Although our planet is called Earth, we must not forget that the oceans represent more than 70% of the Earth's surface and contain 97% of all the water on Earth. Furthermore, they are home to a vast array of flora and fauna. These bodies of saltwater are essential for thousands of species of bacteria, microorganisms, animals, and plants. Human beings also depend heavily on the oceans, as they are an inexhaustible source of natural resources, from food to energy and minerals. Unfortunately, the expansion of human activity has generated what we know as marine pollution.
This serious problem arises from the uncontrolled discharge of chemicals, plastics and waste that alter the balance of these ecosystems. In this article, we will explain in detail what marine pollution is, its causes and how it affects our environment.
What is marine pollution
The ocean is key to terrestrial biodiversity. For centuries, humans have used the sea as a source of resources and as a dumping ground for various wastes. This has led to the destruction of habitats and the alteration of various food chains.
Marine pollution Ocean pollution can be defined as the introduction of physical, chemical or biological agents into aquatic ecosystems, which cause a significant degradation of the natural balance. These agents usually come directly from human activity, such as pesticide, herbicide and fertilizer discharges from agriculture, as well as industrial waste. These pollutants directly affect the health and well-being of marine species and, consequently, of all beings that depend on the ocean ecosystem, including humans.
Pollutants not only disperse, but also accumulate in waters and organisms, affecting both species that live in surface waters and those that inhabit depths as remote as the Mariana Trench.
Causes of marine pollution
There are various sources that cause marine pollution, and most of them are derived directly or indirectly from human activity. It is important to identify the main causes in order to address the problem appropriately.
Pesticides and herbicides
In modern agriculture, the use of pesticides and herbicides is common to maximize crop yields. However, these chemicals end up polluting waterways and eventually reach the ocean. Once in the water, these chemicals disrupt the life cycle of plant organisms such as phytoplankton and algae, causing a deficit of dissolved oxygen . The danger lies in the accumulation of these pollutants in the tissues of marine organisms, which alters food chains and, in the worst-case scenario, affects humans when they consume seafood.
Fertilizers and detergents
Excessive use of fertilizers in agriculture also contributes to the problem through a process known as eutrophication. Fertilizers that reach bodies of water, by containing high levels of nutrients such as nitrogen and phosphorus, cause excessive growth of algae. This creates a layer of biomass on the sea surface, preventing the entry of sunlight and reducing available oxygen, leading to the creation of dead zones.
Detergents that reach the sea through wastewater also contain harmful chemical compounds, which aggravates pollution.
Chemicals and hydrocarbons
Industrial chemicals, including heavy metals such as mercury and lead, are dumped into the oceans directly or indirectly. These chemicals not only cause immediate death of organisms through poisoning, but can also cause genetic mutations and other negative effects in the long term.
Hydrocarbons, for their part, are one of the most visible forms of marine pollution. Spills of oil and other petroleum products suffocate marine organisms, preventing the entry of sunlight and damaging the biological systems of the affected species.
Waste water and plastics
Wastewater that is dumped into the sea without proper treatment also poses a threat. This water can contain organic matter, chemical residues and even pathogens, causing the bacteria proliferation and the decomposition of aquatic ecosystems.
On the other hand, plastics are one of the most harmful elements. Due to their slow decomposition, these pollutants remain in the ocean for decades. Plastics can cause injuries, malformations or even amputations in marine animals. In addition, microplastics, which are generated by the fragmentation of larger plastics, are ingested by numerous species, with potentially lethal consequences, including humans.
Consequences of marine pollution
The consequences of marine pollution are devastating, both for ocean fauna and flora and for humans. Let's break down some of the main ones.
Biodiversity loss
Pollution not only affects individual species, but destabilises ecosystems as a whole. When chemicals or plastics enter the sea, many species are unable to adapt or survive. This has a knock-on effect, affecting not only predator or prey species, but the overall balance of the marine ecosystem.
Accumulation of toxic substances in the food chain
Many of the pollutants that are dumped into the sea enter the marine food chain. Heavy metals and other toxic chemicals accumulate in the tissues of living organisms, causing biomagnification along the food chain. Mercury, for example, is absorbed by small marine organisms and, as it passes from one species to another, concentrates to dangerous levels in larger fish that ultimately end up on the plates of human consumers.
Effects on human health
Consumption of contaminated seafood can have serious consequences for human health. Adverse effects on the nervous system, fetal development and reproduction have been detected due to exposure to heavy metals present in contaminated fish, such as swordfish or tuna.
ocean acidification
The release of carbon dioxide (CO2) by human activities also contributes indirectly to marine pollution. The oceans act as a natural sink for CO2, but by absorbing so much gas, their waters become acidic. This affects organisms such as corals and mollusc shells, weakening them and compromising their survival.
Ocean acidification It is a devastating process that also puts marine biodiversity at risk in the long term.
Other causes and emerging threats
In addition to the products and elements already mentioned, there are other forms of pollution that affect marine life and require urgent attention. Noise pollution, caused by maritime traffic and industrial activities, directly affects marine mammals such as dolphins and whales, whose echolocation is severely disrupted. This causes disorientation and changes in their migratory patterns.
Deep-sea mining and pharmaceutical waste also represent emerging threats that have been largely overlooked. Deep-sea mining releases sediments and heavy metals, while pharmaceutical waste disrupts the metabolism of marine organisms.
Finally, climate change acts as a multiplying factor of the effects of marine pollution, exacerbating the consequences already mentioned.
Marine pollution is one of the most pressing environmental issues of our time. It affects both marine life and the humans who depend on the oceans for their livelihoods. Addressing this crisis will require a concerted global effort between governments, industries and citizens. Reducing the use of plastics, improving waste treatment systems and adopting sustainable energy are key steps to mitigating this serious environmental problem.