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Why Biofuels Can’t Replace Transportation Fuels

Agitation regarding rising greenhouse emissions and petroleum costs has drawn focus to biofuels as renewable source of transportation fuel. However, a study published in Angewandte Chemie  argued that crops should not be harvested for biofuel due to their reduced photosynthetic efficiency (percent light converted to stored energy) and annexation of agricultural land from food plants.  

Biofuels require a massive energy input espoused as transportation costs, fertilizer production and agriculture machinery that amounts to 50% of the energy that biofuels contain. The energy investment is extricated from fossil fuels, leading scientists to believe that the net reduction in carbon dioxide emissions from biofuel production is marginal.

Moreover, repurposing arable land for fuel crop harvest will decrease food production thereby inflaming food prices.

Alternative renewable energy such as photovoltaic cells, which are used to generate solar power, are 150 times more efficient at harnessing energy than plants. Moreover, combustion engines powered by biofuels have 20% thermal efficiency compared to electrical engines, which utilize 80% stored chemical energy in batteries.

Hence, harnessing solar generated electricity to charge electric cars is found to optimize land usage 600 times more efficiently than producing biofuels to power internal combustion engines.

The Biofuel Lifecycle Credit source: Wikipedia

Biomass differs from other renewable sources since its energy is stored as chemical bonds in carbohydrates that are broken down to ethanol to power cars.  

Photosynthetic pigments in plants absorb light, and electrons and protons (negatively and positively charged particles) transfer the radiant energy to reactor centres. Subsequent reactions synthesize ATP,  a biological energy carrier, which assimilates carbon dioxide from the air and converts it to carbohydrate.

As a result of biological inefficacies in electron movement, limited reaction rates, and maximal sunlight absorption of 20% by photosynthetic pigments, only 1% photosynthetic efficiency is observed for most plants. Using the yield of biofuel per unit area of land, the photosynthetic efficiency was calculated for various fuel crops.

Photosynthetic Efficiency for Different Fuel Crops Data Source- Sustainable Energy – without the hot air

Given that biomass is a source of carbon, researchers believe that biomass is best utilized for manufacturing chemicals that are synthesized from petroleum. Leftover plant residues and compost can be used for generating heat and electricity.

Planting trees would fix 2.7 kg of carbon dioxide per square meter,whereas biofeuls with 1% photosynthetic efficiency would produce 0.31 kg of carbon dioxide per square meter when combusted.

Sarrah Putwa

References

Vennestrøm, P. N. R., Osmundsen, C. M., Christensen, C. H. and Taarning, E. (2011), Beyond Petrochemicals: The Renewable Chemicals Industry. Angew. Chem. Int. Ed., 50: 10502–10509. doi:10.1002/anie.201102117

David Mackay. Sustainable Energy – without the hot air http://www.withouthotair.com/c6/page_43.shtml (accessed Feb 28, 2018).

Michel, H. (2012), Editorial: The Nonsense of Biofuels. Angew. Chem. Int. Ed., 51: 2516–2518. doi:10.1002/anie.201200218

 

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Posted on February 28, 2018 by in Chemistry in the news, Issues in Chemistry

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Are Antidepressants as Effective at Treating Anxiety as Benzodiazepines?

Posted on February 27, 2018 by | Leave a comment

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The most common psychiatric conditions are anxiety disorders and depressive disorders, with this being especially true for university students. The two medications designed to treat these two disorders are benzodiazepines (BDZ) and antidepressants (AD) for anxiety and depression respectively. However, in addition to depression, almost all antidepressants treat anxiety and many other psychiatric conditions effectively. In the recent years, there has been a shift from doctors prescribing BDZ to AD. If antidepressants do everything that benzodiazepines do, plus more, why are benzodiazepines still prescribed at all?

First, let’s see how these drugs work. Benzodiazepines work by increasing the action of GABA, a neurotransmitter (chemical in the nervous system) that helps the brain calm down. There are many types of antidepressants, including tricyclic antidepressants (TCA; now less commonly prescribed) and reuptake inhibitors (“modern antidepressants”), which generally work by increasing levels of serotonin in the brain, a neurotransmitter that helps regulate mood, leading to enhanced mood. Figure 1 shows some BDZ and AD used in the review this article discusses.

