Open Marine Archive

Vandecasteele, L.

van Bogaert, N.

Vansteenbrugge, L.

Torreele, E.

144 
Poster presentation Competition poster 
Rise of the thornback ray in the North Sea  
Vandecasteele Loes, van Bogaert Noémi, Vansteenbrugge Lies and Torreele Els 
Research Institute for Agriculture, Fisheries and Food (ILVO), Fisheries and Aquatic Production, 
Ostend, Belgium., Ankerstraat 1 8400 Oostende, Belgium 
E-mail: loes.vandecasteele@ilvo.vlaanderen.be 
 
Thornback ray (Raja clavata) is an important species in the North Sea and is taken in fisheries 
targeting sole (trawl and gillnet), cod (trawl, gillnet and longline), as well as in targeted ray 
gillnet fisheries (ICES, 2017a). Species-specific landings data for rays and skates are missing up 
until 2012, mostly because these species are managed by one general TAC (Total Allowable 
Catch). However, market sampling indicates that thornback ray is one of the most frequently 
landed skates (ICES, 2017a; ILVO fisheries observer data). 
 
According to ICES, the North Sea stock of thornback ray has steadily declined since the start of 
the 20th century and its distribution is largely reduced (ICES, 2017a). Data from International 
Bottom Trawl Surveys (iBTS) shows that over the past 40 years the distribution of thornback ray 
has been concentrated to the southern-western North Sea, especially in the Greater Thames 
Estuary and the Wash (Walker & Heessen, 1996; ICES, 2017a). However, in more recent years, 
scientific surveys such as the International Bottom Trawl Survey iBTS and the Celtic Ground Fish 
Survey (CGFS) show that the abundance of thornback ray has increased (ICES, 2017a; ICES, 2017b). 
Beam trawling is another efficient method to catch rays and skates, so ILVO decided to analyse 
Beam Trawl Survey (BTS) data from the period 2004-2017. For this, we focussed on the Belgian, 
German and Dutch surveys which cover the entire southern North Sea until the German Bight. 
Our analysis confirmed the increasing trend in the southern North Sea (ICES area 4c) with the 
survey index (individuals/km²) for thornback ray in 2017 being a fivefold of the index calculated 
for 2004. Moreover, thornback ray was caught in areas where it has not been seen for a long 
time (e.g. the German Bight). 
 
This ILVO study delivers various important new insights on the abundance and distribution of 
these rays, which could be linked to fishing pressure and a number of environmental factors as 
well as changes in fish community structure. For example, with the rise of sea surface 
temperatures, thornback ray might receive a competitive advantage over other species that are 
less resilient to warmer waters (Sguotti et al., 2016). The outcomes of our study deliver 
important new insights for stock assessments and fisheries management of rays and skates in 
the North-East Atlantic. 
 
References  
- ICES. 2017a. Report of the Working Group on Elasmobranch Fishes (WGEF), 31 May–7 June 2017, 
Lisbon, Portugal. ICES CM 2017/ACOM:16. 1018 pp. 
- ICES. 2017b. ICES Advice on fishing opportunities, catch, and effort Greater North Sea 
Ecoregion. Published 6 October 2017. doi: 10.17895/ices.pub.3174. 
- Sguotti, C., Lynam, C. P., García‐Carreras, B., Ellis, J. R., & Engelhard, G. H. (2016). Distribution of 
skates and sharks in the North Sea: 112 years of change. Global change biology, 22(8), 2729-
2743. 
- Walker, P. A., & Heessen, H. J. L. (1996). Long-term changes in ray populations in the North 
Sea. ICES Journal of Marine Science, 53(6), 1085-1093. 
- Walker, P. A., & Hislop, J. R. G. (1998). Sensitive skates or resilient rays? Spatial and temporal 
shifts in ray species composition in the central and north-western North Sea between 1930 
and the present day. ICES Journal of Marine Science, 55(3), 392-402. 
 
