Fishing for Some Trouble

Posted on February 21, 2017 by ine1

Wow! This sustains the livelihoods of a plethora of living things. Now, how can I exploit it? In general when many people observe something important for the environment, variations of the aforementioned statement come to mind. Needless to say, coral reefs are not above these exploitations. While I could preach to you about the multitudes of ways in which coral reefs are being mistreated by humans, I have chosen to focus on one example—reef fisheries.

To put it simply, reef fisheries are places where coral reef fishes are captured for commercial purposes. While it might not seem like a topic of importance, the industry accounts for approximately 5% of total global catches and averages around $5 billion dollars annually.1 With each catch, a reef’s ecosystem is being disrupted. Some disruptions are not as serious as others, but under many circumstances, fishermen employ questionable fishing techniques. For example with ‘ghost fishing’, we see fishermen failing to retrieve lost traps, thus allowing traps to continue harming reefs and their inhabitants.

Poisons and explosives are heavily utilized by fishermen to acquire fish. This process is normally implemented in parts of Africa and Southeast Asia.2 In this process, we observe fishermen dropping stolen or homemade explosives into the water because it can kill fish over large distances.3 This method requires little effort on the fishermen’s parts. However its effects on reefs are ghastly given that reefs are never fully able to recover from such explosions after being repeatedly subjected to them. An example of these negative effects can be observed in Tanzanian reefs. Figure 1 offers insight into how a booming coral reef can be completely destroyed as a result of explosive fishing.

Figure 1. Image of coral reef in Tanzania that has been completely destroyed by explosive fishing. © Source: Digital Journal 4

In regards to using poison as a method of catching fish, sodium cyanide is dissolved and poured into reef areas and allowed to spread for a while before the fishermen collect the injured or dead fishes that were successfully poisoned.5 As a result of interacting with cyanide, coral reefs and its living constituents die. Cyanide poisoning is detrimental not only to reefs, but also to the humans who consume the fish. Some effects include nausea and even death if cyanide is consumed in great enough quantities. Needless to say, this practice along with explosive fishing is considered illegal, but due to their abilities to catch a lot of fish with minimal effort, these practices still continue to be heavily utilized by fishermen across the globe. In fact, it is estimated that ~1 million kilograms of cyanide has been squirted into Philippine coral reefs since cyanide fishing began in the 1960s. 6

Figure 2. Pictorial representation of different fishing techniques—trap (right), handline (center) and longline (left). ©
Source: The Biology of Coral Reefs (Biology of Habitats) 7

Other more common techniques for reef fishing employ the usage of traps, longlines and handlines. Traps are heavily utilized in the Caribbean and Asia. They vary based on the species one wishes to capture, but they are usually made of wire or bamboo. 8 They can be set in a variety of regions, such as deeper banks, shelfs or reef slopes. Baits are tailored to the organism one wishes to trap. A handline is the tool most people associate with fishing; it is a single line held in the hand, and it contains a hook with bait on it. Longlines contain a long main line from which small lines with hooks branch off. Figure 2 offers a pictorial representation of the three reef fishing techniques mentioned in this paragraph.

While this issue seems relatively black and white, it’s far from it. Yes, exploitation is a bad thing, but the reef fishing industry also serves as a source of food for people living in nearby coastal areas that are relatively poor and offer few alternatives to reef fishing.9 This is what makes the topic of reef fishing so important. It calls to light issues that not only negatively impact reefs, but also negatively impact humans. Consequently in subsequent blog posts, we will delve deeper into the potential impacts of reef fishing as well as propose different solutions that could potentially satisfy both humans and the organisms that make up coral reefs.

References:

1 Sheppard, C., Davy, S. K., & Pilling, G. M. (2012). The biology of coral reefs. Oxford: Oxford University Press.

2 Jennings, S. (1996). Impacts of fishing on tropical reef ecosystems. Jstor, 25(1).

3 Jennings, S., & Kaiser, M. J. (1998). The Effects of Fishing on Marine Ecosystems. Advances in Marine Biology, 201-352. doi:10.1016/s0065-2881(08)60212-6

4http://www.digitaljournal.com/img/8/4/3/0/8/3/i/2/7/6/p-large/blast-1_1.JPG

5 Barber, C. (1997). Sullied seas: strategies for combating cyanide fishing in Southeast Asia and beyond. Popline.

6 Barber, C. (1997). Sullied seas: strategies for combating cyanide fishing in Southeast Asia and beyond. Popline.

7 Sheppard, C., Davy, S. K., & Pilling, G. M. (2012). The biology of coral reefs. Oxford: Oxford University Press.

8 Gomes, I., Erzini, K., & Mcclanahan, T. R. (2013). Trap modification opens new gates to achieve sustainable coral reef fisheries. Aquatic Conservation: Marine and Freshwater Ecosystems, 24(5), 680-695. doi:10.1002/aqc.2389

9 Sheppard, C., Davy, S. K., & Pilling, G. M. (2012). The biology of coral reefs. Oxford: Oxford University Press.

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Drowning Out Disease: Are Coral Reefs the Link?

Posted on February 21, 2017 by ajr7

When most people think of coral reefs, what comes to mind are vibrant scenes of enormous coral colonies surrounded by an immensely colorful array of organisms that would put rainbows to shame. And while these images are often visually astounding, they fail to convey the underlying significance of coral reefs. In addition to providing shelter and sustenance for a plethora of oceanic organisms, coral reefs are an important source of food and income for many tropical communities. However, one of the lesser known but incredibly important uses of coral reefs is in the pharmaceutical industry. In this series of blog posts, I plan to discuss some recent medical developments from coral reefs as well as give you yet another reason why we need to protect coral reefs worldwide.

In 2004, Boston native, Arden O’Connor, was diagnosed with leukemia, a form of cancer, and was subsequently told she likely had less than a year to live. When she was interviewed in 2012 about being cancer-free eight years after her initial diagnosis, she attributed everything to Ara-C (Figure 1), a chemotherapy medication derived from sponges common to coral reefs.¹ For many others with leukemia, Ara-C has proven to be a widely effective treatment when other treatment plans have been exhausted.

