Scophthalmus Rhombus Research Articles

Living between sand and waves: Age and feeding habits of sand sole (Pegusa lascaris, Risso 1810) and brill (Scophthalmus rhombus, Linnaeus, 1758) on the beaches of the Gulf of Cádiz (Southwest Iberian Peninsula)

Within ecosystems that are used as nurseries, surf zones are crucial for many species due to the protection and sustenance these areas provide. Many commercially important species live in these zones during their early years, including the sand sole (Pegusa lascaris) and the brill (Scophthalmus rhombus). The objective of this study was to determine the age and feeding habits of individuals from both species living in the surf zone, as well as any potential variations with the environmental variables such as time of the day, lunar phases or season. The average size was 15.66 ± 3.71 cm (TL) for the sand sole and 11.49 ± 5.66 cm (TL) for the brill. The length-weight relationship for the sand sole was TW = 0.005*TL3.230 (parameter a: 95 % C.I.: 0.004–0.006 and parameter b: 95 % C.I.: 3.134–3.326), while for the brill it was TW = 0.013*TL3.048 (parameter a: 95 % C.I.: 0.012–0.016 and parameter b: 95 % C.I.: 2.988–3.108). In both the sand sole (92.4 %) and the brill (85.6 %), the most abundant age classes were 0+ and 1+, with significant differences in the abundance of age classes, depending on the season, in the case of the brill. The sand sole primarily feeds on cumaceans and bivalves, with significant variations in diet based on the time of the day, moon phases, and season, whereas the brill preys on mysids. This research provides new insights into how both species utilize the surf zone, using these areas as nurseries in their early years of life. This underscores the importance of these zones and the potential of the ecosystem services they offer.

On biomimetic surface texturing and its impact on turbulent flow and hydrodynamic forces acting on an early-stage bio-fouling organism

Recent marine anti-fouling research efforts have sought inspiration from bio-mimetic strategies to develop nontoxic solutions. Surface modifications have shown promising results in their ability to disrupt attachment and growth of early-stage organisms under static immersion conditions but very limited research has attempted to explore the interaction between surface textures and flow under turbulent conditions. The study presented in this article focuses on a simple texture, inspired by the growth rings of the Brill fish Scophthalmus rhombus and developed for applications on the blades of tidal stream turbine. A series of Large Eddy Simulations of fully developed turbulent channel flow were performed to assess the influence of the spacing between the texture elements on turbulent stresses. The aim is to characterize the impact of the texture on turbulent stresses by comparison to a smooth surface and identify whether shelters may form within the gaps between textures. The study clarifies the role of dispersive and Reynolds stresses in terms of their impact on hydrodynamic forces acting on a simplified model of a marine diatom. Reynolds shear stresses predominantly govern the intensity of forces, while dispersive shear stress affects the mean hydrodynamic forces acting on the organism at the early stage of settlement.

Disruption of diatom attachment on marine bioinspired antifouling materials based on Brill (Scophthalmus rhombus)

Bioinspired surfaces, due to their nano and micro topographical features, offer a promising approach for the development of novel antifouling solutions. The study of surface topography has gained popularity in recent years, demonstrating significant potential in mimicking natural structures that could be manufactured for application in the marine environment. This research focuses on investigating the antifouling (AF) performance of bio-inspired micro-textures inspired by Brill fish scales, Scophthalmus rhombus, under static laboratory conditions, using two common fouling diatom species, Amphora coffeaeformis and Nitzschia ovalis. In this study, we evaluate six engineered surfaces, inspired by Brill fish scales, fabricated through a 2-photon polymerization (2PP) process, for their potential as antifouling solutions. The investigation explores the settlement behaviour of microfouling organisms, comparing these mechanisms with theoretical models to guide the future design of antifouling materials. A key emphasis is placed on the impact of surface topography on the disruption of cellular response. Our results suggest that cells smaller than 10 μm, exceeding the peak-to-peak distances between surface features, comfortably position themselves between adjacent features. On the other hand, as peak-to-peak distances decrease, cells shift from settling within uniform gaps to resting on top of surface features. Surfaces with sharpened edges demonstrate a more substantial reduction in diatom attachments compared to those with rounded edges. Furthermore, all micro-textured surfaces exhibit a significant decrease in colony formation compared to control samples. In conclusion, this study shows the potential to manipulate cellular responses through topographical features, providing valuable insights for the design of effective antifouling materials. The results contribute to the growing body of knowledge in biomimetic antifouling strategies using a novel marine organism for inspiration to design practical structures that can be replicated.

