I hope everyone will forgive me for being gone for so long! My work has slid away from popular writing and moved in a more scholarly direction. Unfortunately, scholarly stuff takes more time. Fortunately, scholarly stuff gives you better conclusions. Anyway, here is a bit on coral and Noah's Flood that I have been working on over the past semester under my marine biology professor for Honors Credit. Arguments about Noah's flood seem to revolve mostly around numbers of animals, ark logistics, animal distributions post flood, and where the heck the water came from/went, and I am here to tell the 'figure out whether or not Noah's flood happened' community that CORAL ARE PEOPLE TOO!!! So stop ignoring them. Anyway, I hope ya'll like scientifickee-style writing. I know I do.
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The Effects of a Proposed Model for the Genesis Flood Account on the Mortality of Mature Coral, Coral Gametes, and Swimming Coral
(or)
Noah's Flood Would Have Killed ALL of the Coral Even if it Was a Local Flood <--easier to read and more to the point title for blog purposes
Abstract
The purpose of this inquiry is to examine the historical reliability of the flood account in Genesis. Using modern knowledge of brooding and broadcasting species of coral, I will attempt to deduce whether a cataclysmic flood like the one described in Genesis would cause the extinction of coral. If the flood described in Genesis would cause the extinction of coral, and yet coral are alive today, the Genesis account loses reliability as a historical document. Interpretation is key when comparing Genesis to scientific information. I do not examine every possible interpretation of Genesis, but instead select a single, conservative interpretation to compare with my findings. I acknowledge that alternative interpretations of Genesis are valid, and may result in alternative conclusions. I hypothesize that a global flood of 5137 meters lasting for about one year would cause the extinction of all coral species including (a) mature coral attached to the bottom, (b) coral gametes suspended in the water, (c) coral planula larvae, and (d) pieces of mature coral that break free from the stationary colonies. If my hypothesis is demonstrated to be valid, it is unlikely that the proposed interpretation of Genesis could have taken place.
Introduction
In chapters 4-7 of Genesis, a cataclysmic flood is claimed to have taken place within the last 6000 years. According to Genesis, God decides to judge the earth for its wickedness by flooding it with water. However, God also decides to save a few humans and animals through a man named Noah, whom God instructs to build a massive ark. Once Noah completes his ark, God causes huge amounts of rain to fall and “opens the gates of the deep,” causing the water level to rise. Only Noah, his family, and any animals taken along survive the flood. After about one year the waters subside and Noah is able to disembark upon a cleansed earth (ESV Genesis 6-9).
Due to the multiplicity of valid interpretations of Genesis, I have decided to develop an argument which is valid for almost every interpretation of Genesis which stays true to the text. According to Genesis, a flood took place which covered “all the highest mountains” (Genesis 7:19). This flood could have been global, covering all of the highest mountains on earth, or regional, covering all of the highest mountains in the region. However, even if the flood covered “only the mountains in the region”, sea level around the world would still have to rise to a level at least as high as these mountains. It is impossible to have a flood in which the highest mountains in a region are covered and sea level elsewhere is lower because water fills the container in which it resides. In short, a regional flood which covers mountains in one region may not result in total planetary submersion, but will cause a global flood equal to the height of those mountains.
For the purposes of this inquiry, I have selected Mount Ararat (elevation 5,137 meters) as the highest of the mountains which would have been covered by the flood. I have selected Mount Ararat for two reasons. First, it is probably in the region that Genesis is talking about. Second, it is the highest mountain in the area, and would therefore be included in the category of “highest mountains” for the region. I acknowledge that peaks in other regions could have been the actual mountains covered by the flood, which could result in alternative conclusions. These alternative scenarios could be the subject for future study.
In addition, I will make several assumptions which are necessary at this time for the sake of argument. First, I assume that Mount Ararat was at about the same elevation during Noah’s time as it is today. Second, I assume that sea levels before and after the flood were about equal. Third, I assume a somewhat uniform rate of sea level rise (5137 meters over 40 days and 40 nights) and a slower, more gradual decline in sea level which comes to completion about one year after the flood started. Fourth, I assume that currents generated by the flood would be capable of carrying water-bound coral very long distances. Fifth, I assume that after less than a year of growth in a new environment, coral species will still be capable of polyp bailout. In the future I hope to address these issues so that fewer assumptions are necessary.
While I will rely primarily on general information concerning coral, I have selected three representative species of coral when specific information is needed. These species are Diplori labyrinthiformis, Diploria strigosa, and Diploria clivosa.
