Coral algae symbiosis: adapting to climate change

For all you coral fans out there, here is a short article on how symbiotic relationships can help coral

Macro shot of coral (Salazar F 2013)

Coral has declined by 15 percent in the 17 years as a result of coral bleaching from climate change (Wilkinson 2008). One of the ways to tackle this problem is to enhance the corals tolerance to heat by inoculating them with heat tolerant symbiotic algae. In some species, this can improve coral heat tolerance by 1-1.5 degrees (Birkelmans and Van Oppen 2006). But what evolutionary consequences does changing the composition of endo-symbiotic algae have on the coral and the algae?

Bleached and unbleached mushroom coral: Fungia spp (LTMP AIMS 2015)

This short article endeavours to explain some of the complications involved in changing coral algae.

 About the Coral - Algae relationship

Endo- symbiotic algae such as zooxanthellae live within the coral and give coral nutrients essential for growth and photosynthesis to the coral by making them biologically accessible to the coral. In exchange, coral provides shelter and some nutrients to the algae (Coral reef conservation program 2011). As mentioned above, changing the zooxanthellae can improve coral heat tolerance thus improving their chance of survival (Birkelmans and Van Oppen 2006).

The relationship between coral and algae Symbiodinium (Woolridge 2010)

 So how does this affect the algae?

Typically, the relationship between coral and algae has been thought to be symbiotic. However, recent studies have suggested that the coral is inflicting “controlled parasitism” (Woolridge 2010) on the algae whereby coral limits algal growth. A study by Woolridge (2010) found that the growth rate of algae can be up to 33 times slower in coral when compared to cultured algae. This decreases the genetic fitness of the algae by slowing their reproduction rate (Woolridge 2010).

Zooxanthellae in coral shown in red (Anonymous 2013)

Which algae is best?

 Another complication involved in changing algae is determining which algae are best for each coral. Coral is very adaptable to a range of different algal species, with some even having 2 or more algae species at once. However, researchers have found that the heat tolerance enhancement properties of algae vary depending on the coral species (Abrego et al 2008) meaning that different coral respond better to different algae.

Tubbahata reef, Filipina (Anonymous 2012)

Although there is still much to learn about coral-algal relationships, improving the survival rate of coral would be widely beneficial to marine ecosystems and the ecosystem services they provide (Hoegh-Guldberg 1999)

Button coral Scolyma (Mentone aquarium 2015)

For more information on coral click here

For more information on coral - algal relationships click here or for more in depth information click here

Thank-you for reading : ) check back next week for more information on marine evolution.

References

 Coral Reef Conservation program 2011, NOAA, viewed 5/4/15, http://coralreef.noaa.gov/aboutcorals/coral101/symbioticalgae/#a

Abrego D, Ulstrup K E, Willis B L, Van Oppen M J H 2008, “Species-specific interactions between algal endosymbionts and coral hosts define their bleaching response to heat and light stress”, Proceedings of the royal society: Biological sciences, DOI: 10.1098/rspb.2008.0180 viewed 5/4/15 

http://rspb.royalsocietypublishing.org/content/275/1648/2273.full

 Birkelmans R, M J H Van Oppen 2006, ‘The role of zooxanthellae in the thermal tolerance of corals: a ‘nugget of hope’ for coral reefs in an era of climate change’, Proc. R. Soc. B, vol 273, pp.2305-2312, viewed 22/3/15, doi: 10.1098/rspb.2006.3567

Hoegh-Guldberg O 1999, “Climate change, coral bleaching and the future of the world’s coral reefs”, Marine and freshwater research, vol. 50, no.8, pp.839-866, DOI: 10.1071/MF99078

Silverstien R N, Correa A M S, Baker A C 2012, “Specificity is rarely absolute in coral–algal symbiosis: implications for coral response to climate change”, Proceedings of The Royal society: Biological sciences, DOI: 10.1098/rspb.2012.0055, viewed 5/4/15

Wilkinson, C (ed.) 2008, Status of the coral reefs of the world: 2008, Global coral reef monitoring network and reef and rainforest research center, Townsville, Australia

Woolridge S A 2010, ‘Is the coral-algae symbiosis really ‘mutually beneficial’ for the partners?’, Bioessays, vol 32, no.7, pp. 615-625, DOI: 10.1002/bies.200900182

Images

Anonymous 2012, "the most beautiful coral reefs in the world", viewed 5/4/15 http://worldin1001view.com/beaches/the-most-beautiful-coral-reefs-in-the-world/

Anonymous 2013, "coral and colour", Oropheck, viewed 5/4/15, https://orphek.com/coral-color-2/

LTMP AIMS 2015, EATLAS, viewed 5/4/15 http://eatlas.org.au/content/gbr-gci-symbiodinium-clade-distribution-article

Mentone aquarium 2015, melbourne, viewed 5/4/15, http://mentoneaquarium.com.au/149-scolymia-multi-coloured-button-coral-for-sale-in-melbourne/

Salazar F 2013, where cool things happen, viewed 5/4/15, http://www.wherecoolthingshappen.com/great-marco-shots-of-coral-reefs/

Woolridge S 2010, Bioessays, viewed 5/4/15, http://br9xy4lf5w.search.serialssolutions.com/?ctx_ver=Z39.88-2004&ctx_enc=info%3Aofi%2Fenc%3AUTF-8&rfr_id=info:sid/summon.serialssolutions.com&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.genre=article&rft.atitle=Is+the+coral%E2%80%90algae+symbiosis+really+%E2%80%98mutually+beneficial%E2%80%99+for+the+partners%3F&rft.jtitle=BioEssays&rft.au=Wooldridge%2C+Scott+A&rft.date=2010-07-01&rft.pub=WILEY%E2%80%90VCH+Verlag&rft.issn=0265-9247&rft.eissn=1521-1878&rft.volume=32&rft.issue=7&rft.spage=615&rft.epage=625&rft_id=info:doi/10.1002%2Fbies.200900182&rft.externalDocID=BIES200900182&paramdict=en-US