You might think twice before tossing a piece of plastic into the garbage rather than a recycling bin when you hear how deadly marine debris, such as floating plastic, is to whales, dolphins and other sea creatures.

According to a 2014 report published in the journal Marine Pollution Bulletin, ingestion of trash has been documented in 56 percent of cetacean species, with rates of ingestion as high as 31 percent in some populations. Bottlenose dolphins and various species of whales are also common victims of marine debris, with several tragic cases last year alone.

That's not surprising considering that millions of tons of plastic items end up in the oceans each day. You would think that such small objects would be harmless, but think again.

In August 2014, a 45-foot-long young female sei whale, an endangered species, was found dead floating in St. Julien's creek, off the Elizabeth River, a tributary of the Chesapeake Bay. The cause of death? - a broken piece of DVD case.

"It makes me very sad that a piece of plastic that was not disposed of properly ended up killing a whale," Susan Barco, at the Virginia Aquarium and Marine Science Center Stranding Response Team, told National Geographic. "It was a preventable death."

Plastic ingestion is fatal for these creatures because it can obstruct the stomach or intestine, causing starvation and, as seen in this case, death. It's hard to say just how many marine mammals are impacted by floating marine debris, but the number seems to be on the rise - and not also cases are documented.

"The whales that wash up on the beach are only a small percentage of those that die," said Frances Gulland, a senior scientist with the Marine Mammal Center in California. (Scroll to read on...)

Sperm whales are particularly susceptible to plastic ingestion, according to Gulland, because they easily mistake debris for squid, their main food source. There was one case in 2008 when Gulland discovered two male sperm whales stranded along the northern California coast, their stomachs full of pieces of fishing net, rope, and other plastic trash. One of the mammals had a ruptured stomach; the other was skinny and clearly undernourished.

In another instance in 2010, a 37-foot grey whale stranded near Seattle also succumbed to tons of trash, its stomach filled with more than 20 plastic bags, small towels, surgical gloves, a pair of sweatpants, duct tape, and a golf ball.

"It was," research biologist John Calambokidis said, "a dramatic representation of the degree to which we impact the marine environment."

Whales aren't the only victims of our plastic problem. One NOAA scientist, Blair Mase, estimated that at least 35 bottlenose dolphins, from 2002-2013, became stranded due to marine debris. Seabirds are also threatened by ocean-side plastic pollution, with 94 percent of Cory's shearwaters affected, and 70 percent of Yelkouan shearwaters and Balearic shearwaters. These birds often mistake plastic for food, or otherwise ingest it indirectly through their prey.

"Results are alarming," researcher Jacob Gónzalez Solís, from the University of Barcelona, said in a statement. "All three of the worst affected are of conservation concern, particularly the Balearic shearwater, which is listed as critically endangered by the International Union for Conservation of Nature."

"Plastic floats and is difficult to degrade," he added. "Eventually, all pollutants which are not destroyed on land arrive to the sea. The sea is not a rubbish bin. The control over plastic production and transportation at industrial level has probably improved, but there is an urgent need to develop stricter controls on waste dumping and prohibit ships' discharge into the sea."

To help shrink the amount of waste that ends up in our once-pristine oceans and kills marine wildlife, the Environmental Protection Agency says reducing, reusing and recycling are the three key steps.

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