“We are tied to the ocean. And when we go back to the sea, whether it is to sail or to watch – we are going back from whence we came.” John F. Kennedy
From mermaids and the kraken, to the loch ness monster, the ocean has been fascinating humans for centuries. We’ve all heard about the lost city of Atlantis, listened to scary tales of the oceans and seen cartoons like The Little Mermaid and SpongeBob Squarepants. There is no doubt that the ocean is an absolutely magical place, filled with mystery, wonder and budding lifeforms all contributing to our existence.
Whether you live near a beach, in the countryside or in the middle of a big city, the ocean has a profound effect on your life and vice versa, at every moment of every day. When you turn on your tap to brush your teeth, the water you use, along with the algae in your toothpaste comes from the ocean. Similarly,when you use the internet or watch the television some of the materials involved in those processes also come from the ocean. With that being said let’s backtrack a little and start from the beginning.
What is the ocean?
It is a continuous body of saltwater that covers more than 70 percent of the Earth’s surface. Geographers have divided the ocean into five major basins: the Atlantic, Pacific, Indian, Arctic, and Southern. Smaller ocean regions such as the Caribbean Sea, Gulf of Mexico, and the Bay of Bengal are called seas, gulfs, and bays and inland bodies of saltwater such as the Caspian Sea and the Great Salt Lake are distinct from the world’s oceans.
The world’s oceans hold about 321 million cubic miles (1.34 billion cubic kilometers) of water, which is roughly 97 percent of Earth’s water supply. Because of this, the ocean plays a significant role in controlling global climate conditions and regulating atmospheric temperatures. The majority of radiation from the sun is absorbed by the ocean, particularly in tropical waters around the equator, and then distributed around the globe. When water molecules are heated, they exchange freely with the air in a process called evaporation that occurs constantly and increases the temperature and humidity of the surrounding air to form rain and storms that are then carried by trade winds. Almost all rain that falls on land starts off in the ocean. In the tropics, heat absorption is the highest globally thus ocean evaporation is also highest in this area which is why the region is particularly rainy.
Outside of Earth’s equatorial areas, weather patterns are driven largely by ocean currents. Currents are movements of ocean water in a continuous flow, created largely by surface winds but also partly by temperature and salinity gradients, the Earth’s rotation, and tides. Major current systems typically flow clockwise in the northern hemisphere and counterclockwise in the southern hemisphere, in circular patterns that often trace the coastlines. Ocean currents act much like a conveyor belt, transporting warm water and precipitation from the equator toward the poles and cold water from the poles back to the tropics. Thus, ocean currents regulate global climate, helping to counteract the uneven distribution of solar radiation reaching the Earth’s surface. Without currents in the ocean, regional temperatures would be more extreme, super-hot at the equator and frigid toward the poles and much less of Earth’s land would be habitable.
Despite the size of the ocean it still remains a huge mystery as more than 80 percent of the ocean has never been mapped, explored, or even seen by humans. A far greater percentage of the surfaces of the moon and the planet Mars have been mapped and studied than of our own ocean floor. Although there is still much more to learn, oceanographers have already made some amazing discoveries. For example, it is known that the ocean contains towering mountain ranges and deep canyons, known as trenches, just like those on land. The peak of the world’s tallest mountain, Mount Everest in the Himalaya, which is 8.84 kilometers high, would not even break the surface of the water if it was placed in the Pacific Ocean’s Mariana Trench or Philippine Trench, two of the deepest parts of the ocean. The Atlantic Ocean, on the other hand, is relatively shallow with an average depth of 3,720 meters. This is because large parts of its seafloor are made up of continental shelves—parts of the continents which extend far out into the ocean.
At present, the number of different species that call the ocean their home is also unknown.While scientists know of around 226,000 ocean species, some scientists estimate that there are anywhere between a few hundred thousand to a few million more to be discovered. What we do know however, is that the world’s oceans are home to species as small as tiny, single-celled organisms and as large as the Gargantuan Blue Whale, which is the planet’s largest living animal. It also hosts some of the world’s oldest creatures like jellyfish which have been around for more than half a billion years along with horseshoe crabs. Common species like fish, octopuses, squid, eels, dolphins, and whales swim the open waters while crabs, starfish, oysters and snails crawl and scoot along the ocean bottom. Life in the ocean is heavily dependent on phytoplankton, mostly microscopic organisms that float at the surface and, through photosynthesis, produce about half of the world’s oxygen. Other fodder for sea dwellers include seaweed and kelp, which are types of algae, and seagrasses, which grow in more shallow areas where they can catch sunlight.