Figure 1: Left to right: alaprazomlam, a benzodiazepine; imipramine, a tricyclic antidepressant; venlafaxine, a selective serotonin-norepinephrine reuptake inhibitor.

For those interested, the following videos illustrate detailed mechanisms of how BDZ and AD work respectively.

To see if evidence truly supports the shift towards AD from BDZ, researchers reviewed 22 studies comparing BDZ to AD in treating anxiety disorders. To keep variables constant, they compared only results from studies comparing the use of BDZ and TCA to treat panic disorder (a specific type of anxiety disorder), while analyzing the other studies individually. There were 11 such results, and those for which data was provided are summarized in Figure 2.

Figure 2: Response rates to BDZ and AD found by various studies. Data complied by Offidani et al.

The researchers did not find consistent statistically significant results which suggested that AD treat panic disorder more effectively than BDZ. However, in addition, they also compared the adverse events (unpleasant effects caused by medication) of BDZ and AD. Although the number of studies supplying this information was small, they consistently found that adverse events were less frequently reported for BDZ than for AD (Figure 3), and statistical analysis revealed a significant difference.

Figure 3: Adverse events caused by BDZ and AD. Data complied by Offidani et al.

Furthermore, the researchers also compared the dropout rates for the studies (which all 11 studies reported). This is the percentage of participants who, for one reason or another, chose to discontinue participation in the study. While this does not necessarily indicate that the medication is not working properly or has adverse effects, the researchers did find that BDZ dropout rates were significantly lower than those of AD (Figure 4).

Figure 4: Dropout rates of participants using BDZ and AD. Data complied by Offidani et al.

There were only 3 studies comparing modern antidepressants to BDZ. After analyzing the data, the researchers found no significant difference in response rate between the two groups, but they found similar results for adverse events and dropout rates.

While antidepressants are undoubtedly effective at treating both depression and anxiety, there is little evidence that they treat anxiety better than benzodiazepines. That being said, benzodiazepines seem to have fewer unpleasant side effects, and therefore should still have their place in modern day medicine if anxiety alone is the issue.

-Cliff Ng

References

Schacter, D. L.; Gilbert, D. T.; Nock, M.; Wegner, D. M. Psychology, 3rd ed.; Worth Publishers, Macmillan Learning: New York, NY, 2014.

Offidani, E.; Guidi, J.; Tomba, E.; Fava, G. A. Psychotherapy and Psychosomatics 2013, 82(6), 355–362.

Offidani, E.; Guidi, J.; Tomba, E.; Fava, G. A. Supplementary Material for: Efficacy and Tolerability of Benzodiazepines versus Antidepressants in Anxiety Disorders: A Systematic Review and Meta-Analysis, 2013.

Diagnostic and Statistical Manual of Mental Disorders, 5th ed.; American Psychiatric Publishing: Washington, 2014.

Adverse Events, Near Misses, and Errors https://psnet.ahrq.gov/primers/primer/34/adverse-events-near-misses-and-errors (accessed Feb 24, 2018).

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Reality Check: Mozart Effect vs. Science

Posted on February 27, 2018 by | 2 comments

Rausher, Shaw and Ky‘s 1993 paper in Nature, showing correlation of increase cognitive function and exposure to Mozart’s piano music, triggered a worldwide interest in developing new technology to improve learning.   Government and private corporations invested large sums of money to develop Mozart-based learning tools to improve the intelligence of students.

Rausher et. al original study recruited college students to partake in a standardized cognitive test that extrapolated to an IQ score.  Students were allowed to complete the test in one of three conditions that were assigned to them: with Mozart’s Sonata in D major, K 448 playing, with relaxing music playing in background, in silence.  Rausher’s data (Fig. 1) astonished the world, when students completing the test with Mozart’s sonata playing were found to have a higher IQ score than those under the other conditions.

Data first appeared in the paper, re-presented in graph form for clarity.

