15 years of monitoring the ecological effects of Belgian offshore wind farms still yields new insights

Fifteen years into the programme, monitoring of the ecological effects of Belgian offshore wind farms continues to provide new insights. That is an important conclusion of the latest WinMon.BE report that summarizes the findings on bottom-dwelling invertebrates, fish, harbour porpoises and birds. Only through sustained and adaptive monitoring can we ensure that we design and build offshore wind farms in the most eco-friendly way.

Scientific fieldwork in the Belgian offshore wind farms with the RV Belgica. (Image : Institute of Natural Sciences/MARECO)

At present, eight offshore wind farms are operational in the Belgian part of the North Sea, totalling an installed capacity of 2.26 Gigawatt (GW) and consisting of 399 offshore wind turbines. Together they occupy an area of 238 km² along the border with Dutch waters and produce an average of 8 TWh annually. This accounts for around a third of gross electricity production from renewable energy sources in Belgium.

The impacts on the marine ecosystem, both positive and negative, have been investigated through the WinMon.BE monitoring and research programme from the very start of the construction of the first wind farm in 2008. The scientific insights obtained have always informed the management and development of this first Belgian offshore wind farm zone. In their latest report, scientists of the Institute of Natural Sciences, the Research Institute for Nature and Forest (INBO), the Marine Biology Research Group of Ghent University and the Research Institute for Agriculture, Fisheries and Food (ILVO) discuss the latest findings from 2022, summarize some trends from 15 years of monitoring, and identify where additional research and the development of additional mitigation measures is needed.


Long-term impacts of offshore wind farms on the macrobenthic communities (roughly the organisms that live on the seabed and are visible to the naked eye) that inhabit the surrounding natural soft sediments were investigated over a time span of 13 years (2008–2020). The sediments around and between the wind turbines were also studied in this context.

Because wind turbines interfere with water currents, fine sediments settle more easily here. The sediments in wind farms also get organically enriched by the feces of organisms that colonized the turbines themselves (such as mussels, anemones and crustaceans), and by dead animals that fall from the turbines. For the macrobenthos, a higher abundance, species richness and diversity was found around the wind turbines. Furthermore, higher abundances were also documented in the gullies between sandbanks on which the wind farms are typically constructed. The macrobenthos community continues to change, no stable state has yet been reached after 13 years of offshore wind farm operations.

In addition, macrobenthic diversity, abundance and species richness were also correlated with climate-related predictors (sea surface temperature and its natural variability on a time scale of several decades) which demonstrates the importance of also including such environmental variables in the study.

Demersal Fish

Changes in species distribution patterns were identified for demersal fish, as exemplified for plaice Pleuronectes platessa, a species extensively studied in terms of its spatial distribution, diet and movement patterns in relation to offshore wind farms. A combination of visual diving transects (at the turbine scale), beam trawl samples (at the wind farm scale) and the follow-up of tagged animals demonstrated the significance of the scour protection layer and the sandy patches in between the turbines as a feeding habitat for plaice.

The findings suggest that offshore wind farms serve as a refuge for plaice, potentially mitigating direct fishing mortality and likely enhancing plaice production. It was previously documented that fishing vessels caught more plaice for the same fishing effort just outside the wind farms than at the same places before the construction of the wind farms. However, it remains to be investigated whether this is a true spillover effect that continues to manifest itself in the longer term, and also in the context of the anticipated large-scale expansion of offshore renewable energy zones in the broader North Sea.

Harbour Porpoise

Altered species distribution patterns in relation to the presence of offshore wind farms are not independent of other human activities, such as shipping, fisheries and mariculture. This is particularly the case for highly mobile species like marine mammals. Aerial survey data (2009-2022) allowed for an analysis of the distribution patterns of the harbour porpoise Phocoena phocoena in function of both environmental drivers and anthropogenic stressors.

The distribution of harbour porpoise followed a consistent seasonal pattern, with the highest densities in spring. It was shown that the species prefers the western part of the Belgian North Sea waters, revealing a strong overlap with the marine protected area ‘Vlaamse Banken’. The distribution was also negatively correlated with marine traffic intensity and distance to the closest offshore wind farm. However, it is essential to exercise caution to avoid overinterpreting these correlations. Further monitoring and research is recommended to better understand the interaction between natural factors, such as prey availability, and anthropogenic stressors, driving the spatial distribution of harbour porpoises.

Harbour porpoises documented during an aerial census. (Image : Institute of Natural Sciences/J. Haelters)


The monitoring strategy for seabirds not only aims to detect displacement responses, it is also designed to detect avoidance (or attraction) distances and the effect of turbine density on seabird displacement. The results presented at this stage (data from February 2021 to April 2023) need to be considered as indicative since more data and advanced spatial modelling are needed.

Nevertheless, based on the currently available data, it is interesting to see that the observed responses are in line with what has been found before and elsewhere for several seabird species. The results indicate an attraction effect for great black-backed gull Larus marinus and great cormorant Phalacrocorax carbo, and an avoidance effect for northern gannet Morus bassanus. On the other hand, avoidance of common guillemots Uria aalge was no longer noticed and an increased number of razorbills Alca torda was observed in the wind farms.

