Introduction to Coral Reef Bleaching

Coral reef bleaching is a very serious issue occurring all over the world. Since 1998, there has been a drastic global increase in coral bleaching. Many ecosystems have been affected or have vanished due to coral reef bleaching. In 1998, when coral reef bleaching was first observed, 70 countries reported that their reef ecosystems were being affected. The worst bleaching has occurred in Southeast Asia and the eastern Indian Ocean. Thailand and Indonesia have the most coral mortality rate, both with 80-100% of their coral reef ecosystems bleached.  The Caribbean has also been affected, as well as the Great Barrier Reef in Australia.

            The increased temperature of the ocean waters as well as many other factors have increased the stress levels of coral, forcing them to release the zooxanthellae that live within them. These zooxanthellae provide the coral with nutrients that helps them survive as well as their bright colors. Losing these zooxanthellae is detrimental to the coral. Many coral are able to recover from bleaching, as long as the stress is not too great. Unfortunately, El Niño has increased the water temperature around the world and global warming has added to this temperature increase, putting the stress levels on coral reefs at an all time high.

            Through this blog, our group has tried to raise awareness of the detrimental causes and effects of coral reef bleaching. Three quarters of the world’s population does not know what coral reef bleaching is and how harmful it is to coral reef ecosystems. We hope to reach out to as many people as we can and bring understanding to this topic.

Quirolo, C. (2005). Retrieved from http://www.wri.org/stories/2010/10/have-you-heard-coral-bleaching

Graphic of Solution

Advertisement to bring awareness to Coral reef bleaching.

Solutions for Coral Reef Bleaching

Unfortunately, since the vast majority of the factors that cause coral bleaching are environmental, there is very little humans can do to physically stop or reverse the process directly. The solution lies in raising awareness about this phenomenon and taking measures so as to prevent zooxanthellae loss in the future.

            One possible solution is to create an advertising campaign to raise awareness about coral bleaching and try to convince people to do what they can to prevent further climate change. This would require a team of scientists to consult and a team of advertisers to reach the public through an either written or televised campaign. This would most likely have to be sponsored through a large non-profit organization in order to accomplish. The sad truth is that most people are either completely unaware about the phenomenon of coral bleaching or are sorely uneducated about the facts, such as that this process can actually be reversed if conditions return back to as they were before, and that common commercial products such as sunscreen contribute to the problem.

            Another possible solution is to go through the legal route and actually present legislation to be put into power to protect coral reefs and its zooxanthellae. This would possibly have to be presented with other anti-climate change bills, especially those limiting the use of chlorofluorocarbons (CFCs) and carbon emissions, which largely contribute to the acidification of the ocean. Marine protected areas could be made in the areas where coral is most affected, so as to prevent direct anthropogenic activity that continues the process of coral bleaching.

Graphic of Causes

Global Warming, Tourism, Overexploitation, Pollution

Causes of Coral Reef Bleaching

Coral reefs are found in shallow tropical waters along the shores of islands and continents on a substrate composed of calcium carbonate produced from living and dead corals. Corals, of the phylum cnidaria, are actually small animals related to sea anemones, and live in large colonies that we, as humans, most associate with reefs. Many other invertebrates, vertebrates, and plants live in close association to the corals, with tight resource coupling and recycling, allowing coral reefs to have extremely high productivity and biodiversity, such that they are referred to as ‘the Tropical Rainforests of the Oceans’. Out of all these associations corals experience, they share a close symbiotic relationship with a photosynthetic unicellular alga called zooxanthellae, in which the coral provides protection to the algae and the zooxanthellae provide nutrients and oxygen to the coral. Zooxanthellae are the cause of the many diverse and vibrant colors of tropical reef coral. Without the algae, corals cannot survive.

Coral bleaching occurs when the densities of zooxanthellae in the coral colony decline and/or the concentration of photosynthetic pigments within the zooxanthellae fall to far below normal levels. Most reef-building corals normally contain around 1-5 x 10⁶ zooxanthellae cm^-2 of live surface tissue and 2-10 pg of chlorophyll per zooxanthella. When corals bleach, they commonly lose 60-90% of their zooxanthellae and each zooxanthella may lose 50-80% of its photosynthetic pigments. The pale appearance of bleached corals is due to the cnidarian’s calcareous skeleton showing through the translucent tissues (that are nearly devoid of pigmented zooxanthellae). If the stressor causing the bleaching is not too severe and if it decreases in time, the affected corals usually regain their symbiotic algae within several weeks or a few months. If zooxanthellae loss is prolonged, i.e. if the stress continues and depleted zooxanthellae populations do not recover, the coral host eventually dies.