Keywords: Thornback ray; North Sea; Trawl surveys; Fisheries management 


Rise of the thornback ray in the North Sea

Paepen, M.

Walraevens, K.

Hermans, T.

5 
Oral presentation Brilliant Marine Research Idea 
Using multiple geophysical methods for the assessment of submarine 
groundwater discharge in the Western Belgian coastal area  
Paepen Marieke, Walraevens Kristine and Hermans Thomas  
Vakgroep Geologie, Universiteit Gent, Krijgslaan 281, 9000 Gent, Belgium  
E-mail: marieke.paepen@ugent.be  
 
Submarine groundwater discharge (SGD) is a mix of fresh groundwater discharging from the 
land and recharging seawater. SGD has the potential of influencing shallow coastal 
environments, since it constitutes a gateway for nutrients and pollutants in marine ecosystems. 
In Belgium, the shoreline is delineated by a semi-continuous dune belt, which varies in 
thickness. Freshwater recharges in the dunes during rainfall, leading to the development of a 
freshwater lens. Part of it flows towards the North Sea as submarine fresh groundwater 
discharge (SFGD). Although the existence of SFGD in the western part of the coast is known for 
decades, it has never been thoroughly characterized and quantified. De Westhoek nature 
reserve was chosen as a study site given its wide dune belt and low anthropogenic influence. 
 
To delineate SGD, a combination of several geophysical methods are used for characterizing the 
salt / freshwater interface. Electromagnetic (EM) and electrical resistivity tomography (ERT) 
methods were chosen for their sensitivity to salinity variations. EM mapping was done on the 
beach at low tide with the CMD-MiniExplorer and the DUALEM-421s. Both devices have multiple 
investigation depth ranges up to 4m. Land ERT (Abem Terrameter LS) was performed on the 
beach and in the dunes. Finally, marine ERT (IRIS Instruments Syscal Pro Deep Marine) profiles 
were collected at sea during high tide with logistical support from the Flanders Marine Institute 
(VLIZ). 
 
The combination of techniques provides a lateral and vertical distribution of salinity from the 
dune to the sea. 1 km from the French-Belgian border, we identify a large discharge zone 
located approximately at the low water line. This discharge zone can be followed laterally; it 
shifts seaward towards the French-Belgian border where it is located below the low water line. 
Our study is the first successful combination of EM, land and marine ERT to detect freshwater 
discharge in the intertidal and near-shore zone. Further field campaigns are planned to identify 
other areas of SFGD along the coast and to characterize SGD further (geochemistry, quantity…). 
 
Keywords: Submarine groundwater discharge; Geophysics; ERT; EM  
 
 
  


Using multiple geophysical methods for the assessment of submarine groundwater discharge in the western Belgian coastal area

Van Nieuwenhove, A.H.

Ratsimbazafy, H.

Kochzius, M.

28 
Oral presentation Pre-doc level 
Cryptic diversity and limited connectivity in two commercially important 
octopus species  
Van Nieuwenhove Annelore Hilde, Ratsimbazafy Hajaniaina and Kochzius Marc 
Vrije Universiteit Brussel (VUB), Ecology and Biodiversity, Marine Biology, Pleinlaan 2, 1050 
Brussels, Belgium 
E-mail: annelore18.vn@gmail.com    
 
Due to the increasing global market demand for cephalopods many traditional octopus fisheries 
in the Indian Ocean have expanded very fast in the past decades while shifting their focus from 
local and inland markets to international export. Just as in other regions worldwide, landings of 
these octopus fisheries are decreasing and concern over sustainability is raised. While octopus 
farming might be an option for the future, to date, octopus production relies completely on wild 
fisheries, with many communities having few alternatives to marine resource extraction. To 
maintain the sustainability of these socio-economic important fisheries, management actions 
must be taken, such as the establishment of Marine Protected Areas (MPAs). Connectivity among 
populations through larval dispersal is a crucial factor, which should be taken into account 
when designing MPA networks, since it influences population genetic structure, as well as the 
ability to persist and recover from stressors, like overfishing. In order to obtain baseline data 
for management plans, the present study investigated (1) diversity of Octopodidae in the 
Western Indian Ocean (WIO) and (2) connectivity and genetic structure among populations of 
two commercially important species: Octopus cyanea and O. vulgaris. 
  
