EPIBENGOL 2018

Name: EPIBENGOL 2018
Start: 2018-09-13
End: 2018-09-19
Location: Mediterranean Sea, Western Basin

Type	Oceanographic cruise
Ship	L'Europe
Ship owner	Ifremer
Dates	13/09/2018 - 19/09/2018
Chief scientist(s)	VAZ Sandrine
	IFREMER STATION DE SETE Bd Jean Monnet BP 171 34203 SETE CEDEX +33(0)4 99 57 32 00 https://mediterranee.ifremer.fr/implantations/Sete
DOI	10.17600/18000589
Objective	Among the recommendations of the DCSMM monitoring program, it is necessary to describe the marine habitats and distribution of the main macrobenthic species, to characterize the effects of anthropogenic pressures, or to assess the ability of benthic ecosystems to adapt to human-induced disturbances. On the continental shelf, dragging arts fishing (trawl and dredges) being the source of major bottom disturbance, this research study focuses on the evaluation of the latter. Two sectors will be considered: the Channel and the Gulf of Lion, with very contrasting hydrodynamic and sedimentary regimes. Since the two sectors considered are subject to high trolling arts fishing pressure, the objectives of this project are to assess the impact of trolling arts fishing activities in various hydrodynamic and sedimentary contexts by: 1) determining how best to monitor the status of benthic habitats on the continental shelf; 2) identifying the best indicator species for fishing effort; 3) verifying whether the effects of fishing can be masked by hydrodynamics depending on the habitats considered. The data used, exclusively from trawlable areas, will combine for the biological compartment faunal compositions from skips, dredges, scientific trawling or image analysis. They will also provide information on the sediment types actually encountered (photos, videos or samples). Currently, in the Channel, 104 video dives matched to as many bottom trawls (GOVs) obtained simultaneously are available, 54 of which also have associated dredging data (Rally du Baty dredger). In the Mediterranean, 40 video dives matched to as many bottom trawling (GOC) are also available but these data were collected between 2 and 3 months apart. In addition, they are not coupled with benthic sampling with a bucket or dredger. While, in both cases, the observations already available cover the entire area and its sedimentary, bathymetric and fishing effort gradients observable in situ, additional data remain to be acquired in the Mediterranean. This is the objective of the EPIBENGOL campaign, which aims to complete these observations in the Gulf of Lions, in order to acquire a complete dataset combining simultaneous trawling and video-submarine and adding dredging samples at additional stations.

Sea/Ocean

Mediterranean Sea, Western Basin

(Gulf of Lion)

Ports

Port of departure : Sète (France)

Port of return : Sète (France)

Limits

North	South	West	East
43.5	42.5	3.0	5.0

Scientific Authority

IFREMER STATION DE SETE

Bd Jean Monnet

BP 171

34203 SETE CEDEX

+33(0)4 99 57 32 00

https://mediterranee.ifremer.fr/implantations/Sete

Participating bodie(s)

CNRS

Discipline(s)

PHYSICAL OCEANOGRAPHY
BIOLOGICAL OCEANOGRAPHY
ENVIRONMENT
FISHERIES

Code	Label	Quantity	PI
B01	Primary productivity fluorimeter vertical profiles + pocket ferry box	10 stations	VAZ Sandrine
B02	Phytoplankton pigments (eg chloroph Pocket ferry box	10 stations	VAZ Sandrine
B14	Pelagic fish Trawl catches	10 hauls	JADAUD Angélique
B18	Zoobenthos Trawl catches: megafaunal invertebrates	10 hauls	METRAL Luisa
B19	Demersal fish Trawl catches	10 hauls	JADAUD Angélique
B20	Molluscs Trawl catches	10 hauls	METRAL Luisa
B21	Crustaceans Trawl catches	10 hauls	METRAL Luisa
D90	Other physical oceanographic meas.	-	VAZ Sandrine
G01	Dredge Macrofauna and sediment	30 samples	DESROY Nicolas
G08	Bottom photography HD stills and videos of benthic habitats	10 dives	VAZ Sandrine
G73	Single-beam echosounding	-	VAZ Sandrine
H10	CTD stations	10 stations	VAZ Sandrine
H16	Transparency (eg transmissometer) Vertical profiles and pocket ferry box	10 stations	VAZ Sandrine
H17	Optics (eg underwater light levels)	10 stations	VAZ Sandrine
H21	Oxygen	10 stations	VAZ Sandrine
H28	pH Vertical profiles and pocket ferry box	10 stations	VAZ Sandrine
H71	Surface measurements underway (T,S) On board SBE probe	5 days	VAZ Sandrine
M06	Routine standard measurements	-	VAZ Sandrine