There are several stressors scientists hypothesize cause coral bleaching. Temperature is a huge factor, and is especially relevant now due to climate change and the warming of the world’s oceans. Coral species live within a relatively narrow temperature margin, and anomalously low and high sea temperatures can induce coral bleaching. Bleaching events occur during sudden temperature drops accompanying intense upwelling episodes and seasonal cold-air outbreaks. Bleaching is much more frequently reported from elevated seawater temperature. A small positive anomaly of 1-2 degrees Celsius for 5-10 weeks during the summer season will usually induce bleaching. In truth, any environmental trigger that affects the coral's ability to supply the zooxanthellae with nutrients for photosynthesis (such as carbon dioxide or ammonium) will lead to bleaching. Triggers such as ocean acidification; changes in salinity; bacterial infections; and the addition of toxic chemicals such as herbicides, oil, and, found in a recent study, sunscreen, are all major causes of the phenomenon known as coral bleaching.

Continued Research About Coral Reef Bleaching

·     Coral reefs are found in circumtropical shallow tropical waters.

·     Corals live in very nutrient poor waters and have certain zones of

tolerance to water temperature,salinity, UV radiation, opacity, and

nutrient quantities.

·    Coral reef bleaching occurs when the densities of zooxanthellae decline and/or the

concentration of photosynthetic pigments within the zooxanthellae fall.

·     Coral reefs that suffer from bleaching commonly lose 60-90% of their zooxanthellae and each zooxanthella may lose 50-80% of its photosynthetic pigments.

·     Ecological Causes of Coral Bleaching

o   Temperature

o   Solar Irradiance

o   Subaerial Exposure

o   Sedimentation

o   Fresh Water Dilution

o   Inorganic Nutrients

o   Xenobiotics- a chemical which is found in an organism that is not normally produced or expected to be present in it.

o   Epizootics- a disease that appears as new cases in a certain animal population, during a given time, at a rate that greatly exceeds what is "expected."


Buchheim, J. (2000).http://www.marinebiology.org/coralbleaching.htm. Retrieved from http://www.marinebiology.org/coralbleaching.htm

Control of Zebra Mussels in Pipes

What are Zebra Mussels?

·      Zebra mussels, a freshwater bivalve mollusk, have been invading America’s lakes and streams ever since it was detected in Lake St. Clair in 1988.

o   Located just west of Detroit, Lake St. Clair is a relatively large lake located in between Lake Huron and Lake Michigan, both of which are connected to St. Clair by a waterway.

·      Zebra mussels originate in streams located in the Balkans, Poland, and the former Soviet Union.

·      It is believed that zebra mussels were picked up in a freshwater European port in the ballast water of a ship and were later discharged into the Canadian side of Lake St. Clair.

·      Zebra mussels live 4 to 5 years and inhabit freshwater at a depth of 6 to 24 feet.

o   Zebra mussels begin to reproduce at two years of age and females can lay over 1 million eggs in a spawning season.

·      Zebra mussels use byssal threads to attach themselves to hard surfaces and are difficult to remove, which is unusual of freshwater mussels due to the lack of wave action.

·      Zebra mussels can withstand being out of water for several days as long as conditions are moist and humid.

·      Zebra mussel larvae (called veligers) are microscopic in size and are undetectable by the human eye. They can be unknowingly transported in boat live wells and bait buckets or anything that carries small amounts of water, even on SCUBA equipment.

·      Zebra mussels spread rapidly throughout the Great Lakes region and in the large navigable rivers of the eastern Mississippi drainage including the Mississippi, Tennessee, Cumberland, Ohio, Arkansas, and Illinois rivers. They can also be found in the Hudson River on the Atlantic Slope.

o   Barge traffic in these large rivers helped to disperse zebra mussels their first few years here. Since then, dispersal has been mostly into small lakes within the Great Lakes region.

o   Currently, there are more than two hundred and thirty lakes that have zebra mussels. Much of this recent dispersal can probably be attributed to recreational activities such as boating and fishing.