Northern Gannet in the Belgian part of the North Sea (Image : Institute of Natural Sciences/K. Moreau)

Migrating Birds

As the southern North Sea is one of the main migration flyways in Europe, mitigating the impacts of offshore wind farms also entails measures to reduce collision numbers for migrating birds. The highest flight intensities at sea are recorded at night during spring and autumn migration, mainly of migrating passerines. Normally, these migrate at higher altitudes, but a portion flies at rotor height of the wind turbines and are thus at risk of collision. Especially adverse weather conditions bring large numbers of passerines into the range of the turbine rotors.

Temporarily stopping the turbine operation during high collision risk events for songbirds is expected to substantially prevent collision mortality. However, this management measure has not yet been applied regularly but has already been tested in the Netherlands, among others. Site-specific monitoring programmes remain necessary to assess the effectiveness and the finetuning of the measure. Furthermore, a regional approach may be most appropriate to maximize the efficiency and ecological benefits of such measure.

Long-Term and Adaptive Monitoring

Most environmental monitoring programmes for offshore wind farms are halted five years after installation. WinMon.BE, on the other hand, has adopted a philosophy of long-term investigation, spanning the full life cycle of offshore wind farms, from construction through the operational phase to the final decommissioning. The programme shows that progressive changes in the marine ecosystem are still observed fifteen years after the first installation of offshore wind turbines in the Belgian part of the North Sea, as was the case for the macrobenthos communities. This underlines the importance of long-term research for a sound offshore wind farm management.

The monitoring programme must also be adaptive. Not only continued, but also new research is indispensable to further the understanding on how marine ecosystems respond to wind farms. This research should not only focus on the attraction of hard substrate species (with wind turbines representing artificial hard substrates), but also on species that are less evidently impacted by offshore wind farms, such as plaice and other demersal fish.

Steven Degraer (Institute of Natural Sciences/MARECO), coordinator of the WinMon.BE consortium: “We need to keep critically reflecting on the efficiency and effectiveness of the monitoring and research programme to ensure that we collect the best data, as shown with the re-designed monitoring programme for seabirds. As demonstrated for marine mammals, we need to address the most pertinent questions and contextualise offshore wind farm effects. Progressive insights are necessary to feed evidence-based, efficient and effective mitigation measures, and to develop and design eco-friendly offshore wind farms”.

It’s not over yet for WinMon.BE

An additional Belgian zone for offshore renewable energy, the Princess Elisabeth Zone, anticipating an installed capacity of between 3.15 and 3.5 GW on an area of 285 km², has been designated in the marine spatial plan 2020-2026. The progressive insights of WinMon.BE are also used to guide the design of this zone in an environment-sensitive manner, and also during the construction and operational phases of future wind farms, WinMon.BE will document and learn to understand the effects on the marine ecosystem. As the Princess Elisabeth Zone overlaps with the marine protected area ‘Vlaamse Banken’, additional knowledge on the nature-inclusive design of wind farms was gathered in the EDEN2000 study “Exploring options for a nature-proof Development of offshore wind farms inside a Natura 2000 area” (2019-2023).

Zones for renewable energy, including offshore wind farms, in the Belgian part of the North Sea. Eastern zone (green) = first phase that is completely operational; western zone (blue) = Princess Elisabeth Zone; orange dotted line = Natura 2000 area (source: Marine Spatial Plan 2020-2026)

Moreover, Belgium is not the only country that is investing in wind farms in the southern North Sea. Many parks are already operational, under construction or planned in our neighboring countries, and there is a declaration of intent to install 300GW of wind energy in the North Sea by 2050. Therefore, cumulative ecological effects on a larger geographical scale than the Belgian part of the North Sea are also a concern. The results of WinMon.BE and EDEN2000 can also be directly used in the context of the Greater North Sea Basin Initiative, which strengthens cooperation on marine spatial planning between the North Sea countries. An additional reason why it is important that the monitoring of the ecological effects of offshore wind farms continues!

“WinMon.BE still has a long future ahead of it. It is also encouraging that the programme serves as an example for the environmental monitoring in offshore wind farms in an international context. Discussions are ongoing with policymakers and scientists from various countries, who wish to draw inspiration from the Belgian example” Steven Degraer concludes.


About WinMon.BE

The Monitoring Programme WinMon.BE is commissioned by the Federal Government as part of the environmental permit conditions for offshore wind farms. For the monitoring, use was made of the research vessel Belgica (ship time on RV Belgica was made available by BELSPO and the Institute of Natural Sciences), the research vessel Simon Stevin (operated by the Flanders Marine Institute), several private vessels, the Belgian scientific diving team and the aerial surveillance aircraft of the Institute of Natural Sciences.

WinMon.BE is a cooperation between the Institute of Natural Sciences, the Research Institute for Nature and Forest (INBO), the Marine Biology Research Group of Ghent University and the Research Institute for Agriculture, Fisheries and Food (ILVO), and is coordinated by the Marine Ecology and Management team (MARECO) of the Institute of Natural Sciences. MARECO also coordinated the EDEN2000 study with respect to the anticipated ecological effects of future offshore wind farms in the Princess Elisabeth Zone.