Arm tips of 275 octopus individuals were collected on landing sites and markets, at 15 different 
sites in Madagascar, Tanzania and Kenya. DNA was extracted and a fragment of the 
mitochondrial cytochrome C oxidase subunit 1 (COI) gene was amplified and sequenced. In 
addition, 41 COI sequences of O. vulgaris from South Africa, Brazil, Amsterdam Island, Tristan da 
Cunha, Senegal and Galicia were retrieved from online databases to be included in this study. 
  
DNA barcoding revealed the presence of five different species in our collected tissue samples 
from the WIO, with first records for Octopus oliveri and Callistoctopus luteus in this part of the 
Indian Ocean. For O. cyanea (n = 229, 563 bp), 22 haplotypes were found, forming a single 
haplogroup, with one dominant haplotype present at all sites. Analysis of molecular variance 
(AMOVA) revealed a shallow but significant genetic population structure among all sites (φST = 
0.025, p = 0.02), with signiﬁcant differentiation among: (1) Kanamai (Kenya), (2) southern Kenya, 
Tanzania, North and West Madagascar, (3) Southwest Madagascar and (4) East Madagascar (φCT = 
0.035, p = 0.017). For O. vulgaris (n = 71, 482 bp), 15 haplotypes were identified, forming three 
haplogroups. A significant genetic population structure was found among all sites (φST = 0.82, p ≤ 
0.01). Based on pairwise φST-values and hierarchical AMOVAs, populations of O. vulgaris could be 
grouped as follows: (1) Brazil, (2) Madagascar and (3) all other sites. A signiﬁcant increase in 
genetic distance with increasing geographic distance was found (Z = 232443,81 r = 0.36, p = 
0.039). These results indicate that for O. cyanea four regions should be considered as separate 
management units in the WIO. The very divergent haplogroups in O. vulgaris from Brazil and 
Madagascar might be evolving towards speciation and therefore should be considered as 
separate species in FAO statistics. 
 
Keywords: Marine Protected Area; population genetics; Gene flow; Mitochondrial DNA; COI 
  


Cryptic diversity and limited connectivity in two commercially important octopus species

Knockaert, C.

Tyberghein, L.

Goffin, A.

Vanhaecke, D.

Ong’anda, H.

Wakwabi, O.

Mees, J.

119 
Poster presentation Competition poster 
Data archeology in the framework of a long-term Kenya Belgium 
Cooperation  
Knockaert Carolien1, Tyberghein Lennert1, Goffin Annelies1, Vanhaecke Delphine1, Ong’anda 
Harrison2, Wakwabi Enock2 and Mees Jan1 
1  Flanders Marine Institute (VLIZ), InnovOcean site, Wandelaarkaai 7, 8400 Oostende, Belgium 
 E-mail: carolien.knockaert@vliz.be 
2  Kenya Marine and Fisheries Research Institute Mombasa Centre (KMFRI), P.O. Box 81651, 
80100 Mombasa, Kenya 
The “Kenya-Belgium Cooperation in Marine Sciences” or KBP was initially launched in 1985 as 
collaboration between the Free University of Brussels (VUB) and the Kenya Marine and Fisheries 
Research Institute (KMFRI) under the supervision of the late Prof. Dr. Philip Polk. In 2012, this 
long lasting collaboration resulted in a formal “Memorandum of Understanding” (MoU) between 
the Flanders Marine Institute (VLIZ) and the Kenya Marine and Fisheries Research Institute 
(KMFRI). This MoU aims to promote further partnership in the field of marine sciences between 
Belgium and Kenya (in a coordinated way). One of the activities within this MoU is the recovery 
of data resulting from marine research in Kenya. 
 