Figure 1: Chemical structure of Ara-C, also known as Cytarabine. (Wikimedia Commons)

After reading about O’Connor’s story, I assumed that these medical-reef discoveries began at the turn of the century, but to my surprise, there is over thirty years of research in the topic. In one article, Japanese scientists were cited as using the sea sponge Halichondria okadai to isolate the antitumor molecule halichondrin B back in 1986.² More than 20 years of research and numerous clinical trials later, a form of halichondrin B called eribulin is commercially available for treating breast cancer patients.

Figure 2: Halaven is commercially available for treatment of breast cancer patients. Eribulin, the active ingredient in Halaven, is a chemical derivative of halichondrin B, the antitumor molecule found in the sea sponge Halichondria okadai. (Medscape)

However, pharmaceuticals produced via coral reefs apply well beyond only cancer treatment. The Nature Conservancy, an organization dedicated to worldwide conservation, released a list of some of the most significant medical treatments made available from coral reefs.³ One of the most promising treatments that it lists is secosteroids, a subclass of organic molecules called steroids. Corals utilize secosteroids as protection from certain diseases; however, research into secosteroids (Figure 3) produced by coral in the genus Sinularia has revealed anti-inflammatory properties when used in humans.4,5  These molecules may have the potential to treat many chronic inflammatory diseases like arthritis.

Figure 3: Two secosteroids examined for anti-inflammatory properties (Huang et al., 2012)

Coral reefs have been in the news recently and not for good reasons; massive bleaching events and theories about the “end of the Great Barrier Reef” have plagued the media, leading people to believe the battle to save global reefs has been lost. Rather, we need to be emphasizing the importance of reefs, both to marine ecosystem and to us as humans. If we can effectively do that, then maybe we can mitigate any future damage done to reefs.

¹Caron, C. (2012, April 20). Doctors develop life-saving drugs from coral reefs. NBC News. Retrieved from http://dailynightly.nbcnews.com/_news/2012/04/20/11308813-doctors-develop-life-saving-drugs-from-coral-reefs?lite

²Menis, J., & Twelves, C. (2011). Eribulin (Halaven): a new, effective treatment for women with heavily pretreated metastatic breast cancer. Breast Cancer: Targets and Therapy, 3, 101. Retrieved from http://s3.amazonaws.com/academia.edu.documents/41054948/BCTT-21741-eribulin–halaven—a-new–effective-treatment-for-women-wit_082511.pdf?AWSAccessKeyId=AKIAIWOWYYGZ2Y53UL3A&Expires=1487668408&Signature=k49qNvnPotZaBDSY8weixAtksiM%3D&response-content-disposition=inline%3B%20filename%3DEribulin_Halaven_a_new_effective_treatme.pdf

³Levins, N. (2017). Coral Reefs: Nature’s Medicine Cabinet. The Nature Conservancy. Retrieved from http://www.nature.org/ourinitiatives/habitats/oceanscoasts/explore/coral-reefs-and-medicine.xml

4Huang, C. Y., Su, J. H., Duh, C. Y., Chen, B. W., Wen, Z. H., Kuo, Y. H., & Sheu, J. H. (2012). A new 9, 11-secosterol from the soft coral Sinularia granosa. Bioorganic & medicinal chemistry letters, 22(13), 4373-4376. Retrieved from http://www.sciencedirect.com.ezproxy.rice.edu/science/article/pii/S0960894X12005914

5 Tseng, Y. J., Wang, S. K., & Duh, C. Y. (2013). Secosteroids and norcembranoids from the soft coral Sinularia nanolobata. Marine drugs, 11(9), 3288-3296. Retrieved from http://www.mdpi.com/1660-3397/11/9/3288/htm

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When Air Meets Water: Carbon Dioxide And Ocean Acidification

Posted on February 21, 2017 by ys31

Carbon dioxide (CO2) is not just in the air we breathe; it is also in oceans that harbor coral reefs. Unfortunately, due to increasing atmospheric carbon dioxide concentrations, many reefs are threatened by ocean acidification, which will be the focus of my blog posts. This issue is important because in addition to ecological diversity, coral reefs support economies through tourism and fisheries, they provide coastal protection, and they serve as sources of building materials and new biochemical compounds.1

Figure 1. Negative correlation between atmospheric CO2 levels and coral calcification due to ocean acidification. This image shows how atmospheric CO2 becomes bicarbonate ions and protons, decreasing oceanic pH and carbonate concentrations. © Source: Hoegh-Guldberg et al.1

During the 20th century, ocean acidity decreased by 0.1 pH units.1 (While that sounds insignificant, pH is on a log scale!) From 2000 to 2006, ~25% of CO2 emitted from anthropogenic sources entered the ocean.1 There, it reacted with water to form carbonic acid, which dissociates into bicarbonate ions and protons.1 Bicarbonate ions (CO32-) and protons react with carbonate ions to form more bicarbonate ions, reducing carbonate availability for calcifiers like corals.1 Figure 1 illustrates the process of ocean acidification and the relationship between CO2 and CO32-­ levels.

Figure 2. Average surface water CO32-­ and CO2 levels in the tropical, Southern, and global ocean. This image shows key carbonate chemistry variables as a function of pCO2. © Source: Orr et al.2

Figure 2 also depicts the relationship between atmospheric CO2 and CO32-­ levels, but in more detail than Figure 1, which does not include aqueous CO2 levels or time or site-specific information. Furthermore, Figure 2 projects undersaturation with respect to aragonite, a metastable form of calcium carbonate, and calcite.2

Atmospheric CO2 concentrations surpassed 380 ppm (which is 80 ppm higher than maximum values during the past 740,000 years) a decade ago and are expected to exceed 500 ppm by 2050-2100.1 Anthropogenic CO­2 is estimated to have increased hydrogen ion concentrations in surface waters by 30% since the 20th century, and seawater pH may drop by 0.5 units by 2100.3 Relative to pre-industrial rates, corals, calcifying macroalgae, and other reef-building organisms are expected to calcify 10-50% less by 2050.4

Figure 3. Effects of ocean acidification on marine organisms. (a) P. oceanica with (pH 8.2) and (b) without (pH 7.6) Corallinaceae growth; (c) O. turbinate with (pH 8.2) and (d) without (pH 7.3) intact periostracum; (e) P. caerulea and (f) H. trunculus with eroded, pitted shells (pH 7.4). © Source: Hall-Spencer et al.3