Common dolphin stranded on the beach of Ostend

On the morning of Friday 22 December 2023, a dead Common dolphin (Delphinus delphis) washed up on the beach of Ostend, near the western harbour wall. It was a female measuring 2.07 meters in length.

© Institute of Natural Sciences / Jan Haelters

The Common dolphin is a rare species in the North Sea but is the most common dolphin species in the Bay of Biscay and in the adjacent Atlantic Ocean. In the Bay of Biscay, thousands die in fishing nets every year.

© Institute of Natural Sciences / Jan Haelters

It was no less than the third time in 2023 that a dead Common dolphin washed up on a Belgian beach, which is very exceptional. The specimen on 22 December was by far the freshest of the three and was therefore collected for further research. However, this will not take place until 2024, and will hopefully shed light on the health condition, cause of death and area of origin of the unfortunate animal.

© Institute of Natural Sciences / Jan Haelters

Public consultation: Application for an environmental permit for sand extraction

Betoncentrale Van den Braembussche has applied on October 31th, 2023 for the prolongation of its concession for sand extraction in the Belgian part of the North Sea. This application is subject to an environmental impact assessment procedure.

The application and the environmental impact assessment report, including a design of appropriate assessment, can be downloaded below (in Dutch).


Environmental impact assessment report (original 2020)

Environmental impact assessment report (update 2022)

Environmental impact assessment report (annex study day 2021)


Results of the consultations

Objection 4Sea-20240112


The public consultation runs from December, 8th 2023 until January, 7th 2024.

Any interested party can submit its views, comments and objections to Ms. Brigitte Lauwaert by letter or email until January, 22th 2024.

Institute of Natural Sciences/MUMM
Attn. Ms. Brigitte Lauwaert
Vautierstraat 29
1000 Brussels


Quality Status of the North-East Atlantic

In the Quality Status Report 2023, the 16 contracting parties to the OSPAR Convention, including Belgium, assess the status of the Northeast Atlantic Ocean. The report confirms that climate change and ocean acidification have become drivers of major change. Biodiversity and habitats remain at risk, but a turnaround is noticed with respect to the chemical quality of the marine environment.

More than 400 scientists and policy makers from around the North-East Atlantic have worked together to produce a holistic assessment of the North-East Atlantic marine area: the OSPAR Quality Status Report 2023 (QSR). The work was carried out under the umbrella of the OSPAR Convention for the Protection of the Marine Environment of the North-East Atlantic. It examines the current state of the marine environment and ecosystems, and the human activities benefiting from the marine environment and interacting with it.

Dr Patrick Roose, Operational Director of the Department ‘Natural Environment’ of the Institute of Natural Sciences was one of the coordinators of this titanic work. He summarizes the situation as follows: “There is an ever-more pressing need to address drivers of degradation and biodiversity loss and thereby increase the health and resilience of marine ecosystems in the North-East Atlantic. This area also includes our North Sea. Climate change and ocean acidification have now become drivers of major changes that imperil much of the North-East Atlantic’s marine biodiversity. As such, they now add to the effects of the hitherto ‘traditional’ drivers, such as overexploitation and chemical pollution.”

Biodiversity in peril

The report shows that many parts of the North-East Atlantic still suffer from declining biodiversity and continued habitat degradation, despite the measures that have already been taken by OSPAR Contracting Parties. The impacts of fisheries and other human activities on biodiversity and habitat quality are still deeply felt, and other forms of degradation such as noise pollution are of growing concern.

Although the status of habitats and individual species varies greatly, some general statements can be made: Benthic habitats continue to be damaged, whereas plankton, the base of the marine food web, is impacted in pelagic habitats. The state of marine food webs is of great concern. More and more fish stocks are being fished sustainably, but the overall status of marine fish remains unfavorable. Marine birds are generally still in trouble. Many marine mammals, especially northern seal populations and small toothed cetaceans, remain at risk while the status of some other marine mammals remains unknown. We also appear to know relatively little about the status of marine turtles.

Areas of improvement

Fortunately, the environmental quality has improved in some areas: The most serious hazardous substances such as PCBs, PAHs, and organochlorides remain a cause for concern (mostly because they remain in the system for a long time), but releases have decreased substantially. Pollution by radioactive substances has been prevented, and discharges by the oil and gas industry have been greatly reduced and continue to decrease. Marine litter levels remain high but are better tracked, with significant steps having been taken to reduce it.

Eutrophication, the process in which a water body becomes overly enriched with nutrients, persists but a gradual reduction of the excess nutrients has been witnessed in many parts of the North-East Atlantic. The introduction of new non-indigenous species, another traditional driver of biodiversity loss, also appears to have decreased in the marine environment. As a community, we must ensure that we continue these trends in the right direction. Furthermore, we must also be careful with optimism in the face of climate change and ocean acidification. After all, the impacts of these man-caused phenomena are now clearly measurable and put ecosystems at further risk.

Appropriate measures

The findings from the Quality Status Report 2023 will be used to help OSPAR deliver its North-East Atlantic Environment Strategy 2030, a roadmap to achieving the vision of a clean, healthy and biologically diverse North-East Atlantic Ocean, which is productive, used sustainably and resilient to climate change and ocean acidification.

