though as Welch stresses this genetic possibility is in need of further research.

Extra Reading Sources and References

Cover image taken from http://angielokotz.com/category/career-reboot/

BBC Podcast. URL: Acidic water makes fish lose their survival instinct. Taken from: http://www.bbc.co.uk/programmes/p01xd9fs

Munday, L. P., Cheal, J. A., Dixson, L. D., Rummer, L. J. & Fabricius, E. K. (2014). Behavioural impairment in reef fishes caused by ocean acidification at CO2 seeps. Nature Climate Change, 4, 487-492. Doi:10.1038/nclimate2195

Welch, J. M., Watson, S-A., Welsh, Q. J., McCormick, I. M. & Munday, L. P. (2014). Eects of elevated CO2 on fish behaviour undiminished by transgenerational acclimation. Nature Climate Change, 4, 1086-1089. Doi: 10.1038/nclimate2400 

Compensatory senses

With such serious implications predicted as a result of CO2 induced impaired behaviour, possible solutions have been researched. Of which compensatory cues is one such solution which could reduce the decline in reef populations predicted. This was briefly mentioned in an earlier post which discussed how the ability to learn in larvae is affected by a rise in CO2 and acidity, and so could not be used to substitute other impaired senses.

A similar study led by Lonnstedt published in 2013 looked at the possibility that visual cues could replace impaired olfactory cues.

Pomacentrus amboinensis juvenile. Taken from:http://www.abc.net.au/science/articles/2013/07/29/3811107.htm
Pomacentrus amboinensis juvenile. Taken from:http://www.abc.net.au/science/articles/2013/07/29/3811107.htm

The damselfish species Pomacentrus amboinensis at the end of their larval stage were placed in predicted CO2 of 880µatm. Under these conditions, this species showed no ability to recognise con-specific alarm cues (CAC), meaning that the correct responses to these olfactory cues were absent. When visual cues of a predator were presented to larvae, the anti-predator response of avoiding these visual cues occurred, but the intensity of the response was reduced. Such results show that while visual cues may be able to partially account and replace the lack of olfactory cues in detecting a threat such as a predator, it would not fully replace the impaired ability of larvae to sense predators by olfactory cues. As a result fish species in the future will still have an increased risk from predator mortality due to increased CO2 and ocean acidification.

Results from other studies, have focussed on the behavioural impairment that occurs in prey under high CO2 and acidic environments. A study by Cripps, Munday & McCormack,2011 showed that behavioural impairments occur in reef fish predators as a result of  increased CO2 but that behaviour was not as seriously impaired in comparison to that which occurs in reef fish prey. Suggesting that though future prey populations may not decline as harshly as thought due to behavioural impairment in predators, an overall decline is still likely to occur.

Extra reading sources

Cover image taken from: http://accendoscientia.blogspot.co.uk/2008/12/bubble-eye-goldfish.html

Cripps, L. I.,  Munday, L. P., &  McCormack, I. M. (2011). Ocean acidification affects prey detection by predatory reef fish. PLoS ONE 6(7) e22736. Doi: 10.1371/journal.pone.0022736

Lonnstedt, M. O., Munday, L. P., McCormick, I. M., Ferrari, O. C. M. & Chivers, P. D. (2013). Ocean acidification and responses to predators: can sensory redundancy reduce the apparent impacts of elevated CO2 on fish. Ecology and Evolution, 3(10), 3565 – 3575. Doi: 10.1002/ece3.684 

Gone Fishing

Many of the past studies discussed in previous posts mentions that such impaired behaviour will increased predator mortality. As such future populations are likely to decrease. The podcast with Dr Pippa Moore discusses the implications that such decreases in populations will have on the reef ecosystem.

However reef ecosystems, being such a rich source in terms of biodiversity, have enticed us to utilise this environment as a food supply. With the majority of reef habitats located in shallow areas they are often located near land on continental shelves (as shown in the map below).

reef location
Red dots represent locations of tropical reefs. National Ocean Service, 2008.

This enables them to be easily accessible to humans to utilise such a plentiful supply of resources. In addition these tropical reefs occur around the equator typically in lower developed countries making them a vital food supply for subsistence farming.

It is estimated that 30 millions fishers in the developing world, rely on reefs for food, survival, and a livelihood. UNEP-WCMC (2006).

Such  a significant statistic means that future losses of tropical fish populations will affect humans reliant upon the reef environment as a vital food source.

References and Extra reading

Cover image taken from:http://voices.nationalgeographic.com/2011/05/31/expedition-begins-to-sacred-reef-of-fiji/subsistence-fishing-a-local-fijian-spearfisherman-catches-a-whitespotted-grouper-epinephelus-caeruleopunctatus/

National Ocean Service. (2008). The majority of reef-building corals are found in tropical and subtropical waters. [online image].  Retrieved October 24, 2014 from  http://oceanservice.noaa.gov/education/kits/corals/media/supp_coral05a.htm

UNEP-WCMC (2006) In the front line: shoreline protection and other ecosystem services from mangroves and coral reefs. UNEP-WCMC, Cambridge, UK 33 pp.

The implications to the ecosystem of declining reef fish populations

With my past blogs discussing the type of behavioural impairment that occurs in damselfish and clownfish larvae species and how these impairments would increase mortality rates. I wanted to find out the implications that a decline in these species would have in the future, for both other species and for the reef ecosystem.

Dr Pippa Moore is a Marine Ecologist and lecturer at Aberystwyth University and an expert in Marine Ecology, with her research focussing on how climate change impacts marine ecosystems. This podcast presents Dr Moores’ views on the impact that a predicted decline in these species populations will have within the ecosystem.