Under these conditions, calcium carbonate (CaCO3) levels will drop below saturation, compromising carbonate accretion and making it difficult to maintain the structural complexity of reefs.5 As a result, corals will become rarer, lowering reef biodiversity,1 and reefs and reef organisms will experience more difficulty functioning.4 Figure 3 shows how some reef organisms are affected by ocean acidification. The decline in production and rise in dissolution of CaCO3 will also lessen breakwater effects that shield coastlines and generate habitats for mangroves, seagrass beds, and more.4

Figure 4.  Predicted effect of atmospheric CO­2 levels on reef building worldwide. Values in this image are expressed as a percentage of pre-industrial (atmospheric CO2 concentration = 280 ppm) calcification rates. PIR = pre-industrial rate; TGgross = temperature-dependent gross calcification. © Source: Kleypas et al.4

As ocean acidification proceeds, reefs around the world will shift into net erosional states, with slow-growing reefs transitioning first.5 Figure 4 illustrates the expected progression of reduced reef calcification with respect to increasing atmospheric CO2 concentrations. With CO2 emissions on the rise, we are heading down a dark, dark path. If steps are not taken to effectively combat ocean acidification, the colorful and diverse settings of movies like Finding Nemo may eventually become unrecognizable.  

References:

  1. Hoegh-Guldberg, Ove, et al. “Coral reefs under rapid climate change and ocean acidification.” science 318.5857 (2007): 1737-1742.
  2. Orr, James C., et al. “Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms.” Nature 437.7059 (2005): 681-686.
  3. Hall-Spencer, Jason M., et al. “Volcanic carbon dioxide vents show ecosystem effects of ocean acidification.” Nature 454.7200 (2008): 96-99.
  4. Kleypas, Joan A., and Kimberly K. Yates. “Coral reefs and ocean acidification.” Oceanography (2009).
  5. Kleypas, Joan A., et al. “Impacts of ocean acidification on coral reefs and other marine calcifiers: a guide for future research.” Report of a workshop held. Vol. 18. 2005.
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Racing against Extinction (Plot spoil: We are losing)

Posted on February 20, 2017 by mjs24

Coral reefs are often described as biodiversity hotspots. But just how much diversity is there on reefs? Scientists try to understand reef biodiversity through the estimation of extinction rates, discovery rates, and global biodiversity estimates. Today we are going to address extinction rates in marine life and on coral reefs on the path to understanding just how diverse coral reefs are.

Fewer than 20 marine species have been found to be recently extinct 1. That number sounds pretty good when you consider greater than 800 species have been recorded as recently extinct 2. However, these are only species recorded and evaluated by the International Union for Conservation of Nature (IUCN). Now consider this: fewer marine species are described, and evaluated for extinction risk by the IUCN. Recently, IUCN evaluations have increased in marine species- there are now >1,200 marine species listed as threatened by extinction, including Acropora palmata pictured below. Webb and Mindel tried to determine whether marine species were truly less at risk for extinction or merely less evaluated 2. Previous studies argued that many marine species were out of reach of human anthropological influences that were plaguing terrestrial species 3. However while large range and mobility makes evaluation difficult it does not confer the “extinction resistance” suggested. Scientists have discarded previous thought that fish (and others) could find part of the deep blue to escape to and repopulate.

Photo. Healthy Acropora palmata. Added to the IUCN Red list in 2008 as critically endangered. Populations declined due to contagious infection.Range includes Caribbean 5. Credit: Philip Renaud.

 

In marine research, progress has been restricted by the advancement of technology. Within the last century scientists have gained access to scuba technology and submersibles which have furthered the discovery of anything from entire reef systems to individual species that had never been seen or described. In some cases, the discovery of a new species and the description of a species are far separated events, delayed by insufficient equipment and opportunity. One such species is shown below- Prognathodes basabei was described over 20 years after it was initially seen 4. So while the extinction of known species must be considered, so too must the extinction of unknown species. Once considering the difference in how well studied systems are, the extinction risk of marine and terrestrial species is much closer. For both marine and non-marine, extinction risk appears greater when a greater amount of species have been assessed 2.

photo of a butterfly fish Photo. Prognathodes basabei. Named and documented in 2016 in deep water Hawaiian reef. Species originally seen over 20 years ago at >200 ft. Credit: Richard Pyle

 

 

With the increasing stress on marine environments and in particular the building stress on coral reefs, researchers expect increased extinction rates 3. As extinction rates surpass speciation rates biodiversity on the reef decreases. Estimating the actual rate of extinction remains a challenge in estimating the total biodiversity present on reefs. The race to find species before they disappear continues.

Check out the IUCN Red list to see what species are endangered.

1 Vermeij, G. (1993) Biogeography of Recently Extinct Marine Species: Implications for Conservation. Conservation Biology 7(2):391-397

2 Webb, T. (2015) Global Patterns of Extinction Risk in Marine and Non-marine Systems. Current Biology, 25(4): 506-511

3 http://science.sciencemag.org/content/277/5325/486.full

4 http://sanctuaries.noaa.gov/news/press/2016/new-butterflyfish-species.html

5 http://www.iucnredlist.org/details/summary/133006/0

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Hidden Forests: Deep Water Reefs

Posted on February 20, 2017 by rsa3

When you think of coral reefs, you probably think of a tropical locale with white sand beaches and warm waters which contain a colorful array of coral species, home to a diverse group of fish, algae, sponges and more.  But what if I told you that sometimes you have to dig, or rather swim a little deeper to get to some of the more interesting reefs the ocean has to offer? I’m talking of course (if you read the title), about deep water reefs.

You may have inferred that deep (also known as cold) water reefs, are reefs that form in deeper or colder waters than typical warm, shallow reefs, but the difference can be pretty striking. While shallow water reefs can go from the shore to about 65m (~200ft), deep water corals are generally found between 50-4000m (~150-13,000ft)¹. So while shallow water reefs are limited to depths where the light can support photosynthetic activity, these deep water habitats go all the way to what’s known as the Abyss Zone of the ocean, a place shrouded in total darkness¹².

