Algae wins the race on climate change

In a changing climate, one of the biggest obstacles organisms face is whether or not they can adapt fast enough to survive. Luckily for Emiliania Huxleyi, evolution is not a problem.

Three individual Emiliania Huxleyi Phytoplankton (Young 2004)

 Thanks to the fast evolution of this phytoplankton, scientists have been able to study the potential long term effects of climate change on this alga and its consequent affect on the carbon cycle.

Emiliania huxleyi also known as "Ehux" are microscopic algae known as coccolithophores characterized by their outer shell of calcium carbonate disks.

Emiliania Huxleyi showing detached calcium carbonate disks (Beaumont K 2007)

Ehux are a fairly new species having evolved less than 250 milion years ago and are now one of the most abundant phytoplankton on earth (Bown et al 2004 and Moore et al 2012).

Their global adaptability is caused by a pan genome which allows very high genetic variance between individuals (Read et al 2013). 

Some of the different variations of Emiliania Huxleyi (Read et al 2013)

 Their role in ecology

Some ecological contributions of E.huxleyi (Gorrick G 2001)

Emiliania Huxley are primary producers and provide the baseline food source for most marine life. They also play an important role in the carbon cycle and can account for up to 20% of carbon cycling (Poulton et al 2007).  Under the right conditions algal blooms can be so large they can be seen from space (Moore et al 2012).  

Satelite picture of a coccolithophore bloom (NOC 2015)

Ocean Acidification

There has been major concern that ocean acidification will reduce the amount of carbonate available for E. Huxleyi to produce their shells. As a result, their shells could become lighter hence they would not sink to the ocean floor and the carbon in the CaCO3 shells would not sequester at the bottom of the ocean (Riebesell et al 2000).

The role of coccolithophores in the carbon cycle, “F” refers to CaCO3 disks sinking to the ocean floor and sequestering carbon in sedimentation (Hutchins D  2011)

Thanks to ehux’s fast evolution scientists have found that populations can change within 500 generations in one year through adaptive evolution (Lohbeck et al 2014). Furthermore, pre-adapted populations can perform 55% better in future climate change scenarios than current e-hux populations (Schluter et al 2014). This is good news for emiliania huxleyi and their potential affects on the carbon cycle.

Having said this, the high variation of results in past experiments on CaCO3 production in Emiliania Huxleyi shows that there is still much to learn about this species (Beaufort 2011).  

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

References

Bown P R, Lees J A, Young J R 2004, “Calcareous nannoplankton evolution and diversity through time”, Coccolithophores, pp. 481-508, doi: 10.1007/978-3-662-06278-4_18

Lohbeck K T, Riebesell U, Reusch T B H 2014, “Gene expression changes in the coccolithophore Emiliania Huxleyi after 500 generations of selection to ocean acidification”, The Royal society: Biological sciences, vol.281, no. 1786, doi: 10.1098/rspb.2014.0003

Moore T S, Dowell M D, Franz B A 2011, “Detection of coccolithophore blooms in ocean color satellite imagery: A generalized approach for use with multiple sensors”,  Remote sensing of environment, vol. 117, pp. 249-263, doi:10.1016/j.rse.2011.10.001

Poulton A J, Adey T R, Balch W M, Holligan P M 2007, “relating coccolithophore calcification rates to phytoplankton community dynamics: Regional differences and implications for carbon export”, Deep sea research part II: Topical studies in Oceanography, vol.54, no. 5-7, pp. 538-537, doi: 10.1016/j.dsr2.2006.12.003

Read B Am Kegel J, Klute M J, Kuo A, Lefebvre C, Maumus F, Mayer C, Miller J, Moneir A, Salamov A, Young J, Aguilar M, Claverie J-M, Frickenhaus S, Gonzalez K, Herman E K, Lin Y-C, Napier J, Ogata H, Sarno A F, Shmutz J, Schroeder D, de Vargas C, Verret F, von Dassow P, Valentin K, Van de Peer Y, Wheeler G, Emiliania Huxleyi Annotation Consortium, Dacks J B, Delwiche C F, Dyhrman S T, Glockner G, John U, Richards T, Worden A Z, Zhang X, Grigoriev I V 2013, “Pan genome of the phytoplankton Emiliania underpins its global distribution”,  Nature, vol.499, pp.209-213, doi: 10.1038/nature12221

Riebesell U,Zondervan I, Rost B, Tortell P D, Zeebe R E, Morel F M M 2000, “Reduced calcification of marine plankton in response to increased atmospheric CO2”, Nature, vol.407,pp.364-367, doi: 10.1038/35030078