Positionning system

Geodetic system : WORLD GEODETIC SYSTEM 1984 = WGS84

Positioning system : GPS différentiel

Scientific context

Main results

1) Detecting the harmful effects on the integrity of the seabed

The benthic fauna of Europe's continental shelves is a community seriously affected by intense bottom trawling activity. The effect of trawling can depend on the spatial and temporal distribution of abrasion, the type of habitat, including the intensity of natural disturbance, and the fishing gear used, and there is an urgent need to identify or develop indices that can measure the impact of trawling. To this end, benthic fauna data obtained in scientific bottom trawl surveys covering the English Channel, the North Sea and the north-western Mediterranean were used and compared with the intensity of abrasion induced by fishing on the seabed. Fifteen indices were analysed: taxonomic diversity metrics, functional diversity indices and functional indices, the last two being based on traits of sensitivity to physical abrasion. Their properties, such as their ability to detect trawling, their statistical behaviour or their capacity to provide information on community structure, were studied. Among them, four indices specific to the detection of the effects of fishing based on biological traits seemed to be the best performing benthic indices in relation to these requirements: trawl disturbance index (TDI), modified trawl disturbance index (mTDI), partial trawl disturbance index (pTDI), modified sensitivity index (mT). Maps of the seabed sensitivity distribution captured by each of these four indices were produced. This work has highlighted the need to use specific indices to monitor the impact of trawling on benthic communities, but also that the use of different indices may be necessary to carry out this monitoring in all European waters.

Spatial distribution of benthic sensitivity to trawling in the Gulf of Lion (MEDITS, EPIBENGOL)

The impacts of trawling depend on the spatial and temporal distribution of fishing effort, fishing gear, the intensity of natural disturbances and habitat types. Thus, for each indicator, threshold values need to be defined and a new conceptual approach for defining and detecting seabed integrity thresholds has been proposed. A modelling approach was used to determine abrasion threshold values for each habitat (EUNIS habitat map). The values beyond which trawling has an adverse effect on benthic communities were determined for each habitat. This enabled the ecological status of each habitat to be assessed and mapped, and the percentage of each habitat impacted by trawling to be determined. The method proposed here to assess the impact of trawling on benthic communities has shown that for the vast majority of the regions studied, these communities have suffered a negative impact or have been lost as a result of the intensity of trawling on the seabed.

Schematic relationship between an index, the intensity of a given pressure and the corresponding ecological status.

Ecological state of benthic habitats in relation to bottom trawling

2) Disentangling the impact of trawling from natural variability on benthic communities

Various environmental parameters such as temperature, depth and currents influence the composition and distribution of benthic assemblages. However, the impact of trawling on benthic communities depends on their specific composition, since not all benthic species are equally sensitive to trawling. In addition, trawling can have effects on benthic species similar to certain natural disturbances, such as a local increase in turbidity. Species adapted to these natural disturbances may be resistant to a certain level of trawling. It was therefore important to assess the joint influence of the environment and trawling pressure on the sensitivity of benthic communities in the English Channel, the Gulf of Lion and the east coast of Corsica. The environmental parameters were divided into two groups according to the type of influence they have on the benthic community. The first group of variables, used to model 'Scope for Growth' (SfG), concerns the resilience of species, while the second, 'Disturbance' (Dist), concerns their resistance to physical impacts. This work has shown that the distribution of benthic species in the Channel is mainly linked to physical disturbance and therefore to their resistance, whereas it is mainly parameters linked to the resilience of communities that influence the distribution of benthic fauna in the Mediterranean. The effect of abrasion could be distinguished from natural environmental disturbances in the Channel and the Gulf of Lion, where trawling was found to have a significant effect on functional sensitivity indices. The composition and distribution of benthic communities in Corsica do not appear to be influenced by trawling pressure.

3) Assessment of the impact of trawling on the seabed using video-submarine photography

Because of its non-destructive nature and its ability to focus on benthic macro-epifauna, sampling using a towed video system should also be considered to estimate the impact of trawling on benthic communities.