Critics of Rausher questioned the validity of the data collected in the study.  Kenneth Steele of Applachian State University questioned effects of bias due to the small sample size of the initial study and indirect comparison to a control group on the data.   Steele et al. adapted Rausher et al.‘s methodology to study changes in the cognitive performance college students when exposed to music by Mozart, Phillip Glass (minimalist music empirically shown to have opposite effect of Mozart’s music) and silence.  Steele et al. tested all participants before (pre-treatment) and after/during (post-treatment) exposure (Fig. 2) and found no significant difference between improvements in the scores of students exposed to Mozart, in comparison to the other groups.

Graph created from data presented in Steel et al.’s 1999 paper

Whether or not Mozart’s music can increase cognitive performance remains actively debated in scholarly communications, where Rausher and Steele have both continued to publish articles arguing for and against the existence of the Mozart effect.   Elsewhere, Rausher et al.‘s 1993 study has inspired applications of Mozart’s music in patients with epilepsy    Considering that the original music inspiring this research is over 220 years old, who knows what the future applications of Mozart’s masterpieces might be.

Aydan Con

PS: I don’t have permission to use a recording of the above mentioned Mozart Sonata, and my own recording of the work is not available at the time of this blog.  Instead, I have posted a performance of another work associated with the Mozart Effect, Piano Concerto in A major, K. 488.  The performance is by pianist Natalie Lo (BMus ’16) with the UBC Symphony Orchestra conducted by Dr. Jonathan Girard (used with permission).

 

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Is Sleep Loss a Problem? Not for These Blind Fish!

Not only do all species vary in ability and behaviour, but fundamental biological needs are subject to variation across the animal kingdom. This evolutionary diversity is  reflected in the difference in amount of sleep necessary for each species (1).  Although the considerable variation in sleep is recognized, little information is known about the evolutionary basis that drives the emergence of such diversity.

A prominent example of sleep variation has recently been studied (2), comparing the Mexican cavefish (3) found in the Sierra del Abra region of Northeast Mexico, to their existing surface ancestors. Multiple Pachón cavefish populations have independently evolved to sleep up to 80% less than the surface dwelling species, with no apparent adverse effects on their function or health.

Comparison of Astyanax mexicanus surface fish and Pachón cavefish

Figure 1: A comparison of Astyanax mexicanus , the blind Mexican cavefish (right) to their relatives that live on the surface (left) Credit: J. B. Jaggard et al./eLife/CC BY 4.0

Figure 1: A comparison of Astyanax mexicanus , the blind Mexican cavefish (right) to their relatives that live on the surface (left) Credit: J. B. Jaggard et al./eLife/CC BY 4.0

The Pachón  cavefish have smaller, if not absent, eyes and lack pigment as shown in Figure 1. The enlarged hypothalamus of the Pachón cavefish has been reported, attributing to many behvioural differences from the surface counterparts. It is thought that ecological differences that affect food availability have driven this evolutionary variation in not only the physical features of these species but also in their sleep behaviour (4).

Investigation into to the regulation and expression of hcrt, a highly conserved peptide known to alter sleep in other species, has offered insight in the sleep variation observed in the Mexican cavefish. Researchers found that although the genetic sequence of this regulatory peptide is identical in the adult Pachón and surface cavefish, there is significant increase in the expression of hcrt in adult Pachón (Figure 2).

Figure 2: HCRT Expression in Pachón (orange) and Surface (blue) Cavefish

Figure2: HCRT Expression in Pachón (orange) and Surface (blue) Cavefish

The adult Pachón cavefish expressed the HCRT peptide four times more than the surface species. With this finding, researchers tested how inhibiting this particular peptide would affect the sleep behaviour of the Pachón species. When HCRT expression was suppressed in the Pachón cavefish, increases in time spent sleeping were observed, confirming the dependence of their sleep behaviour on the HCRT peptide.

-Jojo Nijjar

References:
1. Campbell, S. S.; Tobler, I. Neuroscience & Biobehavioral Reviews . 1984, 8,269–300.
2. Jaggard, J.B.; Stahl, B. A.; Lloyd, E.; Prober, D.A.; Duboue, E.R.; Keene, A.C. Life Sciences Journal. 2018, e32637.
3. Keene, A.; Yoshizawa, M.; McGaugh, S. Biology and Evolution of Mexican Cavefish. San Diego, USA, 2016.
4. Menuet, A.; Alunni, A.; Joly, J.S.; Jeffery, W.R.; Rétaux, S. Development. 2007, 134, 5, 845-55.
5. Siegel, J.M. Nature. 2005, 437, 1264-71.