The Kenya-Belgium data collection currently includes about 111,800 biotic observations on 
benthos, algae, fish, zooplankton, phytoplankton, birds and mangroves which cover more than 
400 unique locations that were sampled between 1873 and 1999. The dataset provides a better 
insight into the different types of research conducted between 1985 and 1996 in framework of 
the “Kenya-Belgium Cooperation in Marine Sciences (KBP)” and can facilitate further coastal 
biodiversity research in Kenya. 
 
The Kenya-Belgium data collection is online available through the LifeWatch portal 
(http://www.lifewatch.be/en/marine-data-archeology) and can be assessed through the 
Integrated Marine Information System hosted at VLIZ. 
 
http://www.vliz.be/en/imis?module=dataset&dasid=5821  
 
Keywords: Data archeology; Kenya; Marine; Historical datasets; Biodiversity  


Data archeology in the framework of a long-term Kenya Belgium Cooperation

van de Velde, S.

10 
Oral presentation North Sea Award 2018 
Electron shuttling and elemental cycling in the seafloor  
van de Velde Sebastiaan1,2,3 
1 Department of Chemistry, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Elsene, Belgium 
E-mail: sebastiv@ucr.edu  
2  Department of Biology, Universiteit Antwerpen, Campus Drie Eiken, Universiteitsplein 1, 2610 
Wilrijk, België  
3  Department of Earth Sciences, University of California, Geology Building, 900 University 
Avenue, Riverside, CA 92521, USA 
 
The seafloor (or marine sediment) is an invaluable part for the cycles of chemical elements 
(carbon, nitrogen, sulphur) through planet earth. For example, more than half of the reactive 
nitrogen (e.g. ammonium) is converted to unreactive N2-gas in the sediment. The seafloor is 
also an efficient reactor that recycles 90% of the sulphur and carbon it receives, back to the 
water column. The settling of organic carbon, which is a reduced compound (i.e. rich in 
negatively charged electrons), starts a complex series of redox-reactions (oxidation of organic 
carbon coupled to the reduction of, e.g., oxygen). The transformations that occur when chemical 
species pass through the upper 10 – 100 cm of the seafloor (also called ‘early diagenesis’), 
determines which elements and what fractions are either stored in the deep mantle or are 
recycled back to the ocean and atmosphere. Redox transformations are strongly affected by the 
presence or absence of micro- and macro-organisms. Biological activity by small critters or 
certain types of micro-organisms can have a large effect on geochemical cycling within the 
seafloor. During my PhD project, I investigated the impact of two types of ecosystem engineers 
on the biogeochemical cycling of carbon, iron, sulphur and associated trace elements in the 
seafloor: Long filamentous micro-organisms (cable bacteria) and large macro-fauna 
(bioturbators). Both ecosystem engineers stimulate the recycling of carbon, sulphur and iron. 
Cable bacteria do this by acidifying the top few centimetres of the sediment, and bioturbators 
by enhancing the transport of solid particles and dissolved substances in the sediment. 
 
A field study in the coastal North Sea showed that the acidic environment generated by cable 
bacteria in the upper 5 cm of the sediment promotes the dissolution of acid sensitive minerals 
like FeS and CaCO3. The dissolution of these minerals releases iron and related trace metals 
(manganese, cobalt, arsenic) in the pore water. A fraction of these elements re-precipitates at 
the oxygen-rich sediment-water interface. However, under fluctuating oxygen concentrations 
(from fully oxygenated to oxygen depleted), cable bacteria actually amplify the seasonal cycle of 
arsenic release from the sediment, as revealed by a study in Lake Grevelingen. Animals that 
inhabit the seafloor stimulate the transport of solid particles by their burrowing activity (bio-
mixing) and enhance the exchange of dissolved species between the pore water of the sediment 
and the overlying water column by the flushing of their burrows (bio-irrigation). A field study in 
the Blakeney salt marsh (Norwich, UK) showed how bioturbation actually limits the burial of 
organic carbon and reduced iron-sulphide and diagenetic modelling reveals that the 
geochemical effects are already noticeable at very low bioturbation activity. Implementing these 
results in a long-term model, showed that the evolution of burrowing could have induced a low-
oxygen atmosphere in the past and might have triggered global warming by increasing 
atmospheric CO2 during the Cambrian explosion (when multicellular life developed in the 
ocean, ~500 million years ago). Finally, field data following a human-induced sediment mixing 
event (which is essentially equivalent to human bioturbation) from the Belgian Coastal Zone 
suggests that bottom trawl fishing and dredging also limits organic carbon burial, and provides 
a clear illustration of how human activity can inadvertently change the coastal carbon cycle. 
 
