The world’s oceans (which is really, one giant ocean), are not doing very well. The last hundred years have not been kind to the 71 percent of the Earth’s surface covered by ocean. Human industry has dumped an ever-increasing amount of trash and pollution into its waters while ripping out an equally increasing amount of fish and other sea life. We dirty its waters with our oil spills and choke it with plastics that can persist in an environment for tens of thousands of years. We’re disrupting marine ecosystems everywhere you look and driving countless species toward extinction.

You would think that we’d be more respectful to the ocean, considering the fact that it is a vital source of nutrition for around a third of people on the planet.

But it’s hard to fight against the lure of short-term financial gain and for every step made in protecting parts of the ocean, it seems that we fall two steps behind. For every new marine park established, there are a hundred oil-spills. For every recovery in one species, there are sharp declines in five others.

You can’t fight against that which you can’t see and it’s important to know your enemy. Take a little time and familiarize yourself with some of the biggest threats to the ocean.

Humans are too good at catching fish and other sea life. Technological advancements has given us the ability to scoop up hundreds of miles of floating nets, taking any fish, dolphin, whale, or shark caught within. Large fleets of towering fishing ships spend months at sea harvesting its life, docking with enormous floating factories that take in their catch to freeze and prepare for shipment to shore. History is strewn with historic fish stocks that collapsed after being overfished (and it’s continuing today). The problem is exacerbated by the shifting baseline phenomenon — people compare how things are now with how things were when they were young, failing to see that conditions had already degraded far from their natural state by the time they were born. We look at fish stocks now and compare them to how things were in the 1950s and 60s, not how they were hundreds and thousands years ago before widespread human exploitation.

We once thought that the ocean was too big for our activities to really have an impact. We’re seeing all over the world that that supposition is a stupid, short-sighted one. As we plunder the ecosystems and marine biospheres with our nets and hooks we rob ourselves of a future where we can feed ourselves from the sea. We’re racing to see who can pull out the last fish.

Habitat destruction
One of the things that makes protecting the ocean more challenging is that it’s hard to see underneath its waters. We don’t see the damage wrought by fishing trawlers which drag their bulldozer-like nets over the sea floor, scraping up and netting everything in their wide path. We don’t see the negative impact of the countless loads of trash and waste that are dumped into the seas every day (inadvertently or not). We miss the fields of dying coral and the seagrass and mangrove forests that get whittled away by chemical and oil spills.

Plastic is, at once, one of the greatest and one of the worst of humanity’s inventions. It has facilitated a world of technological advancement and proven its utility by becoming virtually indispensable to modern life (look around where you are sitting right now and take note everything made of plastic, remembering that many of our clothes and fibers are made of plastic). But on the flip side, the very durability that makes plastic so valuable as a building material makes it an ecological monster — an immortal and invulnerable material that resists the pull of time and the biodegredation that return most natural materials back into biologically useful forms.

Our addiction to plastic has not been good for the ocean. As our use of plastic has risen, so too has the amount that has been dumped, blown, lost, or dropped into the worlds oceans and rivers (which tends towards the sea). You might have heard of the Great Pacific Garbage Patch, an area in the Pacific Ocean between the west coast of America and Hawaii that, due to the circular ocean currents surrounding it, collects and aggregates plastic waste. There are places within the garbage patch that have more plastic than plankton. Sadly, this phenomenon is happening all over the world wherever currents circle. Plastic in the waters leach chemicals and are often mistaken as food by marine wildlife. Instead of biodegrading, plastic just breaks down into smaller and smaller pieces, leaching toxic chemicals and invading food webs at every break.

Invasive Species
Like their land-based counterparts, invasive marine species have caused widespread damage to ecosystems all over the world. Species like the lionfish, shore crab, Asian clam, and even the humble starfish have disrupted food webs and driven native marine plants and animals to extinction. The loss of one species in an ecosystem is bad enough, but knock enough out of the picture and entire food webs can collapse. This is happening in oceans all over the globe and shows little sign of slowing down.

The danger posed by sunblock pales in comparison to the other four threats on our list, but I’m including it here because most people have no idea that the lotion they put on their skin ahead of a day in the sun can fatally damage coral reefs. A little sunscreen may not sound like a real threat, but when you multiply it by a few tens of millions of swimmers jumping into the oceans every day, you get thousands of tons of sunscreen polluting the waters. What’s an eco-conscious swimmer to do? Wear more clothes (think light and airy), buy ecologically friendly sunscreen, and wear a wide-brim hat.

Main photo credit: Green Fire Productions/Flickr, overfishing photo credit: John Wallace/NOAA, habitat destruction photo credit: Bruno de Giusti, plastic photo credit: Falken, invasive species photo credit: OpenCage, sunblock photo credit: Victor Martinez/Flickr