Destruction of habitats

Due to human population growth the available land for the rest of life has decreased significantly. Humans have successfully inhabited every habitat on earth. However this has occurred at the detriment to the natural species. In some cases the population of species has been driven to near extinction and in the case of some aquatic megafauna, to extinction. The Baiji river dolphin, a freshwater river dolphin has recently been driven to extinction through anthropogenic impacts such as the building of the Three Gorges Dam in the Yangtze river.

Marine Pollution

Human pollution comes in many forms including chemical, plastic, agricultural, light noise and air pollution. In the terrestrial environment, these forms of pollution are apparent. In comparison, the marine environment can hide the pollution, with effects diluted through the volume of water. This can be seen in agricultural pollution. Eutrophication, which is the bloom in phytoplanktonic life from excess nutrients in water, is a common occurrence in habitats polluted by agricultural runoff, saturated with fertilisers and pesticides.

Humans are the greatest waste producing organism on Earth. We have littered almost every terrestrial and marine habitat, and continue to add to the vast mountains of waste every single minute. Our effectiveness at producing waste can even be seen outside of our planet, with all types of space debris in low earth orbit.

Plastic pollution

Plastics are the symbol of 21st century materials and used extensively across all industries, from beverages to aerospace, this material can be found across the globe. Plastic has become widespread due to a multitude of useful properties, including low cost, diversity of form, heat resistant properties, insulating properties - the list goes on! Unfortunately, plastic lacks the ability to biodegrade in a reasonable time frame. Most plastic end up in landfill, not recycled , where they can take up 1000 years to break down. Even when they breakdown, the plastics can form microplastics, persisting for many years.

Plastics in the marine environment have become a real problem which cannot go unnoticed. Over 8 million tonnes of plastic enter the ocean every year, equivalent of a garbage truck's worth of plastic entering the ocean every minute. By 2050, the plastics in the ocean are estimated to outweigh all the species of oceanic fish combined.

Chemical Pollution

With the industrial revolution, the quantity of chemicals produced has exponentially increased.

Chemical pollution is the introduction of harmful contaminants. Common man-made pollutants that reach the ocean include pesticides, herbicides, fertilizers, detergents, oil, industrial chemicals, and sewage.

Many ocean pollutants are released into the environment far upstream from coastlines. Nutrient-packed fertilizers applied to farmland, for example, often end up in local streams and are eventually deposited into estuaries and bays. These excess nutrients trigger massive blooms of algae that rob the water of oxygen, leaving dead zones where few marine organisms can live. Some chemical pollutants climb high into the food webs—like DDT, the insecticide that placed the bald eagle on the United States Fish and Wildlife’s endangered species list.

Scientists are starting to better understand how specific pollutants, leached into the ocean from other materials, affect marine wildlife. PFAS, a chemical incorporated into many household products, accumulates in human and marine mammal blood. Even pharmaceuticals ingested by humans, but not fully processed by our bodies, end up in aquatic food webs.

 Agricultural Pollution

Most of the ocean pollution associated with agricultural activities comes in the form of nutrient runoff. Since most of the human population resides near to the coast, the farming activities also occur close to the coast. Pesticides and fertilisers are used extensively across farmland to increase the growth efficiency of crops. Modern techniques involve using helicopter and plane dispersion which spread the chemicals fast and with great coverage. However the chemicals can spread too far, reaching nearby water sources i.e. rivers. Upstream water sources eventually estuaries, leading into the ocean. These chemicals can severely damage marine life by impacting embryo development, shell formation in birds and turtles, and chemical poisoning. Organophosphates, including diazinon and chlorpyrifos, are insecticides that contain phosphorus; they are nerve poisons and act by inhibiting important enzymes in the nervous system in animals. Pyrethroids are another class of insecticides that are not as toxic to humans and other mammals, but are quite toxic to fish and invertebrates.  Both the organophosphates and pyrethroids pose serious threats to aquatic invertebrates.

 Light Pollution

Since the invention of the lightbulb, light has spread across the globe, reaching almost every ecosystem. Often thought of as a terrestrial problem, scientists are starting to understand how artificial light at night affects many marine organisms. Light pollution penetrates under the water, creating a vastly different world for fish living in shallow reefs near urban environments. Light disrupts the normal cues associated with circadian rhythms, to which species have evolved timing of migration, reproducing, and feeding. Artificial light at night can make it easier for predators to find smaller fish prey and can affect breeding in reef fish.

