Noor Banihashem Ahmad                                 September, 2012

Earth Science                                                   Current Event

Article: 

From: http://www.macroevolution.net/deep-sea-life.html#.UE56LWAQdJE

Sept. 5, 2012 — A new study of deep-sea life across the globe aims to understand how natural gradients in food and temperature in the dark, frigid waters of the deep sea affect the snails, clams, and other creatures that live there.

Similar studies have been conducted for animals in the shallow oceans, but our understanding of the impact of food and temperature on life in the deep sea — the Earth's largest and most remote ecosystem — has been more limited.

The results will help scientists understand what to expect in the deep sea under future climate change, the researchers say.

 "Our findings indicate that the deep sea, once thought remote and buffered against climatic change, may function quite differently in the future," they write.

All living things need energy in the form of food, heat and light to survive, grow, and reproduce. But for life in the deep sea — defined as anything beyond 600 feet (200 m) — energy of any kind is in short supply. Descend more than a few hundred feet beneath the ocean surface, and you'll find a blue-black world of near-freezing temperatures, and little or no light.

Because so little of the sun's light penetrates the surface waters, there are no plants for animals to eat. Most deep-sea animals feed on tiny particles of dead and decaying organic matter drifting down from the sunlit waters above. It is estimated that less than 1% of the food at the surface reaches the ocean's watery depths.

The researchers wanted to know what this energy deprivation means for deep sea habitats across the globe, and for the animals that live there. "How much of the differences that we see across different groups of deep-sea animals in terms of growth, or lifespan, or the number of species, are related to differences in the temperature or amount of food where they occur?" said co-author Craig McClain of the National Evolutionary Synthesis Center in Durham, North Carolina.

To find out, the researchers compiled previously published data for hundreds of different deep-sea organisms across the globe, ranging from crabs and snails, to fish and tube worms. The data included parameters like metabolic rate, lifespan, growth, biomass, abundance, size and diversity.

The results suggest that the relative importance of the two basic forms of energy available in the deep sea — food and warmth — vary considerably, said co-author Michael Rex at the University of Massachusetts in Boston.

Temperature has the biggest impact on parameters at the individual level, such as metabolism and growth rate. For example, deep sea animals living in warmer waters tend to have faster metabolisms.

But for higher-level parameters such as abundance or biodiversity, food is more important. Generally speaking, food-rich areas tend to have animals that are bigger, more abundant and more diverse.

The results add to the growing body of evidence that the deep sea isn't isolated from the effects of climate change, the researchers say.

"The oceans are getting warmer and they're producing less food," McClain said. Warmer water in the deep sea due to climate change could mean faster growth and metabolism for the animals that live there, but that could be bad news if the oceans produce less food to support them.

"The news is not good," Rex added. "Changes in temperature and food availability associated with climate change could cause widespread extinction in the deep ocean if environmental changes occur faster than deep-sea organisms can respond by shifting their ranges or adapting to new conditions."

CITATION: McClain, C., A. Allen, et al. (2012). "The energetics of life on the deep sea floor." PNAS. http://dx.doi.org/10.1073/pnas.1208976109

Deep Sea Life: Threatened By Global Warming

        Response: 

This article is primarily talking about how the creatures at the bottom of the ocean are not getting enough food that they need to survive. The Earth’s largest ecosystem has had limited food and near freezing temperatures. These creatures such as: snails, brittle stars, sea pen, sea cucumber, claims and other assorted invertebrates, do not have the necessary nutrients that they need to survive. The sun’s rays are not strong enough to heat the bottoms of the ocean, and on top of that, these animals only receive one percent of the food that is at the surface. As you can see, there resources are very limited. Researchers have recently done tests to see what this lack of energy means for the deep-sea habitats across the world. Researchers at the National Evolutionary Synthesis Center in Durham, North Carolina have tested on many snails, cabs, and tubeworms. They checked the things like metabolic rate, lifespan, growth, biomass, size, and biomass. The bottom line is that the oceans are heating up, and there is less food out there. This could be good news in the sense that it is warming up, but it is also bad if less food is being produced. In conclusion, the news is not the best. Due to the changes in temperature and obtainability to food associated with climate change could cause an extinction in deep-sea creatures if they do no react fast enough to the changes conditions. These organisms have little food, and the temperatures down at the bottom of the ocean are getting warmer. Warmer water causes organisms to have faster metabolisms. Food is not being produced as much anymore, and a faster metabolism means that these creatures will get hungry faster. The problem would be that there would be no food to eat.

         This tragedy could affect a lot of creatures in the sea. If these deep-sea organisms go extinct, then a food source could be wiped out for some of the other creatures. I’m sure that snails, crabs, and claims are a food source to another creature in the sea. If these animals go extinct, then another creature might not get the nutrients that it needs. If this creature doesn’t get the nutrients that it needs, it could go extinct as well. It could even set off a chain reaction. Our whole sea life has the potential to be completely wiped out. If these deep-sea animals go extinct, we might lose our access to crab, claims, and other deep-sea creatures that we eat too. This would be very sad because I know that I personally love seafood. Our source of seafood, if these creatures were to go extinct would be very scarce.

         I thought that this article was a pretty good one because everything was backed up by some means of evidence. The only thing that I’m a little confused about is that fact that global warming has been a known conflict problem in the past. Why is it that scientists are only realizing this now? Deep-sea life has probably endured many dramatic climate changes in the past, so why would they be affected now? The climate has been drastically changing for a while, and they have seemed to be fine until now. It would have been nice to know if the population of deep-sea life has been decreasing in the past decade or not. Other than that, I think this article has provided lots of good information that is very useful and alarming.