Table of contents:
- Teach a person to fish - and then what?
- Destruction of the last frontier of the Earth
- In warm water
- The way forward
Of all the threats to which our planet is exposed today, one of the most alarming is the inevitable approach of the world's oceans to an ecological catastrophe. The oceans are undergoing evolution in the opposite order, turning into barren primeval waters as they were hundreds of millions of years ago.
A witness who saw the oceans at the dawn of the world would find the underwater world almost completely devoid of life. At one time, about 3.5 billion years ago, the main organisms began to emerge from the "primordial ooze". This microbial soup, made up of algae and bacteria, needed a small amount of oxygen to survive.
Gradually, simple organisms began to evolve and take on more complex life forms, and the result was a surprisingly rich variety, consisting of fish, corals, whales, and other forms of marine life that we currently associate with the ocean.
However, marine life is under threat today. Over the past 50 years - a paltry amount in geologic time - humanity has come dangerously close to reversing the near-miraculous biological abundance of the deep sea. Pollution, overfishing, habitat destruction, and climate change are devastating the oceans and allowing lower life forms to regain their dominance.
Oceanographer Jeremy Jackson calls this the rise of slime: it is about the transformation of formerly complex oceanic ecosystems, where intricate food webs with large animals existed, into simplified systems dominated by microbes, jellyfish and diseases. In reality, human beings destroy the lions and tigers of the seas, thereby making room for cockroaches and rats.
The prospect of extinction of whales, polar bears, bluefin tuna, sea turtles and wild coastal areas should in itself be a concern. But the destruction of the ecosystem as a whole threatens our very survival, since it is the healthy functioning of this diverse system that sustains life on Earth. Destruction of this level will cost humanity dearly in terms of food, work, health, and quality of life. Moreover, it breaks the unwritten promise passed down from one generation to the next for a better future.
The problem of the oceans starts with pollution, the most visible part of which is catastrophic leaks from offshore oil and gas production and from tanker accidents. But as devastating as such incidents may be, especially at the local level, their overall contribution to sea pollution pales in comparison to the much less spectacular pollution carried through rivers, pipelines, drains and air.
So, for example, garbage - plastic bags, bottles, cans, small plastic granules used in production - all of this ends up in coastal waters or thrown into the sea by large and small ships. All this rubbish is carried out into the open sea, and as a result, huge islands of floating waste are formed in the North Pacific Ocean. These include the infamous Great Pacific Garbage Patch, which stretches for hundreds of kilometers in the North Pacific.
The most dangerous pollutants are chemicals.The seas are polluted by toxic elements that persist in the environment for a long time, they travel great distances, accumulate in marine animals and plants and enter the food chain. Among the biggest contributors to pollution are heavy metals such as mercury, which is released into the atmosphere from burning coal and then drips into oceans, rivers and lakes in rain drops; mercury can also be found in medical waste.
Thousands of new industrial chemicals enter the market every year, and most of them are not tested. Of particular concern are the so-called persistent organic pollutants, which are commonly found in streams, rivers, coastal waters and, increasingly, in the open oceans.
These chemicals slowly accumulate in the tissues of fish and shellfish, and then enter the larger marine animals that eat them. Research by the US Environmental Protection Agency has confirmed the association of persistent organic pollutants with death, disease and abnormalities in fish and other wildlife. In addition, persistent chemicals can adversely affect the brain, the neurological system, and the human reproductive system.
And then there are nutrients that are increasingly appearing in coastal waters after they have been used to fertilize on farms, sometimes far from the coastline. All living things need nutrients; however, their excessive amount is detrimental to the natural environment. Fertilizers that enter the water cause an explosive growth of algae.
When these algae die and land on the bottom of the sea, they decompose, thus reducing the amount of oxygen in the water needed to support the complex life of marine life and flora. In addition, when some algae bloom, toxins are formed that can kill fish and also poison people who eat seafood.
The result is what marine experts call “dead zones,” which are areas devoid of the part of marine life that people most value. The high concentration of nutrients in the Mississippi River, which then ends up in the Gulf of Mexico, has created a seasonal marine dead zone that is larger than New Jersey. An even larger dead zone - the largest in the world - can be found in the Baltic Sea and is comparable in size to California. The deltas of China's two largest rivers, the Yangtze and the Yellow River, have also lost their complex marine life. Since 2004, the total number of such aquatic wastelands in the world has more than quadrupled, from 146 to over 600.
Teach a person to fish - and then what?
Another reason for the depletion of the oceans is that people simply kill and eat too many fish. An often cited Nature study in 2003 by marine biologists Ransom Myers and Boris Worm shows that the abundance of large fish - both in open water (tuna, swordfish, and marlin) and large benthic fish (cod, halibut and flounder) - has decreased by 90% since 1950. This data has become the basis for disputes between scientists and managers of the fishing industry. However, subsequent studies have confirmed the evidence that the number of fish has decreased significantly.