Keywords: Electron shuttling; Elemental cycling 
  


Electron shuttling and elemental cycling in the seafl­oor

Vlaminck, E.

Voet, H.

Vanaverbeke, J.

Degraer, S.

Moens, T.

Cattrijsse, A.

Soetaert, K.

Van Colen, C.

154 
Poster presentation Competition poster 
Experimental approach towards the understanding of food web 
interactions in an offshore wind farm environment under different 
climate and aquaculture scenarios  
Vlaminck Ellen1, Voet Helena2, Vanaverbeke Jan2, Degraer Steven2, Moens Tom1, Cattrijsse Andre3, 
Soetaert Karline4 and Van Colen Carl1 
1 Universiteit Gent, Onderzoeksgroep Mariene Biologie (UGent-MARBIOL), Campus De Sterre, 
s8, Krijgslaan 281, 9000 Gent, Belgium 
 E-mail: evlaminc.vlaminck@ugent.be 
2 Koninklijk Belgisch Instituut voor Natuurwetenschappen: Operationele Directie Natuurlijk 
Milieu (IRScNB/KBIN-OD Natuur), Vautierstraat 29, 1000 Brussel, Belgium 
3  Flanders Marine Institute (VLIZ), InnovOcean site, Wandelaarkaai 7, 8400 Oostende, Belgium 
4  Koninklijk Nederlands Instituut voor Onderzoek der Zee: Estuarine and Delta Systems (NIOZ-
EDS), Korringaweg 7, Postbus 140, 4400 AC Yerseke, The Netherlands 
 
Coastal areas are under an increasing pressure originating both from local and global sources. 
On a local scale, the pressures are often induced by a local human activity. The installation of 
offshore wind farms (OWFs) in the Belgian part of the North Sea (BPNS) results in a large change 
in the marine environment. The introduced artificial hard substrates (AHSs) are rapidly 
colonised by large quantities of fouling fauna, which are expected to modify the local food web 
by introducing new trophic links. Modifications of this local food web will possibly affect the 
stability and resilience of the trophic network. The planned aquaculture activities within the 
wind farms will further increase change in the local food web by affecting both trophic-and non-
trophic links. In addition to these local changes, coastal ecosystems are also challenged by 
global climate change stressors, such as ocean warming and acidification.   
 
The aim of the PERSUADE (ExPERimental approaches towards Future Sustainable Use of North 
Sea Artificial HarD SubstratEs) project is to investigate ecosystem-wide responses to combined 
global and local stressors by quantifying interactions between biotic and abiotic compartments 
in the OWF environment. To this end, a large-scale mesocosm experiment was conducted, using 
the EMBRC tank facilities at VLIZ (Ostend). Both fouling fauna harvested from an artificial hard 
substrate garden and the sediment community collected in the vicinity of OWFs were incubated 
in the mesocosms, together with area-typical mobile predators, under three conditions: (1) a 
“control” treatment reflecting the current situation, (2) a “Climate Change” treatment with an 
elevated temperature and lowered pH according to the IPCC 2100 scenario, and (3) a “Climate 
Change + Aquaculture” treatment reflecting the scenario where blue mussel aquaculture takes 
place within an OWF under a future climate setting.  
 
