World Ocean Review 2025: Marine protection can work - if it is implemented correctly

Marine protection works - if it's done right

"Many marine species and habitats that were once almost wiped out by humans are recovering as a result of conservation measures," the WOR reports hopefully. The resilience of marine ecosystems is even so high that extensive recovery is possible by 2050 - provided that action is taken now.

The report comes to the conclusion that the successes of the protection measures to date are certainly impressive, but are not sufficient overall. It is true that marine protected areas, the number of which has increased significantly in recent years, play an important role. However, they only address local problems; they cannot counteract factors such as the warming of the oceans or the ever-increasing spread of microplastics. They can therefore only be one building block in global marine protection.

For water sports enthusiasts, however, they mean increasing restrictions, such as temporary closures of certain areas during breeding seasons. The report refers to the scientific data that shows that these measures can contribute to the conservation of marine ecosystems. However, it also emphasises that successful protected areas are created through transparent planning involving all interest groups. Where all stakeholders are involved in the planning process, acceptance of temporary restrictions also increases.

What is the World Ocean Review?

The World Ocean Review has been published since 2010 by maribus gGmbH, a non-profit organisation founded in 2008 by Hamburg-based mareverlag to raise public awareness of marine science.

The WOR deals with various issues such as the extraction of raw materials from the sea or the coasts as endangered habitats in a scientifically sound manner, but in a language that is also easy to understand for laypersons,

It is intended for anyone who wants to understand the sea, but can also help water sports enthusiasts and associations who want to participate in competent discussions, for example when it comes to the designation of new protected areas.

The reports reflect the current state of scientific knowledge and are made available free of charge as print and online versions. Their aim is to promote more effective marine protection through knowledge transfer.

A cosmos beneath the surface of the water

The current WOR focuses on biodiversity. What stirs beneath the hull of a boat can appear as dazzling as a kaleidoscope. But increasingly, friends of warm waters are seeing the coral reefs once inhabited by countless species fade away, and coastal skippers are plagued by invasive species such as the Australian chalk tube worm, which attaches itself to the underwater hull and clogs up shipboard passages.

Life even exists where humans long thought it impossible, for example under the ice shelves of the Antarctic or in the seabed of hypersaline deep-sea basins in the Mediterranean. "Everything is there: from the fringed carpet shark, which actually looks like a floating bedside rug, to sea spiders with legs as long as a full-grown human, to jellyfish that shimmer like disco balls and worms in the shape of a miniature Christmas tree," says WOR, describing the dazzling diversity in the world's oceans and seas.

Under pressure from all sides

This diversity is under pressure. The WOR sees many direct and indirect threats. For example, the direct removal of marine organisms, primarily through overfishing, has already led to many stocks shrinking to less than half their original size. At the same time, the use of the coasts and seas has changed fundamentally - an industrialisation of marine resources that has increased dramatically since the 1950s and has either damaged, destroyed or caused the disappearance of many original ecosystems.

Ocean warming, acidification and oxygen depletion are forcing thousands of species to flee, tearing apart established food webs and bringing biological processes to a standstill. This development is exacerbated by the ubiquitous pollution of the oceans with waste, microplastics and pollutants. Even in the most remote corners of the Arctic, mercury concentrations are now 20 to 30 times higher than before industrialisation.

Added to this is the threat posed by alien species, which can enter new habitats through shipping, canal construction or targeted releases and disrupt the ecological balance there. The growing demand for energy generation at sea, the intensification of shipping traffic and the expansion of aquaculture are also causing problems for marine ecosystems.

Why species richness is important

Less species richness also means less resilience, as species-rich ecosystems are more robust. If biodiversity declines, the productivity of the affected biotic communities also decreases. According to the report, a decline in productivity as a result of drastic biodiversity loss can already be observed in many marine regions.

The report uses the example of a kelp forest in Monterey Bay to describe how a small stone can set an entire avalanche in motion. Kelp forests harbour fish, act as natural breakwaters to reduce coastal erosion and protect coastal regions from storm damage. At the same time, they bind considerable amounts of carbon, counteract ocean acidification and filter excess nutrients from the water - a complete service package for the climate, coast and fisheries.

At the same time, they are one of those sensitive ecosystems in which a small change can have serious consequences. In kelp forests, sea urchins normally only eat dead plant material. This balance was disturbed in Monterey Bay in 2014: a heatwave and, as a result, a starfish epidemic eliminated the sea urchins' main predators. The echinoderms multiplied explosively and destroyed large parts of the kelp forest. Surprisingly, even the growing sea otter population did not help as expected - the marine mammals only ate the sea urchins in the remaining intact forest areas and spurned the echinoderms in the bare zones. This unexpected reaction prevented forest recovery and shows how complex marine ecosystems function.

Not all aliens cause damage

Clear signs of change are also alien species that suddenly appear in areas where they have never been seen before. They are either introduced by humans or migrate independently after humans have removed barriers to their spread - for example by building canals or as stowaways in the ballast water of ships.

The effects of such maritime migratory movements can only ever be guessed at in advance; not all species have to be as troublesome as the calcareous tubeworm, which is spreading more and more along the coasts of the North Sea and Baltic Sea, especially in brackish water.

The Vikings introduced the North American sand clam to the waters of the Kattegat 800 years ago. From there, they migrated to the Wadden Sea, where today they are an important food source for crabs and seabirds. In the Wadden Sea, the more than 100 known alien species have not yet displaced any of the native species. The introduced Pacific oysters even strengthen the local ecosystems - mixed reefs of oysters and mussels survive storms better than pure mussel beds.