In fact, if we look at what was long before 1950, then the data for about 90% turns out to be conservative. As historical ecologists have shown, we have gone far from the days when Christopher Columbus reported large numbers of sea turtles,migrated along the shores of the New World; from the time when 5-meter sturgeon, filled with caviar, jumped out of the waters of the Chesapeake Bay; from the time when George Washington's Continental Army was able to avoid starvation by feeding on the shedi, whose flocks rose up the river to spawn; from the days when the oyster banks practically blocked the Hudson River; from the time early 20th century American adventure writer Zane Gray admired the huge swordfish, tuna, king mackerel and sea bass he discovered in the Gulf of California.
Today, human appetite has become the reason for the almost complete extinction of these fish. It is not surprising that schools of predatory fish are constantly decreasing in size when you consider the fact that one bluefin tuna can be sold for several thousand dollars in the Japanese markets. High prices - in January 2013, a 230-kilogram Pacific bluefin tuna was auctioned in Japan for $ 1.7 million - justify the use of aircraft and helicopters to scan the ocean in search of leftover fish; and the inhabitants of the deep sea can not oppose the use of such technologies.
But it's not just big fish that are in danger. In a large number of places where tuna and swordfish once lived, predatory fish species are disappearing and fishing fleets are switching to smaller and plankton-feeding fish such as sardines, anchovies and herring. Overfishing of smaller fish deprives food of the larger fish still remaining in these waters; aquatic mammals and seabirds, including osprey and eagles, also begin to suffer from hunger. Marine experts refer to this sequential process down the food chain.
The problem is not only that we eat too much seafood; it is also how we catch them. In modern commercial fishing, drag lines with many hooks are used that trail vessels several kilometers away, and commercial trawlers on the high seas lower their nets thousands of meters into the sea. As a result, many species not intended for the capture, including sea turtles, dolphins, whales, and large seabirds (such as albatrosses), become entangled or entangled in nets.
Millions of tons of non-commercial marine life are killed or injured each year as a result of commercial fishing; in fact, one third of what the fishermen catch from the depths of the sea is completely unnecessary for them. Some of the most destructive fishing methods destroy 80% to 90% of what is caught in nets or otherwise caught. In the Gulf of Mexico, for example, for every kilogram of shrimp caught by a trawler, there are more than three kilograms of marine life, which are simply thrown away.
As the oceans become scarce and the demand for marine products increases, the development of marine and freshwater aquaculture may represent an attractive solution to the current problem. After all, we are increasing the livestock population on land for food production, why can't we do the same on offshore farms? The number of fish farms is growing faster than any other form of food production, and today most of the fish commercially traded and half of the seafood imported into the United States comes from aquaculture. If done properly, fish farms can be environmentally acceptable.
However, the impact of aquaculture can be very different depending on the specialization, while the methods used, the location and some other factors can complicate sustainable production. Many farmed fish species are highly dependent on wild fish for feed and this negates the benefits of aquaculture for preserving fish wealth.Farmed fish can also end up in rivers and oceans, endangering wildlife through infectious diseases or parasites, and competing with locals for food and spawning grounds. Fenced farms are also capable of contaminating the water with all sorts of fish waste, pesticides, antibiotics, uneaten food, diseases and parasites that get directly into the surrounding water.
Destruction of the last frontier of the Earth
Another factor is causing the oceans to deplete. It is about the destruction of habitats that have provided amazing marine life for millennia. Residential and commercial construction has devastated the once-wild coastal strip. People are especially active in destroying coastal marches, which serve as foraging and breeding grounds for fish and other wildlife, and filter environmental pollutants and fortify shores to protect them from storms and erosion.
The general destruction of oceanic habitat is hidden from view, but it is equally worrisome. For fishermen looking for elusive prey, the depths of the sea have become the last frontier of our planet. There are underwater mountain ranges called high seas (they number in the tens of thousands and in most cases are not marked on maps) that have become particularly desirable targets. Some of them rise from the seabed to heights comparable to the Cascade Mountains in Washington state.
The steep slopes, ridges and peaks of the high seas in the South Pacific and elsewhere are home to a wide variety of marine life, including a significant number of as-yet undiscovered species.
Today, fishing vessels are dragging huge nets with steel plates and heavy rollers along the seabed and along the underwater hills, destroying everything in their path at a depth of more than one kilometer. Industrial trawlers, like bulldozers, make their way, and as a result, the seas cease into sand, bare rocks and heaps of rubble. Deep-sea corals, which prefer low temperatures, are older than California evergreen sequoias and are also being destroyed.