PAGURE towed video sled on the EPIBENGOL survey

Example of organisms detected and counted by video (here a facies with Leptometra phalangium during the EPIBENGOL survey)

A study of the taxonomic and functional differences between the communities sampled by trawl and by video was therefore carried out. The influence of the characteristics of the video system (e.g. image quality) and abrasion on nine indices that could be used to monitor the effect of trawling on benthic communities was studied. Of these, three specific indices for detecting the effects of fishing based on biological characteristics were found to be the most effective with video data: the modified Trawling Disturbance Index (mTDI), the partial Trawling Disturbance Index (pTDI) and the modified sensitivity index (mT).

Relationship between trawl abrasion and the pTDI index. This relationship is negative and significant for all the habitat types observed (black line and dotted 95% confidence interval).

The effectiveness of these indices in monitoring the effect of trawling was evaluated and compared between data from scientific trawling and video sampling. This work has shown that video sampling can be a good alternative, or at least a complementary method, to destructive sampling methods for monitoring the effect of trawling on benthic communities.

4) Benthic sensitivity to bottom trawling in the French Mediterranean

The benthic habitats of the Mediterranean continental shelf have been subjected to high-intensity bottom trawling for decades. This has led to an erosion of benthic biodiversity and a degradation of seabed conditions. The ICES Working Group on Benthic Impact of Fisheries and Trade-offs (WGFBIT) has developed an evaluation framework, based on a life history trait, longevity, to assess the benthic impact of fisheries on a regional scale. This framework has been applied to the French Mediterranean.

Initially, Mediterranean databases on the longevity of benthic fauna were aggregated and a single database based on fuzzy coding of longevity classes was developed. It was then applied to benthic invertebrate by-catch data from French scientific bottom trawling surveys, including the EPIBENGOL data set. This database therefore made it possible to associate existing data on benthic biomass with the different classes of potential longevity of the species caught.

Map of the French EEZ illustrating the major habitat types of the MSFD and the survey data (here 2018) mobilised.

For each major habitat type (coastal circalittoral sand and mud, offshore circalittoral mud, bathyal sediment), a multinomial GLMM was fitted, linking biomass by longevity class to environmental predictors. This model was then used to predict the mean value of benthic community longevity under reference conditions as an indicator of benthic sensitivity. We predicted more sensitive habitats in the upper and lower bathyal sediments, and less sensitive habitats in the shallower muddy sediments.

Median predicted longevity for the French Mediterranean (combining four different habitats).

Finally, the predicted longevity curve parameters were used to estimate local carrying capacity and benthic vulnerability (expressed as relative benthic status) based on known fixed depletion rates, observed biomass and abrasion rate. In line with previous studies, our estimate of relative benthic condition suggests heavily impacted areas close to the coast in the Gulf of Lion, and less impacted habitats around Corsica.

Relative benthic status for the French Mediterranean (combining four different habitats). The scale goes from 0 = poor state to 1 = good state.

Data acquired and analyses carried out at sea and on shore

A total of 10 benthic video profiles were acquired and the image data was converted to a standard format during the survey and sent to SISMER for archiving on return to shore (https://video.ifremer.fr/). The videos were analysed using image analysis software (AviNotes). They were used to obtain density data for each taxon and to qualify the nature of the surface sediments. They were then used to calculate sensitivity and vulnerability indicators as part of a thesis and research work on quantifying the impact of trawling.

Deployment of the PAGURE underwater video sled on EPIBENGOL

After each video dive, 3 one-minute tripliquas at 1.5 knots were carried out using the Ralier Bathy dredge (for a total of 30 samples over the entire survey). A 10L sub-sample of the sediment taken was sieved through a 1mm mesh to focus only on the macro-fauna. The reflux was fixed in 4% formalin and then preserved in 70% alcohol after the organisms had been sorted. This sorting and the detailed faunal analysis were carried out on land, providing densities (nbr/10L) for each species. A sediment sample was also kept for sediment analysis on land. These data were used to calculate sensitivity and vulnerability indicators as part of a thesis.

