Even Resilient Reefs in American Samoa Threatened by Mass Bleaching

Posted on February 18, 2016 by jwh11

For Americans who want to experience a tropical Pacific vacation where they can sit under palm trees and dive in coral reefs, American Samoa is a popular choice, you don’t even need a passport to go! Unfortunately, American Samoan reefs have taken a beating in the last few decades, and more harm may come to the reefs this year.

American Samoa is a small collection of tropical islands in the South Pacific composed of the five islands and two atolls. The largest island is Tutuila, with tiny Aunu’u nearby. About a hundred kilometers to the east is the Manua group, containing the islands Ofu, Olosega, and Ta’u. Scattered several hundred kilometers out are the atolls, Rose Atoll to the east, and Swains Island to the north [1].

Screen Shot 2016-02-18 at 4.43.48 PM

Map of American Samoa, from Lundblad et al.

Samoan reefs are known to be some of the most resilient in the world, even so, they have not been immune from many of the troubles coral reefs around the word have been facing. The reefs suffered greatly from an outbreak of crown of thorns starfish (COTS) in 1978, which decreased coral cover by as much as 68%. The reefs have been damaged by a half-dozen hurricanes since the 1980’s, and have dealt with extreme low tides on three occasions since 1998. In 1994, 2003, and 2004, American Samoan reefs suffered bleaching events [2]. Bleached corals have also been seen in 2014 and 2015 [3].

XL-Catlin-Seaview-Survey-American-Samoa-5

Coral bleaching captured between December 2014 and February 2015, from http://www.globalcoralbleaching.org/

Part of the American Samoan reefs’ resilience may come from their natural tolerance of high temperatures. For instance, Acropora corals near Ofu island have been seen weathering temperatures over 32°C [4].

For the more than 200 coral species found in reefs in American Samoa, climate change caused by humans puts them at risk for bleaching and leaves them susceptible to disease [5]. Sick corals are bad news to industries such as tourism and fishing, and particularly impact native peoples who rely on the sea.

This year, reefs in American Samoa are threatened once again. Bleaching has already been observed in late 2014 and early 2015 [3]. According to the National Oceanic and Atmospheric Administration’s (NOAA) Coral Reef Watch project, American Samoa and the surrounding oceans are facing a warning for mass coral bleaching events [6]. 2016 may see some tough times for reefs in American Samoa.

BleachWarning

NOAA’s Coral Reef Watch warnings for the South Pacific. From http://coralreefwatch.noaa.gov/

As climate change progresses, be prepared to see more and more reefs around the world fall ill due to mass bleaching events

1.) Lundblad, Emily R., Dawn J. Wright, Joyce Miller, Emily M. Larkin, Ronald Rinehart, David F. Naar, Brian T. Donahue, S. Miles Anderson, and Tim Battista. “A Benthic Terrain Classification Scheme for American Samoa.” Marine Geodesy 29.2 (2006): 89-111. Web.

2.) Wilkinson, Clive R. Status of Coral Reefs of the World: 2008. Townsville, Australia: Global Coral Reef Monitoring Network, Reef and Rainforest Research Centre, 2008.

3.) Global Coral Bleaching. Underwater Earth, 2015. Web. <http://www.globalcoralbleaching.org/>.

4.) Global Coral Bleaching. Underwater Earth, 2015. Web. <http://www.globalcoralbleaching.org/>.

5.) Aeby, Greta, Thierry Work, and Eva Didonato. Coral and Crustose Coralline Algae Disease on the Reefs of American Samoa (2005): 1-25. Web.

6.) “NOAA Coral Reef Watch Homepage.” NOAA Coral Reef Watch Homepage. US Department of Commerce, n.d. Web. 18 Feb. 2016.

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Third Global Coral Bleaching Event Threatens Recovering Seychelles

Posted on February 18, 2016 by amk12

The year 2015 was the hottest on record, according to statistics from the National Oceanic and Atmospheric Association. The year 2015 was also the year that NOAA scientists announced that the world is experiencing its third global bleaching event, where an estimated 38% of corals worldwide could be affected, threatening the state of coral reef  ecosystems and the people that rely on them.1 Coral bleaching remains visibly indicative of climate change and local stressors because corals and their symbioses with dinoflagellate algae is a fragile and complex system.

Purple coral symbiodinium

Photo Credit: Dr. Andy Bruckner

To understand what bleaching is, it is relevant to understand the symbiosis between corals and the dinoflagellate algae that live in their tissues. These algae, also called zooxenthellae, or Symbiodinium, and corals have a mutualistic relationship, whereby their living together benefits both partners. Most stony, shallow, reef-building corals of the order Scleractinia have zooxenthellae while soft corals and deep-water corals generally do not. Corals capture planktonic food and excrete nitrogenous waste that is recycled by zooxenthellae and used for coral growth. Zooxenthellae are autotrophic and provide carbon for building the corals’ skeleton and produce sugars and starches for the coral by means of photosynthesis. The coral provides shelter and a fixed habitat for the zooxenthellae.