A deepwater fish swims through a L. pertusa forest. Wikimedia Commons

So what makes these reefs different? Well first of all, the stony coral species that construct these deep reefs are azooxanthellate, which means they’re lacking the microscopic algae that use photosynthesis to produce organic molecules needed for the shallow water coral to live. The deep water coral make up for this by filtering out plankton and other microorganisms out of the water to provide them with the nutrition they need without sunlight. While living without the necessity of relying on other organisms for help might sound handy, it isn’t easy. For one, while there are over 800 reef building stony corals that thrive in warm shallow waters, only 10 have been found that can survive in the depths of deep water reefs. All 10 species are not created equal however, and a branching coral known as Lophelia pertusa often dominates deep water sites¹³.

Lophelia pertusa reef. Lack of photosynthetic algae causes coloration from bone white to orangish brown. High branching creates complex habitats. © C. Dullo, IFM-GEOMAR
http://2014.extrememarine.org.uk/theunfathomabledeepmarineenviroment/introduction/index.html

While you might think L. pertusa is overwhelming the competition with a high capacity to proliferate, it actually has a slow growth rate characteristic of deep water corals due to the cold temperatures and lack of photosynthetic assistance, and averages between 4-20mm (.16-.79in) per year. In contrast, shallow water corals can grow up to 10cm (4in) per year, (relatively) quickly building up reef structures. Despite this, L. pertusa, is responsible for many of the large deep water structures scattered around the world. Large structures such as the Darwin Mounds and Porcupine Seabight near the UK and Sula Ridge in Norway can form reefs 300m high that stretch for kilometers. These complex structures are built up over thousands or even millions of years of slow reef growth. These ever changing geologic and biologic marvels can be used to provide great insight into ocean conditions in past millennia and are great homes to many diverse ocean creatures, from sharks to sponges, which is why they should be preserved ¹³°.

Like many parts of our natural world today, these deep sea habitats are threatened by human action. Physical destruction from fishing trawlers and deep sea oil drilling, and slowing of growth processes due to large scale ocean acidification are destroying these complex and diverse habitats. In order to keep these intact to preserve ocean life and find more out about what conditions were like millennia ago, we need to protect these delicate environments.

¹Roberts JM (2006) Reefs of the Deep: The Biology and Geology of Cold-Water Coral Ecosystems. Science 312:543–547.

²http://192.171.193.68/assets/pdf/marine_healthcheck05.pdf#page=75

³Sheppard C, Davy SK, Pilling GM (2012) The biology of coral reefs. Oxford University Press, Oxford.

°Rogers AD (1999) The Biology of Lophelia pertusa (Linnaeus 1758) and Other Deep-Water Reef-Forming Corals and Impacts from Human Activities. International Review of Hydrobiology 84:315–406.

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An Unlikely Invasion: A Threat to Oceans Everywhere

Posted on February 20, 2017 by ssp3

They call the United States the melting pot because the country is a perfect example of diversity. But, it is not only the land that houses such diversity, the oceans that surround the U.S. are also homes to highly biodiverse coral reef ecosystems (Figure 1). When we look at pamphlets of tropical tourist destinations, generally the first thing that comes to mind are the vibrant reefs and marine life we would get to see during snorkeling or scuba diving excursions. What would happen if these reefs turned a pastel white and no longer supported the beautiful fish and sea creatures that we are so used to seeing in pictures? This is a fear environmentalists are facing today and is important to address.

Figure 1. Image of coral reef habitat in Florida Keys. Source: Flickr1

 Complex reef ecosystems are easily disturbed when either biotic or abiotic factors are changed. One major example of a biotic factor that may skew the balance of coral reef habitats are invasive species. What is an invasive species? Well, an invasive species, also known as an alien species, invades a habitat that it is not native to. As methods of transportation have progressed over the past few centuries, introduction of invasive non-native species has increased dramatically – with new foreign species establishing once every 32 to 85 weeks at ports in countries such as the U.S., Australia, and New Zealand. 2 The difference between invasive and other foreign species is that while invasive species take over the native species of the habitat, other foreign species are integrated into the new habitat without damaging the natural balance of the marine ecosystem.2

The introduction of invasive species can be broken down into three different groups according to Molnar et al.

  1. Transportation-Related Pathways – including movement of ballast water, fouling, and canals connecting water ways.3 (The advent of ship vessels and travel across oceans introduced processes such as fouling, in which organisms attach to ship vessels, and ballast water tanks on ships, which introduce new species through the recycling of water in the tanks. 4)
  2. Commerce in Living Organisms Pathways – including live seafood trade and aquaculture.3
  3. Other Human-Assisted Pathways – including climate change.3

Figure 2, below, shows the number of invasive species introduced through some of the most common human-assisted pathways. These processes of introduction of invasive species show the role we play in disturbing the biodiversity make up of reef habitats. Understanding the unintentional impact we may have on the marine ecosystem is the first step towards protecting and restoring native marine habitats.

Figure 2. Breakdown of the most common methods of introduction of invasive species and other foreign species. Source: Ecological Society of America3

So how serious is the damage being done by alien species? Invasive species have the ability to take over other native species and potentially even eradicate native species. The disturbance of a single species also influences other species interactions and therefore can upset the balance of that specific ecosystem. For example, the invasion of the New Zealand screw shell, in Tasmania, had the effect of changing the seabed habitat by introducing attaching points for other species and hiding spaces for hermit crabs, in turn, shifting the food web. 2 Alien species not only have an ecological impact, but can also have an economic impact. While the Chinese mitten crab may disturb natural habitats and compete with native species, it also damages fishing gears and river banks (Figure 3).5 The invasion of the comb jelly in the Black Sea has also led to the demise of coastal fisheries while ballast water can transport viral and bacterial pathogens such as those that may cause cholera.2 Clearly alien species have the potential of causing high ecological and economical damage.

Figure 3. Map of Chinese Mitten Crab Invasion using data from 2008. Red circles represent established population in non-native range, blue circles represent non-established populations in non-native range, and green circles represent populations in native range. Source: Journal of Marine Biology and Ecology6

 Acknowledging the harmful effects human activity may have on the marine ecosystem is vital. Several different pathways have led to the introduction of invasive species, and there are currently 44 invasive species that have high ecological impact in the North Atlantic.5 In my next few blog posts, I will delve deeper into interesting cases related to specific invasive species that have had, or potentially may have, the effect of critically damaging the reef habitats around the coasts of the United States.