The interpretation of Genesis 6-9 I use is as follows: Within the last 6000 years, God caused sea level to rise to a depth greater than 5000 meters in 40 days and 40 nights. After about 10 months, the water subsided to the level that it was before the flood.
Background
Coral are marine animals of the class Anthozoa and phylum Cnidaria. Coral generally live in colonies consisting of many identical polyps. They have the ability to capture prey using nematocysts, but primarily receive sustenance from symbiotic algae known as zooxanthellae. Because the zooxanthellae require light for photosynthesis, coral typically live in shallow, clear water. Coral reproduce sexually once a year, typically during the summer and fall months. . Coral reproduce sexually through either broadcast spawning or brooding. Broadcasting species discharge sperm and eggs into the water at specific times each year (Gleason). The positively buoyant gametes float to the surface, meet, and form zygotes. The zygotes develop into free-swimming planula larvae which settle on the bottom and become primary polyps. Over time the primary polyps grow and reproduce asexually until they are large enough to generate gametes of their own. Brooding species do not release eggs into the water. Rather, eggs are kept inside of the coral’s body and negatively buoyant sperm are discharged into the environment. Once the sperm reach the eggs, planula larvae develop inside of the coral for some time before being released. The mature planula larvae swim away from the parent coral, find a place on the bottom to settle, and form a new colony. Coral can also reproduce asexually through fragmentation and parthenogenesis. Fragmentation occurs when a piece of coral breaks off from the colony and settles in a new location. Parthenogenesis takes place when unfertilized eggs transform into larvae (Richmond 176-178).
Mature coral do not typically move, but through the process of polyp bailout coral can actively leave their skeletons behind, transform into swimming coral, and find a new location to settle (Richmond 176).
Methods
I conducted a keyword search on coral to find scientific literature using the Mendeley search engine.
They key words I used are as follows:
- Coral
- Coral reproduction
- Coral sexual reproduction
- Coral asexual reproduction
- Coral broadcasting
- Coral brooding
- Coral and temperature
- Coral and depth
- Coral and salinity
- Coral and pressure
- Coral and light
- Planula larvae
- Coral gametes
- Buoyancy of coral gametes
- Survivability of coral gametes
- Competency of planula larvae
- Timing of coral reproduction
After collecting scientific papers through my keyword search, I compiled information pertaining to the survival capabilities of mature coral, gametes, planula larvae, and pieces of mature coral that break free from the stationary colonies. My goal was to examine every potential venue for the survival of coral species.
I started by examining the effects of a 5,137 meter increase in depth on mature coral. I gathered information on the effects of depth increase on pressure, temperature, and light penetration. Next I gathered information on the expulsion of coral gametes during broadcast spawning, the motion of gametes through the water, and potential mechanisms for gamete survival and reproduction. I then found information pertaining to the motion of planula larvae produced by brooding corals. I focused on information concerning whether or not these larvae have tendencies to swim up towards the surface, down towards the bottom, or both sequentially. I also collected information pertaining to alternative forms of coral reproduction, including fragmentation and budding as they relate to potential mechanisms for coral survival. Finally, I determined the timing of spawning for three coral species: D. labyrinthiformis, D. clivosa, and D. strigosa. In future studies I hope to include information on additional coral species.
Results
For every increase in depth of 10 meters, pressure increases by 1 atm (Castro and Huber 48). Therefore, an increase in depth of 5,137 meters would cause the amount of pressure on all mature, stationary coral on the planet to increase by 513.7 atmospheres. Less drastic increases in depth (Less than 100 meters) have been shown to decrease the growth rates in coral (Logan).
As depth increases, temperature drops. As depth increases from the surface to 200 meters the temperature quickly decreases. As depth continues to increase past 200 meters the temperature continues to drop, but at a slower rate. Once the depth becomes greater than 1000 meters, the temperature remains fairly constant at a range of 0 to 5 degrees Celsius (Castro and Huber 52-54).
As depth increases, the amount of light able to penetrate decreases. The maximum depth at which photosynthesis occurs is about 200 meters, depending on how clear the water is. Some light can penetrate deeper than 200 meters, but it is not enough for photosynthesis. At depths greater than 1000 meters, no light penetrates (Castro and Huber 332).
Mature coral colonies attached to the bottom are not capable of avoiding the dramatic environmental changes introduced by the flood. Coral tissue which actively leaves the skeleton through polyp bailout, however, can swim through the water and change their location (Richmond 176).
