Unseen Damage: How Ghost Nets Disrupt Marine Life, Coral Growth, and Ocean Health

Insights from a scientific mission supported by DWS reveal the far-reaching impacts of ghost nets on biodiversity, recovery dynamics, and microplastic contamination

Descending into the turquoise, silence of the underwater world of the Ionian Sea. The shadow of a wreck, just off the shores of Zakynthos. A wreck resting for decades on the seabed, a witness to time, tides, and life itself.

This world is not untouched. Ghost nets, abandoned of lost fishing nets, are clinging on it. What lies beneath these nets? Do they choke life or nurture it? These are questions we aim to answer with our project Wrecks of Life: Tracking Biodiversity After the Nets, a Healthy Seas initiative supported by DWS.

The Zakynthos Wreck is a time capsule, a reef, and a witness of change. Life is thriving around the wreck. The ghost nets hang like curtains over the wreck, hiding its structures.

Ghost nets are more than just marine litter. When they settle over a shipwreck, they can change that ecosystem. Light is blocked, water flow slows, the wrecks’ surfaces are smothered. Does marine life struggle to grow or are the nets perhaps a habitat for them? Comparing ghost net impacted areas with untouched sections of the same wreck lets us measure exactly what’s growing on a ghost net, what’s lost under it, and what comes back once it’s removed. It’s like watching a forest regrow, only underwater, and in a habitat made of history. This matters because shipwrecks are more than metal and memory. They can be biodiversity hotspots, nurseries for fish, stepping zones for marine life

Why it matters

The biggest question driving our research on the Zakynthos wreck off Kyllini is: What grows back after a ghost net is removed? Understanding how marine life returns once freed from these nets gives us insight into the resilience of underwater ecosystems and their ability to recover from human impacts.

Ghost nets can reduce available habitat by smothering shipwreck surfaces, changing both the abundance and diversity of organisms that can survive there. Our study also explores whether these nets act solely as death traps, entangling and killing marine life, or if they might, over time, create their own artificial reef habitats.

By answering these questions, our research guides conservation efforts and helps develop strategies to protect and restore these unique underwater habitats. The findings inform us about what is happening below the surface and also inform future decisions on whether, when, and how to remove ghost nets. We ground choices on data, balancing ecosystem recovery with practical conservation action.

Our first results

Life around the wreck told three very different stories

On the wreck itself, we found the greatest variety of marine life: colourful sponges, corals, algae, and ascidians (sessile, marine invertebrate filter-feeder) thriving on its surface.

On the ghost nets, less life was observed. The nets acted like heavy curtains – limiting light and slowing water flow. Only a handful of hardy species managed to cling on.

In the newly cleared areas, we found bare surfaces with little life where the ghost net had smothered the wreck’s surface. Recovery has not started yet, showing that removing nets is only the first step—nature now needs time to return.

Corals reflected this same pattern. The solitary coral Caryophyllia inornata grew tallest and most abundant on the wreck, while on the net it was still small, maybe due to its later settlement or due to less ideal conditions. On cleared surfaces no coral were found where ghost nets once hung. This is either because existing coral were smothered or because settlement was inhibited by the net.

The Journey of a Coral

Following Its Stages from Tiny Larva to Polyp

Planula Larva – The fertilized egg (zygote) develops into a free-swimming, planktonic planula larva. This stage drifts in the water column, carried by currents.
Metamorphosis – Before settlement, the larva begins metamorphosis. Early morphogenesis includes the development of tentacle buds, internal septa, and the pharynx.
The larva attaches to a hard surface on its aboral end (the side opposite the mouth). Once settled, it completes transformation into a polyp, the adult coral form, which then secretes a skeleton and begins growth.

Coral Growth Differences Across Substrate Types

In our study, coral growth differed strongly between substrate types. Caryophyllia inornata polyps on the wreck reached significantly greater heights than those under ghost nets, while no corals were observed in the newly cleared zones. This pattern likely reflects both age and settlement opportunities. The wreck itself, being older and structurally complex, has allowed corals to establish and grow over decades. In contrast, the ghost net is a more recent and unstable substrate, inhibiting settlement and potentially restricting nutrient flow, which can limit growth. The absence of corals under the ghost net supports this notion: continuous shading and smothering may hinder larval settlement and the early stages of growth. These findings highlight how ghost nets not only reduce biodiversity but can also directly affect the development of long-lived sessile organisms.