Most notable impact of light pollution is in the impact on turtle species. A marine turtles life begins beneath the sand of the beach it’s mother laid them. Once the turtles breaks through their egg shell, they dig through the sand and exit towards the sea. To guide them, they follow moonlight. However, with the vast amount of light around the coast from nearby buildings and street lights, they often become disorientated and head away from the sea. Most who do not reach the sea will perish, either through human contact or predation by other animals.

 Noise Pollution

In the oceans, where distances can be long and visibility can be short, many animal species rely on sound to communicate, navigate, and monitor their surroundings. The haunting cries and clicks of whales are both beautiful and vital to their survival. Using "songs" cetaceans can communicate with one another across several hundred kilometres of ocean. Whale sonar allows the animals to find food, safely travel along irregular coastlines, and migrate to and from breeding and feeding grounds. Some whales uses bursts of loud noise to drive and confuse their prey.

These activities are becoming more and more difficult as man-made noise in the sea has increased dramatically. Ship traffic, oil and gas exploration, scientific research activities, and the use of military sonar and communications equipment have caused an increase in ambient marine noise of two orders of magnitude in the last 60 years.

Recent studies suggest that noise pollution can harm whales directly by damaging their hearing, and in extreme cases, causing internal bleeding and death. More commonly, it appears that excessive or prolonged noise can cause behavioural changes that interfere with the health and survival of the animals.

Noise produced by the cetaceans is between 100 - 500 hz which allows the sound waves to travel great distances for communication. Unfortunately most of the underwater sonar deployed by the navies of the world also operate in this frequency band. This commonly results in beaching and stranding of dolphins and whales on the world’s beaches. This happens because below 200 metres, most of the light from the sun is filtered out by the ocean. Thus these magnificent animals need to rely on sound to navigate the world. We can now understand how additional noise is responsible for the death of these animals.

 Bycatch

FIshing provides food for much of the world. Since most of the human population resides around the coast, fish is an important food source. In most of the developing worlds i.e Africa, India, fish is the only source of protein. To increase efficency of the practice, boats were utilised with large nets attached. The nets are deployed and trawled for hours. These nets do not discriminate between species. Any organism greater than the diameter of the mesh size is captured. This can include dolphins, sharks rays and even whales.

 Shark Finning

Shark finning is the act of removing fins from sharks and discarding the rest of the shark back into the ocean. The sharks are often still alive when discarded, but without their fins. Unable to swim effectively, they sink to the bottom of the ocean and die of suffocation or are eaten by other predators. Shark finning at sea enables fishing vessels to increase profitability and increase the number of sharks harvested, as they must only store and transport the fins, by far the most profitable part of the shark; the shark meat is bulky to transport. Some countries have banned this practice and require the whole shark to be brought back to port before removing the fins.

 Medicinal Exploitation

Animal exploitation has occurred for centuries. Humans have experimented and researched the benefits of using marine life to heal various alignments. Hai Ma is a marine cucumber which the Chinese believe is responsible for maintaining the health of the kidney.

The most commonly listed ingredients derived from cetaceans are oil, pancreas, and liver. These are prescribed for intestinal disorders, inflammation, and a variety of skin conditions. Dugong oil and ground bone are believed to have haemostatic properties. Pinnipeds and mustilids are generally used as either an enhancer or suppressor of various human appetites. There is little information on how prevalent the current use of marine mammal parts are in TCM but an agreement between Canada and China in 20111, allowing the import of Canadian seal parts to China, plus a proposal to increase trade in 20152, indicates that a market certainly exists.

Urban Development

With the human population approaching 7 billion, urban developments have significantly encroached into marine habitats. With the expanding Estuaries, the nurseries of the oceans, are being destroyed on a daily basis. Wetlands are filled and mangroves are bulldozed for urban development. The 20th century alone saw the destruction of 50% of the world’s mangrove forests. The very chemistry of the ocean itself is threatened with acidification as the release of green house gases explodes and carbon dioxide levels skyrocket. New developments are being approved every week. Most notably, the building of the Three gorges dam across the Yangtze river in China. This dam has impacted the population of many aquatic animals including the extinction of the Baiji River dolphin.

 Carbon Production

Industrialisation over the 20th century has impacted the carbon production across the globe. Much has been reported about the effect of elevated carbon in our atmosphere. The effect would be significantly greater without carbon sequestration. This process is the removal of atmospheric carbon by natural causes. The terrestrial environment sequesters a significant portion of the additional carbon through primary producers i.e. trees. However most of this important process is performed by marine ecosystems. The mangroves and seagrass meadows captures enormous quantities of carbon within their roots and stems. Seawater itself also captures significant quantities the transfer of carbon from the surface of the sea, progressively travelling deeper and deeper, before depositing in sediment on the ocean floor.