Category Archives: Rosenstiel School of Marine and Atmospheric Science

Coral Bleaching of the Great Barrier Reef

The following article first appeared on the Research Blog for Dr. Neil Hammerschlag’s Shark Research and Conservation (SRC) Lab website at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science. To learn more about SRC, visit here:, or to learn more about the University’s marine science school, please click here:

By Delaney Reynolds, SRC intern

Coral reefs are some of planet earth’s most spectacular, diverse and important ecosystems. Our planet’s coral reefs provide important shelter, habitats, and a source of food for many different species of marine organisms. They also act as a critical food source to humans, as well a natural barrier to help protect our coastlines from hurricanes and associated storm surges. Sadly, coral reefs face growing risks including the possibility of extinction from a variety of stresses that leads to coral bleaching.

Coral Bleaching

Figure 1: Coral from which the zooxanthellae has been expelled, causing it to turn white (Image Source:

Coral bleaching is the process in which zooxanthellae, algae living symbiotically within the coral, are expelled from coral colonies due to a number of factors including an increase in temperature, decrease in pH, exposure to UV radiation, reduced salinity, and bacterial infections. Zooxanthellae provide the coral 30% of its nitrogen and 91% of its carbon needs to the coral host in exchange for a shelter, as well as waste produced by the coral from nitrogen, phosphorus, and carbon dioxide that is required for the algae’s growth (Baird, 2002).

When corals bleach, it effects entire marine communities due to their immense diversity. Fish populations that reside around coral reefs “are the most species dense vertebrate communities on earth, contributing critical ecosystem functions and providing crucial ecosystem services to human societies in tropical countries” (Graham, 2008). Researchers have found that when an ecosystem endures physical coral loss, fish species richness is extremely likely to decline due to their heavy reliance on the coral colony itself (Graham, 2008).

Perhaps the most famous current example of coral bleaching is Australia’s Great Barrier Reef. Scientists have determined that the main cause of Great Barrier Reef coral bleaching is induced thermal stress and that about 90% of the reef has been bleached since 1998 (Baird, 2002). As the corals bleach and temperatures increase, researchers have determined that shark and ray species that live in the area may be vulnerable to these climactic changes.

Exposure of Ecological Groups of GBR Sharks and Rays to Climate Change Factors

Figure 2: Exposure of Ecological Groups of GBR Sharks and Rays to Climate Change Factors. This figure displays the vulnerability different elasmobranch species face due to climate change, as well as the specific effects of climate change that they are vulnerable to, in the specific zones of the Great Barrier Reef. (Image Source: Chin et al. 2010)

Most of the Great Barrier Reef is located on the mid-shelf of the ocean floor, the approximate mid-point between the shallower coast of Australia and the continental shelf where the ocean bottom significantly drops in depth. Researchers found that the mid-shelf is the area where most of the shark species studied reside, while most rays dwell in coastal waters or closer to the continental shelf. It was also found that both areas are the susceptible to rising temperature, increased storm frequency and intensity, increasing acidity, current alterations, and freshwater runoff, all being caused by climate change (Chin, 2010). Based on these findings, researchers have concluded that the areas these elasmobranchs live in should be protected and preserved. Species in these highly vulnerable areas should also be monitored and considered for future conservation actions, as many of the shark species are already experiencing the effects of climate change from some of the aforementioned factors.

Typically, sharks are considered some of the strongest animals on earth, and while they have lived on earth for at least 420 million years, they are slow to adapt. This slowness has impeded their ability to survive in our rapidly changing climate. In the near future it will be common to see some species of marine organisms demonstrate plasticity, the ability to adapt to their changing environment, but other species, such as elasmobranchs, are expected to simply distribute to other habitats in search of cooler waters. Even though sharks are a highly vulnerable species to climate change, they sit at the top of the trophic level in many different niches and, thus, wherever they migrate to, it will be easier for them to find food than it would be for other species such as fish or rays. However, this is most likely only the case for adult sharks as embryos and juvenile sharks may be more vulnerable to increased temperatures. For instance, researchers found that the survival of bamboo shark embryos decreased from 100% at current temperatures to 80% under future ocean temperature scenarios and that the embryonic period was also shortened, not allowing the embryo enough time to develop fully (Rosa, 2014).

To decrease the effects of climate change on coral bleaching, corrective and mitigation measures can be taken. By utilizing green energy sources such as implementing solar power or wind power, walking or biking, and driving electric cars, we can reduce our use of fossil fuels and carbon footprint, thus decreasing the amount of carbon dioxide polluting and warming our atmosphere and oceans. While underwater and not always visible, coral reefs are truly a vital part of our ecosystem and need to be cherished and protected for generations to come.


Baird, A. H., & Marshall, P. A. (2002, July 18). Mortality, growth and reproduction in scleractinian corals following bleaching on the Great Barrier Reef. Retrieved from

Chin, A., Kyne, P. M., Walker, T. I. and McAuley, R. B. (2010), An integrated risk assessment for climate change: analyzing the vulnerability of sharks and rays on Australia’s Great Barrier Reef. Global Change Biology, 16: 1936–1953. doi:10.1111/j.1365-2486.2009.02128.x

Graham, N. A., McClanahan, T. R., MacNeil, M. A., Wilson, S. K., Polunin, N. V., Jennings, S., . . . Sheppard, C. R. (2008, August 27). Climate Warming, Marine Protected Areas and the Ocean-Scale Integrity of Coral Reef Ecosystems. Retrieved from

Rosa, R., Baptista, M., Lopes, V. M., Pegado, M. R., Paula, J. R., Trubenbach, K., . . . Repolho, T. (2014, August 13). Early-life exposure to climate change impairs tropical shark survival. Retrieved November 2, 2017, from

Righteousness or Reality?