During sexual reproduction through spawning, coral gametes are expelled into the water. Initially the gametes are positively buoyant and will rise to the surface. The gametes can potentially travel large distances. When sperm and eggs meet, they unite to form a planula larva which swims to the bottom to form a new colony (Richmond 187).
Brooding species expel only negatively buoyant sperm into the water. Eggs remain inside of the coral, waiting to be found by sperm. Once a sperm arrives, it unites with an egg to form a zygote. The zygote then becomes a planula larva which develops inside of the coral. After a period of development, the larva will exit the coral and swim until it finds a place to settle. For most species, once a planula larva settles on the bottom it commits to the location. However, for a few species, larvae can settle, decide that conditions are not right, transform back into a swimming larvae, and attempt to settle again. I did not find any instances in which a larvae could settle, switch locations, settle, and then switch locations again. The nutrient carrying ability of larvae limits the length of time that they can spend in the water without settling (Richmond 178-187).
D. strigosa and D. clivosa spawn anywhere from July to September. D. labyrinthiformis spawn anywhere from April to May. All three species are broadcasters which expel gametes once a year (Weil 417).
D. strigosa and D. clivosa have a minimum reproductive size over 100 square centimeters. D. labyrinthiformis has a minimum reproductive size over 50 square centimeters (Weil 417).
Discussion
Stationary coral that had been growing on the bottom before the flood would be subjected to a year-long increase in pressure of 513.7 atmospheres, a decrease in temperature to below 5 degrees Celsius, and the absence of light. These individuals would not have survived, leaving reef skeletons behind.
Mobile forms of coral have the potential to avoid these drastic environmental changes. In order for the gametes of broadcast spawners to survive, sea level rise due to the flood would have to correspond directly with the timing of gamete release into the environment. Positively buoyant gametes would be able to stay near the surface until gametes unite resulting in the formation of planula larvae, which swim towards the bottom to settle. It would not be impossible for currents to carry gametes and subsequent larvae quite far. While the vast majority of the broadcast spawner’s offspring would die, a unique combination of currents, species durability, avoidance of predators, and timing for the unification of sperm with eggs would make it possible for some of these coral to survive the initial sea level rise. Even though the timing of the flood (about one year) corresponds directly to the timing of spawning (once a year), any coral that survived the sea level rise due to broadcast spawning would not be able to produce gametes themselves because one year is not nearly enough time for single planulae larva to reach the minimum reproductive size. This does not, however, rule out the possibility of these corals reproducing asexually.
Because of the differences in timing for spawning in D. strigosa and D. clivosa (Jul-Sep), compared to D. labyrinthiformis (Apr-May), and the rate at which the flood caused sea level rise (5137 meters over 40 days and 40 nights), it is unlikely that all three species would be able to send out potential survivors through broadcast spawning. If additional species of coral spawn at other times , then the number of coral species excluded from the window of opportunity during which coral could expel gametes will decrease. In short, if the timing is correct for certain species of coral, it will be incorrect for other species, in which case the gametes will be subjected to the increase in pressure, decrease in temperature, and decrease in light reception.
Coral planulae which result from brooding species spend more time developing, which could potentially allow them to swim farther (Richmond 178-187). However, the larvae have a tendency to swim downwards in order to settle on the bottom. Depending on currents, it would be possible for a brooded planula spawned at the correct time to survive the initial rise in sea level and settle. As with broadcast spawning, however, a single year would not be long enough for settlement, development, and growth to the point that the brooding coral could produce gametes to brood.
When the water drops, any stationary coral that managed to settle in a place with appropriate depth, temperature, salinity, pH, and light (for example, near the peak of Mount Ararat or on the slopes of mountains around the world) would once again be killed due to lack of water. The only way for coral to survive would be to make it past the initial rise in sea level, settle and survive for a year, and then once again find a way to become mobile and make the long journey back as sea level dropped.
It is important to note that brooding coral, like broadcasters, do not send out their planulae all at the same time (Weil 417). Once again, if the timing is correct for certain species of brooders, it will not be correct for other species, resulting in the death of 100% of either one group of species or the other.
Two final ways for coral to become mobile and potentially survive the sea level rise both involve asexual reproduction. If pieces of coral broke free from the colony and were carried by currents up to a viable location, they could survive. I find this scenario extremely unlikely due to the negative buoyancy of coral structures.
