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What Happens To Fish During A Hurricane


(thunder booms) – [Narrator] Normally when a hurricane is barrelling towards us, we
tend to run the other way. But not Isla, she’s a leatherback turtle who was meandering off
the coast of Virginia when she accidentally swam
straight into Hurricane Florence. Scientists were worried
she’d get caught up in the middle of the storm,
but Isla managed to survive by swimming towards deeper waters. Turns out there’s a part of hurricanes we don’t often think about:
what happens under the surface. And Isla is just one example. (compelling music) Far out at sea, fish that
live near the surface might feel some turbulence
as a storm passes, but most sea creatures including
dolphins, whales and sharks avoid the rough surface water
and swim to calmer seas. But it’s a different story near shore. Changes in water temperature and salinity can be
catastrophic for marine life. Hurricanes can generate massive waves, which mix warm surface water with cooler, saltier water
below, generating currents that extend up to 91
meters below the surface. These currents are so strong, that they can sweep manatees
inland into canals and ponds, or away from coastal waters altogether and into the open ocean, where they can become
disoriented and even die. Hurricanes also bring heavy rains, so freshwater often floods coastal areas. And because freshwater is
less dense than saltwater, it sits on top of the
saltwater like oil on vinegar, where it can prevent oxygen from reaching the salty layer below and disrupt salinity levels, which can lead to sores,
lesions and ultimately death in whales, dolphins and porpoises. Hurricanes can also kick up
dirt and sand in shallow seas, which can kill fish by
clogging their gills. Experts think that this is
probably one of the factors that killed an estimated
9.4 million saltwater fish in 1992 during Hurricane Andrew. The dirty, murky water
also blocks sunlight from reaching corals and sea grass. In fact, scientists found that coral cover in the Caribbean decreases on average by 17% a year after a hurricane strikes. And that’s in addition to the stress coral already face from human interference from things like global
warming or pollution. But hurricanes are not
always bad news for sea life, believe it or not. After Hurricane Katrina
damaged or destroyed 90% of fishing boats in the Mississippi Sound, scientists observed a huge
increase in dolphin births. Without all the fishing boats around, dolphins suddenly found themselves with tons of fish all at their disposal, and their populations thrived. And of course, hurricanes
impact land animals, too. Sometimes they change
ecosystems altogether. For instance, the Hawaiian island of Kauai is now inundated with feral chickens. Locals say they are the descendants of domesticated chickens that escaped when hurricanes blew open coops. And in North Carolina, torrential rains from Hurricane Florence overwhelmed more than 100 hog waste lagoons, possibly releasing pig waste
into the local water supply. Unfortunately, research indicates that the intensity of
hurricanes will only increase with climate change. So if we don’t get a handle on it soon, we’ll be in some deep shh pig waste, we’ll be in some deep pig waste. (compelling music) (electronic tones)

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