Environmental stressors and increased anthropogenic factors can easily disturb this key relationship and result in corals releasing their zooxenthellae.2 Interestingly enough, symbiodinium live in habitats 1-2°C below temperatures that cause stress and bleaching.2 Bleached coral appears pale and there is little to no pigment left in its tissues. Coral colonies are able to recover if the influx of warm temperatures dissipates, however; prolonged periods of warm temperatures will most likely cause too much damage to corals and they will become diseased or die3.

Figure 4. “An extended bleaching outlook showing the threat of bleaching expected in Kiribati, Galapagos Islands, the South Pacific, especially east of the dateline and perhaps affecting Polynesia, and most coral reef regions in the Indian Ocean.” (3)

[5]

Map of seychelles

[6]

The Seychelles is an archipelago of islands off of the coast of East Africa in the Indian Ocean that is home to a diverse array of coral communities. The Seychelles faced the brunt of the widespread El Niño induced warming and subsequent global bleaching event in 1998 and experienced 90% loss of coral cover.4 An El Niño has again occurred in the past year. The large swath of hot water temperatures in the Pacific that are indicative of coral bleaching has been nicknamed, “The Blob,” and this kind of warming is predicted to occur in the Indian Ocean during the spring and summer of 2016.5 The predicted graph above is particularly worrisome because it shows a 60% probability of Alert Level 1 and Alert Level 2 warming events occurring across the Indian Ocean and these temperatures are very likely to cause another bleaching event in the Seychelles, which is still recovering from the devastating effects of the 1998 bleaching event.5 Read my next blog entry to learn more about the status of recovery in the Seychelles and how reef composition changes in response to bleaching events.

  1. “El Niño and the 2014-2016 Global Coral Bleaching Event.” NOAA Satellite and Information Service. 2016. http://coralreefwatch.noaa.gov/satellite/analyses_guidance/enso_bleaching_97-99_ag_20140507.php.
  2. Sheppard, Charles R.C., Simon K. Davy, and Graham M. Piling. The Biology of Coral Reefs. Oxford University Press, 2009.
  3. Wilkinson C, O. Linden, H. Cesar, G. Hodgson, J. Rubens, and A.E. Strong, 1999. Ecological and socioeconomic impacts of 1998 coral mortality in the Indian Ocean: An ENSO impact and a warning of future change? Ambio 28, 188-196.
  4. Graham, N. A. J. et al. Dynamic fragility of oceanic coral reef ecosystems. Natl Acad. Sci. USA 103, 8425–8429 (2006)
  5. “NOAA Declares Third Ever Global Coral Bleaching Event.” NOAA. October 8, 2015. Accessed February 18, 2016. http://www.noaanews.noaa.gov/stories2015/100815-noaa-declares-third-ever-global-coral-bleaching-event.html.
  6. http://www.worldatlas.com/webimage/countrys/africa/sc.htm 18 Feb. 2016
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Reefs off the Kenyan Coast in Danger

Posted on February 18, 2016 by mcj2

Coral reefs make up the largest biological structures that currently exist on our planet and take many thousands of years to form [1].  Today, the world’s already deteriorating reefs are further threatened by looming temperature increases due to global climate change. Coral bleaching is the main culprit responsible for the death of these coral colonies [2]. Bleaching occurs when corals lose their relationship with their partners, microscopic algae called zooxanthellae [3]. In a healthy reef, the corals depend on this relationship with zooxanthellae which live inside the coral tissue [3]. Not only to these microscopic algae give corals their brilliant colors, they are the main providers of food for the animals [3]. Under certain environmental stressors, the algae will leave its animal host, leaving the coral bleached [2]. A bleached coral has little means to feed itself and is put at a high risk for disease [2].

Without their xoozanthellae partners, corals take on an eerie white color. source: coralreefwatch.noaa.gov

Causes of coral bleaching also include pollution from runoff, low tides that expose the corals to air, and overexposure to intense sunlight and UV radiation [1]. Temperature increases are, however, the primary cause [1].  Many corals are extremely sensitive to heat stress. In fact, an increase of a few degrees over the corals’ tolerance level can cause bleaching and prove deadly [4].  If the bleaching is severe, it can have debilitating effects on both the ecosystem and any economy that relies on it [1].  It can take decades for a badly bleached reef to fully recover (if it recovers at all) [2].

