Marine ecosystems are negatively impacted by coastal and underwater critical infrastructure development such as subsea communication cables. Our current linear model also indirectly impacts our ocean spaces as bigger shipments of more material goods require bigger ships to be built and expanded ports for them to sail into. The sea is used, too, as a setting for water desalination and marine energy technologies; each, to varying degrees, disrupt habitats and displace the species that rely on them.

At sea, overexploitation is, while less visible, no less extensive.
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Fish are often the first thought: the Global Fishing Index estimates that worldwide fish stocks have been depleted to less than 40% of their pre-industrial fishing population. Other experts suggest the loss could be even greater. Much of this loss has been fuelled by destructive practices such as deep ocean trawling – an indiscriminate method of industrial fishing that has an enormous negative impact on ocean sediment and marine habitats.

Beyond food, humans extract vast amounts of materials from the ocean. As well as the obvious – such as offshore drilling for crude oil – many other industries overexploit the ocean’s resources: from aquatic organisms used for nutraceuticals (marine-derived health and beauty products including collagen supplements) to minerals and metals which supply everyday electronics. 

Ocean spaces are more frequently being looked to for materials cultivation. As land-based sources run low, deep sea phosphate reserves are being mined to sustain the conventional global agricultural system. Meanwhile, sand and marine aggregates are dredged from seabeds to be turned into concrete, transport infrastructure, and glass. The adverse impacts of excavations span multiple scales: from the loss of specific species and physical damage of marine ecosystems which provide essential climate regulating services, to the release of harmful contaminants into the water column. 

As it is on land, so it is at sea. 

Although industrial farming of fish and aquatic organisms has fewer direct GHG emissions than other animal proteins – equivalent to 4% of global food production – there are other indirect emissions. For example, a major ingredient of the feed required to sustain the 214 million tonnes of fisheries and aquaculture output is soybean – one of the world’s largest single crop contributors to climate change. Meanwhile, the diet of livestock – including methane-producing Kansas cattle as well as other farmed animals – are sometimes supplemented with fishmeal protein. Similarly, Chinese rice paddies may be fortified with fertiliser extracted from underwater sedimentary phosphate reserves off the Gulf of Mexico. Each example further highlights the land–ocean interconnections. 

Pollution can also flow in the opposite direction.

It can occur at sea and impact aquatic and terrestrial environments alike. Offshore drilling for oil and gas releases high levels of GHG emissions and other air pollutants into the atmosphere, damaging the entire planetary system. Nutrient pollution discharged from industrial aquaculture, for example, can cause localised algal blooms which are toxic to humans and animals as well as marine life. 

Other introductions are intentional, even if the consequences are not.

‍Global aquaculture is a fast-growing supply sector; industrial scale operations that intensively farm non-native species without considering the impact on local waters risk the accidental spread of invasive alien species which can dominate and disrupt the delicate balance of surrounding ecosystems.