Previously, the deepest reaches of the ocean were thought to be devoid of life, as light does not penetrate beyond 1,000 meters deep. However, chimney-like structures called hydrothermal vents were discovered. These vents allow tube worms, clams, mussels, and other organisms to survive not via photosynthesis, but chemosynthesis, a process in which microbes convert chemicals released by the vents into energy. As science improves and new technologies emerge, underwater drones, for example, are being deployed to explore undersea frontiers, and new tools are helping scientists to both discover new wonders of the ocean and measure and understand what they find.
Why is the ocean important?
We live on a blue planet! The oceans feed billions of us worldwide, support the greatest biodiversity on the planet,regulate our climate, and generate most of the oxygen we breathe. Phytoplankton which are tiny plant-like organisms that live in the sea are responsible for at least 50% of the oxygen on Earth. These organisms contain chlorophyll which they use to capture sunlight and carry out photosynthesis to convert it into the energy that they need, which in turn produces oxygen as a byproduct. They also consume carbon dioxide, transferring about 10 gigatonnes of carbon from the atmosphere deep into the ocean each year. It does not matter how far we live from the sea, for every ten breaths we take, seven come from the ocean. The oceans also serve as the foundation for much of the world’s economy, supporting sectors from tourism and fisheries to international shipping. For many of us around the world, the ocean is also our sanctuary – a place of recreation, peace and rejuvenation.
Despite its incredible importance to our lives and livelihood, human activities are destroying our oceans. With 90% of big fish populations depleted, and 50% of coral reefs destroyed, we are taking more from the ocean than can be replenished and entire marine ecosystems are rapidly changing.
Some of the main threats to the oceans include:
1.Plastic Pollution
Plastic is a synthetic, organic polymer made from petroleum with properties ideally suited for a wide variety of applications, including packaging, building and construction, household and sports equipment, vehicles, electronics and agriculture. It is cheap, lightweight, strong and malleable. Over 300 million tons of plastic are produced every year, half of which are used to design single-use items such as shopping bags, cups and straws. Unfortunately at least 8 million tons of plastic end up in our oceans every year – this equates to a truckload of plastic entering the ocean every minute.
It makes up 80% of all marine debris, from surface waters to deep-sea sediments and has been found in the oceans as deep as 11km, meaning that these synthetic fibres have contaminated the remotest places on Earth. It has also been detected on shorelines of every single continent, with more plastic materials being found near popular tourist destinations and densely populated areas. This damages ecosystems and enters the food chains as turtles, dolphins and seabirds can mistake it for food or become entangled, injured or die. Scientists have predicted a chilling estimate that suggests that by 2050 there will be more plastic in the oceans than fish (by weight).
2. Overfishing
Of all the threats facing the oceans today, overfishing takes the greatest toll on sea life and people. Catching fish is not inherently bad for the ocean, but a problem arises when vessels catch fish faster than stocks can replenish. According to the Food and Agriculture Organization of the United Nations, globally, the number of overfished stocks has tripled in half a century and today, one-third of the world’s assessed fisheries are currently pushed beyond their biological limits. Overfishing is also closely tied to bycatch which is the capture of unwanted sea life while fishing for a different species. This, too, is a serious marine threat that causes the unnecessary loss of billions of fish, along with hundreds of thousands of sea turtles, seabirds and sharks. The damage done by overfishing goes beyond the marine environment. Billions of people rely on fish for protein, and fishing is the principal livelihood for millions of people around the world. Furthermore, The rapacious greed of the fishing industry has resulted in rampant human rights abuses of workers aboard fishing vessels usually termed slavery at sea and can result in workers being thrown overboard or severely beaten.