 

 

 

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Posted on February 26, 2018 by in Chemistry in the news

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Practice Testing: Prevent Stress from Affecting Your Memory

Posted on February 26, 2018 by | 2 comments

Figure 1. Studying student. Image courtesy of: Skokie Public Library on Flickr

Round two of midterm exams is approaching fast and before you know it, it is final exam season. This can cause a lot of stress for students, so how can you increase your marks before the end of the school year? Researchers have found that practice testing as a learning strategy can protect your memory from the negative effects of stress.

No matter how many exams a student has written in their life, they can still get stressed hours before writing an exam. When you are stressed, it is difficult to retrieve information from your memory because your body is preparing for a flight or fight response. The best way to prevent stress from affecting your memory is to study effectively.

Most students tend to study by re-reading the textbook and re-writing notes; this is known as study practice. Another method of studying involves taking practice tests to study for an exam; this is known as retrieval practice.

In 2016, researchers at Tuft University conducted an experiment with 120 students comparing the learning strategies of retrieval practice versus study practice. Participants were asked to learn 30 nouns presented as words and 30 nouns presented as images. This was done using a computer program which displayed an item for a few seconds. Then participants typed a sentence including the item displayed to simulate note taking.

Half of the participants were put into the study practice group and the other half in the retrieval study group. The participants learning by study practice had the items re-displayed multiple times on the computer. The participants learning by retrieval practice took timed practice tests where they had to recall as many items as possible.

For both learning strategies there were non-stressed and stressed participants. Half of the participants from each learning strategy were put under stress conditions and the other half in non-stress conditions. Stress conditions were created by having participants give a speech or solve difficult math problems in front of a group 24 hours after studying.

The memory test for stressed participants was taken during the stressful task to accurately represent the feelings of most students before a test. The non-stressed group took the memory test during a non-stressful task. The participants were asked to accurately recall as many items possible.

Figure 2. Average number of words and images accurately recalled immediately after stress.

As seen in Fig. 2, retrieval practice is the best way of studying because participants in stressful situations recalled the same number of items as participants in non-stressful situations. With this learning strategy, stress had little to no effect on the number of items recalled. The stressed retrieval practice group also recalled more items than the non-stressed study practice group.

Why is retrieval practice effective? The learning strategy forces you to recall information repeatedly and this helps strengthen long-term memory retention. So, for your upcoming exam, try studying through retrieval practice to handle the stress and ace your exam!

Want to know more about retrieval practice? Check out the video above!

– Sara Djondovic

References

  1. Agarwal, P. K. [Retrieval Practice]. (2017). Retrieval Practice Overview. Retrieved February 25, 2018 from https://www.youtube.com/watch?v=ZO8abw3DHxs&feature=youtu.be.
  2. Agarwal, P. K. Retrieve!. Retrieval Practice. Retrieved February 25, 2018 from https://www.retrievalpractice.org.
  3. McLeod, S. A. (2010). Long-term memory. Retrieved February 25, 2018 from www.simplypsychology.org/long-term-memory.html.
  4. N.A. (n.d.). The fight or flight response: Our body’s response to stress. Young Diggers. Retrieved February 25, 2018 from http://www.youngdiggers.com.au/fight-or-flight.
  5. Segal, J., Smith, M., Segal, R., Robinson, L. (2018). Stress Symptoms, Signs, and Causes. HELPGUIDE.ORG. Retrieved February 25, 2018 from https://www.helpguide.org/articles/stress/stress-symptoms-signs-and-causes.htm.
  6. Smith, A. M., Floerke, V. A., Thomas, A. K. (2016). Retrieval practice protects memory against acute stress. Science, 354(6315), 1046-1048. http://science.sciencemag.org/content/354/6315/1046.
  7. Tufts University. (2016). Practice testing protects memory against stress. ScienceDaily. Retrieved February 24, 2018 from www.sciencedaily.com/releases/2016/11/161124160426.htm.