Predicted stress levels with dark red representing areas most likely to see bleaching between February and May of 2016. source: www.noaanews.noaa.gov

Predicted stress levels on the East African coast with dark red representing areas most likely to see bleaching between February and May of 2016. source: www.noaanews.noaa.gov

Last October (2015), the National Oceanic and Atmospheric Administration (NOAA) declared the third global coral bleaching event and highlighted reefs that are predicted to be most severely impacted by the event [1]. One such area is the reefs off the coast of Kenya in eastern Africa [1]. The reef extends from just north of the city of Lamu to the nation’s southern border with Tanzania [5].

Grey areas show location of reefs on Africa's east coast. source: ICRI: Status of Coral Reefs of the World

Grey areas show location of reefs on Africa’s east coast. source: ICRI: Status of Coral Reefs of the World

Currently, there are many groups researching and monitoring Kenya’s reefs including the Kenya Marine & Fisheries Research Institue (KMFRI), Coastal Ocean Research and Development in the Indian Ocean (CORDIO), Kenya Wildlife Services (KWS), and the Wildlife Conservation Society (WCS) [6]. In 1998, a massive bleaching even struck the reef, and data from that event can inform scientists’ predictions about the aftermath of the current global bleaching event [5]. During the 1998 bleaching event, an astounding 90% of coral cover was destroyed [5]. It took over two decades for coral cover to reach between 18 and 40% depending on the area surveyed [6]. One surprising find in monitoring the reef’s recovery was that the recovery of MPAs (Marine Protected Areas) was no faster than that of areas where activities such as fishing were unregulated [6]. However, recovery in newly-declared MPAs was substantially faster than reef recovery of unprotected and older MPAs [6]. It is still unclear what causes this difference in recovery rates, but researchers say there are multiple environmental variables at work [6].

fishing is a vital part of Kenya’s coastal communities. source: chans-net.org

Over a 14 year period that included the 1998 bleaching event, the size of coral colonies decreased significantly [5]. This decrease was in part due to over-fishing of the coastal waters by local fishermen [6] Though the Kenyan government has enacted measures to promote better fishing practices that are less harmful to the reef, unfortunately such policies are hard to enforce [6].

Watamu Marine National Park, source: watamu.biz

Watamu Marine National Park off the coast of Kenya, source: watamu.biz

While the fate of Kenya’s reefs is unknown at the moment, predictions from NOAA are less than hopeful. It is likely that these reefs will be dramatically impacted in the months to come. A glimmer of hope exists in the ecosystem’s ability to bounce back from such environmental tragedies and the nation’s growing efforts to protect their natural treasures.

References:

  1. NOAA Coral Reef Watch Methodology, Product Description, and Data Availability of NOAA Coral Reef Watch (CRW) Operational and Experimental Satellite Coral Bleaching Monitoring Products (2011) NOAA Satellite and Information Service.
  2. Wilkinson, C. (2008). Status of coral reefs of the world: 2008. Global Coral Reef Monitoring Network and Reef and Rainforest Research Centre, Townsville, Australia, 296 p.
  3.  Sheppard, Charles, Simon K. Davy, and Graham M. Pilling. (2009) The Biology of Coral Reefs. Oxford: Oxford UP.
  4. Reaser, J. K., R. Pomerance, and P. O. Thomas (2000) Coral bleaching and global climate change: Scientific findings and policy recommendations, Conservation Biology, 14, 1500-1511.
  5. McClanahan, T.R. (1988) Seasonality in East Africa’s coastal waters. Mar. Ecol. Prog. Ser. 44: 191-199.
  6. ICRI: Status of Coral Reefs of the World, 2008 (2008) 91- 96.

 

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Islands of Kiribati: Saved by the Current?

Posted on February 18, 2016 by akw6

Think of the most beautiful natural environment you can. The place where you would just stand there, in awe of the sights before you. If you are like most people, you likely pictured a coral reef. Their stunning array of marine organisms, all fitting into their ecological niches, is truly a sight to behold. The island nation of Kiribati is no exception. It consists of a collection of 33 atolls, 21 of which are inhabited. They are located just west of the International Date Line (6).

Figure 1. “Sharks swim of a pristine reef at Millennium Atoll in the southern Line Islands, Kiribati.” (7)

Figure 1. “Sharks swim of a pristine reef at Millennium Atoll in the southern Line Islands, Kiribati.” (7)

Figure 2. Map of Kiribati, showing three groups of Islands. These are the Gilbert, Phoenix, and Line Islands. (2).

Figure 2. Map of Kiribati, showing three groups of Islands. These are the Gilbert, Phoenix, and Line Islands. (2).