References:

1 TiagooOOooOO. “Coral_Reef%2C_Florida_Keys[1].” Flickr. Yahoo!, 10 Oct. 2007. Web. 20 Feb. 2017. <https://www.flickr.com/photos/14850624@N06/1537421470/>.

2 Bax, Nicholas, Angela Williamson, Max Aguero, Exequiel Gonzalez, and Warren Geeves. “Marine Invasive Alien Species: A Threat to Global Biodiversity.” Marine Invasive Alien Species: A Threat to Global Biodiversity. Marine Policy, 23 May 2003. Web. 14 Feb. 2017. <http://www.sciencedirect.com/science/article/pii/S0308597X03000411>.

3 Molnar, Jennifer L., Rebecca L. Gamboa, Carmen Revenga, and Mark D. Spalding. “Assessing the Global Threat of Invasive Species to Marine Biodiversity.” Wiley Online Library. Ecological Society of America, 1 Nov. 2008. Web. 15 Feb. 2017. <http://onlinelibrary.wiley.com.ezproxy.rice.edu/doi/10.1890/070064/full>.

4 Hulme, Philip E. “Trade, Transport and Trouble: Managing Invasive Species Pathways in an Era of Globalization.” Journal of Applied Ecology – Wiley Online Library. British Ecological Society, 14 Jan. 2009. Web. 17 Feb. 2017. <http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2664.2008.01600.x/full>.

5 Plymouth University. “Forty-four invading species ‘loose’ in North Atlantic.” ScienceDaily. ScienceDaily, 30 January 2017. <www.sciencedaily.com/releases/2017/01/170130100807.htm>.

6 Dittel, Ana I., and Charles E. Epifanio. “Invasion Biology of the Chinese Mitten Crab Eriochier Sinensis: A Brief Review.” Invasion Biology of the Chinese Mitten Crab Eriochier Sinensis: A Brief Review. Journal of Experimental Marine Biology and Ecology, 17 May 2009. Web. 20 Feb. 2017. <http://www.sciencedirect.com/science/article/pii/S0022098109001415>.

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Diverse Colors in Coral Reef Ecosystems: More Than What Meets the Eye

Posted on February 20, 2017 by sft4

Aesthetically, I think we can agree that as ecosystems go, coral reefs are not too shabby. Coral reefs are characteristically colorful and visually dynamic, and coral reef ecosystems are brimming with diverse, multi-colored fish. The photo below captures just one example of the variations in shape, color, and size that make coral reefs so unique. In this series of blog posts, I’ll be exploring the world of color on coral reefs. I’ll be writing about coral reef pigmentation, colorful reef fish, and ultimately why reef colors have important implications on ecosystem function.

Learning about corals is especially important today. Rising ocean temperatures and increasing ocean acidification have led to widespread coral disease1. Many coral species provide homes for symbiotic algae. That is, algae (called zooxanthellae) and corals have formed a partnership. Zooxanthellae get to live in coral skeletons and in return provide corals with food and protection from disease. When corals are stressed—by UV light, increasing sea surface temperatures, or a variety of other factors—they expel their symbiotic algae. If corals go too long without their algal partners, they die. If we want the planet’s coral reefs to remain beautiful for years to come, we need to first learn about the complex and balanced biodiversity, in all of its colorful beauty.

Figure 1. Coral reef ecosystems are highly diverse and highly productive. This image shows multiple species of coral and coral reef fish in clear, shallow water. Source: Wikimedia Commons

We’ll start from the beginning. Where do the colors on coral reefs come from? Endosymbiotic zooxanthellae, the tiny algae that live in coral skeletons and photosynthesize, are critical for keeping corals well fed. Zooxanthellae are also responsible for the underlying brownish hues in coral colonies2. Zooxanthellae cells contain chlorophyll (green pigment) in varying concentrations. The intensity and wavelength of the light hitting a specific coral also alter the perceived color. Depending on the light in the surrounding water, corals can appear a wide variety of colors.

A study on Montastrea cavernosa corals sought to shed light on color diversity. Researchers found that color diversity in these corals can be explained by varying levels of gene expression. Specifically, genes code for proteins similar to green fluorescent proteins (GFP). When these corals’ genes cause proteins to be expressed, they emit at three general wavebands: cyan, green, and red3. So, fluorescent proteins are also super important contributors to the variety of colors on reefs.

But what makes reef colors evolutionarily or ecologically important? A study by Salih et al. published in Nature describes how fluorescent pigments (FPs) in corals are photoprotective. Think sunscreen. These FPs scatter light and filter out damaging UV light, effectively protecting the corals from damage4. These scientists studied corals on the Great Barrier Reef and found that 124 species in 16 sampled families contained fluorescent morphs as well as non-fluorescent morphs. The different colors observed in different species are generally outlined in the figure below (Figure 2). Fluorescent morphs were especially common in shallow sites and were also more common in sunny areas than shady areas.

Figure 2. Fluorescent pigments found in blue, green, yellow, and red combinations (a, c, e, g). In Acropora nobilis (a, b) blue was found to be dominant. In Pocillopora damicornis (c, d) green was dominant. Porites cylindrica (e, f) showed emissions of all FPs. Source: Salih et al. 

The figure below is from the same study. Graph A shows that corals with lots of fluorescent pigments recovered faster and more completely than non-fluorescent Acropora palifera when exposed to full sunlight. Graph B shows a significant correlation between bleaching resistance, measured by the biomass of symbiotic algae, and concentration of fluorescent pigments. Together, these graphs evidence the benefits of colorful, fluorescent pigments. Salih writes that “by changing their optical properties with the help of these [green fluorescent protein]-like pigments, coral polyps are able to optimize the photosynthetic activity of their tissues for the better survival of the organism.”

