2/17/2024 0 Comments Lazarus species loss![]() Pictured on the left is the sample in its raw form (left) and after cleaning and sieving (right). Trubovitz used tropical deep-sea sediments obtained from the International Ocean Discovery Program (IODP) Gulf Coast Core Repository. “I had known we lacked a full inventory of tropical radiolarian species, but had not accounted for the sheer number of undescribed species in my samples.” “Once the deep-sea sediment samples were processed and mounted onto slides, the first thing I noticed was the remarkable number of radiolarian morphospecies, many of which could not be identified by my colleagues or from illustrations in previous radiolarian literature,” Trubovitz said. Paula Noble (Professor in the Department of Geological Sciences and Engineering) and Dave Lazarus (Museum für Naturkunde, Berlin), Trubovitz embarked on the tedious process of identifying and cataloging tens of thousands of tropical radiolarian fossils found in deep-sea sediment samples to see if she could uncover the missing polar species. However, he could not determine whether the missing plankton had migrated to warmer waters, as ecologists suspected, or if they had gone extinct. Johan Renaudie showed that a large assemblage of radiolarian species in the Southern Ocean had disappeared from polar environments as the planet cooled several million years ago. A similar survey of polar radiolarians completed in 2013 by Dr. ![]() Trubovitz started this research with the goal of completing the first full census of tropical radiolarian species over a 10-million-year interval of the Neogene and Quaternary periods. Photo taken prior to March 2020 and the COVID-19 pandemic. We don’t know enough about ecological interactions between plankton species to say exactly what will happen, but we should anticipate some cascading effects throughout the marine foodweb if a significant number of radiolarian species go extinct.” A complete history Since change is happening at such a rapid rate, there will not be time for evolutionary processes, such as the origination of new species, to offset extinction. ![]() Furthermore, the amount of warming projected in the next 300 years is comparable to the amount of cooling that occurred at high latitudes over the last 10 million years. “The extinction of these radiolarians alone will significantly lower the biodiversity of high-latitude ocean ecosystems. “There are approximately 100 radiolarian species currently living and adapted to cold conditions in the Southern Ocean, many of which will be unable to survive as the climate continues to warm,” Trubovitz said. The implications of this research for marine plankton in our rapidly warming climate are dire. Trubovitz’s findings contradict previous assumptions that marine plankton did and would migrate to follow favorable climate conditions in the event of large temperature shifts, instead confirming extinction as a more likely response. In an investigation of an abundant group of microscopic plankton called radiolarians and their reaction to temperature shifts during the Neogene period several million years ago, it was discovered that large changes in temperature led to dramatic decreases in polar radiolarian biodiversity. Plankton living in the world’s coldest waters surrounding Antarctica, the Southern Ocean, are at highest risk of disappearing as temperatures rise. candidate Sarah Trubovitz and published in the journal Nature Communications. Marine plankton-the foundation of many marine ecosystems, producers of about half of the oxygen we breathe, and regulators of carbon dioxide in our atmosphere-may be at risk of extinction as our planet continues to warm, according to a study led by Ph.D.
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