Deployment of the Ralier du Bathy dredge on EPIBENGOL

Following the video dives and dredging, ten 30-minute trawl samples were validated. The scientific trawl catch data (bottom trawl with doors and deployment protocol standardised at international level, MEDITS) were acquired at sea. Although the initial objective of the survey only concerned benthic invertebrates, all the species caught were taken into account. Biological observations were made using the MEDITS protocol. All the species collected, including mega-benthos, were sorted, weighed and counted. In order to minimise the mortality of the most sensitive species (particularly sharks and rays), they were kept alive and then released as soon as possible. All captured species (vertebrates and invertebrates) were fully sorted and identified, and certain species of commercial fish or invertebrates (cephalopods, crustaceans) were also measured for size. Marine litter of anthropogenic origin was also monitored, as were species of gelatinous macro-zooplankton (jellyfish, salps, etc.), these two compartments also being the subject of studies and monitoring under the MFSD. All the catch data was collected in the data entry software used by Ifremer. By the end of the survey, almost all the trawl catch data had been digitised and was available for analysis. These data, coupled with the areas trawled, were used to determine the biomass (g/km²) and density (nbr/km²) of the benthic invertebrates encountered. These data were then used to calculate sensitivity and vulnerability indicators as part of a thesis and research work on quantifying the impact of trawling.

Sorting of trawl catches (here dominated by Leptometra phalangium) on EPIBENGOL

Alongside these catches, a multi-parameter probe was deployed to acquire environmental data associated with the catches and over the entire water column. A vertical profile of temperature, salinity, dissolved oxygen, fluorescence, turbidity and pH was obtained at each trawl. In addition, a Pocket Ferry Box was used en route to obtain information on surface temperature, salinity, dissolved oxygen, fluorescence, turbidity and pH, as well as monitoring the signature of the fluorescence spectrum. The latter should eventually enable a better discrimination between the main functional groups of phytoplankton. All this environmental data has been validated and sent to SISMER where it is available to the scientific community.

Published data

Vaz Sandrine, Laffargue Pascal, Pelletier Dominique, Jac Cyrielle (2023). PAGURE example dataset from data acquisition to the computation of Essential Biodiversity Variables and Essential Ocean Variables. https://doi.org/10.17882/97472

Hazevis Gaëtan, Baudrier Jerome, Vaz Sandrine (2019). Minimum level of taxonomic identification of benthic invertebrates by-catches on Ifremer's fisheries vessel. https://doi.org/10.17882/62260

Data managed by SISMER

Dives

Bibliography

Publications

Millot Jade, Georges Vincent, Lauria Valentina, Hattab Tarek, Dominguez-Carrió Carlos, Gerovasileiou Vasilis, Smith Christopher J., Mytilineou Chryssi, Teresa Farriols M., Fabri Marie-Claire , Carbonara Pierluigi, Massi Daniela, Rinelli Paola, Profeta Adriana, Chimienti Giovanni, Jadaud Angelique , Thasitis Ioannis, Camilleri Kelly, Mifsud Jurgen, Vaz Sandrine (2024). Habitat shifts of the vulnerable crinoid Leptometra phalangium under climate change scenarios. Progress In Oceanography, 229, 103355 (16p.). https://doi.org/10.1016/j.pocean.2024.103355

ICES (2023). Working Group on Fisheries Benthic Impact and Trade-offs (WGFBIT; outputs from 2022 meeting). ICES Scientific Reports/Rapports scientifiques du CIEM, 5(16), 106pp. Publisher's official version : https://doi.org/10.17895/ices.pub.22123193 , Open Access version : https://archimer.ifremer.fr/doc/00822/93400/

Jac Cyrielle, Desroy Nicolas , Foveau Aurélie , Vaz Sandrine (2022). Disentangling trawling impact from natural variability on benthic communities. Continental Shelf Research, 247, 104828 (17p.). Publisher's official version : https://doi.org/10.1016/j.csr.2022.104828 , Open Access version : https://archimer.ifremer.fr/doc/00791/90279/

Jac Cyrielle, Desroy Nicolas , Duchêne Jean-Claude, Foveau Aurelie , Labrune Céline, Lescure Lyvia, Vaz Sandrine (2021). Assessing the impact of trawling on benthic megafauna: comparative study of video surveys vs. scientific trawling. Ices Journal Of Marine Science, 78(5), 1636-1649. Publisher's official version : https://doi.org/10.1093/icesjms/fsab033 , Open Access version : https://archimer.ifremer.fr/doc/00689/80143/