Figure 3. a) For the Acropora palifera species, the maximum yield of dinoflagellates (zooxanthellae) over time. NF stands for non-fluorescent, BF stands for brown medium fluorescent, and GF stands for green highly fluorescent. The highly fluorescent corals recovered best and most rapidly. b) Positive correlation between FPs concentration and increased zooxanthellae biomass. Source: Salih et al. 

Not only are corals colorful, but the fish that inhabit coral reefs are brilliantly colored as well. Various studies have explored the benefits of bright patterns on reef fish. John Endler asserts that color patterns in reef fish are important for communication within the same species for courtship or mating, to confuse or escape visual predators, and can advertise danger5.

Colorful reef fish are often camouflaged, blending into their surroundings, to avoid being eaten by predators. A study described in Behavioral Ecology investigated the effects of coral bleaching and habitat degradation on coral reef fishes’ susceptibility to predation. Predation rates on coral-dwelling damselfish were found to be 17% higher on bleached or dead coral colonies6.

Coral reef fish and coral reefs are interdependent; in order for the whole ecosystem to function, the colors of each must remain in balance. Coral bleaching, the loss of coral pigmentation, can lead to the collapse of the entire underwater ecosystem. In the next blog post, I’ll talk more about coral reef fish, specifically how they respond to changes in coral reef coloration.

References:

1 “NOAA Declares Third Ever Global Coral Bleaching Event.” NOAA. National Oceanic and Atmospheric Administration, 8 Oct 2015. Web. 16 Feb 2017.

2 Factors That Influence Coloration. “Factors That Influence Coloration.” N.p., n.d. Web. 16 Feb 2017.

3 Ilya V. Kelmanson, Mikhail V. Matz; Molecular Basis and Evolutionary Origins of Color Diversity in Great Star Coral Montastraea cavernosa (Scleractinia: Faviida). Mol Biol Evol 2003; 20 (7): 1125-1133. doi: 10.1093/molbev/msg130

4 Salih, Anya, et al. “Fluorescent pigments in corals are photoprotective” Nature. 14 Dec 2000. Web. 19 Feb 2017.

5 Sabbagh, Stephanie M. “Significance of Colors and Patterns of Coral Reef Fishes: An Overview.” ReefCI. N.p., 31 Oct. 2013. Web. 12 Feb 2017.

6 Coker, Darren J. et al. “Coral bleaching and habitat degradation increase susceptibility to predation for coral-dwelling fishes.” Behavioral Ecology. 19 August 2009. Web. 19 Feb 2017.

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Flower Garden Banks: a Coral Reef in your Backyard

Posted on February 20, 2017 by ak56

Welcome to my coral reefs blog! This semester I’ll be blogging periodically about the Flower Garden Banks National Marine Sanctuary, a coral reef in the Northern Gulf of Mexico that is notable for being one of few reefs along the United States coastline. The focus of my blog will be on the conservation status and general health of the Flower Garden Banks, and will discuss the major threats to the reef as well as the key components that keep the reef’s rich and complex ecosystem functioning.

Before we can start talking about these main issues, it’s important to have a clear picture of what the Flower Garden Banks look like. Over millions of years, salt deposits, known as salt domes, deep underneath the seafloor of the Gulf of Mexico rose up until they almost breached the water’s surface1. These mounds of salt formed the foundation that enabled coral colonies to develop. This topography, while crucial, is not the only thing needed to build a reef. A variety of factors such as water temperature, salinity, nutrient profile, wave energy, and even sedimentation must all lie within specific vital ranges for corals to live and grow. In the case of the Flower Garden Banks, these conditions have not only all been achieved, but have also persisted for millions of years- long enough for the vibrant reefs we know about today to form!

The Flower Garden Banks Sanctuary actually consist of three separate reefs: East Flower Garden banks, West Flower Garden banks, and Stetson Bank. These reefs, along with their proximity to one another and with reference to the Gulf coast, can be seen on the map below. Due to their relative proximity to one another, these three reefs are considered as a single system. These reefs are less than 200km from the Texas coast, making them a convenient location for someone looking to go reef-diving without travelling across the world (as long as the correct steps are taken to ensure the reef is treated well and left pristine). Compared to other Caribbean or Gulf of Mexico Reefs, the Flower Garden Banks have relatively low diversity in terms of coral species, with the boulder star coral (pictured below) comprising about half of the live coral cover and a handful of other species comprising the rest3.

Note the relative positions of the East and West Banks as well as Stetson Bank to eachother and to the Texas coastline. The salt domes are visible as raised topographical features within the seafloor basin.

By: NOAA, National Marine Sanctuaries – http://www.sanctuaries.noaa.gov/pgallery/atlasmaps/fg.html, Public Domain, https://commons.wikimedia.org/w/index.php?curid=1284294

 

Despite this relatively low coral diversity, the Flower Garden Banks exhibit a very rich diversity of other species, including algae, sponges, crustaceans and other invertebrates, and almost 300 species of fish3! A handful of ray species can also be observed year-round. The corals and surrounding topography provide sustenance and shelter for countless species which in turn create even more ecological relationships and further boost biodiversity, although human interference such as fishing can quickly destabilize these relationships and threaten the health of the reef2.

Boulder Star Coral (Montastraea annularis) with parrotfish bite scars. This is the dominant reef building coral of the Flower Garden Banks.

By: George Stoyle, Flickr Creative Commons, https://www.flickr.com/photos/georgestoyle/5844308723/in/photolist-9UrBnv-9s4yaA-9UrGJe-krqLZJ-BgZzrp-5TKXWx-8a6Qna-fKfC16-qjFSNV-446EjW-bUedkM-Hr5Qon-qnCz1D-yrAi1z-eJBkEn-7Jj9hG-dN3vhu-qidZC6-h3uem-G9unLJ-uzzozR-q7Y5jf-7j481A-7tCWJf-e9aQa6-cPkvHw-8yQB6W-pd6QHK-he2JrF-9x9NCA-Jbeuc-h61RTA-dLeJSX-h626h7-9UrBsF-9UrBEg-9UrBzg-drbQMp-7TViNn-drc1ts-NwEb3x-9tFuUv-Fncsiq-drc1nj-drc1mh-6MfiPD-drc1h7-drbQs8-drc1ks-drbQJM

Although the outlook for coral reefs around the world is grim and worsening over time, the Flower Garden Banks are one of the world’s most pristine and untouched reefs3. The Banks have been the subject of close monitoring for decades4. Live coral cover, one of the best measures of reef health, is high at all three banks. Since the reefs started being monitored in the 1970s, incidences of coral disease, bleaching, and die-offs has been lower than the global average3. Investigating the reasons for success of the Flower Garden banks could give insight into how to conserve other reefs which are struggling. The clock is ticking for many of our planet’s coral reefs, and we are at a very real risk of losing one of nature’s most priceless and beautiful phenomena. As we closely monitor the health of the Flower Garden banks and study the patterns of reef death and growth, we should look for the ways in which we can apply this knowledge to reef conservation efforts globally.