The carbon flow through the three experimental food webs was quantified by means of a pulse-
chase experiment and bio-deposition of organic matter by the fouling fauna on the benthic 
community was determined using sediment traps. By investigating the carbon flow through the 
food web, an understanding of the effect of global and local stressors on the coastal carbon 
budget will be obtained.  
 
Keywords: Climate change; Aquaculture; Food webs; Wind farm; North Sea; Biodiversity-
Ecosystem functioning 
  


Experimental approach towards the understanding of food web interactions in an offshore wind farm environment under different climate and aquaculture scenarios

Ponsar, S.

Van den Eynde, D.

131 
Poster presentation Competition poster 
Impact of climate change on storm surges and wave heights on the 
Belgian Coastal Zone 
Ponsar Stéphanie and Van den Eynde Dries 
Royal Belgian Institute of Natural Sciences (RBINS), Rue Vautier 29 1000 Bruxelles, Belgium  
E-mail: stephanie.ponsar@naturalsciences.be  
 
In the framework of the CREST project, the RBINS aims at quantifying the impacts of climate 
change on the Belgian Coastal Zone both for physical parameters and sediment transport. 
Results of eight regional climate models were analyzed and were used to force a hydrodynamic 
model and a wave model. Two regional climate model simulations were prepared in the 
framework of the CORDEX.be project, i.e. simulation from the Royal Meteorological Institute and 
the Catholic University of Leuven while atmospheric forcings from six other regional models 
were obtained for an evaluation run for the period 1980-2010, a historical run (1976-2005) and 
for a climate run based on the IPCC RCP 8.5 scenario for the period 2070-2100. 
  
To interpret the estimated impacts of climate change, an analysis of the wind forcing is firstly 
presented. Changes in wind speed and direction between historical and RCP 8.5-time series are 
assessed by computing the wind density function. To estimate the changes in storm surges and 
wave heights, a statistical analysis has been carried out at stations located along the Belgian 
Coast. The bias in the model results is corrected by applying the quantile mapping method. 
  
Results for wave heights indicate a possible increase of about 20cm for return periods of 20, 50, 
100 and 200 years at Bol van Heist. Concerning the storm surges at Ostend, the expected 
increase varies from 20 cm for return periods of 20 years up to 40 cm for return periods of 200 
years. These changes are interpreted in terms of wind changes and are in good agreement with 
expected changes in wind speed and direction at these locations. 
  
Keywords: Climate change; Numerical modelling; Statistical analysis  


Impact of climate change on storm surges and wave heights on the Belgian Coastal Zone.

Everaert, G.

Van Cauwenberghe, L.

De Rijcke, M.

Koelmans, A.

Vandegehuchte, M.

Janssen, C.R.

108 
Poster presentation Competition poster 
Risk assessment of microplastics in the ocean   
Everaert Gert1, Van Cauwenberghe Lisbeth2, De Rijcke Maarten1, Koelmans Albert3, Mees Jan1, 
Vandegehuchte Michiel1 and Janssen Colin2 
1  Flanders Marine Institute (VLIZ), InnovOcean site, Wandelaarkaai 7, 8400 Oostende, Belgium 
 E-mail: gert.everaert@vliz.be 
2  Universiteit Gent, Laboratorium voor Milieutoxicologie en Aquatische Ecologie (UGent-
GhEnToxLab), Coupure Links 653, 9000 Gent, Belgium 
3  Wageningen University, Aquatic Ecology and Water Quality Management Group, P.O. Box 
8080, 6700 DD, Wageningen, The Netherlands 
 
The presence of microplastics in the marine environment has been an issue of concern for over 
a decade now, but their environmental risk in the ocean have, to date, not been addressed and 
quantified. The environmental risk assessment of microplastics presented here quantifies, 
based on a regulatory framework for assessing environmental risks of pollutants (i.e. REACH), 
safe concentrations for the marine pelagic and marine benthic compartment. Above these safe 
concentrations adverse biological effects are likely to occur. At most locations, the in 
situconcentrations in the upper pelagic compartment remain below the safe concentration 
(6650 particles m-3). However, local exceedances of this threshold are already taking place in 
sites that are heavily polluted with buoyant microplastics. In addition to the pelagic phase, also 
inshore, harbour and beach sediments are of concern. As human populations continue to grow, 
and if our dependence on plastic does not change under a business as usual approach, we may 
expect a steady and substantial increase in microplastic concentrations in both the pelagic and 
benthic marine environment. Adverse effects of microplastics are to be expected on highly 
polluted beaches and in coastal ecosystems as of the second half of this century if plastics 
emissions are not reduced. 
  