Unfortunately for Kiribati, it is extremely vulnerable to the effects of climate change. Already, rising sea levels are having detrimental effects on the island nation. Studies have shown that global sea levels have risen by approximately eight to ten inches since 1880. Some projections have indicated that sea levels may rise by three feet by 2100. Kiribati could become the first nation for face a refugee crisis due to climate change (1).

However, the potential social and economic problems that Kiribati faces due to the climate change are not the whole picture. Other effects of climate change will have drastic effects on the surrounding coral communities. Rising sea temperatures have repeatedly been connected to coral bleaching events. This produces biological stress that causes their symbiotic algae to be expelled (6). This process is known as coral bleaching and it is a worldwide ecological phenomenon. When these symbiotic algae are expelled, the corals lose the benefits for their biological relationship. This has cascading effects on the rest of the coral reef ecosystem, thus destabilizing a whole region (5).

NOAA, the National Oceanic and Atmospheric Administration, has identified the third global coral bleaching event (4). Using a synthesis of their climatic data, the organization has created predictions for the threat levels of global coral reefs. While Kiribati does not seem to be in grave danger in the 4-month bleaching outlook, they do have Alert Level 1 status in the extended bleaching prediction.

Figure 3. “NOAA’s standard 4-month bleaching outlook shows a threat of bleaching continuing in the Caribbean, Hawaii and Kiribati, and potentially expanding into the Republic of the Marshall Islands.” (3)

Figure 3. “NOAA’s standard 4-month bleaching outlook shows a threat of bleaching continuing in the Caribbean, Hawaii and Kiribati, and potentially expanding into the Republic of the Marshall Islands.” (3)

Figure 4. “An extended bleaching outlook showing the threat of bleaching expected in Kiribati, Galapagos Islands, the South Pacific, especially east of the dateline and perhaps affecting Polynesia, and most coral reef regions in the Indian Ocean.” (3)

Figure 4. “An extended bleaching outlook showing the threat of bleaching expected in Kiribati, Galapagos Islands, the South Pacific, especially east of the dateline and perhaps affecting Polynesia, and most coral reef regions in the Indian Ocean.” (3)

Interestingly, there has been some evidence that the islands of Kiribati are fairing better than some of their nearby counterparts. This may be due to a cool current that specifically targets this area. While it is not thought that that this current will save corals from the global bleaching event, it may slow the process to a point where intervention may have a chance (5). Read the next entry of this blog to find out how these changes have affected the Kiribati Island reefs!

 

References

  1. Davenport, C. (n.d.). Rising Seas. The New York Times. Retrieved February 17, 2016, from http://www.nytimes.com/interactive/2014/03/27/world/climate-rising-seas.html?_r=0
  2. Map of Kiribati. (n.d.). Retrieved February 17, 2016, from http://www.climate.gov.ki/wp-content/uploads/2012/10/map_kiribati.gif
  3. NOAA Bleaching Predictions. (n.d.). Retrieved February 17, 2016, from http://www.noaanews.noaa.gov/stories2015/100815-noaa-declares-third-ever-global-coral-bleaching-event.html
  4. NOAA declares third ever global coral bleaching event. (n.d.). Retrieved February 17, 2016, from http://www.noaanews.noaa.gov/stories2015/100815-noaa-declares-third-ever-global-coral-bleaching-event.html
  5. Pacific Islands Protect Coral Reefs from Bleaching. (n.d.). Retrieved February 17, 2016, from http://www.pri.org/stories/2012-06-28/pacific-islands-protect-coral-reefs-bleaching
  6. Rising Sea Level in the Republic of Kiribati | Global Warming Effects. (n.d.). Retrieved February 17, 2016, from http://www.climatehotmap.org/global-warming-locations/republic-of-kiribati.html
  7. Sharks Over Millennium Atoll. (n.d.). Retrieved February 17, 2016, from http://blogs.ei.columbia.edu/2015/08/17/can-we-save-coral-reefs/

 

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Paradise in Peril: Coral Bleaching and its Effects on Hawaiian Reefs

Posted on February 17, 2016 by Sasha

We have all dreamed of visiting the idyllic waters of Hawaii, with colorful fish flitting around corals that reach up from the ocean floor towards light filtering in from above. Perhaps a moray eel sticks his head out from one of the many crevices in the reef to say hello – or is he warning you away? A few meters away, a green sea turtle dives down to graze on sea grass waving gently with the current.

But this perfect scene might remain a dream, if scientists’ predictions are correct. Current ocean conditions are putting corals at risk of coral bleaching, a phenomenon where corals lose their color. Some reefs in Hawaii have already begun to bleach, while others will likely bleach in the near future. So what is coral bleaching, and why is it happening?