Elliott Sam, Deleys Noemie , Rivot E, Acou A, Réveillac E, Beaulaton L (2021). Shedding light on the river and sea lamprey in western European marine waters. Endangered Species Research, 44, 409-419. Publisher's official version : https://doi.org/10.3354/esr01113 , Open Access version : https://archimer.ifremer.fr/doc/00691/80277/

Jac Cyrielle, Desroy Nicolas , Certain Gregoire, Foveau Aurelie , Labrune Céline, Vaz Sandrine (2020). Detecting adverse effect on seabed integrity. Part 2: How much of seabed habitats are left in good environmental status by fisheries? Ecological Indicators, 117, 106617 (13p.). Publisher's official version : https://doi.org/10.1016/j.ecolind.2020.106617 , Open Access version : https://archimer.ifremer.fr/doc/00634/74575/

Jac Cyrielle, Desroy Nicolas , Certain Gregoire, Foveau Aurelie , Labrune Céline, Vaz Sandrine (2020). Detecting adverse effect on seabed integrity. Part 1: Generic sensitivity indices to measure the effect of trawling on benthic mega-epifauna. Ecological Indicators, 117, 106631 (14p.). Publisher's official version : https://doi.org/10.1016/j.ecolind.2020.106631 , Open Access version : https://archimer.ifremer.fr/doc/00635/74693/

References of Technical Reports

Facq Jean-Valery, Vaz Sandrine , Laffargue Pascal , Carlier Antoine (2023). Outil PAGURE : Résultats et perspectives après 10 ans d’utilisation. PDG/REM/RDT/LHyMar 14LHYMARBL23. https://doi.org/10.13155/95331

Cuyvers Daan, Vaz Sandrine (2023). Seabed sensitivity to bottom trawling in the French Mediterranean. Application of ICES WGFBIT assessment framework. RBE/MARBEC/LHM. https://doi.org/10.13155/92506

Menot Lenaick , Georges Vincent, Fabri Marie-Claire , Vaz Sandrine (2022). Méthodologie pour le calcul des indicateurs de l’objectif environnemental D01-HB-OE10 visant à éviter l’abrasion et l’étouffement des zones les plus représentatives des habitats profonds et réduire l’abrasion des structures géomorphologiques particulières (2ème cycle de la DCSMM). REM/BEEP/LEP/2022.02. 44p. https://doi.org/10.13155/89168

Hazevis Gaëtan (2019). Harmonisation des suivis de la mégafaune invertébrée benthique sur les campagnes halieutiques de l’Ifremer. https://archimer.ifremer.fr/doc/00587/69920/

Thesis using campaign data

Jac Cyrielle (2020). Intégrité des habitats benthiques du plateau continental face aux perturbations physiques naturelles et aux arts trainants : quelles méthodes d'observations ? Comment suivre le retour vers un bon état écologique ? PhD Thesis, Université de Montpellier. https://archimer.ifremer.fr/doc/00679/79149/

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1	177	PAGURE2	20180914 11:09:4814/09/2018 11:09:48	43° 21.309' N 4° 19.168' E
2	178	PAGURE2	20180914 15:53:4114/09/2018 15:53:41	43° 16.014' N 4° 23.669' E
3	179	PAGURE2	20180915 06:39:1615/09/2018 06:39:16	43° 0.883' N 4° 0.821' E
4	180	PAGURE2	20180915 11:05:4015/09/2018 11:05:40	43° 2.007' N 3° 50.142' E
5	181	PAGURE2	20180916 06:27:4316/09/2018 06:27:43	43° 8.943' N 5° 2.020' E
6	182	PAGURE2	20180916 12:12:2216/09/2018 12:12:22	43° 3.509' N 4° 50.794' E
7	183	PAGURE2	20180917 06:27:2717/09/2018 06:27:27	42° 41.382' N 3° 35.885' E
8	184	PAGURE2	20180917 11:23:0117/09/2018 11:23:01	42° 50.380' N 3° 28.015' E
9	185	PAGURE2	20180918 06:47:3318/09/2018 06:47:33	42° 42.024' N 3° 14.889' E
10	186	PAGURE2	20180918 12:57:2818/09/2018 12:57:28	43° 12.242' N 3° 32.227' E