Some coral can also detach from the parent colony, transform into swimmers, and swim to alternate locations (Richmond 176). If currents were favorable, and the coral neglected to settle too early, they could potentially survive the sea level rise. This type of reproduction is extremely important to this inquiry because corals budding off of the parent colony could survive the decrease in sea level, unlike the processes of broadcasting and brooding.
Conclusions
It is certain that any stationary coral would die because of a year-long increase in pressure of 513.7 atmospheres, a decrease in temperature to below 5 degrees Celsius, and the coral would be well over 4000 meters below the photic zone.
The only way for all species of coral to survive the flood is through polyp bailout because it can take place at any time during the year and it provides a viable mechanism for surviving sea level decrease. Broadcast spawning (as well as parthenogenesis) and brooding may be more likely to allow some species of coral to survive the initial rise in sea level, but the timing of the flood would exclude species that do not expel gametes at the correct time. In addition, neither broadcast spawning nor brooding are viable mechanisms for surviving the decrease in sea level.
I neither reject nor confirm my hypothesis that a 5137 meter deep flood lasting for about one year would cause the extinction of coral at this point. However, I would strongly recommend readers to take into account the fact that polyp bailout is the only way for every species of coral to survive both the increase and decrease in water level (because it is the only method of survival that is not time sensitive). As opposed to broadcasting and parthenogenesis, polyp bailout is not a phenomenon in which an immense number of coral are ejected into the water. Polyp bailout is neither the standard method for reproduction, nor does it generate a large number of water-bound coral. Because of this, polyp bailout does not enjoy the increased odds of success due to sheer numbers. In future studies I will examine whether or not all species of coral are capable of polyp bailout, and whether or not a minimum size is required in order for polyp bailout to occur. In addition, I hope to determine the amount of time that gametes, larvae, and other forms of water-bound coral can survive before settling on the bottom.
Summary Table!
Survival method
|
Advantages
|
Disadvantages
|
Broadcast Spawning
|
· Huge numbers
|
· Time sensitive- if the timing allows one group of species to survive, another group will die.
· Requires unification of sperm and egg
· Once sperm and egg unite, they become negatively buoyant (the sink)
|
Brooding
|
· Huge numbers
· Increased maturity may allow for longer periods of time spent before settling
· Sperm and eggs will unite before the larvae starts swimming
|
· Time sensitive- if the timing allows one group of species to survive, another group will die.
· Sperm are negatively buoyant
· Larvae seek out the bottom to settle
|
Parthenogenesis
|
· Huge numbers
· Unification of sperm and eggs not required
· Eggs will not become negatively buoyant due to merging with sperm
· Eggs will spend more time suspended near the surface before changing into a larvae
|
· Time sensitive- if the timing allows one group of species to survive, another group will die.
· Once eggs do turn into larvae, they will become negatively buoyant (not as much of a disadvantage in this case)
|
Pieces of coral physically breaking off of the colony
|
· Coral skeletons are negatively buoyant
· Low numbers
· Extreme currents required for any survival
| |
Polyp Bailout
|
· Not timing-sensitive
· Coral are mobile
|
· Low numbers
· Larvae tend to seek out the bottom
|
Bibliography
Castro, Peter, and Michael E. Huber. Marine Biology. 8th ed. New York: McGraw-Hill, 2010. Your Page Title. Web. 15 May 2012. <http://glencoe.mcgraw-hill.com/sites/0011062009/student_view0/>.
English Standard Version Bible. London: Crossway, 2010.
Gleason, D. F., & Hofmann, D. K. (2011). Coral larvae: From gametes to recruits. Journal of Experimental Marine Biology and Ecology, 408(1-2), 42-57. Elsevier B.V. doi:10.1016/j.jembe.2011.07.025
Logan, A., Yang, L., & Tomascik, T. (1994). Linear skeletal extension rates in two species of Diploria from high-latitude reefs in Bermuda. Coral Reefs, 13(4), 225-230.
Richmond, R. (1997). Reproduction and recruitment in corals: critical links in the persistence of reefs. Life and death of coral reefs. Chapman & Hall,. Retrieved from http://www.kewalo.hawaii.edu/docs/richmond/Publications/1997Richmond.pdf
Weil, E., & Vargas, W. L. (2010). Comparative aspects of sexual reproduction in the Caribbean coral genus Diploria (Scleractinia: Faviidae). Marine Biology, 157(2), 413-426. doi:10.1007/s00227-009-1328-5
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