Systemic overfishing is also made worse by illegal catches and trade. Experts estimate illegal, unreported, and unregulated (IUU) fishing nets estimates up to $36.4 billion each year. These illegal catches move through opaque supply chains due to a lack of systems to track fish from catch to consumers and import controls in much of the sector. Government subsidies are another key driver of overfishing as it can lead to overcapacity of fishing vessels and skewing of production costs so that fishing operations continue when they would otherwise not make economic sense. Overall inadequate government capacity and cooperation to manage, regulate, and control fisheries and fisheries trade, especially in developing nations and on the high seas, are also key factors contributing to the current problems in oceanic fisheries.
Overfishing impacts entire ecosystems changing the size of remaining fish, how they reproduce, as well as the speed at which they mature. Unfortunately when too many fish are removed from the ocean, this creates an imbalance that negatively affects the food chain/web and leads to loss to other marine life and ecosystems such as corals. Millions of people especially in developing countries depend on the fishing industry and half of the world’s population heavily relies on fish as a major source of protein, therefore, when fish disappear so do jobs and coastal economies.
3. Ocean acidification
While carbon dioxide emissions have increased significantly since the beginning of industrialization in the 19th century, the concentration of CO2 in the atmosphere has only risen by around 40 percent. This is because much of the CO2 ends up in the oceans, as the gas dissolves in water. Oceans, therefore, help slow the effect of global warming – but that help comes at a price. When CO2 dissolves in water it increases ocean acidity, leading to a drop in pH, the scale used to measure acidity or basicity. In 1870, the average pH of seawater was 8.2; today, it’s at 8.1. By 2100, that value is predicted to even become more acidic, dropping to 7.7.
Though it appears to be only a minor change, that drop of 0.1 corresponds to a 30% percent increase in acidity. Many sea creatures aren’t able to cope with such an extreme change, and will stop reproducing and eventually die out.These changes are already impacting many ocean species, especially organisms like oysters, clams, sea urchins, corals and calcareous plankton that make hard shells and skeletons by combining calcium and carbonate from seawater. If the pH gets too low, these shells and skeletons can begin to dissolve. An example of this is seen in pteropods, more commonly known as the “sea butterflies,” These tiny sea snails about the size of a small pea are an important part of many food webs as they are eaten by organisms ranging in size from tiny krill to whales. When pteropod shells were placed in sea water with pH and carbonate levels projected for the year 2100, the shells slowly dissolved after 45 days.
In 2005, oyster farms along the California coast were forced to close because seawater there had become too acidic for oyster larvae. They died, and with them, a whole industry.
4. Marine Pollution
For decades the oceans have been targeted as a dumping site of sewage, chemicals, industrial waste, garbage, and other debris from the land. According to reports, mining companies across the world dump 220 million tonnes of hazardous waste directly into water bodies every year. Furthermore the shipping industry also uses the ocean as a dumping ground as pollutants such as oil and gas, the waste and garbage generated on board ships, both solid and liquid waste in the form of ballast water, grey water, food waste, dunnage and packing material, paper products and cleaning material and rags etc. all pollute the seawater and significantly affects marine lives.
Another key source of ocean pollution is the waste coming from the nonpoint sources, which happens as a result of runoff. Surface runoff from both agricultural land and areas carry soil and particles mixed with carbon, phosphorus, nitrogen and minerals which pose a huge threat to marine life. Crossing streams and rivers, the water filled with toxic chemicals like reactive nitrogen and phosphorus produced from industrial agriculture make their way to the ocean, resulting in harmful algal blooms and even ocean “dead zones”. This kind of pollution threatens the species of fish, turtles, shrimp and also humans through the food chain.
It is important to note that we cannot speak of marine pollution without mentioning oil! Oil pollution is one of the most conspicuous forms of damage to the marine environment. We generally take notice of the problem of marine oil pollution when an oil tanker breaks up in heavy seas, or a disaster occurs at an oil platform, one example being the Deepwater Horizon incident in the Gulf of Mexico in 2010. However, these horrific incidents account for approximately only 10% of global marine oil pollution. Most of the oil enters the seas along less obvious pathways, which makes it difficult to precisely estimate global oil inputs into the marine environment. Around 5 percent comes from natural sources, and approximately 35 per cent comes from tanker traffic and other shipping operations, including illegal discharges and tank cleaning.