Dr Roose provides some important nuances: “The general conclusions of the QSR contain no major surprises, but we must become better at developing the necessary science-based policy, and therefore at translating scientific insights into effective measures. To be effective, we need to pool our efforts and move to international evaluations and joint measures. It makes no sense to assess everything on a national basis as there are no borders in the seas, and no undesirable effects can be overcome in national parts of a bigger basin.”

There is also additional work to be done for science: “Still, there are indicators for which we have insufficient data and can better coordinate the data collection. Sufficient, continuous and coordinated data collection is key, in other words, so is continuous policy support. Also, not all assessment methods and thresholds are already sufficiently established, particularly for cumulative effects” Dr Roose adds.

Dr Patrick Roose presenting the key findings of the OSPAR Quality Status Report 2023 at the Annual Science Conference of the International Council for the Exploration of the Sea (ICES) in Bilbao, Spain, 13 Sep 2023.

About OSPAR and the QSR

OSPAR – the Oslo and Paris Commission – is the mechanism by which 15 Governments and the EU cooperate to protect the marine environment of the North-East Atlantic. The fifteen Governments are Belgium, Denmark, Finland, France, Germany, Iceland, Ireland, Luxembourg, The Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom.

OSPAR started in 1972 with the Oslo Convention against dumping and was broadened to cover land-based sources of marine pollution and the offshore industry by the Paris Convention of 1974. The two conventions were unified, updated and extended by the 1992 OSPAR Convention. A new annex on biodiversity and ecosystems was adopted in 1998 to cover non-polluting human activities that can adversely affect the sea. More information on the OSPAR website and YouTube.

The Quality Status Report (QSR) 2023 is the most authoritative assessment of the whole North-East Atlantic and reflects the collective work of the 16 Contracting Parties to the OSPAR Convention. It assesses the status of various components of the North-East Atlantic and examines how conditions have changed since the last QSR in 2010.

Publication of the QSR 2023 was announced at the Annual Science Conference of the International Council for the Exploration of the Sea (ICES) in Bilbao, Spain, on September 13, 2023. In Belgium, the results, with a focus on the North Sea, were presented during the event ‘Nature restoration in our North Sea’, organized by the FPS Public Health, Food Chain Safety and Environment, on December 5, 2023 in Bruges.

The Belgian input for the QSR came about thanks to the cooperation of many actors, all of which are explicitly thanked for their cooperation: the Directorate-General for the Environment (FPS Public Health, Food Chain Safety and Environment), the Institute of Natural Sciences, the Federal Agency for Nuclear Control (FANC), the Flanders Environment Agency (VMM), the Research Institute for Nature and Forest (INBO), the Flanders Research Institute for Agriculture, Fisheries and Food (ILVO), the Flanders Marine Institute (VLIZ), Maritime Access (Department Mobility and Public Works), the Public Waste Agency of Flanders (OVAM) and the Directorate-General Shipping (FPS Mobility and Transport).

Conservation priority of stony reef habitats in the Belgian North Sea

Stony reefs in the Belgian North Sea host a unique fauna that is highly vulnerable to bottom-disturbing activities. Currently, these reefs are targeted by bottom-contacting fisheries. This paradox  underpins the urgent need for a more effective protection of marine gravel beds and their fauna.

Figure 1. Indicative overview of the variable life forms found in the Belgian stony reef areas. (A) the soft coral Alcyonium digitatum (B) the common spider-crab Maja brachydactyla (C) the small-spotted catshark Scyliorhinus canicula (D) the branching hydrozoan Nemertesia spp. (© Institute of Natural Sciences/MARECO)

The Belgian seafloor consists primarily of soft sediments that form a widespread and very prominent geomorphological system of large sandbanks. However, approximately. 16% of the seafloor is composed of natural hard substrates, typically referred to as “stony reefs” or “gravel beds”. These stony reefs, ranging from gravels to pebbles, cobble stones and larger boulders, are patchily distributed over the predominantly sandy seafloor.

Stony reef areas provide a stable holdfast for a unique, diverse and specialized fauna. Several organisms, such as soft corals and branching hydrozoans or bryozoans, form complex three-dimensional body structures. These areas, characterized by increased habitat complexity and heterogeneity compared to the surrounding sandy environment, act as oases and serve as refuge, settling, foraging, spawning and nursery grounds for organisms at various levels of the food web. Many of these are of commercial and conservation importance (Fig. 1). These habitats are as ecologically valuable as they are fragile and they are highly susceptible to anthropogenic disturbances, including bottom-contacting fisheries.

Minimally invasive research

Gaining a deeper understanding of the effects of commercial bottom-disturbing fisheries on stony reefs in the Belgian North Sea was the goal of the investigation led by Giacomo Montereale Gavazzi and fellow researchers from the MARECO group (Marine Ecology and Management) of the Institute of Natural Sciences. Their results, spanning a period of 7 years (2016-2022), are presented in a 2023 publication in the scientific journal Frontiers in Environmental Science.

