The Indian Ocean Monsoon began abruptly, 12.9 million years ago, say scientists after studying cores of sediment in the Maldives. (Photo: Gregor Eberli/UM Rosenstiel School of Marine and Atmospheric Science)
Week 31 | 31 July to 6 August
Five things we learned this week! Everything here is published open-access. That means you can read the original scientific research yourself for free with no annoying pay-walls. Enjoy!
1) Species previously unknown to science discovered in an area of the Pacific Ocean targeted for deep-sea mining. Scientists have discovered a rich and diverse ecosystem in the Clarion-Clipperton Zone–an area in the equatorial Pacific Ocean. Mining companies have been granted contracts to mine for so-called polymetallic nodules, which are potentially valuable sources of copper, nickel, cobalt, and manganese. But during their survey of the seabed, scientists discovered that half of the collected species were new to science. Species diversity seems to depend on the presence of the nodules, and may be negatively affected by any mining activity in the area.
2) One of the last populations of Woolly Mammoths died out 5,600 years ago on St Paul’s Island, Alaska–once a part of the Bering Land Bridge before sea level rose at the end of the Last Ice Age. Scientists have now produced the most precise date for this extinction event using fungi spores found in lake sediments on the island. The spores are only associated with the dung of large animals, like mammoths. All evidence of them suddenly disappeared in the sediments laid 5,600 years ago, long before polar bears and humans colonised the island. The new results document how the mammoths disturbed the lake sediments as they dug for water–much like elephants do today–before the last mammoth finally died out.
3) The golden tegu lizard from Brazil has three new relatives. Scientists have discovered three new members of the golden tegu lizard family–once thought to consist of just a single species. Scientists studied museum samples of the lizard collected from sites across northern South America. All four lizards look very similar but are genetically distinct.
4) Early North Americans started farming due to rapid population increase and dwindling supplies of wild food. Anthropologists in the USA studied published radiocarbon dates from artefacts left behind by people, such as charcoal, nutshells, and animal bones from across mid west USA. They assumed that in periods of population growth they would see more artefacts. They discovered a number of swings in population, but around 6,900 years ago populations suddenly shot up and didn’t slow down until 5,200 years ago–around the time of the initiation of farming in North America.
Read more here or try the original scientific paper.
5) The Indian Ocean Monsoon began abruptly, 12.9 million years ago, say scientists after studying cores of sediment in the Maldives. Before the onset of the monsoon, the Maldives were surrounded by coral reefs during a time period called the Miocene Climate Optimum–around 15 million years ago. The scientists found evidence for a subsequent period of global cooling and lowered sea level, which exposed the reefs and seasonally changing winds over the oceans, which are typical of Monsoons. When the world warmed once again, rising sea levels inundated the reefs, and a newly initiated Indian Ocean Monsoon drove ocean currents and sediments towards the Maldives in a bipolar ocean circulation that still exists today. The reef never recovered. The new results not only narrow down the onset of the Indian Ocean Monsoon, but also shed new light on the future of coral reefs due to sea level rise and shifting ocean currents and sediment supply.
Amon, D., Ziegler, A., Dahlgren, T., Glover, A., Goineau, A., Gooday, A., Wiklund, H., & Smith, C. (2016). Insights into the abundance and diversity of abyssal megafauna in a polymetallic-nodule region in the eastern Clarion-Clipperton Zone Scientific Reports, 6 DOI: 10.1038/srep30492
Betzler, C., Eberli, G., Kroon, D., Wright, J., Swart, P., Nath, B., Alvarez-Zarikian, C., Alonso-García, M., Bialik, O., Blättler, C., Guo, J., Haffen, S., Horozal, S., Inoue, M., Jovane, L., Lanci, L., Laya, J., Mee, A., Lüdmann, T., Nakakuni, M., Niino, K., Petruny, L., Pratiwi, S., Reijmer, J., Reolid, J., Slagle, A., Sloss, C., Su, X., Yao, Z., & Young, J. (2016). The abrupt onset of the modern South Asian Monsoon winds Scientific Reports, 6 DOI: 10.1038/srep29838