Jun 20, 2017

Drowned wildebeest feed the Serengeti

Every year, over a million wildebeest make their way across the Serengeti in the largest remaining land migration. New research shows the thousands of wildebeest that drown crossing the Mara River in the process are an important source of nutrients for the entire Serengeti Mara ecosystem.

What they found: Wildebeest carcasses take about 28 days to decompose, and as they did they were integrated into the food chain at every level, from scavenging birds to fish to bacteria. Crocodiles, possibly because of their slow metabolism, only ate about 2% of the carcasses. After the meat was consumed, the bones leached nutrients downstream.

How they did it: The scientists used historical reports of mass drownings from 2001-2014 and conducted field surveys from 2011-2015. They studied the carcasses as they decomposed, measured nutrient levels downstream of the drownings, used cameras and chemical analysis to estimate how much of the carcasses were eaten by each scavenger.

By the numbers: According to the researchers, up to 1600 tons of wildebeest end up in the river each year - that's roughly the equivalent of ten blue whales. As the carcasses decompose, they raise the phosphorous levels in the river by as much as 451%, the carbon by up to 191%, and the nitrogen by up to 78%.

For comparison, this is four times the mass moved by the salmon runs of the Pacific Northwest. Some scientists think the Northwest owes its lush forests to these salmon, which scavengers distribute through the forest like fish fertilizer. It's possible wildebeest play a similar role in the Mara.

Bottom line: River systems that no longer have large migrations may have lost a vital source of nutrients, say the researchers.

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Trump signs $2 trillion relief bill as U.S. coronavirus case count tops 100,000

Data: The Center for Systems Science and Engineering at Johns Hopkins; Map: Andrew Witherspoon/Axios

President Trump signed a $2.2 trillion coronavirus relief package on Friday, as infections in the U.S. topped 100,000 and more cities experience spikes of the novel coronavirus.

The big picture: The U.S. has the most COVID-19 cases in the world, exceeding China and Italy, per data from Johns Hopkins. A second wave of American cities, including Boston, Detroit, New Orleans and Philadelphia, are reporting influxes of cases.

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Coronavirus updates: Italy records deadliest day with nearly 1,000 dead

Data: The Center for Systems Science and Engineering at Johns Hopkins, the CDC, and China's Health Ministry. Note: China numbers are for the mainland only and U.S. numbers include repatriated citizens and confirmed plus presumptive cases from the CDC

Italy on Friday reported 969 COVID-19 deaths over a 24-hour period, marking the deadliest single-day for the country since the global outbreak began, according to data from the Health Ministry.

The big picture: The U.S. now leads the world in confirmed coronavirus cases, as the number of global cases nears 600,000. Governments around the world are trying to curb the medical and financial fallout of COVID-19, as infections surge across Europe and the U.S.

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Coronavirus dashboard

Illustration: Sarah Grillo/Axios

  1. Global: Total confirmed cases as of 9 p.m. ET: 595,800 — Total deaths: 27,324 — Total recoveries: 131,006.
  2. U.S.: Leads the world in cases. Total confirmed cases as of 9 p.m. ET: 103,942 — Total deaths: 1,689 — Total recoveries: 870.
  3. Federal government latest: President Trump signed the $2 trillion coronavirus stimulus bill to provide businesses and U.S. workers economic relief.
  4. State updates: Nearly 92% of cities do not have adequate medical supplies — New York is trying to nearly triple its hospital capacity in less than a month.
  5. World updates: Italy reported 969 coronavirus deaths on Friday, the country's deadliest day.
  6. Business latest: President Trump authorized the use of the Defense Production Act to direct General Motors to build ventilators for those affected by COVID-19. White House trade adviser Peter Navarro has been appointed to enforce the act.
  7. 🏰 1 Disney thing: Both Disney World and Disneyland theme parks in the U.S. are closed until further notice.
  8. What should I do? Answers about the virus from Axios expertsWhat to know about social distancing.
  9. Other resources: CDC on how to avoid the virus, what to do if you get it.

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