·      They are primarily algae feeders. They feed by filtering the water through a siphon, up to a liter per day.

o   This is why they like the insides of pipes so well, there is a constant supply of water and food flowing by them.

o   One adult zebra mussel can filter almost a quart of water per day, and whole colonies can filter all the water in a lake in one day. The massive loss of algae in the water causes a great increase of water clarity in infested lakes.

·      Native species do not feed heavily enough on zebra mussels to keep the population under control.

Why are they a Problem?

·      Zebra mussels will attach to almost any hard surface, either natural or manmade.

o   On boats, they may attach to the hull, motor, or any item immersed in the water. Both large and small boats can be severely impacted by increased drag caused by thousands of mussels. Small zebra mussels may get into the engine cooling systems, causing overheating and other damage.

·      Zebra mussels pose a threat to navigational buoys, piers, docks, and other structures in the water.

o   Navigational buoys have been sunk under the weight of attached zebra mussels. Wood, steel, and concrete are all damaged by prolonged attachment of the mussels.

·      Many power plants and water users have had to spend millions of dollars cleaning out zebra mussels from their facilities. In addition, more money has been spent on retrofitting facilities with devices to keep zebra mussels out and to monitor for them. These costs get passed along to consumers.

o   Mussels have blocked pipes, screens, condenser units, and many other small openings through which water passes. They do this by forming druses (clumps of mussels) or simply attaching to available hard substances with byssal threads.

·      There is evidence that zebra mussel byssal threads may accelerate corrosion around joints and rivets of metal structures of power plants. Bacteria are present in the area between the substrate and the pad of the byssal thread. Through anaerobic respiration, these bacteria produce an acidic compound that increases the corrosion and pitting of iron and steel surfaces.

·      Even if mussels are killed by a control technique, the shells and any decaying animal material may remain behind, causing additional problems. Thus, killing the mussels may be only part of the solution to opening a blockage. A complete solution may require removal of mussel shells.

Possible Removal Solutions

·      Acoustics

o   Advantages:

§  Less likely to kill non-targeted organisms

§  Has no obvious residue effects

§  Equipment can be installed relatively easily

o   Disadvantages

§  Investigations of the effectiveness of acoustics have been inconsistent and more research is needed to adequately develop this strategy

o   Three approaches to solution:

§  Cavitation – the formation and collapse of microbubbles.

§  Sound treatment – the use of water-borne acoustic energy (acoustic waves) having intensity below the cavitation threshold. These include sounds (20-Hz to 20-kHz) and ultrasound (above 20-kHz) waves.

§  Vibration – the use of solid-borne acoustic energy (vibration) in mechanical structures (pipes, walls, etc.).

·      UV radiation

o   Advantages:

§  Zebra mussel veligers and adults are sensitive to UV-B radiation, provided that the radiation is applied constantly.

§  UV lights easily installed at intake bays of pipes

o   Disadvantages:

§  Non-target species may also be killed

§  Most applicable to medium to small sized raw water systems

Poaching

What is Poaching?

·     Poaching is the illegal hunting, killing, or capturing of animals

·     Failure to comply with regulations for legal harvest

·     Illegal taking of wildlife

·     Can also refer to the taking of animals from a gazzetted wildlife sanctuary, such as a national park, game reserve, or zoo

Reasons for Poaching

·     Animals are poached for game meat

·     Some animals have religious value and are used as totems

·     Many animals are killed for ceremonial purposes, such as cleansing a bad omen

·     Animals are also believed to have medicinal value

·     It is believed by some Lendu in Eastern Congo that the lion’s liver cures skin diseases

·     To kill the animals and stop them from encroaching on farms.

Reasons Poaching is Illegal

·     Game or fish is not in season

·     Hunter does not have permission to hunt on the land

·     Hunter does not possess a valid permit

·     Illegal selling the animal for profit

·     Hunting outside of legal hours

·     Bait is inhumane

·     The animal or plant is protected by law

·     It has been listed as extinct or endangered

·     The animal or plant has been tagged by a researcher

Solutions

·    Greater consequences if you get caught poaching

·    Better surveillance on land that people do not have permission to hunt on

·    Hunting is permitted in some game reserves under specific regulations

·    Countries enforce bans, restrictions, and monitored trade