The study focused on two distinct offshore stony reef areas in the Belgian part of the North Sea: the Northwest and the Hinder Banks (Fig. 2). The Northwest site, first observed in 2018 and celebrated as a biodiversity hotspot, has been designated as a search zone for biodiversity protection, but also as a prospecting area for marine aggregate extraction under the Marine Spatial Plan 2020-2026 that is currently in force. The Hinder Banks site partly overlaps with the Marine Protected Area ‘Vlaamse Banken’ under the EU habitats Directive, which was delineated in 2012 to protect reefs and sandbanks.

Figure 2. Overview of the stony reef study areas (red outlined polygons) in the Belgian part of the North Sea (black polygon). The larger of the two study sites (Hinder Banks) is situated inside the Natura 2000 area (green outlined polygon), with the overlapping blue polygon delineating the planned area for future renewable energy development. The blue polygon at the border with the Netherlands marks the current renewable energy zone with operational offshore wind farms. (© Institute of Natural Sciences/MARECO)

Given the fragility of these habitats, the research team relied solely on minimally invasive remote sensing technologies. Commercial fishing activity data (mapping the spatial and temporal distribution of fisheries), echo sounding (seabed mapping with sound waves) and underwater photography (documenting the structure and fauna of the seabed) were combined to provide a comprehensive overview of the ecological status of the two areas. The data analysis confirmed that both were hotspots for bottom-contacting fisheries during the studied period.

Reefs as fishing hotspots

The Northwest site has experienced a boom in fishing activities from 2021 to 2022 (32% increase in the number of operating vessels), with an overall extent of the area disturbed reaching 86%. In the Hinder Banks area, the estimated disturbed area was calculated at 89%, and while fishing activities decreased by 60% from 2021 to 2022, this site has been chronically under very high fishing pressure going back for centuries.

This intense fishing pressure is reflected in the response of the stony reef benthic communities. These shifted from immobile, long-living and habitat-forming taxa with low resistance and recovery potential to disturbance (typical of such habitats) to opportunistic taxa lacking these typical characteristics. The effect that bottom-trawling has on the seafloor was also evident by the trawl marks captured by the hydroacoustic surveys (Fig. 3), appearing as plough marks scarring and smoothing the geomorphology, with their impact persisting for at least four months. The overall results showcase that bottom-contact fishing practices can have detrimental effects on the ecological functionality of these conservation priority biotopes.

Figure 3. Display of trawling marks scarring the seafloor when bottom-contact fishing gears are used. Examples from two locations at the Northwest stony reef site. (© Institute of Natural Sciences/MARECO)

Marine Spatial Planning

While both study sites are subject to different environmental management regimes, they share a common challenge with respect to ongoing direct anthropogenic disturbance. Considering that the Hinder Banks area is designated as a Marine Protected Area, it becomes evident that this legislative status alone is insufficient for achieving the desired protection level. More comprehensive regulations are in trajectory under the current Marine Spatial Plan. Both stony reef sites have been designated as search zones for seafloor protection with the intention of restricting bottom-disturbing fishing practices to facilitate nature restoration and conservation.

The study by Montereale Gavazzi and his colleagues provides additional scientific information to be considered for the next Marine Spatial Plan and as such supports the protection of local natural biodiversity. It strongly advocates for adequate regulation of bottom-disturbing fishing practices in stony reef areas and emphasizes the importance of translating the planned management measures into concrete reality.

Additional challenges

At the same time, other human activities compete for the same space, with the planned Princess Elisabeth Zone for offshore wind farms overlapping the Vlaamse Banken Marine Protected Area (Fig. 2) and marine aggregate extraction being prospected at the Northwest site. With respect to the Princess Elisabeth Zone, the EDEN2000 study “Exploring options for a nature-proof Development of offshore wind farms inside a Natura 2000 area”, also coordinated by the MARECO team between 2019 and 2023, provided the necessary knowledge for a nature-proof development of wind farms.

EDEN2000 was commissioned by former Minister for the North Sea Vincent Van Quickenborne and the Department for the Marine Environment of the Federal Public Service Health, Food Chain Safety and Environment. The results serve as advice in the framework of public procurement procedures for the construction of wind turbines under the responsibility of AD Energy of the FPS Economy.


Paul Van Tigchelt, Minister of the North Sea: “Our North Sea is home to more than 2,000 different species. At the same time it is very busy with numerous activities. Our seabed has suffered greatly from intensive fishing. To protect the integrity of the seabed, we have identified the most valuable zones based on scientific research and in consultation with the competent services and the sector, within which we have now proposed fishing measures. We must cherish and support the biodiversity in our North Sea. We must restore nature that has been lost or severely reduced. Such as the European flat oyster and the gravel beds. Belgium has strong ambitions regarding nature restoration and we want to get started on this as quickly as possible.”

Living Loggerhead turtle on Bredene beach

On Saturday, November 25, 2023, a live Loggerhead turtle washed up on the beach of Bredene. This species has never before been identified with certainty in Belgium. The animal is currently being closely monitored in SEA LIFE Blankenberge.

