Use and Impact | Umweltbundesamt

How we use the oceans

For centuries, the oceans have been an essential source of food. However, overfishing, bycatch, and habitat degradation due to destructive fishing methods are placing a heavy burden on marine ecosystems. While improvements in fisheries management are urgently needed, everyone can contribute to effective marine conservation by making environmentally conscious choices when consuming fish and seafood.

The oceans also serve as key transportation routes for global trade. Even during regular operations, maritime shipping releases pollutants such as nitrogen and sulphur into the sea and generates continuous underwater noise, which can interfere with marine animals' communication. In addition, accidents and shipwrecks pose an ongoing risk, as oil and other pollutants can be released at any time.

Oil and gas extraction from the seabed remains a common practice - one that carries significant ecological risks. For example, exploration activities generate high levels of underwater noise that can harm marine life, and catastrophic spills continue to occur, releasing oil and other pollutants into the environment.

At the same time, the oceans are the scene of technological innovations. Energy production from offshore wind farms plays an important role in combating climate change, but requires strict ecological regulations to protect marine mammals and seabirds in particular.

Other emerging technologies, such as marine geoengineering, are being explored to enhance the ocean’s capacity to absorb CO_₂. While these methods may support climate mitigation efforts, they also pose uncertain ecological risks.

Another focus is deep-sea mining, which aims to extract raw materials from the ocean floor. While these resources have significant economic potential, their extraction threatens little-explored and highly sensitive ecosystems.

The diverse use of the oceans offers opportunities but also demands clear ecological guidelines and effective measures to reconcile human needs with the protection of marine environments.

Environmental impact: The oceans under pressure

Intensive ocean use leaves its mark. One major issue is pollution caused by land-based sources. Large quantities of nutrients, pollutants and plastics enter the oceans via rivers, direct discharges, and the air. Excessive nutrient concentrations lead to over-fertilisation of the oceans (eutrophication), while pollutants such as industrial chemicals, pesticides, and pharmaceutical residues harm marine life and accumulate in the food web. Additionally, plastic waste (micro-, meso- and macroplastics) poses a severe threat to marine species through entanglement, ingestion, and the substances it contains. Marine ecosystems respond slowly to reductions in pollution, and current input levels remain too high to ensure a healthy marine environment.

Another urgent issue in the North and Baltic Seas is the legacy of World War II. Large amounts of ammunition and sunken wrecks lie on the seabed of German coastal waters. These pose a threat not only to marine ecosystems but also to fisheries and maritime shipping.

While there is no such thing as a ‘silent ocean’, human activities at sea generate a high level of noise in addition to the natural sounds. This underwater noise disrupts marine life, particularly species that rely on acoustic communication. For example, shipping, seabed resource extraction, and the construction of offshore wind farms generate noise, affecting marine mammals such as whales and seals, as well as seabirds, fish and molluscs. Noise mapping has shown: Human-generated noise is omnipresent in the oceans.

The effects of climate change are particularly evident in the oceans. Rising water temperatures and ocean acidification threaten calcifying organisms such as corals and sea snails. At the same time, marine ecosystems are shifting, as cold-adapted species increasingly migrate further north.

A major challenge for marine conservation is the cumulative and chronic impact of human activities. These effects emerge over time and result from the combined influence of multiple stressors of marine ecosystems. Often, these impacts interact synergistically, intensifying the overall impact on the marine environment with consequences that are difficult to predict. The German Environment Agency is researching new approaches to better assess and manage cumulative impacts in environmental assessments. One effective control instrument for addressing this challenge is maritime spatial planning, which regulates where and how various activities can take place in marine areas.

The intensive use and increasing pressures on the oceans require coordinated action at international, European and national levels. Only through close collaboration between governments, sectors, and stakeholders can ensure both the protection and sustainable management of the ocean. Marine governance plays a crucial role in establishing the legal and organisational frameworks necessary to safeguard marine ecosystems for the future.