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Rise of the Anti-Vaccinations: The European Outbreak of the Measles Virus

Posted on February 25, 2018 by | 2 comments

With over 20,000 cases and 35 deaths, measles is on the rise again in Europe. Could the “anti-vax” movement be to blame?

Figure 1: Vaccine being drawn into a needle Source: Flickr

According to the World Health Organization’s (WHO) most recent report, after a record low of 5273 cases in 2016, there were four times as many cases of the measles virus in 2017.

Of the 53 countries in the region, 21 had reported large outbreaks. A classification of a large measles outbreak includes over 100 reported cases. Some countries on this list include Germany, Greece and the United Kingdom. The countries that top this list are Romania, Italy and Ukraine, all nearing or over 5000 reported cases.

Figure 1: List of all European countries that have large outbreaks of the measles virus Source: WHO Europe

So how could Europe go from a record low to a four-fold increase in only a year?

The WHO claims that this is because of the decrease in routine vaccinations, interrupted supply of vaccines and underperforming disease surveillance systems.

In the retracted 1998 publication from the Lancet, a medical journal from the United Kingdom, an article stated that there was a correlation between the measles vaccination and autism.

Although this statement was highly discredited, the anti-vaccination (anti-vax) movements in recent years have surged from these false claims. The influence from the opinion of the “anti-vax” movement has led to an overall loss of trust in vaccinations.

Figure 3: Bumper sticker promoting the views of the anti-vax movement Source: Flickr

Some countries, such as Italy, have had government intervention where legislation requires children to get vaccinated if they plan on attending state-run schools.

The French Health Ministry has also promised to enforce mandatory vaccinations for young children by early 2018.

Unsurprisingly, this decrease in vaccinations is the largest risk in spreading the measles. Any individuals unvaccinated, regardless of age, are at risk of catching and spreading the virus to others who are not protected.

For now, the WHO intends to increase vaccination rates in Europe by improving the supply chain of vaccines and informing the public with awareness campaigns.

-Brandon Kato

References:

Europe observes a 4-fold increase in measles cases in 2017 compared to previous year http://www.euro.who.int/en/media-centre/sections/press-releases/2018/europe-observes-a-4-fold-increase-in-measles-cases-in-2017-compared-to-previous-year (accessed Feb 25, 2018).

Wakefield, A. J. The Lancet. 1998, 351(9103), 637–641.

Italy makes 12 vaccinations compulsory for children http://www.bbc.com/news/world-europe-39983799 (accessed Feb 25, 2018).

8 nouveaux vaccins obligatoires pour les enfants de moins de 2 ans http://www.gouvernement.fr/argumentaire/8-nouveaux-vaccins-obligatoires-pour-les-enfants-de-moins-de-2-ans (accessed Feb 25, 2018).

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Life Stress and Telomere Length

Posted on February 23, 2018 by | 2 comments

Dr. Elizabeth H. Blackburn, a biochemist at the University of California, San Francisco, shared the 2009 Nobel Prize in Medicine or Physiology for her discovery of the process of telomere shortening. Her research revealed that telomeres and telomerase may play central roles in how we age. Telomeres are special segments of noncoding DNA at the very ends of chromosomes. 

The telomeres protect the ends of chromosomes from fraying. The problem is that every time the cell divides and the DNA is copied, some of that telomere get shortened until the length would hit a critical point. She also discovered an enzyme that could replenish and restore the length of telomeres, and she named it telomerase.

The shortened telomeres play a role in aging by the erosion of the DNA over time. It means that the telomeres’ length is connected to ageing and going from healthy to diseased. She revealed that telomere attrition is also contributing to physiological changes in the body such as increasing risks of getting various types of diseases, such as cardiovascular diseases, Alzheimer’s, some cancers, and diabetes.

The risks of the diseases of ageing cannot be reduced by telomerase since although increasing the telomerase decreases the risks of some diseases, the higher levels of it also increase the risks of certain and rather serious cancers such as brain tumours, melanoma, and lung cancers. So, she carried out experiments to discover ways to control our telomeres’ length and thus health, without taking cancer risks.

