![]() Different orders of radiolarians thrive at different depths in the ocean, so they make a good study subject in investigations on how extinctions were related to the depth of the water. The skeletons of radiolarians are well preserved, even in deep water sediments. The distribution of these single-celled floating organisms is controlled by the conditions in the ocean, such as temperature, depth, and the amount of oxygen. Radiolarians are marine plankton that are widespread throughout the oceans and have persisted from the Cambrian period (540 million years ago) to modern times. One way to learn how oxygen levels impacted ancient life is to study the fossils of marine plankton known as radiolarians. Understanding the sequence of events that took place in a mass extinction hundreds of millions of years ago is no easy task. ![]() The decay process of this organic matter consumed oxygen, and depleted the oxygen faster than it could be replenished. The additional nutrients in the water encouraged the growth of algae, which increased the amount of organic matter that sank into the ocean depths. Intensified weathering then washed this soil, along with extra nutrients, into the ocean. In the atmosphere, the volcanic gases mixed with water to form acid rain, which decimated forests and left the soil with no roots to keep it in place. This hindered the layers of water from mixing, and thus contributed to the depletion in oxygen. As warmer water is lower in density than cold water, the density difference between the deep layers and the surface increased. The increased heat also warmed the surface waters more than usual. The rising temperatures were a major factor as oxygen becomes less soluble in water as temperatures increase. There are several factors that contributed to the widespread ocean anoxia that exterminated so many species during the transition from the Permian to the Triassic. This increase in temperature ultimately caused the oxygen levels in the oceans to become dangerously low, a condition known as anoxia. ![]() The extra carbon dioxide, methane and water vapor in the atmosphere retained more radiation from the Sun, and global temperatures rose by between 10 to 15 degrees Celsius (18 to 27 degrees Fahrenheit). The gases and ash that spewed out caused catastrophic changes to the environment by initiating a greenhouse effect. ![]() Today this area is known as the Siberian Traps. Lava poured from fissures over an area the size of Europe and this period of volcanic activity lasted between one and two million years. It didn't just form one volcano, rather it was an event known as a flood basalt eruption. In this scenario, a mantle plume rose from deep within the Earth and burst through the crust at Siberia. Several theories have been proposed to explain this mass extinction, but scientists believe that the most likely trigger for this mass extinction was one of the largest volcanic eruptions ever recorded.Ī paper by Qinglai Feng and Thomas Algeo entitled "Evolution of oceanic redox conditions during the Permo-Triassic transition: Evidence from deepwater radiolarian facies," recently accepted in the journal Earth-Science Reviews details how tiny marine plankton known as radiolarians are shedding light on the sequence of events that led to this mass extinction. Solving the intricate puzzles of mass extinctions is vital when it comes to understanding the external factors that could hinder life on other planets. ![]()
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