Although they look like rocks, corals are animals. Each coral is made up of tiny polyps that deposit calcium carbonate underneath them as they grow. This means that only the outside layer of the coral is alive, the rest has become stone. Corals get their coloration from tiny single-celled algae called zooxanthellae. The zooxathellae are in a symbiotic relationship with the coral, meaning both the algae and the coral benefit from the relationship. The zooxanthellae are photosynthetic and create carbohydrates and other nutrients for the coral, while the coral provides protection and nutrients that the algae needs in order to photosynthesize1.

Polyps

Coral polyps evident on a coral in Florida. Image Credit: Brett Levin

Coral bleaching occurs when the symbiosis between coral and zooxanthellae breaks down. This usually occurs in high-stress environments, such as when the water temperature remains too high for long periods of time, or when sunlight reaching the corals is too direct and bright. During coral bleaching, the zooxanthellae leave the coral tissue, which makes the coral appear pale or white. It is unclear whether the coral kick out the zooxanthellae or whether they leave on their own2. Coral bleaching is a problem because most corals cannot obtain enough nutrients without the help of the symbiotic algae. So although corals can survive a bleaching event if they get their algae back, they have a limited time frame in which to do so.

The National Oceanic and Atmospheric Administration (NOAA) recently released a report warning that we are entering the third global bleaching event ever recorded3. Each bleaching event has been correlated with El Niño, a climate pattern that raises ocean temperatures in the Pacific Ocean. The first two events happened in 1998 and 2010. Although some reefs had mortality rates as high as 80-90% during the 1998 event, Hawaiian reefs were left largely unscathed4. This was not the case during the 2010 event. In Kaneohe Bay, which makes up 15% of all coral in the United States, 75% of coral species bleached to some extent, and 12% died5. The most recent  bleaching event is predicted to cause even more damage.

Bleached Coral in Kaheohe Bay Hawaii 2

Bleached coral in Kaneohe Bay (2015). Image Credit: XL Catlin Seaview Survey

Coral ecosystems are extremely important. Corals provide a 3-dimensional structure that is home to huge numbers of fish and other marine species. Bleaching has the potential to ruin these ecosystems, putting thousands of organisms in danger. Scientists are worried about coral bleaching because it could cause chain reactions and lead to effects that we wouldn’t usually consider, like coastal erosion. Reefs protect coasts by reducing wave energy. If the reefs die and disintegrate, coastal areas will be hit with more wave energy and could be drastically altered.

From what we have observed, bleaching events seem to be correlated with El Niño, because temperatures are raised for long periods of time. But water temperatures recorded during each global bleaching event have continued to rise, and bleaching events have become more common. This is where climate change comes in, and where we may be able to alter our behaviors to help the corals. By stopping or slowing down climate change, we may be able to give corals a chance to adapt to higher water temperatures. We can also help corals by deterring their competitors, macroalgae6. When corals bleach, they are unable to compete with other algae (not the symbiotic zooxanthellae). The algae overgrow the coral and prevent the coral from recolonizing the area. Because algae like water with a lot of nutrients and algae prefer water with few nutrients, we can help corals by refraining from polluting the water with nutrients, such as fertilizers. In this way, each of us may be able to contribute to maintaining the picturesque tropical scenes that we love so much.

1 “Symbiotic Algae.” Coral Reef Conservation Program. NOAA, 2011.

2 Rowan, Rob. “Review-Diversity And Ecology Of Zooxanthellae On Coral Reefs.” Journal of Phycology 34.3 (1998): 407-17.

3 “NOAA Declares Third Ever Global Coral Bleaching Event.” NOAA, 8 Oct. 2015.

4 Goreau, Tom, Tim McClanahan, Ray Hayes, and Al Strong. “Conservation of Coral Reefs after the 1998 Global Bleaching Event.” Conservation Biology 14.1 (2000): 5-15.

5 Tribune Wire Reports. “Most of Hawaii’s Coral Recover from Mass Bleaching: DNR Survey.” Chicago Tribune, 29 Jan. 2015.

6 Associated Press. “Hawaii to Experience Worst-ever Coral Bleaching Due to High Ocean Temperatures.” The Guardian. Guardian News and Media, 13 Sept. 2015.

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Coral Greefs – Threats in the Galapagos Islands

Posted on February 17, 2016 by aay1

For me, it’s always been hard to wrap my mind around the fact that corals are actually living organisms. They eat, they fight, and they reproduce. Yet, I still tend to think of them as underwater rocks. However, the real shocker is that they are all currently in danger.

