NEW YORK—“Plankton. Life as we know it depends on plankton … not just for the ocean, but for the planet,” said narrator Dr. Sylvia Earle in the opening of Jean-Michel Cousteau’s 40-minute documentary, “Secret Ocean,” referring to the tiniest creature in the ocean, upon which all other marine animals eventually depend. But failure to protect plankton and other tiny creatures threatens the survival of ocean ecosystems—and the planet.
The film, shown at the American Museum of Natural History (AMNH) since July, allows us to experience a little-known world located in the depths of various oceans like in the Bahamas, Fiji, and Bimini. Through the magic of 3-D photography, it introduces us to more than 30 of the tiny, unusual creatures. But the majesty of nature’s mysteries aside, there is a lesson to be learned about why mankind should protect these creatures.
Through overfishing and unintended manmade mistakes, the natural balance of ocean ecosystems is being stressed. These mistakes cause fish and other sea creatures to either die off or move to different bodies of water, resulting in nearly empty oceans or an overabundance of misplaced fish. Although water is surviving without fish, scientists really don’t know what will happen after diverse ecosystems have been completely destroyed.
Where Life Begins
Cousteau, son of the famous French marine explorer Jacques Cousteau, said in the film that throughout the years he and his father had scoured the oceans, they often did not see the secret world of the smallest life in the sea, which is the foundation for the biggest.
The tiniest life, plankton, is most vital to the creation of an ecosystem. Ecosystems are the communities of living creatures that make up an environment and they each depend on one another for life. Every member of the food chain relies on the abundance of plankton to breathe life and feed them.
“Those are your primary producers, the phytoplankton,” said John Sparks, curator of the Department of Ichthyology (study of fish) at the American Museum of Natural History. Sparks, who encounters numerous coral reefs during his studies of fish, said phytoplankton, which is plant based, is considered to be primary because it takes in sunlight and converts it to energy for the other creatures.
Earle said they produce more than half the oxygen on Earth. “So every other breath we take is a gift from the sea,” she said.
The tiniest animal in the ocean, zooplankton is a source of food for many species. The zooplankton feed on the phytoplankton. It just floats to the surface at night, and even creatures like giant clams that can’t move around are automatically fed as the current moves the zooplankton into their mouths.
“It’s the largest migration of animals on the planet,” said Earle about the zooplankton.
But even with the natural abundance of the tiniest marine animals, the survival of ocean ecosystems is threatened by unintended human behaviors.
Damaging Diverse Ecosystems
It’s important to know that ocean ecosystems are not all the same, so we can’t, for example, throw a saltwater fish that has gotten too big for the fish tank into just any saltwater ocean. Nor can we expect fish populations to easily recover from huge impacts such as overfishing.
“When we damage the ecosystem, even for a single species, many things can go wrong,” said Cousteau.
According to Sparks, global warming increases ocean temperatures and can cause fish to die or migrate into new territories—ultimately shifting the entire ecosystem and threatening the survival of some species.
Sparks said there are certain fish swimming in Michigan lakes that were not there when he was growing up in the Midwest. “These are southern fish and they’ve moved all the way up just since I was a kid,” he said, “either getting away from the warmer temperatures or just being able to tolerate going further north because it’s gotten warmer.”
According to NASA, the Earth’s climate has changed over thousands of years, but the current warming trend has been proceeding at an unprecedented rate in the past 1,300 years, and it’s likely human-induced. The NASA climate website states that much of the warming is due to increased levels of greenhouse gases (GHGs).
Right now, almost the entire world is responding to climate change, and the focus includes protecting oceans.
On Oct. 7, the U.S. State Department announced that over 80 new initiatives on marine conservation and protection valued at more than $2.1 billion were agreed on at the second Our Ocean conference, held in Valparaiso, Chile, Oct. 5–6. In addition, participants committed to the protection of nearly 735,000 square miles of oceans.
Sparks said everything is interconnected and it’s not just temperature changes that can throw an ecosystem off balance. Other things such as the introduction of lionfish into the wrong ocean by people who accidentally release their aquarium pets back into the wild have caused a significant imbalance in the Caribbean.
In the film, Earle describes these highly predatory creatures: “The beauty and grace of a lionfish are a disguise,” she warns. “The tall fins on its back have venomous stingers. Tentacles above its eyes are decoys to attract fish. His stripes and polka dots are meant to confuse. And its delicate fins are a cloak to herd and trap small fish.”
She said one big lionfish could consume 40 fish in an hour. They’ve wiped out all of the small reef fish, according to Sparks, who has seen it firsthand. He said there is no way to get rid of them because there’s just too many now, and although hundreds could be speared and removed in a day, hundreds more would show up the next day.
“It’s really sad because some of these reefs were just gorgeous 10 years ago,” Sparks lamented, “and now you go down and you hardly see fish swimming around—this is throughout the Caribbean.”
Overfishing
Overfishing is another manmade pressure on the oceans that damages their ecosystems.
We have depleted the Caribbean reef of large predatory fish that could naturally control the lionfish, said Earle, referring to overfishing. Fishery stocks are way down in plenty of places because we don’t regulate fishing enough, said Sparks, and “even in the United States we have tons of regulations but there’s still stocks that get wiped out.”
The National Oceanic and Atmospheric Administration (NOAA), the federal agency that manages fisheries and supports marine commerce, periodically issues interim rules to specify limited catches of particular types of fish that are in danger of depletion, then lifts the restriction after fish have replenished. But some fish aren’t capable of bouncing back, says Sparks. Because they are not widespread, they don’t re-colonize.
He mentioned the situation in the Mediterranean, for example, which he described as “pretty barren.” “It’s just been fish, fish, fish for so long and it used to be very diverse, abundances of fish; they’re just not there,” he said.
And even though new types of fish can come in and replace depleted fish, Sparks worries that the ecosystem is losing its original diversity. “Once you start wiping out a lot of these things these other things may come in, but you could get in a situation where the whole system crashes at some point,” he said.
Sparks said scientists really don’t know what’s going to happen once the oceans lose their diverse ecosystems. People have been studying the surge of lionfish “like mad” for the last 10 years, he said, but they still don’t know how things will develop.
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