She discovered the relationship between perceived stress and telomere length, which clearly indicated that the more chronic stress you are under, the significantly shorter the telomeres. The results of the study are shown below, Figure2.

In addition, her further study discovered that negative thinkers who perceive their life events under greater stress were found to have shorter telomeres and lower telomerase activity. On the other hands, people, who experience their circumstances not as a threat, but as a challenge had been able to maintain their telomeres. 

This study indicates that we have control over the way we age all the way down into our cells. People’s life events and the way they perceive these events can affect on the telomeres length. Physical activity as a form of meditation may also control the shortening effect on telomeres. Therefore, telomere length wasn’t just a matter of age counted in years, but it was a matter of attitude.

People who have experienced emotional neglect, exposure to violence, or bullying consistently have shorter telomeres while tight-knit communities and lifelong friendships improve telomere maintenance. Dr.Elizabeth H. Blackburn said, ” It‘s telling us that I have the power to impact my own telomeres, and I also have the power to impact yours. Telomere science has told us just how interconnected we all are.”

The video below explains the relationship between accelerated telomere shortening and life stress. See source here.

-Subi Kim

 

References:

E. S. Epel et al. Accelerated telomere shortening in response to life stress. 2004. The National Academy of Sciences. 101:17312-17315. doi: https://doi.org/10.1073/pnas.0407162101.

Roxy, P., Chris, O., Jay, D. (2011) Introduction to Statistics and Data Analysis. Boston, MA: Nelson Education.

 

 

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Artificial Photosynthesis as an Energy Source – Revised

Posted on February 9, 2018 by | 2 comments

For centuries, fossil fuels have been the most common energy source in the world, and are still used extensively. However, with the growing problem of climate change due to climbing levels of carbon dioxide in the atmosphere, combined with the prospect of limited sources of fossil fuels available, interest in renewable and more environmentally friendly sources of energy is growing.

Sunlight is a well-known source of natural energy, and can be converted into usable energy sources. Probably the most well-known method is the use of solar cells to produce electricity from sunlight, as cells have been in use for decades, in applications ranging from satellites to calculators. Today, research in renewable energy continues, as scientists investigate the possibilities of using sunlight to produce other usable energy sources besides electricity.

In photosynthesis, water is split into hydrogen and oxygen, which are combined with carbon dioxide to build biochemical molecules. Within the last half a century, laboratory processes have replicated the splitting, imitating photosynthesis in plants. The hydrogen can be collected and used immediately as a fuel, e.g. in rocket engines, or used to make other fuels. The most basic of such methods involves using electricity passed between two electrodes in water, producing hydrogen and oxygen gas at the electrodes, as shown below(1). This method does not use sunlight directly, but the electricity could be supplied from solar cells. An alternative method of water splitting uses a solar cell containing a Titanium Oxide (TiO2) electrode to absorb sunlight and produce hydrogen and oxygen on the cell surface. However, the energy conversion of this method is highly inefficient, and is therefore not widely used (2).

Another approach to artificial photosynthesis involves a closer imitation of its biological analogue, using both water and carbon dioxide to produce fuels. One known method, also using a TiO2 catalyst, converts water and CO2 to oxygen and small hydrocarbon molecules including methane and methanol. Both of these are common fuels. The Titanium catalyst can be modified with elements such as copper, platinum or silicon to make the production of hydrocarbons more selective. For example, adding platinum to the catalyst increases the preference of methane over methanol eight times higher than before (3). Despite the useful carbon compounds produced in these process, carbon monoxide (CO), a toxic gas, is also produced. However, the amount of CO produced can be decreased by further catalyst modification, but not entirely eliminated.

These catalytic methods are beneficial in producing useful fuels from clean and renewable energy sources and consume a greenhouse gas (CO2) in the process. This provides a favourable solution to both climate change as well as an energy crisis. The downsides of these methods are the expense and inefficiency, and thus are not yet used in mass production of fuels.

