Animal populations across the globe are decreasing in numbers, with many at risk of extinction. Many animals that aren't even endangered have drastically reduced populations compared to one-hundred years ago. Possibly the gravest examples are marine animals.
The krill, Euphasia superba, "may be the most abundant animal on the planet." However, densities have declined by 80% in the last 75 years. Since krill is critical to the survival of many marine species such as whales, its decline has affected the entire ocean.
A possible solution may be genetic engineering: due to overfishing, hatcheries have been made to basically farm salmon. This article: http://www.flmnh.ufl.edu/fish/InNews/calamity2004.htm states that genes from ocean pout have been spliced into the DNA of salmon to trigger growth hormones, allowing the salmon to grow incredibly fast.
Could genetic modifications be used to allow krill and other organisms to grow and multiply faster, and thus counteract our effect on animal population densities?
How is this counteracting natural evolution? Will this work well, and if not, what would be the negative side effects?
Consider what we learned in the ecology unit about carrying capacity.
I am very glad that you asked about the ethics behind such a question because humans will be able to manipulate species populations. The question now becomes, should we? The answer to this, except under rare circumstances, is no. As we have learned throughout the course is that nature is a series of very delicate balances that can adapt over a long periods of time, but has trouble adapting in short periods of time.
ReplyDeleteOne balance that would be thrown into havoc with the manipulation of species populations is the food web of the ecosystem. We learned earlier this year that predator/prey relationships are an integral part of any ecosystem. Artificially increasing or decreasing a certain species population will throw off the species predator/prey relationship. In addition to this, the artificial change in species population will throw off other predator/prey relationships that have even a single link to the species. What this means is that by changing one predator/prey relationship, the entire food web becomes affected.
Like many other prompts, this prompt is asking about the ethics behind the use of technology by humans to affect our environments. It is clear that just because humans can alter the environment, they should think before using such technology.
If humans were to genetically modify krill so that they grow and hence reproduce faster, the increase in krill won't necessarily undo the damage that humans have caused the oceanic ecosystem. Yes, krill are an extremely important member of the food web. Birds, crabeater seals, balleen whales, carnivorous plankton, as well as smaller fish all consume krill. Plus, the larger animals consume the animals that consume krill, so all oceanic life is somehow connected to krill, one of the species very low on the food chain/web. (I like the food web on this site: http://www.econguru.com/fundamentals_of_ecology/image/grazingfoodweb.gif)
ReplyDeleteWhether or not increasing the number of krill will have a positive or negative effect on the ocean ecosystem is debatable.
Due to global warming, polar ice caps are quickly melting, and according to a science daily report, "over the next 40 years...winter sea-ice coverage of the Southern Ocean [will decline] by up to 30 per cent in some key areas". Whales dependent on ice (such as the Antarctic minke whales) will have to swim a longer distance, and therefore expending more energy, to obtain less food. If more food, like krill, were to be put in those areas, it is possible that certain whale species could fight against extinction/endangerment.
(http://www.sciencedaily.com/releases/2008/06/080629143936.htm).
Relating to carrying capacity, if more krill were to be placed in the ocean, then all species of the ocean could possibly benefit. But how much can the ocean hold? If all the krill have newly inserted genes to reproduce faster due to a quickened life cycle, couldn't that have a negative effect on the ecosystem due to overpopulation? If more krill are consumed, allowing other species to thrive (survive and reproduce), then the ocean might reach its carrying capacity --"the maximum population size that a particular environment can support at a particular time with no degradation of the habitat" (Campbell 1160). Of course, researchers don't have an exact way of knowing what the carrying capcity of the ocean is (like predictions of human specie's carrying capacity were often undershot).
If humans are solely concerned with genetically modifying krill in order to decrease fish market prices or help out farmers, there is some debate. If humans can genetically modify salmon to help out the salmon market (see the link in the question), why can't humans genetically modify krill in order to help out the entire fish market? But just like David was saying, just because humans have the ability to change the environment through technology, it doesn't mean that humans should use that ability.
Umm... well contradicting what the two posters before me said I think it is nessecary and vital that we use gene splicing to try and fix our screw-ups. If we are the main cause that the world's various ecosystems are basically dying out, we should do everything in our power and knowledge to fix the problem before its too late. If we leave it up to "nature" or "god" to let the problem fix itself, the various speices will most likely die out because of competition from humans and then when all the humans die out the earth begins a "new" evolutionary cycle to get in a new set of species. It is a ridiculous idea that we should not try and fix a world we almost single-handedly destroyed.
ReplyDeleteYes various problems and factors can come into the equation, (economic, ethical, etc.), but this also some what mirrors the debate of the theory of evolution and intelligent design. Why are so many people hating on gene splicing? Because they don't want people to tamper with "nature" or "god's" work, which is ridiculous. If it wasn't for gene splicing china would be facing famine yearly, there'd be no hope for population growth for the future and people all over the world would simply begin to war each other for food and resources. Gene splicing in a sense is a "miracle", and we should use it to its fullest potential to try and better the world.
I must agree with Mr. Bruk on this subject. I believe that splicing in genes for growth hormones into other species to counteract environment destruction and over-fishing by humans is just a treatment to the symptoms and not the root of the problem. This possible course of genetic engineering could have massive effects on the environment that would almost certainly be negative. By splicing in abnormal amounts of growth hormones, the populations of the spliced organisms would boom due to shortened life cycles. These booms could disrupt many ecosystems. For example, the splicing of growth hormones (or their equivalent) into phytoplankton would cause algal blooms and eutrophication of freshwater biomes. The result of this would be catastrophic, mainly with the disruption of food webs and mineral cycling.
