Asteroid impacts killed off many species, but marine life was affected more than land life. Why?

Question

Most scientists believe that the early Earth was buffeted by a series of asteroid impacts, each of which wiped out many species, at least one coming close to wiping out all life itself. I was surprised to learn that the marine life suffered much greater losses than life on land. I would have thought that life in the seas would have had some protection from the blast of such impacts, and the subsequent atmospheric effects, including the drop in temperature, but it seems not to be the case. Any idea why not?

Answer 1

When an asteroid impacts, regardless of on land or sea, its sends up a massive plume of earth that will circulate around the globe for some time. Depending on the size of the asteroid, this dust plume could block out the sun. Remember that in the sea plankton are really the bottom or base of the food chain, and it jus so happens that some of them are phototrophic. With lower levels of light, these creatures die off and the base of the oceanic food chain is compromised, thus all larger species that depend on food that depends on food that depends on these plankton as food will be severly affected. Kill of the primary producers in any populations and the secondary and tertiary consumers will suffer. On land this happens, but we don't have water between us and the sun that blocks light to begin with depending on depth so we get all of what comes to the surface, not what makes it to the surface and through X amount of water that reduces the light intensity/amount by a factor of Y by that depth. At least this is what I remember from undergrad.

Answer 2

From wikipedia
http://en.wikipedia.org/wiki/Gamma_ray_burst
Mass extinction on Earth
One line of research has investigated the consequences of Earth being hit by a beam of gamma rays from a nearby (about 500 light years) gamma ray burst. This is motivated by the efforts to explain mass extinctions on Earth and estimate the probability of extraterrestrial life. The consensus seems to be that the damage that a gamma ray burst could do would be limited by its very short duration, but that a sufficiently close gamma ray burst could do serious damage to the atmosphere, perhaps wiping out the ozone layer and triggering a mass extinction. The damage from a gamma ray burst would probably be significantly greater than a supernova at the same distance.

The idea that a nearby gamma-ray burst could significantly affect the Earth's atmosphere and potentially cause severe damage to the biosphere was introduced in 1995 by physicist Stephen Thorsett, then at Princeton University [1]. Scientists at NASA and the University of Kansas in 2005 released a more detailed study that suggests that the Ordovician-Silurian extinction events of 450 million years ago could have been triggered by a gamma-ray burst. The scientists do not have direct evidence that such a burst activated the ancient extinction; rather the strength of their work is their atmospheric modeling, essentially a "what if" scenario. The scientists calculated that gamma-ray radiation from a relatively nearby star explosion, hitting the Earth for only ten seconds, could deplete up to half of the atmosphere's protective ozone layer. Recovery could take at least five years. With the ozone layer damaged, ultraviolet radiation from the Sun could kill much of the life on land and near the surface of oceans and lakes, disrupting the food chain. While gamma-ray bursts in our Milky Way galaxy are indeed rare, NASA scientists estimate that at least one nearby event probably hit the Earth in the past billion years. Life on Earth is thought to have appeared at least 3.5 billion years ago. Dr. Bruce Lieberman, a paleontologist at the University of Kansas, originated the idea that a gamma-ray burst specifically could have caused the great Ordovician extinction. "We don't know exactly when one came, but we're rather sure it did come - and left its mark. What's most surprising is that just a 10-second burst can cause years of devastating ozone damage." [2]

and NASA
http://www.nasa.gov/vision/universe/starsgalaxies/gammaray_extinction.html

from Science daily
http://www.sciencedaily.com/releases/2005/04/050411101721.htm
With the ozone layer damaged, ultraviolet radiation from the Sun could kill much of the life on land and near the surface of oceans and lakes, and disrupt the food chain.


I hope this helps. The idea is that radiation from the sun after the gamma ray burst strips the ozone would kill everything using the shallow parts and upper layers of the Oceans. That would be the majority of ocean life. The deep ocean creatures would likely carry on. The fossil record seems to agree with this hypothesis.
The extinction they are thinking about is the first one that there is a record of in the geology.

Answer 3

land animals had a larger verity of food and land temp from elevation. in the water the sun stoped and the plants died and that is the breeding ground for sea life.

Answer 4

If we glance at what befell sixty 4.9 million years in the past, the Chicxulub effect wiped out 70% of all species on earth, and that replaced into approximately 8-10 miles in diameter. permit's say one 25 miles in the time of have been to hit (no prevalent close to Earth Asteroid is that super). If it have been to land in an ocean, the tsunami could be properly over a mile intense, over 1000 cubic miles of ocean could turn to steam and canopy the full planet in a dense cloud layer for as much as a twelve months, and over 500 cubic miles of airborne dirt and mud could be secure, settling to Earth in approximately six months. The stress wave interior the sea and the tsunami could shuttle around the planet a number of situations, effectively assuring ocean existence varieties have been killed. during the few seconds it moved interior the process the ambience, such intense warmth could be generated that the flash could kill existence varieties out to 4 hundred miles, accompanied with the help of the sweetness wave killing and destroying out to over 1000 miles. The ozone layer could be destroyed with the help of chemical compounds positioned into the air. Following six weeks or so of intense temperatures hence effect, the cloud and airborne dirt and mud conceal could reason a drop in temperatures such that interior of six months equatorial temperatures could hover around 0 Fahrenheit (-16C), and this could persist for a minimum of four to 5 months. daylight hours for on the brink of a twelve months could be dark as hour of darkness with no Moon. this could bring about surviving animals dying of the chilly or loss of nutrition, as in simple terms about all vegetation could die. If it struck the midsection of a continent, the crater ensuing could smash interior the process the mantle, arising a significant volcano. The crater could be 250 miles in the time of. If it landed, say, close to the midsection of North u.s. (North Dakota) there could be no survivors between the Rockies and the Appalachians, and the climatic consequences suggested above could be from the airborne dirt and mud quite than steam. this could drop the temperature slightly speedier. The factors on the 250-3 hundred edge of the effect could have huge firest fires or grassland fires, putting extra CO2 interior the ambience alongside with different gaseous combustion products. as quickly as the sky cleared this could produce intense warming, yet there could be few existence varieties left to notice, different than possibly interior the deep oceans. friendly objectives once you sleep this evening.

Answer 5

there is more air than water, so a change in water will have more relative impact. in the air, there is more "wiggle room" for changes to spread out more evenly. eg, a tablespoon of water will heat up a lot faster than two tablespoons of air.

Answer 6

God does what He does and as for an explanation we might never know in this life. He has His own way and a good reason for everything.