© Walter Rogiers

Strong northwesterly winds are known to cause all kinds of dead and living material from the sea to wash up on our coasts, and the storm of November 24-25, 2023 was no different. Sometimes surprising animals or objects are also found in the wash-up. In the afternoon of November 25, walkers on the beach of Bredene came across nothing less than a live sea turtle.

The young animal, with a carapace length of only 14 cm, was recovered from the beach by the Ostend fire brigade and reported to the experts of the Institute of Natural Sciences, who identified it as a very young Loggerhead turtle (Caretta caretta). The Institute then arranged for the transport of the lost animal to Sea Life Blankenberge.

© Institute of Natural Sciences/Francis Kerckhof

First time in Belgium?

Although the Loggerhead Turtle is not exclusively confined to warm waters and is one of the most widespread sea turtles, the North Sea falls outside the range of this species. A number of strandings are known from the Netherlands, including from the 21st century, but as far as we know there have been no confirmed sightings from Belgium. Some old cases are questionable or involve sea turtles of unknown identity. Bredene’s turtle could therefore go down as the first confirmed Loggerhead turtle in Belgium.

When Loggerhead turtles hatch from the egg, their carapace is only 4 to 5 cm long. The carapace of adult animals can reach a length of more than one meter. The animals that previously washed up in the Netherlands had widely varying carapace lengths, from about 20 cm to almost a meter. These therefore involved animals of varying ages, but most were immature. Female Loggerhead turtles only reproduce when they reach a carapace length of 70-80 cm, and are then at least almost 20 (to more than 30) years old.

Atlantic origin?

The Loggerhead turtle is found in all oceans except the polar regions. Like all sea turtles, they lay eggs on beaches. The closest laying beaches to us are in the Mediterranean Sea, but that does not mean that the Bredene turtle comes from there. In the Atlantic Ocean, the main breeding areas should be sought in the Cape Verde Islands (East Atlantic) and in the south-east of North America (Florida, Gulf of Mexico; West Atlantic), and an Atlantic origin is certainly possible in the case of the Bredene Loggerhead turtle.

This can be explained as follows. Immature Loggerhead turtles from North America and Cape Verde make a multi-year tour of the Atlantic Ocean before returning to their native areas. During this life stage, strong currents can cause them to drift away, with the youngest – and therefore smallest – specimens being at greatest risk. Western currents in the Atlantic Ocean mainly occur in autumn and winter, so it is no coincidence that sea turtles in the North Sea also appear most often during this period.

The northwesterly storm of November 24-25, 2023 also caused a lot of material to wash ashore that certainly has an Atlantic origin. In addition to driftwood and other objects with Atlantic biological growth (such as many goose barnacles), this also included buoys from the United States and Canada. It is therefore not unlikely that the Loggerhead Turtle came to us from the Atlantic Ocean on November 25 with the same westerly current.

However, it cannot be deduced from this where the Belgian Loggerhead Turtle was born. For another species that previously washed up along North Sea coasts, the Kemp’s Ridley Turtle (with a dead specimen in Belgium, on January 6, 2012 in Nieuwpoort), a transatlantic origin is the only possibility, because this species only reproduces in the Gulf of Mexico.


Because sea turtles that wash up alive in our region have ended up in an area that is unfavorable to them, shelter is always being considered. The Bredene Loggerhead Turtle also had damage to the back of the carapace. SEA LIFE Blankenberge is authorized to take sea turtles into care and organized an initial examination by a veterinarian immediately upon the animal’s arrival. The weight was 770 g, some barnacles were professionally removed from the abdominal shield and a course of antibiotics was started. Additional examination will follow on November 26, during which the animal will be internally screened with x-ray.

The Loggerhead Turtle stays in SEA LIFE Blankenberge in a tank of a suitable size for the animal, where the water temperature is systematically raised. It is still too early to determine whether the animal can be released back into the wild, and where or when that could possibly happen.

Public consultation ‘Princess Elisabeth zone’

The Federal Public Service Economy, SMEs, Self-Employed and Energy has submitted an application for an authorization for the construction and a permit for the operation of offshore windfarms and parc cabling in the Belgian part of the North Sea. This application is subject to an environmental impact assessment procedure.

The application, the environmental impact statement and the non-technical summary can be consulted from 12 December 2023 to 11 January 2024 at the offices of MUMM (Management Unit of the Mathematical Model of the North Sea) in Brussels (Institute of Natural Sciences, Vautierstraat 29, 1000 Brussels; mdevolder@naturalsciences.be; tel 02 627 43 52) or Ostend (3de en 23ste Linieregimentsplein, 8400 Ostend; jhaelters@naturalsciences.be; tel. 02 788 77 22), by appointment only and during office hours between 9:00 am and 5:00 pm. The application can also be consulted at every coastal community, during office hours. The list of locations and contact persons of coastal communities is available by simple request to MUMM.