Map of the Galapagos Islands (http://www.traveldiscounters.ca/Travel-Vacations/DestinationImages/Galapagos-Islands-Map.jpg)

The Galapagos Islands, located in the Eastern Pacific Ocean, are an archipelago of volcanic islands surrounded by a vastly diverse ecosystem of large populations of marine life and coral communities. These coral reefs are being threatened with extinction. Pressures include changes in temperature, acidification, sedimentation, pollution, and overfishing. (1)

In 1982-1983, El Niño caused the temperatures in the Galapagos to rise 3-4 degrees Celsius above the usual maximum sea temperatures. (3) An increase in temperature leads to stress in the corals, which in turn causes them to expel the symbiotic algae living in their tissues and become white in color. Without the algae, the coral loses its major source of food and is more susceptible to disease. This process is referred to as coral bleaching. (2) Currently, the area around the Galapagos Islands is about 29 degrees Celsius, a degree and a half warmer than the critical temperature for bleaching for corals at that site. (2) If the stress is only temporary, corals are expected to recover. However, none of the Galapagos’ southern reefs show any signs of recovery. (3)

Coral Bleaching in the Galapagos  (http://www.haugancruises.com/images/news/galapagos-reefs.jpg )

In addition to changes in temperature, another big factor in coral bleaching near the Galapagos Islands is seawater acidity. Upwelling, the rising of deep, cold water towards the surface, along the coasts of the Galapagos has lead to high carbon dioxide concentrations. As a result, the seawater has a lower pH, making it more acidic. High levels of carbon dioxide negatively affect corals as well as other organisms. These conditions are expected to reach the rest of the tropics by the 2050’s. (3) Derek Manzello, a coral ecologist and researcher for NOAA’s National Coral Reef Monitor Program, conducted field studies and determined that at present day acidification levels corals can recover, but their recovery is dependent on water quality conditions. (3)

 

Only one surviving reef off the coast of Darwin Island in the northern Galápagos Islands. Photo Credit: Joshua Feingold (3)

Right now, coral bleaching is one of the largest threats to coral reefs all around the world. The current conditions have been declared the third global coral bleaching event. (4) Estimates have proposed that 20% of the world’s coral reefs are already dead and an additional 24% are endangered. (1) This event has been projected to last well into 2016, and very likely to continue spreading worldwide. (4) If nothing is done to help the coral reefs, marine organisms everywhere will continue to suffer.

NOAA Coral Reef Watch 60% Probability Coral Bleaching Thermal Stress for Oct-Jan 2016

NOAA Coral Reef Watch 60% Probability Coral Bleaching Thermal Stress for Oct-Jan 2016 (4)

 

Sources:

  1. Kazan, Casey. “The Galapagos Islands – Destruction of the World’s Coral Reefs.” The Daily Galaxy. N.p., 16 Dec. 2009. Web. <http://www.dailygalaxy.com/my_weblog/2009/12/galapagos-islands-a-harbinger-for-the-destruction-of-the-worlds-coral-reefs.html>.
  2. Viets, Patricia. “EL NINO CAUSING CORAL BLEACHING IN GALAPAGOS, NOAA ANNOUNCES.” NOAA, 20 Jan. 1998. Web. <http://www.publicaffairs.noaa.gov/pr98/jan98/noaa98-004.html>.
  3. “The Galápagos Islands: A Glimpse into the Future of Our Oceans.” NOAA AOML, 2006. Web. <http://www.aoml.noaa.gov/keynotes/keynotes_0115_galapagos.html>.
  4. “NOAA Declares Third Ever Global Coral Bleaching Event.” NOAA, 8 Oct. 2015. Web. <http://www.noaanews.noaa.gov/stories2015/100815-noaa-declares-third-ever-global-coral-bleaching-event.html>.
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Coral Bleaching in South Atlantic: The Abrolhos Marine National Park

Posted on February 17, 2016 by pb21

NOAA (National Oceanic and Atmospheric Administration) has recently declared the third ever Global Bleaching Event (1). You might have heard of Coral Bleaching, but what exactly is that? Well, first we have to understand what gives corals their colors. Stony corals, which are animals related to anemones and jellyfish, adopted a sedentary lifestyle, where they sit on a rock and grow by building their own Substrate (CaCO3), which later becomes limestone and builds the solid reef structures. But they are not alone in this process: they do it with the help of Zooxanthella, unicellular algae in the genus Symbiodinium.

The Symbiodinium cells live inside the coral colonies, in between their cells, where the algae make photosynthesis and both organisms help each other in a relation know as symbiosis (somewhat like a friendship). To make the Photosynthesis, algae carry many different photosynthetic pigments, what gives them (and the coral colonies) their multiple colors. However, when corals are under stressful conditions, such as increased temperature, their relation with the algae is disturbed, and they lose their algae friends. The result is the so called Coral Bleaching: Colonies turn white, the color of their CaCO3 skeletons, sadly now free of the algae (Figure 1).