Schluter L, Lohbeck K T, Gutowska M A, Groger J P, Riebesell G U, Reusch T B H 2014, “Adaptation of a globally important coccolithophore to ocean warming and acidification”, Nature climate change, vol.4, pp.1024-1030, doi: 10.1038/nclimate2379

Images

• NOC 2015, “Eutrophication and health” viewed 15/4/15, http://www.seos-project.eu/modules/oceancolour/oceancolour-c03-p04.html

• Young 2004, “Emiliania Huxleyi”, viewed 15/4/15, http://www.nhm.ac.uk/nature-online/species-of-the-day/biodiversity/climate-change/emiliania-huxleyi/index.html

• Hutchins D 2011, “Coccolithophore carbon chemistry”, viewed 15/4/15, http://www.nature.com/nature/journal/v476/n7358/fig_tab/476041a_F1.html

• Gorrick G 2001,”E. Huxleyi importance, viewed 15/4/15 https://microbewiki.kenyon.edu/index.php/File:E._huxleyi_importance.jpg 

• Read et al 2013, “Pan genome of the phytoplankton Emiliania underpins its global distribution” viewed 15/4/15 http://www.nature.com/nature/journal/v499/n7457/full/nature12221.html

• Beaumont K 2007, “Acidification”, viewed 15/4/15, http://www.antarcticanimation.com/content/thesaurus/a/acidification01.php

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

Turtles: The gender issue.

 Have you ever wondered what it would be like if the entire population was one sex? Well, turtles might soon find out.

Endangered Loggerhead Turtle Caretta caretta (Anonymous 2013)

Turtles have been around for over 100 million years and have survived various climates, ice ages and even temperatures 4 degrees warmer than today (Hirayma et al 1994), (NOAA 2008) and (Spotila et al 2000). Despite this, marine turtle populations have declined to the point where six of the 7 species of marine turtle have become threatened or endangered (Department of the Environment 2015).

So how is climate change threatening the future of marine turtles?

Critically endangered Hawksbill turtle Eretmochelys imbricata (Freund 2015)

 The gender issue

The vulnerable green sea turtle Chelonia mydas, (Harasti 2015)

There are three ways gender is determined in turtles: genetic sex determination (GSD) and temperature dependant determination (TSD) and thermo-sensitive genetic sex determination (Valenzuela et al 2014). Like most reptiles, the majority of turtles have temperature dependent sex selection (TSD). This means that temperature during egg development determines gender. For most TSD species, an increase in temperature increases the proportion of female hatchlings. 

Vulnerable Flatback turtle Natator depressus (Reinhold 2013)

For most marine turtles, a global increase of less than 3 degrees could cause populations to become 100% female (Hawkes et al 2007). With global temperature expected to rise anywhere between 2-7 degrees in the next 100 years, turtles could become extinct within the next 20-50 years (Tapilatu et al 2013) and (Fuentes et al 2010). Luckily there are some ways turtles have adapted to this. 

Behavioral adaptations to climate change.

Critically endangered baby leather back turtle Dermochelys coriacea (Leonard 2012)

For species such as the green turtle Chelonia mydas which is currently 95% female, breeding behaviour has masked the effects of TSD. Astudy by Wright et al (2012) found that male turtles visit breeding grounds more often than females meaning that on average there was 1.4 males to every fecund female. Increased temperature has also caused a delay in nesting by ten days (Weishampel et al 2008).

Genetic adaptations to climate change. 

Genetic gender selection Black marsh turtle Seibenrokiella crassicollis (Hakim 2011)

Some turtle species have evolved GSD whereby turtle gender is determined by chromosomes instead of temperature (Carr and Bickham 1981) and (Valenzuela 2008). This has allowed these species to completely avoid the gender issue. However, there are variations where even GSD can be affected by temperature change (Valenzuela et al 2014). There are also variations in TSD where temperature change either above or below the optimum can cause gender bias. This allows turtles to maintain a balance through natural climate fluctuations (Ewert et al 2005).

Endangered Olive Ridley turtle Lepidochelys olivacea (Nature 2007)

Want to read more about TSD in turtles? Check out these sites: 

http://onlinelibrary.wiley.com/doi/10.1002/jez.1402700103/abstract

http://www.ncbi.nlm.nih.gov/pubmed/15066448

http://onlinelibrary.wiley.com/doi/10.1002/jez.1402600117/abstract

Thankyou for reading.  :)

Check back next week for more information on how climate change is affecting marine life. 