The documents can also be consulted electronically:

Any interested party may submit its views, comments and objections to Ms Brigitte Lauwaert by letter or email until 26 January 2024:

Institute of Natural Sciences/MUMM

Attn. Ms. Brigitte Lauwaert

Vautierstraat 29

1000 Brussels


Successful first EcoMPV Sampling Campaign: Insights into Early Colonization on Littoral Modules

Scientists of the Institute of Natural Sciences have concluded the first sampling campaign of the littoral modules within the EcoMPV project (Eco-designing Marine Photovoltaic Installations). This sampling event, conducted on October 23, 2023, aims to investigate the habitat provisioning effect of artificial floating structures for marine fouling fauna and fish, one of EcoMPV’s objectives.

For this purpose, three littoral modules were designed and developed by Jan De Nul Group, in collaboration with the Institute of Natural Sciences and EMBRC Belgium (European Marine Biological Resource Centre). These floating modules act as the foundation for various settlement plates, constructed out of materials interesting for marine offshore installations. The littoral modules were deployed in May/June 2023 in the safety zone of Mermaid offshore wind farm by the RV Belgica and the Zeetijger. This test site closely resembles the water mass present in the Princess Elizabeth Zone (PEZ), a newly designated zone for offshore energy production.

During the campaign, the scientific diving team of the Institute of Natural Sciences retrieved the first batch of settlement plates from each littoral module. On board of the RV Belgica, each plate was photographed for quantitative coverage image analysis and subsequently preserved for taxonomic analysis. The data collected from the littoral modules will provide a comprehensive understanding of early colonization processes, offering crucial insights for the development of eco-friendly marine photovoltaic installations. The EcoMPV project is financed by the Energy Transition Fund of the FPS Economy, GD Energy.

One of the littoral modules, prior to the sampling event. (© Institute of Natural Sciences/MARECO)

After the completion of the EcoMPV project, the littoral modules will be integrated as scientific equipment in the Artificial Hard Substrate Garden. This is an innovative in-situ experimental platform, managed by the Institute of Natural Sciences, that consists of flexible and modular artificial hard substrate devices. It is designed to study the impacts of man-made structures, including mariculture installations, renewable energy devices, antifouling treatments, coastal protection structures, and more, on marine environments. Graphic designer Hendrik Gheerardyn has recently crafted an informative infographic providing an overview of the devices and their respective sampling range.

Overview of the different components available within the Artificial Hard Substrate Garden. (© Hendrik Gheerardyn)

The Artificial Hard Substrate Garden is offered as an EMBRC research service to both the scientific community and the industry. For further details, please visit the MARECO website or contact Wannes De Clercq (wdeclercq@naturalsciences.be).


This news item was originally published on the EMBRC website on Nov 9th, 2023.

Text: Wannes De Clercq, MARECO, Institute of Natural Sciences

Orca stranding on the Belgian coast

On October 29, a male orca was spotted off the coast of Coxyde, the first confirmed case of this species in Belgium in the 21st century. A few hours later, the severely weakened animal washed up in De Panne, where it died almost immediately. The autopsy took place on the beach on October 30. To what extent the weakening and death of the orca should be associated with old age or health problems remained unclear. The origin of the animal is also not yet known.

Image: Institute of Natural Sciences/Jan Haelters

In the morning of Sunday, October 29, a large but unidentified sea animal was spotted on the border of Nieuwpoort and Oostduinkerke. A little later, Laurent Raty noticed the large sword-shaped dorsal fin of a marine mammal off the coast of Coxyde. It was immediately clear that it could only fit a male orca (also called killer whale). The animal moved slowly southwest along the coast and news spread quickly.

Image: Filip De Ruwe

When, an hour later, it appeared that the orca had meanwhile barely moved on to off Saint-Idesbald, and was lingering there, hundreds of spectators rushed to the shore hoping to catch a glimpse of the animal. This did not prove difficult, as the flat sea made the orca visible from afar. However, the animal also sometimes approached to within just a few dozen metres of the tide line.

Image: Vincent Legrand

Inevitable stranding

Lots of ‘oohs and ahhs’, but the apearance of this orca in the southern North Sea, its slow swimming and dangerously close approach to the shoreline were bad signs. The euphoria quickly turned when it became clear that the animal would wash up with the rising tide. An ultimate attempt by the lifeboat Brandaris (Ship Support, Nieuwpoort) to encourage the orca to choose open sea had no effect.

Image: Institute of Natural Sciences/Kelle Moreau

At a quarter past two in the afternoon, the orca washed ashore in De Panne, just across the border with Saint-Idesbald. Once the tide had gone out, the very skinny animal died almost immediately. Apart from its weakened condition, the loss of the supporting power of the water also plays a role. On dry land, the pressure of its own weight on organs, blood circulation and respiration quickly becomes too great.

Image: Institute of Natural Sciences/Kelle Moreau


Because of the size of the animal – 6.13 m long – and the desire to keep the body as intact as possible for the autopsy, and also to preserve the skeleton, it was decided to organise the investigation into the medical background and cause of death of the orca on site.

The autopsy was performed on Monday morning, 30 October, by staff from the faculties of veterinary medicine at Ghent University and Université de Liège and the Institute of Natural Sciences. The general public could follow the event, which took about three hours, from a distance. All body parts and organs were inspected externally and internally, and various tissue samples were collected for further microbiological (diseases) and ecotoxicological (chemical contamination) studies.

Image: Institute of Natural Sciences/Kelle Moreau

Cause of death?