1

Figure 1: Bleaching in a Colony of Siderastrea stellate, a common species in South Atlantic reefs. Picture by Beatrice P. Ferreira, available at 2.

 The exact reason why corals do that is unclear, but scientists know what triggers it. Most coral bleaching events are caused by changes in water temperature (3), such as those that happen during the El-Niño phenomenon in the Pacific Ocean. In fact, both previous Global Bleaching Events (1998 and 2010) happened in years with strong El-Niños, and this year, with the strongest El-Niño in decades, is not different. This phenomenon affects not only the Pacific Ocean, but also has an influence on global ocean temperatures at different intensities and times. In the Atlantic Ocean, the North portion is affected first from October to January, and South Atlantic is usually affected between February and May (Figure 2)

2

Figure 2: Temperature Anamalies and Bleaching Risk Map of the Atlantic Ocean. Blue arrow shows aproximate location of The Abrolhos Marine National Park. Image adapted from NOAA (1)

Reefs is South Atlantic Ocean are characterized by relatively low diversity, with only 18 coral species. However, Abrolhos Marine National Park houses all of them, being thus a very important conservation site in South Atlantic (4). Abrolhos (Figure 3) was the first Brazilian ocean National park, established in 1983. It is comprised of five islands and their respective fringing reefs (2), in addition to one isolated coastal bank reef and other smaller mushroom-shaped structures locally known as chapeirões (5). It is located 70 Km (43 miles) offshore of the Brazilian Bahia State between the latitudes 17º25’ -18º09’ South.

Abrolhos area has been affected by bleaching in the past, and those events are usually related to ocean surface temperature anomalies, like those caused in years of El-Niño (2). The first record of coral bleaching is from 1994 (6), where up to 70% of corals had some bleaching. It happened again in 1998, during the first Global Bleaching Event, and 60% of coral colonies bleached in the months of March, April and May (7), when the thermal anomalies of El-Niño affect South Atlantic. In 2003, a local ‘hot spot’ caused up to 17% of bleaching, not that bad when compared to previous ones. In 2005, again coinciding with an El-Niño, bleaching affected up to 33% of coral colonies, not surprisingly, between March and May. In 2006, a milder event occurred, with about 7% of bleaching. 2007 and 2008 where years in which some species bleached, again in the first semester of the year, with up to 90% of colonies of some species showing pigmentation alterations (3). This was the most recent bleaching event recorded in the literature for the area.

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Figure 3: Abrolhos Marine National Park five islands and their fringing reefs. Picture by Marcelo Skaf, available at 8.

               As a consequence of the current temperature anomalies and in the context of the current Global Coral Bleaching Event, Abrolhos Marine National Park is likely to face another Bleaching event during the following months. A study group led by Dr. Kikuchi and Dr. Leão, both professors of the Federal University of Bahia, in Brazil, is going to monitor bleaching in the Abrolhos area during the following months, and as it has been before, if it happens, they may get it on act.

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(1)http://www.noaanews.noaa.gov/stories2015/100815-noaa-declares-third-ever-global-coral-bleaching-event.html, accessed in 14/2/2016.

(2)Ferreira, B. P., & Maida, M. (2006). Monitoramento dos recifes de coral do Brasil. MMA, Secretaria Biodiversidade e Florestas.

(3)Sassi, R., Costa Sassi, C. F., Gorlach-Lira, K., & Fitt, W. K. (2015). Pigmentation changes in Siderastrea spp. during bleaching events in the costal reefs of northeastern Brazil. Cambios En La Pigmentación de Colonias de Siderastrea Spp. Durante Los Eventos de Blanqueamiento En Arrecifes Costeros Del Noreste de Brasil., 43(1), 176–185. http://doi.org/10.3856/vol43-issue1-fulltext-15

(4)Leão, Z.M.A.N., Kikuchi,R.K. and Testa,V., (2003). Corals and coral reefs of Brazil. In Latin American Coral Reefs, J. Cortés (Ed.), pp. 9–52 (Amsterdam: Elsevier). In In Krug, L. A., Gherardi, D. F. M., Stech, J. L., de Andrade, Z. M., & de Kikuchi, R. K. P. (2012). Characterization of coral bleaching environments and their variation along the Bahia state coast, Brazil. International Journal of Remote Sensing, 33(13), 4059–4074. http://doi.org/10.1080/01431161.2011.639505

(5)Rodríguez-Ramíres, A., Bastidas, C., Rodríguz, S., Leão, Z., & Kikuchi, R. (2005). The of Coral Bleaching in Southern Tropical America: Brazil , Colombia, and Venezuela. Status of Caribbean Coral Reefs after Bleaching and Hurricanes in 2005, 105–114.