References:

  1. https://energy.gov/eere/fuelcells/hydrogen-production-electrolysis. (Accessed 08/02/2018.)
  2. Bard, Allen J., and Marye Anne Fox. “Artificial photosynthesis: solar splitting of water to hydrogen and oxygen.” Accounts of Chemical Research 28.3 (1995): 141-145.
  3. Mul, Guido et al. “Artificial photosynthesis over crystalline TiO2-based catalysts: fact or fiction?.” Journal of the American Chemical Society 132.24 (2010): 8398-8406.

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Males Outnumbered: Why 99% of Sea Turtles are Turning Female.

Posted on January 22, 2018 by | 1 comment

A hatchling green sea turtle on the shore of Raine Island. Source: Queensland Government

Climate change has many consequences that most people are familiar with, such as rising temperatures, melting glaciers and floods, but there is one effect that you may not be familiar with. Climate change is causing sea turtle populations to be 99% female; male sea turtles are disappearing.

The sex of a sea turtle is determined by the temperature of the sand in which the eggs are incubated. Higher temperatures tend to favour female offspring, and rising air and sea temperatures are causing sand to retain more heat. Scientists who went to Australia’s Ingram Island expected the female-to-male ratio to be slightly in favour of females. Instead, they found that the gender ratio was significantly in favour of females, 116 to 1.

This discovery highlighted the extent of climate change’s effect on sea turtle populations. Scientists find this concerning as Australia’s sea turtles primarily nest in two locations: a collection of islands near Brisbane and a remote island known as Raine Island. If these two populations are predominantly female, then their futures are at risk.

Source: Queensland Government

A map of Australia’s north eastern coast showing Raine Island and Brisbane, where turtle populations were studied. Source: Queensland Government

By making incisions to determine gonads and examining blood samples for gender specific hormones, Camryn Allen, a scientist with the National Oceanic and Atmospheric Administration, and Michael Jensen, the lead investigator, determined that the turtle population on Raine Island has been predominantly female for the last 20 years. This is no small find; Raine Island is home to one of the biggest sea turtle rookeries on earth with more than 200,000 females nesting on the island. “It was worse than we thought”, remarks Jensen.

On the other hand, Allen and Jensen also found that turtles hatching from the south of Brisbane, where sea temperatures are fairly stable, have a healthy ratio of 2 to1, females to males.  This clearly shows the effects of climate change on sea turtle gender.

But just how consequential is this phenomenon? Because the populations’ gender coincides with sea temperatures, it is difficult to say at the moment. However, it may prove advantageous. Male sea turtles mate frequently and with more than just one female. Therefore, having more females than males can allow for more genetic diversity among populations.

Sea turtles have outlasted hunting, poaching, pollution, disease and habitat loss for hundreds of years. Why should they not outlast changing sea temperatures? Jensen believes that rapidly changing sea temperatures will make it more difficult for sea turtles to bounce back.  Adding that “evolution requires many generations for animals to adapt.” Sea turtles and other reptiles are so sensitive to changes in temperature that the slightest change could produce populations of only female offspring.

“The northern Great Barrier Reef is one of the most genetically distinct populations of sea turtles in the world. What’s really scary though is to think about applying this problem to populations where the numbers are low” says Allen on the implications of her research.

Allen and Jensen plan to continue their work at other nesting locations around the world, having already collected data from Guam, Hawaii and Saipan.

https://youtu.be/zOemoIbgx2c

From Youtube: Time lapse of turtles arriving at Raine Island by Biopixel.

– Ashlea Ahmed

References:

  1. Jensen, M. P.; Allen, C. D.; Eguchi, T.; Bell, I. P.; Lacasella, E. L.; Hilton, W. A.; Hof, C. A.; Dutton, P. H. Environmental Warming and Feminization of One of the Largest Sea Turtle Populations in the World. Current Biology [Online] 2018, 28, 154–159 (accessed Jan 22, 2018).https://news.nationalgeographic.com/2018/01/australia-green-sea-turtles-turning-female-climate-change-raine-island-sex-temperature/
  2. Welch, C. 99% of These Sea Turtles Are Turning Female-Here’s Why https://news.nationalgeographic.com/2018/01/australia-green-sea-turtles-turning-female-climate-change-raine-island-sex-temperature/ (accessed Jan 22, 2018).

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