14. Life below water

The oceans cover 70 per cent of our planet and more than three billion people depend on marine and coastal biodiversity for their livelihoods and survival. The world's oceans - their temperature, chemistry, currents and life - drive global systems that make the Earth habitable for humanity. Sweden faces many challenges in this goal, with the Baltic Sea, for example, being one of the world's most polluted inland seas with a disturbed ecological balance (Glokala Sverige n.d.).

The goal in a local context

Malmö has a coastline of 43 kilometres, more than half of which is sea. Malmö's marine area, together with the rest of Öresund, is a unique and sensitive area. Among other things, the sea is a popular tourist destination, is of great importance for biodiversity, has a regulating effect on the local temperature and contributes to food supply. Caring for the marine environment is therefore important for Malmö. Malmö's environmental programme emphasises the need to protect marine and river ecosystems and to minimise pollution, waste and nutrient leakage. Some of the challenges for Malmö include minimising the leakage of nutrients and pesticides and reducing the untreated water discharged during heavy rainfall and flooding, known as sewer overflows. Another challenge is that large parts of the coastline are affected by buildings, jetties, quays, embankments, etc.

What it looks like in Malmö

Protecting and restoring marine ecosystems

To slow down the degradation of marine ecosystems and the collapse of fish stocks, marine protected areas exist. The aim is to create oases in the sea where human activities are limited and where animals and plants can recover. This can also make marine life more resilient to climate change and other impacts such as nutrient and chemical discharges, which may become a growing concern as torrential rainfall becomes more frequent and intense. For the seas, it is also important to protect areas of land adjacent to the sea that affect watercourses and their catchment areas, which discharge their water into the seas.

In its environmental programme, Malmö has the objective ‘More marine protected areas in Malmö and sustainable management of water and sea’ (Malmö stad 2021). Since 2010, two nature reserves affecting marine areas in Malmö have been established. The total protected marine area in Malmö has remained at 6 per cent since 2013. For Sweden, the interim target was that 10 per cent of Sweden's marine areas would be protected by 2020, a target that was achieved when 12 per cent of the marine area was protected in December 2020 (Miljöbarometern n.d.).

A positive development is the expansion of eelgrass beds on the seabed. Since 2000, eelgrass can be seen growing in deeper waters, indicating that light conditions have improved. This in turn indicates that the nutrient conditions in the sea have improved and the production of plankton and algae that contribute to eutrophication has decreased. Most importantly, eelgrass has benefited from the ban on trawling in Öresund, which has preserved large areas of eelgrass in Öresund.

Pollution and nutrients in the sea

One of the key elements to protect and preserve marine environments is to avoid destroying or putting unnecessary pressure on them. Regarding heavy metals in harbour sediments, a positive trend can be observed, with lead and mercury decreasing and cadmium remaining unchanged since 2018, which is also the base year for measurements. However, a deterioration can be seen in the wastewater treatment of metals such as copper, chromium, zinc and nickel. Only one of the substances measured shows an improvement, namely arsenic. This trend has been observed since 2020, which is also the base year for the measurements. A deterioration can also be seen in the number of oil spills taking place.

Nutrient discharges to the sea are also increasing, and this can be seen for both nitrogen and phosphorus. The amount of nutrients discharged varies greatly from year to year, which is due to variations in precipitation. During high precipitation, more nutrients are washed into the waterways, which largely drain agricultural land, and are then transported to the sea. The same variation can be seen in discharges from wastewater treatment plants, but these increase over time as the population increases and thus also the load on the treatment systems (Miljöbarometern n.d.).

Indicators

14.1 Phosphorus emissions to the sea, tons per year

14.2 Coastline affected by development, percentage (%)

14.3 Nitrogen emissions to the sea, tons per year

14.4 Protected marine area, percentage (%)

14.5 Eelgrass coverage, meters

References

Glokala Sverige (u.å.). Arbetsbok – Agenda 2030. Tillgänglig: https://fn.se/wp-content/uploads/2021/04/Arbetsbok_Glokala_Sverige_2021.pdf

Malmö stad (2021). Miljöprogram för Malmö stad 2021 – 2030. Tillgänglig: https://malmo.se/Miljo-och-klimat/Miljo--och-klimatmal.html

Miljöbarometern (u.å.). Miljöbarometern. Tillgänglig: https://miljobarometern.malmo.se/