As a result, an unknown number of species from these unique islands of biological diversity - they may also contain new medicines and other important information - are doomed to extinction before humans even have a chance to study them.
The relatively new challenges present additional challenges. Invasive species, including lionfish, zebra mussel and Pacific jellyfish, disrupt coastal ecosystems and, in some cases, cause fisheries to collapse completely. Noise from sonar systems used by military systems and other sources are devastating to whales, dolphins and other marine wildlife.
Large ships sailing along busy trade routes kill whales. Finally, melting Arctic ice poses new environmental hazards as habitat for marine life is being destroyed, while mining is facilitating and sea trade routes are expanding.
In warm water
But that's not all. Scientists estimate that human-induced climate change will push the planet's temperatures between four and seven degrees Fahrenheit over the course of this century, and the oceans will become warmer as a result. Water levels in seas and oceans are rising, storms are getting stronger, and the life cycle of plants and animals is changing dramatically, changing migration patterns and other serious disruptions.
Global warming has already devastated coral reefs, and experts now predict the destruction of the entire reef system over the next few decades. The warmer waters wash away the small algae that feed them, and the corals starve to death in a process called bleaching. At the same time, rising ocean temperatures are contributing to the spread of disease in corals and other marine wildlife. Nowhere is this kind of complex interdependence causing the sea to die more actively than it does in fragile coral ecosystems.
The oceans have also become more acidic as the carbon dioxide released into the atmosphere dissolves into the world's oceans. Acid build-up in seawater reduces calcium carbonate, a key building block for the skeletons and shells of coral, plankton, shellfish, and many other marine organisms. Just as trees force each other to reach out for the light by growing wood, many marine life require solid shells to grow as well as to ward off predators.
In addition to all these issues, it should be borne in mind that it is not yet possible to predict what the greatest damage to the oceans could be from climate change and ocean acidification. The world's seas support the processes that are essential for life on Earth. They include complex biological and physical systems, including nitrogen and carbon; photosynthesis, which provides half of the oxygen inhaled by humans and forms the basis for the biological productivity of the ocean; and ocean circulation.
Many of these activities take place in the open ocean, where water and atmosphere interact. Despite such horrific events as the Indian Ocean earthquake or the 2004 tsunami, the delicate balance that sustains these systems has remained remarkably stable long before the rise of human civilization.
However, complex processes of this kind affect the climate on our planet, and also react to it, and scientists regard some events as a red flag announcing an impending catastrophe. To take one example, tropical fish are increasingly migrating to the colder waters of the Arctic and southern oceans.
This kind of change could lead to the destruction of some fish species and jeopardize a critical food source, especially for developing countries in the tropics. Or take satellite data, which suggests that warmer waters mix less with colder, deeper waters. Reducing vertical mixing separates near-surface marine life from deep-seated nutrients, eventually driving down populations of plankton, the backbone of the ocean food chain.
Transformations in the open ocean can have a significant impact on the climate, as well as on the complex processes that support life on land and at sea. Scientists do not yet fully understand how these processes work, but ignoring the warning signals can lead to very serious consequences.
The way forward
Governments and the public have become much less expecting from the sea. Environmental margins, good governance and personal accountability have dropped dramatically. This kind of passive attitude towards the destruction of the seas is all the more shameful if we take into account the fact how easy it is to avoid such consequences.
There are many solutions, and some of them are relatively simple.For example, governments could establish and expand marine protection zones, enact and enforce stricter international regulations for biodiversity conservation, and establish a moratorium on the catch of declining fish species such as Pacific bluefin tuna. However, these kinds of solutions also require changes in society's approaches to energy, agriculture and natural resource management. Countries will need to significantly reduce greenhouse gas emissions, move to clean energy, eliminate the most dangerous toxic chemicals and end large-scale nutrient pollution of river basins.
These changes can seem daunting, especially for countries focused on basic survival issues. However, governments, international institutions, non-profit organizations, academics and business representatives have the expertise and ability to find answers to the problems of the oceans. They have been successful in the past through innovative local initiatives on all continents, they have made impressive scientific progress, they have enacted strict environmental regulations, and they have taken important international measures, including a global ban on the dumping of nuclear waste into the oceans.
As long as pollution, overfishing and ocean acidification remain a concern for scientists only, little will change for the better. Diplomats and national security experts who understand the potential for conflict in an overheated world should understand that climate change may soon become a matter of war and peace. Business leaders need to better understand most of the direct links that exist between healthy seas and healthy economies. And government officials tasked with overseeing the well-being of society must undoubtedly be aware of the importance of clean air, land and water.
The world faces a choice. We should not go back to the Oceanic Stone Age. The question remains open whether we can concentrate political will and moral courage to rebuild the seas before it is too late. Both this challenge and these opportunities exist.