Algae: Architects of the Ocean, Growing on Nets

Powering Life, Producing Oxygen, and Creating Vital Marine Habitats

Algae form the base of marine ecosystems. As primary producers, they capture sunlight and turn it into energy, supporting grazers and many other organisms higher up the chain. Through photosynthesis, algae also produce a large share of the Earth’s oxygen. At the same time, they help regulate the climate.
In addition to being a food source, macroalgae provide important habitats. These algae create underwater forests that shelter fish, invertebrates, and many other species. In our study, we found an abundant growth of algae present on ghost nets, transforming these abandoned materials into unexpected microhabitats that support a surprising diversity of life. In this way, algae sustain life not only by producing energy and oxygen but also by offering protection and living space to organisms, even on man-made debris.

Illustrating the Invisible

Scientific diving gives us data and photographs, but illustrations allow us to tell the story of the wreck and its biodiversity in another way. The illustrations for Wrecks of Life were created by Stefania Sbrighi, working closely with our scientific diving team.

Why illustrations? Because they make the unseen visible. Photography and Illustrations are both art and science: a way to communicate complexity clearly, and to inspire curiosity in audiences who may never dive into the Ionian Sea themselves.

Every illustration was designed to complement the data we collect. These visual stories make the science accessible, for schoolchildren, the public, and decision-makers, while still being grounded in research and field observations.

In this way, the illustrations become part of our mission: documenting biodiversity, raising awareness of ghost nets, and ensuring that the hidden world of the Zakynthos wreck can be shared, understood, and protected.

We invite you to explore some of the mission’s most fascinating aspects and discoveries through the illustrations and boxes, each brining the story of the wreck closer to you.

Science in Action

Beneath the surface our work is part exploration, but also part detective story. We dove with photo quadrats: underwater photo frames, that capture snapshots of life on wrecks in a standardised manner, so we can make a reliable comparison with the data taken. With laboratory bottles we scooped up sediment and water from the water column to check for microplastics.

A day at the scientific diving project

Impact of Microplastics. Microplastics: Tiny Threats, Big Impact

In our study, we found microplastics from the ghost nets in the water column as well as in the sediment, showing that ghost nets are a persistent source of microplastic contamination in multiple marine compartments.

What are microplastics? Tiny plastic particles, often invisible to the naked eye.
Why do they matter? Microplastics enter the marine food web when ingested by plankton, fish, and shellfish, causing physical harm and chemical exposure.

Broader ecosystem effects: Microplastics accumulate in sediments and water, affecting benthic organisms and altering nutrient cycles.
Human connection: Microplastics can travel up the food chain, eventually reaching seafood on our plates.

Behind the scene from the mission

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“We’re diving into the study of a shipwreck and the diverse marine ecosystem that now surrounds it. Alongside this, we’re also examining the presence and potential impact of ghost nets in the area”. Isadora Abuter, Scientific Diving Team Healthy Seas.

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Ghost Net Removal

Every dive brought a moment of surprise: curious fish darting between algae, an unexpected patch of growth where we thought life had vanished.
We carefully removed a part of the net, to see how life grows back on the wreck and marine life settles.

How a ghost net retrieval is done:
1. Locate & Assess: Divers identify nets and evaluate the safest way to remove them.
2. Cut & Untangle: Nets are carefully cut with knives, keeping in mind safety, gas supply and avoiding self-entanglement.
3. Lift & Surface: Lift bags are attached to the nets and inflated, bringing them to the surface.
4. Recycle & Restore: Nets are recycled or safely disposed of, and divers monitor how marine life returns.

How it will continue

Our work here is not over. This wreck will become our underwater time capsule. We will return to the exact same locations on the site, marked and mapped during our dives, to record how marine life grows back after the ghost net has been removed. These repeated observations will give us a clear, measurable story of recovery, proof of what the ocean can do when given a second chance.

About the partnership DWS x Healthy Seas

DWS partnership with Healthy Seas is a prime example of how the financial sector can support hands-on, science-driven conservation—while also driving awareness and accountability within the industry and beyond.

From supporting the purchase of our first boat, MAKO, to funding historic shipwreck cleanups and our most recent biodiversity-focused scientific mission in the Mediterranean, DWS has shown how investing in the planet can be direct, measurable, and inspiring.

Thank you to all the diving team: Isadora Abuter, Ramona Reichert, Ben Oortwijn, Pascal van Erp, Michael Westreicher and Michalis Livanis.