ReplyDeleteOne thing to consider, however, is that the limiting factors of the ecosystem that the spliced organism is in will restrict the population. There will be an initial boom in the spliced population, but eventually the population will reach the carrying capacity and level out. This is very important because this shows that shortening the life cycle of a species will allow the species' population to increase until a limiting factor is met.
While my last paragraph seems to offer support for using gene splicing to restore damaged populations, I am definitely not in support of it. The problem with gene splicing is that it circumvents evolution and that it has potentially devastating ramifications. Any gene splicing that shortens life-cycles will cause a massive disruption in the predator-prey relationships of that ecosystem. For example, if a fox population was increased through gene splicing, then the hare population would dramatically decrease due to unnaturally high rates of predation.
Overall, I believe that humans should not introduce new genes into other organisms in order to achieve so called "normalcy" because this is just circumventing nature and could be more dangerous than helpful. Instead of changing other organisms, why don't we just change ourselves? We should work on treating the root of the problem - human exploitation of the environment - instead of treating the symptom - declining populations of other organisms - if we truly want to return to normalcy.
One of the major concepts of ecology is the existence of an intricate balance between the quantities of all organisms in the biosphere. Ben and Erin bring up the valid point that the enhanced growth of krill populations will provide a necessary food source for some endangered species, and will also allow the fishing industry to continue their heavy fishing of krill. However, the consequences of meddling with a natural ecosystem are so severe that they greatly outweigh the benefits.
ReplyDeleteErin discussed the faster movement of an ecosystem towards its carrying capacity due to the introduction of this transgenic krill. This is a great point, and depicts the extreme consequences that yield from only relatively mediocre benefits.
I find the introduction of transgenic krill a futile effort in battling the extinction of species. Although the mass reproduction of krill would "save" those who prey on the krill, the prey OF the krill, phytoplankton, would be drastically reduced. Many aquatic primary consumers depend on the photosynthetic phytoplankton for food, just as there are many organisms who depend on the krill. If the krill population were enhanced, the extra competition for a constant source of food would yield the elimination of other predators of krill, which would bring us back to where we started, except this time we'd be wondering about another aquatic organism.
Furthermore, the article that Ben posted specifies that "the transplanted genes trigger the salmon's growth hormones, making the fish grow five times faster than normal." This excess growth, although highly beneficial to fishing companies, is detrimental to the ecosystem, because the increased muscle strength and size would enhance the krill's dominance over its prey, phytoplankton, which would only facilitate the drastic reduction of the phytoplankton population.
I know this is unrelated to ecology, but the harvesting of transgenic fish by fishing companies may prompt a fierce counter-campaign, similar to the controversy about genetically modified (GM) crops. Does the fishing industry really want that?
The mere proposal of introducing this transgenic fish into a natural ecosystem goes to show how selfish we have become. Our horrible fishing industry shrinks natural krill populations, and then only seeks to bolster the populations of it's "cash cow" regardless of the effect that this may have on other organisms. The fishing companies are probably thinking, "Who cares about the 'other organisms', I can't make money off of these organisms, so therefore they don't matter." Such parochial thinking lacks understanding of a cornerstone principal of ecology, which is that all organisms are related in a massive food web that ensures the survival of us all. Killing of one species will eventually lead to our demise as well.
The BEST way to fix the problem proposed in Ben's prompt is to reform fishing practices, which will allow recovery of the NATURAL krill population, and return the ecosystem back to homeostasis. But that would involve a change of mind of stubborn CEOs who see only company profits. :(
In response to Erin, I believe that a rise in krill populations could repopulate the ocean with krill predators. The great numbers of krill would raise the carrying capacity for other organisms: as Aaron said, the populations would level off after meeting the carrying capacity. I don't think this would mean overpopulation, since there would theoretically be plenty of resources for all organisms.
ReplyDeleteVissagan pointed out a flaw with the plan of modifying krill: krill eat phytoplankton. If the krill would grow 5 times faster than normal, then they would need at least 5 times more food. To this, I suggest that instead of consumers, we can instead modify plants and other primary producers.
There are flaws with this plan, too: Aaron suggested that algal blooms would disrupt the environment. However, if there are enough consumers like krill to contain the growth of algae, then what could go wrong?
Also, algae usually don't grow out in the open ocean because of a lack of minerals, and especially iron. So couldn't we just dump minerals out in the ocean like fertilizer? This article [http://www.nytimes.com/2007/05/01/business/01plankton.html?pagewanted=2&_r=1&ref=science] proposes the possibility of dumping iron into the oceans to promote algal growth. By promoting the mass growth of algae, we may not only help krill (and other ocean animals) populations to grow, but also reduce carbon dioxide levels in the air! We'd hit two birds (for lack of a biophilic term) with one stone! What could go wrong?
The fact is that a LOT can go wrong. There are infinite possible problems that could come up, and as Murphy's law proposes, everything that can go wrong will. Maybe the algae will take over the oceans and choke the wildlife to death? An example of human intervention in nature that ended up horribly was the introduction of cane toads to Australia. The toads were supposed to rid farms of insect pests, but have become a pest themselves and a threat to the ecosystem.
Maybe with extensive controlled experiments, the solutions I brought up may prove to be safe. I doubt this, though. I believe that the best solution for helping the environment is to stop intervening, and instead back off and let nature do its thing.