Infographic: http://www.vliz.be/imisdocs/publications/319070.pdf  
 
Keywords: Microplastics; Ecological effect; Ambient concentrations; Simulations  


Risk assessment of microplastics in the ocean 

Missiaen, T.

Hablützel, P.I.

Lambert, O.

Germonpre, M.

Langeveld, B.

124 
Poster presentation Competition poster 
The Scheur: A unique prehistoric fossil graveyard off the Belgian coast  
Missiaen Tine1, Hablutzel Pascal1, De Rijcke Maarten1, Lambert Olivier2, Germonpre Mietje2 and 
Langeveld Bram3 
1  Flanders Marine Institute (VLIZ), InnovOcean site, Wandelaarkaai 7, 8400 Oostende, Belgium 
 E-mail: tine.missiaen@vliz.be 
2  Koninklijk Belgisch Instituut voor Natuurwetenschappen (IRScNB/KBIN), Vautierstraat 29, 
1000 Brussel, Belgium 
3  Natuurhistorisch Museum Rotterdam, Westzeedijk 345 (Museumpark), 3015 AA Rotterdam, The 
Netherlands  
 
Over the past few decades Dutch fishermen have dredged up large amounts of unique 
prehistoric palaeontological material at the Scheur, a navigation channel northeast of the 
harbour of Zeebrugge. Especially the large number of walrus bones from the last ice age 
(116,000-12,000 years ago) is striking. The excellent state of the bones and the find of both 
males, females and young animals indicate that a large colony must have lived here, possibly 
the most southern walrus colony in the world. In the same area also a number of vertebrae from 
ancient whales were dredged up, dating from the Middle Eocene (roughly 43 million years ago). 
Remains of these primitive marine mammals are very rare in NW Europe (only three known sites 
in the North Sea). The unusual size of the vertebrae (width c. 30 cm) could suggest a hitherto 
undiscovered species of the family Protocetidae. 
 
Two targeted surveys in 2017 and 2018 produced additional finds of Late Pleistocene land 
mammals, related to interglacial fauna (wild horse, aurochs, red deer, roe deer, rhinoceros, boar 
and hippo) as well as glacial fauna (brown bear; wild horse; red deer). All the bone material is 
most likely preserved in situ, derived from layers exposed at the seafloor. Due to maintenance 
dredging of the navigation channel 10 to 12 m of sediments were removed, thereby exposing 
older Late Pleistocene and even Paleogene strata. Determination and dating of the fossils are 
currently ongoing, including the screening for ancient DNA. Radiocarbon analysis of the walrus 
bone is ambiguous (the method only goes up to 40,000 years), and palaeogeographic 
reconstructions suggest that the bone material predates the last ice age. Further planned 
research of the site includes the acquisition of shallow sediment cores and dating based on 
shell residue and other indicators for climate (e.g. pollen, diatoms, dinoflagellates). Combined 
with acoustic subbottom data this should allow to reconstruct the evolution of the 
palaeolandscape at the site. 
 
Keywords: Scheur; Fossil bones; Palaeolandscape 
  


The Scheur: A unique prehistoric fossil graveyard off the Belgian coast

Mollen, F.H.

Making Louis Agassiz’s wish come true: combining forces and a new protocol for collecting comparative skeletal material of sharks, skates and rays, as a comment and an addition to ‘The need of providing tooth morphology in descriptions of extant elasmobranch species’ by Guinot et al. (2018)

Flanders Marine Institute

Not a member yet