Depending on the circumstances, oil spills can be very harmful to marine birds, sea turtles and mammals, and can also harm fish and shellfish. Oil destroys the insulating ability of fur-bearing mammals, such as sea otters, and the water-repelling abilities of a bird’s feathers, exposing them to the harsh elements. Many birds and animals also swallow oil and are poisoned when they try to clean themselves or when eating oiled prey. Fish and shellfish can also digest oil, which may cause changes in reproduction, growth rates or even death. Commercially important species such as oysters, shrimp, mahi-mahi, grouper, swordfish and tuna may also suffer population decline or become too contaminated to be safely caught and eaten.
5. Climate Change
For decades, the oceans have served as a crucial buffer against global warming, soaking up roughly a quarter of the carbon dioxide that humans emit from power plants, factories and cars, and absorbing more than 90 percent of the excess heat trapped on Earth by carbon dioxide and other greenhouse gases. Without that protection, the land would heat up much more rapidly. Unfortunately, this protection comes at a cost and life in most of the ocean, from the north pole to south pole and from the sea surface to the depths of the ocean, is already experiencing higher temperatures due to human-driven climate change. In some places, that increase is barely measurable, but at the surface level, warming has already had drastic impacts on marine animals, plants and microbes.
The warming of the top layer of the ocean also affects the fisheries which humans rely on. It is predicted that the warming can cause mass migration of marine species in search of the right conditions for feeding and spawning. Already, several marine species have been moving poleward in search of cooler climates. If this continues, science suggests that fish stocks could decrease by nearly 20 percent by the end of the century. Change in water temperatures can also directly affect the development and growth of most fish and cephalopods (such as octopus and squid). For the billions of people worldwide who rely on fish as their chief source of protein, the prospect of fewer and smaller fish in the sea is bad news.
Warming oceans also means melting ice caps. This is bad because it not only contributes to the rise of sea levels but impacts the production of algae. The Arctic food web is heavily dependent on the presence of sea ice; as sea ice diminishes, algae diminishes, this has ripple effects on species from Arctic cod to seals, whales and bears. Additionally, diminished sea ice results in the loss of vital habitat for seals, walruses, penguins, whales and other megafauna. In recent years, as sea ice has decreased, Antarctic krill populations have declined, resulting in declines in species dependent on the krill.
Warmer waters also cause coral bleaching. Coral reefs are considered the “rainforest of the sea” supporting entire ecosystems, thousands of marine species and directly supporting over 500 million people worldwide, who rely on them for daily subsistence. When the temperature increases, corals expel the symbiotic algae living in their tissues, responsible for their colour. A spike of 1–2°C in ocean temperatures sustained over several weeks can lead to bleaching, turning corals white. If corals are bleached for prolonged periods, they eventually die. Reefs around the world have suffered from mass bleaching events, some iconic reefs such as the Great Barrier Reef in Australia and the Northwestern Hawaiian Islands in the United States have all experienced their worst bleaching on record with devastating effects. The bleaching of the Great Barrier Reef in 2016 and 2017, for instance, killed around 50% of its corals. Closer to home, Tobago has also experienced several bleaching events negatively impacting our reef ecosystems.
Corals cannot survive the frequency of current bleaching events from the rise in global temperatures and if this continues, bleaching events will increase in intensity and frequency. The first global scientific assessment of climate change impacts on World Heritage coral reefs, published in 2017 by UNESCO, predicted that the coral reefs in all 29 reef-containing World Heritage sites would cease to exist as functioning coral reef ecosystems by the end of this century, if humans continue to emit greenhouse gases under a business-as-usual scenario.
Lastly, as aforementioned, climate change not only impacts ocean temperatures but also affects wind patterns and together this can alter oceanic currents. Many marine species’ migratory patterns may change as the currents they follow are altered and the species that depend on ocean currents for reproduction and nutrients will also be affected. For example, many reef-building coral and reef fish species rely on dispersal of their larvae by currents.
The negative impacts on marine ecosystems, food, water security, human well-being, livelihoods and more, caused by the changes already occurring in the ocean are undeniable and for those living along coastlines, especially in developing countries, the devastation will be astronomical. There is no denying that there is a need for immediate, transformative action to protect our oceans.
Is all hope lost for the oceans?
Can our oceans be saved?
Stay tuned for our next article!
“No Water, No Life. No Blue, No Green” – Silvia Earle
Written by Khadija Stewart of @ecovybz