Just when I thought I’d heard everything possible from the Trump Administration’s attack on our environment, including doing all they could possibly dream up to deny that man’s use of fossil fuels to power our cars and utilities and lives contributes to our planet’s climate crisis, comes this headline:

Energy chief Rick Perry says fossil fuels can prevent sexual assault



It will not surprise anyone that Perry, the former Governor of Texas and 2016 Presidential Candidate who is now President Trumps Energy Secretary, is a loyalist to fossil fuels given that his home state is filled with the stuff and that most of America’s biggest oil companies are based there. But now it appears that we’ve learned he is not only deeply biased but perhaps delusional too.

At an event sponsored by Axios and NBC News Perry explained that on a recent trip to Africa a girl there told him that electricity was important to her because she wanted to avoid using a lamp that produces noxious fumes to read at night, to study. He then went on in the interview to say:

“electricity also was important from the standpoint of sexual assault. When the lights are on, when you have light that shines the righteousness, if you will, on those types of acts.”

When I read the word righteousness I immediately think of its use in the context of religion or morality. To hear the United States Energy Secretary, a member of the President’s Cabinet, use it to tout the use of fossil fuels or to seemingly suggest that fossil fuels serve a righteous purpose is alarming. Could he be trying to suggest that God supports the use of fossil fuels? Or that the distribution and use of fossil fuels hold some moral purpose? You can decide for yourself by reading the article that caught my attention here but such a statement is troubling on any level (sickening really) and to read his comments that there is a link, or what he called a ‘positive role’, between fossil fuels and preventing sexual assault, is deeply disturbing. 

REAL NEWS FLASH To Secretary PerryElectricity is generated all over the world by all sorts of power sources other than fossil fuels including clean, sustainable sources such as the sun (solar), water (hydro) and wind.


I’ve been to Africa but I’ve not yet been to India. Thankfully former late night TV host and comedian David Letterman traveled to India as a Correspondent for the Season Two Premier of National Geographic’s Years of Living Dangerously entitled ‘A Race Against Time’ where he reported finding children studying at night by noxious kerosene burning lamps. He also reported that some 300 Million people in India (nearly the equivalent of the entire population of the United States) have no electricity of any type and that solar power is being used to provide electricity to change their lives for the better.

If you’ve not seen Years of Living Dangerously, a show that’s been called ‘must watch television’, then click here and start with David’s excellent episode and while you’re at it catch the episode entitled Saving Miami to learn about Miami’s plight.


I believe that our planet’s climate change crisis is the most significant issue that my generation will ever face. Of that I am certain and while I don’t know Jeff Dorian I sure do agree with what he wrote in a Letter to the Editor in the November 2nd edition of the Miami Herald and want to share it as a dose of reality.


I smoked cigarettes for 30-plus years. I ignored the warnings — liked them too much; kept thinking they wouldn’t affect me. The odds were in my favor. There is no family history of cancer, and my diet and exercise regimes were excellent.

Then came the heart attack.

I quit smoking, but the damage was done: irreversible loss of functioning capacity. If only I’d quit sooner, surely my health would be much better today.

All of us face a similar dilemma today. We must give up fossil fuels. Most Americans don’t think carbon emissions will affect them. The threat seems unsure and far in the future. We enjoy cheap fuel and fast cars too much. We don’t know how to give them up.

The warnings, again from scientists, again are clear and easy to understand. The deniers in Congress are once again denying and supporting business interests over protecting the public interest.

Once again, the damage is irreversible. My heart is not going to get stronger, and the ocean is not going to recede. People are now dying from effects of carbon emissions and associated climate change.

The solution, though not easy, is exquisitely simple: Just Google carbon fee.

– Jeff Dorian, Plantation

The debate on whether man has impacted our climate is long over97% of all scientists agree that that’s exactly what has happened and that carbon in our atmosphere has never been higher and that earth’s temperatures have, in 137 years of recorded data, never been hotter. And if we set politics, and ridiculous statements such as what Secretary Perry said last week aside, even the Trump’s Administration knows the truth and just published it on Friday November 3rd in America’s annual National Climate Assessment.

Hundreds of experts from 13 agencies in our federal government and the academic world researched and wrote the report which was then peer-reviewed by the National Academy of Sciences. You can find the report here and once you’ve read it, or read one of the many articles published about it in recent days like this one, we should all ask ourselves whether we, as citizens of this planet, will continue to allow politicians and their puppets to lie to us, to disrespect us, or do we decide to elect leaders who are serious about solving this well documented problem?

IF the Trump Administration’s goal is to truly do what’s righteous for our country’s future then allow me to suggest that the President announce that the United States will quickly become the world’s leading manufacturer of solar panels and that America will install solar power any and everywhere in our Country as well as in places such as Africa and, for that matter, India too. Make it our generation’s ‘trip to the moon’ as President Kennedy did in the early 1960’s when he made sending men to explore the moon our national focus. The reality is that such an inspirational initiative would create millions of jobs while changing people’s lives and our environment for the better at the same time.

Now that is a reality that I can support and one that would be truly filled with righteousness.

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