Analysis of the digestive system showed that the stomach and intestines were completely empty, meaning that the animal had not managed to obtain food for some time. The thin layer of subcutaneous fat and severely worn teeth also seem to be related to this. These findings are consistent with the externally observed emaciation and weakening of the animal.

Inspection of the other organs revealed signs of infection of the lymphatic system, and minor bleedings in the intestinal wall. The severity and role of these in the weakening and death of the orca are being further investigated microbiologically. The other organs showed no visible signs of infection or obvious pathology. No suspicious amount of internal or external parasites was found either.

The extent to which the orca’s weakening and eventual stranding and death should be linked to advanced age (and natural death), underlying health problems, or a combination of both, is thus not yet fully established.

Image: Institute of Natural Sciences/Kelle Moreau

Orcas in Belgium

There are hardly any well-documented cases of orcas in Belgium from past centuries. Four reports are known from the 20th century, and for an older stranding we need to move back in time to 1850. More recent cases (including some reported in 2022) could not be sufficiently documented to be retained as certain. The animal of 29 October 2023 thus concerns the first confirmed orca in Belgium in the 21st century. In the meantime, it became known that he was also filmed at sea on Thursday, October 26, along the northern French coast between Wimereux and Boulogne-sur-Mer.

Although an orca also washed ashore in Cadzand (The Netherlands) in October 2022, an orca was found in the French river Seine in May of the same year (neither of which survived), and other rare and unexpected marine mammals turned up in the southern North Sea in recent years, we should be cautious in interpreting these figures because of the low numbers. The same goes for pointing out causes for the appearance of these species in areas where they do not normally occur.


The origin of the Belgian orca also remains unknown for now. The orca is a cosmopolitan species, meaning it can be found all over the world, but usually lives in populations that are more or less resident within well-defined areas (which can be quite large). The southern North Sea has no local population; the closest orcas live in Scotland, Norway and the southern part of the Bay of Biscay (N Spain).

Orca populations are invariably well monitored by local scientists, and individuals are usually known and documented in photo databases. Individual recognition is thereby often possible based on markings, fin shape and any damage and scars. The orca from the Belgian coast is currently being compared with photos from these databases. So far, no similarities were found with orcas from the Iberian Peninsula (Spain – Portugal), Madeira, Scotland and Ireland. A possible origin from populations of Norway, Iceland and the Azores is still being investigated further.


Thank you

An explicit word of thanks goes to the local police and fire brigade, the city services of De Panne, the rescue services, the civil protection, the staff of Ghent University and the Université de Liège, the colleagues from the Institute of Natural Sciences and the FPS Public Health, Safety of the Food Chain and Environment, and to the numerous volunteers and other stakeholders who played a role in monitoring and documenting the orca, managing the beaching, the public and the autopsy.

The municipality of De Panne gave the unfortunate orca the name ‘Reveil’, after the initiative that aims to take Flemish mourning culture into the 21st century and of which De Panne may call itself ‘consolation capital’ in 2023. On the eve of the orca’s stranding, 10,000 candles were placed on De Panne’s beach in this context.

Publication Nature Communications Earth and Environment : International maritime regulation decreases sulfur dioxide but increases nitrogen oxide emissions in the North and Baltic Sea

Collaborating with researchers from Germany, the Netherlands, Sweden, and Denmark, researchers from the Institute of Natural Sciences (Ward Van Roy and colleagues) assessed the effectiveness of ship emission regulations that have been in place in the North and Baltic Seas for more than 15 years. The findings of this study were published today, October 26th, 2023,  in the leading scientific journal Nature Communications Earth and Environment. The study was based on more than 110,000 remote ship plume measurements and on-board inspections. Remote measurements were conducted using various fixed monitoring stations and aerial measurements using drones, helicopters, and fixed-wing aircraft.

Belgian Coastguard aircraft operated by the Institute of Natural Sciences (© Institute of Natural Sciences/MUMM)

The data revealed a substantial improvement in compliance rates for sulfur emission limits since the initiation of these measurements. This positive trend was observed across the Baltic Sea and the North Sea. Nevertheless, it was observed that the introduction of the global cap limit of 0.5% FSC (fuel sulfur content) led to a slight increase in SO2 emissions in the SECA (Sulfur Emission Control Area) from 2020 onward, possibly due to the increased use of scrubbers and the fuel price inflations.

Evolution of potential non-compliance in the European SECA

In contrast to the successful reduction of SO2 emissions from ships, the international ship emission regulations appeared to have no impact on the nitrogen oxide (NOx) emissions from ships. In fact, there was even an increase observed of ships’ NOx emissions. This outcome can be attributed to various regulatory gaps in the NOx regulations, an issue on which the Institute of Natural Sciences and other researchers have published before.

Increase in NOx emissions between the periods 2019-2020 and 2021-2022

These research findings are of particular importance to policymakers and other stakeholders responsible for environmental regulation and enforcement, as they offer valuable insights for developing more effective regulations and strategies for the implementation of emission regulations and their enforcement at sea and in ports.

The full study can be consulted here, with a ‘Behind the paper’ blog post being accessible here.