References

Carr J, Bickham J 1981, ‘Sex chromosomes of the Asian black pond turtle, Seibenrokiella crassicollis (testudines Emydidae)’,  Cytogenetics and cell genetics, vol.31, no. 3, pp. 178-83, viewed 29/3/15 url<http://www.ncbi.nlm.nih.gov/pubmed/7326996>

Department of the environment, year unknown, Australian government, viewed 2/4/15 <http://www.environment.gov.au/marine/marine-species/marine-turtles>

Ewert M A, Jackson D R, Nelson C R 2005, ‘patterns of temperature-dependant sex determination in turtles’, Journal of experimental zoology, vol.270, no. 1, pp.3-15, doi: 10.1002/jez.1402700103

Fuentes M M P B, Limpus C J Hamann M 2010,”vulnerability of sea turtle nesting grounds to climate change”, Global change biology, vol. 17, no.1, pp.140-153, doi: 10.1111/j.1365-2486.2010.02192.x

Hawkes L A, Broderick A C, Godfrey M H, Godley B J 2007,' Investigating the potential impacts of climate change on a marine turtle population', Global Change Biology, vol.13, pp.923-932 Doi: 10.1111/j.1365-2486.2007.01320.x

Hirayma R 1994, “Phylogenetic systematics of Chelenoid sea turtles”, The Island Arc, vol.3, pp.270-284 viewed 2/4/15, http://scholar.google.com.au/scholar_url?url=http://www.researchgate.net/profile/Ren_Hirayama/publication/256198221_Phylogenetic_systematics_of_chelonioid_sea_turtles/links/00463521fa2ee9f83c000000.pdf&hl=en&sa=X&scisig=AAGBfm2tPzF_sdyAUSfbG_I5aFA3oZmt3w&nossl=1&oi=scholarr&ei=RsMcVbKME4Wl8AWIioKIBQ&ved=0CBsQgAMoADAA

NOAA, 2008, Nesdis, viewed 29/3/15, url:< http://www.ncdc.noaa.gov/paleo/ctl/100k.html>

Spotila J R, Reina R D, Steyermark A C, Plotkin P T, Paladino F V 2000, “Pacific leatherback turtles face extinction”, nature, vol.405, pp.529-530, doi:10.1038/35014729

Tapilatu R F, Dutton P H, Tiwari M, Wibbels T, Ferinandus H V, Iwanginn W G, Nugroho B H 2013, “long-term decline of the western pacific leatherback, Dermochelyscoriacea: a globally important sea turtle population”, Ecological society of America, vol. 4, no. 2, doi:http://dx.doi.org/10.1890/ES12-00348.1

Valenzuela N 2008, ‘Relic thermosensitive gene expression in a turtle with genotypic sex determination’, Evolution, vol.62, no. 1, pp. 234-40, viewed 29/3/15, url:< http://onlinelibrary.wiley.com/doi/10.1002/jez.1402600117/abstract>

Valenzuela N, Badenhorst D, Montiel EE, Literman R 2014, ‘Molecular cytogenetic search for cryptic sex chromosomes in painted turtles Chrysemys picta’, Cytogentic genome research, vol. 144, no.1, pp.39-46, doi: 10.1159/000366076

Weishampel J F, Bagley D A, Ehrhart L M 2008,  “Earlier nesting by loggerhead sea turtles following sea surface warming”, Global change biology, vol. 10, no. 8, pp.1424-1427, doi:DOI: 10.1111/j.1529-8817.2003.00817.x

Images:

Anonymous 2013, Northern travel Ltd,viewed 29/3/15, https://cyprusnorth.wordpress.com/2013/06/25/the-caretta-caretta-turtle/

Freund J 2015, wwf, viewed 29/3/15, https://www.worldwildlife.org/species/hawksbill-turtle

Harasti 2015, NSW government, viewed 29/3/15, http://www.mpa.nsw.gov.au/simp-explore.html

Hakim J 2011, Asian herp blogs, viewed 29/3/15, https://bangkokherps.wordpress.com/2011/10/23/black-marsh-turtle/

Leonard S S 2012, Five point Five, viewed 29/3/15, http://fivepointfive.org/making-a-difference-turtle-conservation/

Nature 2007, PBworks, http://seaturtles.pbworks.com/w/page/15571583/Olive%20ridley

Reinhold L 2014, Phys.org, viewed 29/3/15, http://phys.org/news/2013-12-threatened-flatback-sea-turtle-natator.html