 

References:

  1. “Introduction to Flower Garden Banks National Marine Sanctuary.” Flower Garden Banks National Marine Sanctuary. National Ocean Service, n.d. Web. 20 Feb. 2017.
  2. Clark, Randy, Chris Taylor, Christine Buckel, and Laura Kracker. “Fish and Benthic Communities of the Flower Garden Banks National Marine Sanctuary: Science to Support Sanctuary Management.” NOAA Technical Memorandum NOS NCCOS 179 (n.d.): n. pag. Web.
  3. Schmahl, George P. “Status of the Flower Garden Banks of the Northwestern Gulf of Mexico.” Flower Garden banks National Marine Sanctuary. National Ocean Service, n.d. Web.
  4. Gittings, S.r., K.j. Deslarzes, G.s. Boland, and T.j. Bright. “Ecological Monitoring At The Texas Flower Garden Coral Reefs.” American Academy of Underwater Sciences (n.d.): n. pag. Web.
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Out of the Frying Pan… The Future of America’s Barrier Reef

Posted on April 19, 2016 by meh9

For the past two months, I’ve been following coral reefs in the Florida Keys (the only barrier reef on the continental U.S.) as record-breaking sea temperatures persist globally. Corals in the Keys experienced the harshest conditions and bleaching in August – September of 2015 [A]. The result of this bleaching event was reduced coral growth and overall coverage.

Figure 1. Current bleaching threat levels due to surface temperature. This image shows that these reefs are not currently stressed [F].

Fortunately, temperatures in the Florida Keys have returned to normal, and are not causing stress on these reefs (Figure 1). In fact, sea surface temperatures are predicted to stay within tolerable ranges throughout the summer (Figure 2). This return to normal conditions is essential for corals to recover from previous trauma and presents hope for a healthy reef in the future.

Figure 2. Projected bleaching threat levels due to surface temperature through July. This image shows that Florida’s reefs will likely not experience bleaching in the coming months [G].

But here’s where I may have misled you: high temperatures and coral bleaching aren’t the only causes of reef decline. In fact, the list goes on for quite a while [B]. To name a few other threats that corals face:

  • Ocean acidification, which dissolves coral skeletons
  • Overfishing, which removes fish that keep competing algae growth in check
  • Predatory starfish
  • Invasive species
  • Destructive fishing practices, like using cyanide and dynamite
  • Pollution from sewage and agriculture

So even corals that survived the bleaching event can’t be classified as safe. They’re still subject to other stressors and are in a weakened state to face them. For corals reefs, it’s not death by fire, it’s death by a thousand cuts.

For the Florida Keys, a region that is very close to large populations of people, those additional factors may prove disastrous. One of the newest potential threats is a proposal to widen shipping channels to access Port Everglades in Fort Lauderdale by dredging. If Congress approves the plan, excavation of the sea floor could begin at the beginning of next year [C].

Figure 3. A large brain coral crushed by a grounded vessel off Port Everglades, Florida. The typical growth rate of this coral is very slow: about .41 cm, or about half of the length of a Cheerio, per year [H]. Photo: Dave Gilliam, National Coral Reef Institute

Beyond actually physically crushing corals (Figure 3), dredging is so harmful because it upsets the sea floor and sends blankets of sediment to nearby areas. Recently, dredging in the port of Miami layered as much as 14 cm of sediment on to nearby areas, clogging parts of the Florida reef [C]. Research that was specifically done in the Florida Keys has also shown that changes in light availability and quality by suspended particles limits the productivity of reefs [D].

Despite overwhelming evidence of the disastrous environmental consequences, the promise to “create 7,000 new jobs regionally and support 135,000 jobs statewide over the next 15 years [E]” may win in the end.

It might seem like too much is going against corals, but the fight isn’t over! Despite reef decline, corals remain. This means that there are still things we can do to promote conservation.

For starters, we can focus on removing immediate local stressors like sediment plumes by not dredging the canal to Port Everglades. Simple enough! You can help by writing to Congress about your concerns. Here are a few tips on how to do so!

Another impactful change that you can make is to be careful of the fish you eat. I didn’t touch on it much, but healthy fish communities are essential to coral reef health. Removing some members of that community can be more impactful than others. Here’s a pocket guide for fish to eat/not eat in Texas.

Finally, you can spread awareness about these issues your friends and community. These are global issues that are happening because of small contributions from lots of individuals. The more the people who are fighting to make a change, the stronger the change will be.

Coral reefs are very tangible reminder about how beautiful our planet is, and how fragile that beauty is. It’s an uphill battle, for sure, but it’s one worth fighting for. After all, we’ve only got this one planet and this one lifetime to make a change!

Figure 4. Beautiful, pristine corals near the Millennium Atoll in the central Pacific. Photo: Jennifer Smith

SOURCES:

[A] “El Niño and the 2014-2016 Global Coral Bleaching Event.” NOAA Satellite and Information Service. National Oceanic and Atmospheric Administration, 2015. Web. 17 March 2016.

[B] “Threats to Coral Reefs.” Defenders of Wildlife. Defenders of Wildlife, 2016. Web. 19 April 2016.

[C] Milman, Oliver. “Dredging Florida coral reef is ‘lunacy’ says Philippe Coustea, grandson of Jacques.” The Guardian. Guardian News and Media Limited, 24 March 2016. Web. 19 April 2016.