(6)Castro, C. B. & Pires, D. O. (1999). A bleaching event on a Brazilian coral reef. Brazilian Journal of Oceanography, 47: 87-90.

(7)Leão, Z., Kikuchi, R., Oliveira, M., & Vasconcellos, V. (2010). Status of Eastern Brazilian coral reefs in time of climate changes. Pan-American Journal of Aquatic Sciences, 5(2), 224–235. http://doi.org/10.1016/B978-044451388-5/50003-5

(8)Leão, Z. M. A. N. (1999). Abrolhos-The south Atlantic largest coral reef complex. Schobbenhaus, C; Campos, DA; Queiroz, ET; Winge, M.

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The Marshall Islands are experiencing their worst historical coral bleaching event

Posted on February 17, 2016 by Hanna

If you’ve heard anything about coral reefs recently, you’ve probably heard something about coral bleaching. Maybe you’ve heard about El Niño’s oceanic effects or seen before and after pictures of once colorful reefs. Coral bleaching is a real threat to reefs, and it occurs when abiotic conditions like temperature, nutrients, or exposure change. This causes corals to stress and get rid of their helpful algal tissue components. These symbiotic algae are what normally give corals their bright colors, and without them corals turn white, leading to the name coral bleaching[1].

XL-Catlin-Seaview-Survey-American-Samoa-5-1024x682

A before photo (December 2014) and after photo (February 2015) of coral bleaching in American Samoa (XL Catlin Seaview Survey).

This blog will focus on the coral reefs surrounding the Marshall Islands, an island nation in the central pacific. The Marshall Islands are grouped into 5 coral islands and 29 coral atolls (that’s more than 10% of the world’s atolls!)[2]. The islands are made up of two main chains—the upper, Ratak, means sunrise, while the lower, Ralik, means sunset.

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Map of the Marshall Islands.(http://www.myinterestingfacts.com/marshall-islands-facts/)

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A closer view of the Marshall Islands. (http://www.worldatlas.com/webimage/countrys/oceania/lgcolor/mhcolor.htm)

Although the Marshall Island’s reefs are fairly isolated and well-protected, they have still suffered some significant damage. Increasing threats to coral reefs in the area include overfishing, pollution, coral disease, and extreme weather patterns[3]. The current major threat to the Marshall Islands is due to the latter. Climate change and El Niño are combining to significantly increase oceanic water temperatures, causing coral bleaching in many reefs in the Pacific[4]. By the end of this year, it is estimated that this event will kill over 533 square miles of reef.

This event is known as mass coral bleaching, and this isn’t the first time it has happened. From 1997-98, sea surface temperatures rose and caused a global bleaching event. The same pattern occurred due to 2010’s El Niño event[5]. Below, you can see a comparison of sea surface temperatures between then and now.  This data shows that we are now in the midst of third global bleaching event.

 

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Comparison of sea surface temperatures at peak global bleaching events in 1997 and 2015 (NOAA, http://www.globalcoralbleaching.org/)

In the Marshall Islands, coral bleaching has already begun to impact reefs. Temperatures have been building in the island’s oceans since September, and it has been described as the worst coral bleaching to ever occur in the area[6].

Coral-Bleaching_3145708b

Bleached Marshall Islands coral (The Telegraph, http://www.telegraph.co.uk/news/worldnews/australiaandthepacific/marshallislands/11308173/Global-warming-blamed-for-worst-ever-Marshall-Islands-coral-bleaching.html).

Experts are continuing to monitor reef conditions in the Marshall Islands and surrounding Oceania. Be sure to check back here for more updates on coral bleaching in the Marshall Islands as weather patterns continue and more information is available!

 

 

[1] National Oceanic and Atmospheric Administration (NOAA). “What is coral bleaching?” 2015.  http://oceanservice.noaa.gov/facts/coral_bleach.html

[2] National Oceanic and Atmospheric Administration (NOAA). “Coral Reef Information System: Republic of the Marshall Islands” 2015.

[3] U.S. All Islands Coral Reef Committee. “Republic of the Marshall Islands”. http://allislandscommittee.org/aboutaic/jurisdictions/rmi/.

[4] Colarossi, J. “Massive Coral Bleaching Event is Sweeping Across the World’s Oceans”. 2015. http://thinkprogress.org/climate/2015/10/08/3710257/ocean-coral-bleaching-catastrophe/.

[5] “Global Coral Bleaching- 2015/2016”. 2015. http://www.globalcoralbleaching.org/

[6] The Telegraph. “Global warming blamed for ‘worst ever’ Marshall Islands coral bleaching’. 2014. http://www.telegraph.co.uk/news/worldnews/australiaandthepacific/marshallislands/11308173/Global-warming-blamed-for-worst-ever-Marshall-Islands-coral-bleaching.html.

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