[D] Toro-Farmer, Gerardo et al. “Characterization of Available Light for Seagrass and Patch Reef Productivity in Sugarloaf Key, Lower Florida Keys.” Remote Sens. 8.2 (2016): 86. Web. 19 April 2016

[E] “Expansion.” Port Everglades. Broward County Port Everglades Department, 2016. Web. 19 April 2016.

[F]  “Florida Keys: 5-km Bleaching Thermal Stress Gauge.” NOAA Satellite and Information Service. National Oceanic and Atmospheric Administration, 2016. Web. 19 April 2016.

[G] “NOAA Coral Reef Watch: Seasonal Coral Bleaching Thermal Outlook.” NOAA Satellite Information Service. National Oceanic and Atmospheric Administration, 2016. Web. 19 April 2016.

[H] Livingstone, S., Polidoro, B. & Smith, J, eds. “Colpophyllia natans.” Encyclopedia of Life, 2008. Web. 19 April 2016.

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Bleaching Reported in the Seychelles

Posted on April 19, 2016 by amk12

Conditions are worsening in the Seychelles, as is indicative of a transition from a bleaching warning to an Alert Level 1 [4]. Figure 1 shows that two monitoring stations in the Seychelles have reported high and extreme bleaching events [3]. A reef in Cousin that had only showed 1% incidence of bleaching back in January is now faring worse in this month [1, 4]. In order to monitor the situation for the rest of the year, Nature Reef Rescuers scientists paired up with Nature Seychelles staff to survey the reef in Cousin and record its response to rising thermal temperatures [1]. It will be interesting to hear their reports in the next few months.

Screen Shot 2016-04-19 at 3.10.42 PM

Figure 1. [3] Orange and red dots indicate high and extreme bleaching respectively. The Seychelles are located in the upper right-hand corner of the map.

What’s notable about the reef at Cousin is that many colonies that were transplanted there were grown from corals that survived the 1998 bleaching event [1]. It is highly probably and entirely possible that these transplanted colonies will exhibit higher levels of stress tolerance [2]. Research has shown that corals exposed to high temperature stressors that survive are less likely to bleach in future events [2]. It is also becoming evident that these adaptations to a high thermal stress environment can pass along to the next generation [2]. Even though bleaching has occurred in Cousin, the single source I could gather information from did not indicate exact locations of bleaching or whether it was patchy bleaching as opposed to widespread occurrence. Thus, it is still possible that transplanted colonies may not have bleached. The bad news is that temperatures are likely to become hotter in the next 1-4 weeks, with stress levels projected to rise to Alert Level 2. From the graph below, Figure 2, you can see that the Seychelles are experiencing their sixth degree heating week, and widespread bleaching and mortality is expected at only eight degree heating weeks. Stress is expected to dissipate in 5-8 weeks to a watch level [4]. The good news is temperatures are expected to drop during the month of May, as previous SST data from previous years have suggested [4]. Still, it may be too late for some reefs in the Seychelles. It has taken 10-15 years for some reefs in the Seychelles to recover from 1998, and with a greater likelihood of more bleaching events, the Seychelles could be slammed again before the reefs have adequate time to recover.

Screen Shot 2016-04-19 at 3.25.35 PM

Figure 2. [4] Data set shows thermal data from 2015 alongside the current trends of 2016. This data set is current as of April 18, 2016.

The outlook for the future of reefs is grim. Humans have disrupted the natural flux of the earth’s climate and sped up rates of warming to a level where biological systems can’t acclimate and adapt to these changes. Coral reefs are some of the most complex, if not beautifully intricate, ecosystems that exist and they are the most visible indicator of climate change. By jeopardizing the health of these ecosystems, humans are inadvertently causing humanity’s own demise. There is hope left, and this hope lies in the fragile symbiotic relationship between a coral and its dinoflagellate algae. If these algae can acclimate or adapt quickly enough to higher thermal tolerances, perhaps with assistance from scientists, then it could be possible to buy time for reefs [2]. After all, reefs are not only faced with the threat of higher ocean temperatures, but also from a decreasing aragonite saturation level caused by the acidification of the oceans, increased fishing pressure, increased levels of bioerosion, mass influxes of nutrients that favor algal domination, and increased infrastructure along the coasts.

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Nick Graham. [6] A healthy coral reef on the left and a macroalgal covered reef on the right. Both images were taken in the Seychelles. Reefs in the Seychelles will probably look more like the image on the right in the near future due to the effects of climate change and a greater occurrence of bleaching events.

The number one threat to the Seychelles as assessed by the Seychelles Foundation is climate change [5]. It is time that concerned citizens and national leaders bring themselves together to seriously discuss the impact of destroyed reef ecosystems due to climate change and how to combat local stressors that harm reefs. The most obvious wide-scale option is to lower carbon emissions collectively and turn to cleaner renewable resources such as solar. Another sure-fire option is to create Marine Protected Areas, places where there is zero extraction and zero tolerance for poachers. Less pronounced but equally important measures would be to slowly eliminate human obsession with plastics and waste, curbing the growth rate of the human population, and creating more effective waste water treatment options on islands that are home to large populations of people and reefs. This is my last blog post, but I certainly hope that all you continue to read about this massive bleaching event. I have found that the easiest way to do so is to follow Coral Reef Watch on Facebook in order to receive current updates.

  1. Malaisé, Louise. “Coral bleaching, again!” Saving Paradise. Wildlife Direct Feb 4, 2016. Web. April 18, 2016.
  2. van Oppen, M. J., Oliver, J. K., Putnam, H. M., & Gates, R. D. (2015). Building coral reef resilience through assisted evolution. Proceedings of the National Academy of Sciences. DOI: 10.1073/pnas.1422301112
  3. “WIO Coral Bleaching Alert.” Cardio East Africa. Web. 18 Apr. 2016.
  4. “Western Indian Ocean 5-km Coral Bleaching Data Products/Seychelles 5-km Bleaching Thermal Stress Gauges.” Coral Reef Watch. NOAA Satellite and Information Service. Web. 18 Apr. 2016.
  5. “Impacts of Global Warming on Corals.” WWF. Web. 18 Apr. 2016
  6. Hajira, Amla. “Seychelles Coral Reefs Just Beginning to Show Signs of Recovery, Says Researchers.” Seychelles News Agency. 14 July 2014. Web. 18 Apr. 2016.
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