Changes in catch efficiency and selectivity in the beam trawl fishery for sole when mechanical stimulation is replaced by electrical stimulation

Beam trawl fisheries for sole are characterised by large amounts of unwanted bycatch (i.e. discards) consisting of fish below the Minimum Conservation Reference Size, unwanted fish due to low commercial value or lack of quota, and benthic invertebrates. In order to reduce the quantity of discards, a substantial part of the Dutch beam trawl fleet was allowed to replace the conventional tickler chain beam trawl (BT) with the pulse trawl (PT) on an experimental basis. The PT used electrical stimulation to immobilise and capture fish. Here we study whether pulse trawling reduced the amount of discards by comparing catch rates of landings and discards of BT and PT in the period 2009–2018 for a wide range of species. The PT caught (kg.km-2) significantly more marketable sized sole (Solea solea, 48 %), turbot (Psetta maxima, 8 %), brill (Scophthalmus rhombus, 28 %) and whiting (Merlangius merlangus, 95 %), and significantly less marketable sized plaice (Pleuronectes platessa, −16 %), cod (Gadus morhua, −32 %) and gurnards (−12 %). No significant difference was found for dab (Limanda limanda), gadoids, or rays and sharks. Among discards, the PT caught more undersized sole (27 %) and whiting (42 %) but less undersized plaice (−21 %), dab (−19 %) and grey gurnard (Eutrigla gurnardus, −31 %). The observed differences in species selectivity are discussed in relation to the response of fish to bottom trawl gear and the effects of pulse stimulation. For the benthic invertebrates Ophiuroidae, bivalves and crabs the PT caught fewer individuals (between −38 % and −57 %). No significant difference was observed in sea urchins and sea stars. Overall, this study shows that the transition from the BT to PT resulted in a 36 % decrease (95 % prediction interval: 31–42 %) in discards (kg.hour-1).

First releases of hatchery-produced Senegal sole (Solea senegalensis), brill (Scophthalmus rhombus), and wedge sole (Dicologoglossa cuneata) juveniles in the South-western Spanish coast

The regression of fisheries in the Gulf of Cadiz is evident since current fish catches are 33% of that 30 years before. Consequently, some initiatives for the replenishment of exhausted wild stocks are welcome. The objective of the present work is to describe and analyse the results coming from the first flatfish stock enhancements in Andalusia. A total of 3189 fish from three flatfish species: Senegal sole (Solea senegalensis Kaup), wedge sole (Dicologlossa cuneata Moreau), and brill (Scophthalmus rhombus Linnaeus) were tagged and released. Several variables were calculated through the data analysis of recovered fish. Some variables were calculated only for Senegal soles since wedge sole and brill recaptures were not significant. The Senegal sole recapture rate was 2.71 ± 0.72, similar to other published data, the recapture rates for bigger fish being higher though not significant. No significant differences were detected for distance, time, growth, or recapture rate amongst initial Senegal sole sizes. Around 80% of recaptures were registered within 15 weeks after release. The results show that it is possible for the release and recovery of tagged Senegal soles in the Gulf of Cadiz. Future long-term programmes on stock enhancement could help to determine the effects on fisheries and recover stocks.

Three new records of fishes and their parasite fauna from Pomeranian Bay, Baltic Sea

This paper reports the occurrence of three new fish species, extremely rare in the Baltic Sea, and provides new data on their parasite fauna. The fish collected were Barbus barbus (Linnaeus, 1758), Salvelinus fontinalis (Mitchill, 1814), and Scophthalmus rhombus (Linnaeus, 1758). Their taxonomic identity was confirmed through genetic analyses using DNA extracted from fin clips. The stomach contents were examined, and age was determined by otolith or scale readings. Parasitological examinations focused on the skin, vitreous humour, eye lenses, mouth and nasal cavities, gills, gonads, viscera, and muscles. Furthermore, the changes of fish species composition over 20 years in Pomeranian Bay were analysed. The sequence comparisons against GenBank records revealed that sequences obtained for B. barbus and S. rhombus from Pomeranian Bay represent new rhodopsin barcodes. Record of the juvenile B. barbus in this study is the first in the Baltic Sea. Scophthalmus rhombus is a new host for the ciliate Trichodina jadranica, while Neogobius melanostomus (Pallas, 1814) is a new food item in the diet of S. rhombus in the Baltic Sea. Acanthocephalan Pomphorhynchus laevis found in the adult specimen of B. barbus and myxozoan Myxobolus musculi, noted in the juvenile specimen, have not been recorded previously in this fish species in Polish waters. Species collected as bycatch can potentially be used for monitoring potential changes in the overall fish community structure and biodiversity.

Species identification of two closely exploited flatfish, turbot (Scophthalmus maximus) and brill (Scophthalmus rhombus), using a ddRADseq genomic approach

Abstract Application of genomics tools for conservation purposes (i.e. conservation genomics) allows looking deep into the genetic structure and adaptations of populations and species in order to define management units, trace exploited stocks, and identification of species. In this work, a double‐digestion restriction‐site‐associated DNA sequencing (ddRADseq) approach was performed to identify individuals belonging to two important commercial flatfish, the turbot (Scophthalmus maximus) and the brill (Scophthalmus rhombus), and their potential hybrids. A total of 83 diagnostic single nucleotide polymorphisms (SNPs) between brill and turbot were detected in the genomic RAD‐tag database created with 122 turbot and 20 brill individuals. Markers consisted of an SNP with alternative alleles fixed in each species. From these diagnostic markers, a molecular tool comprising 10 SNPs located far apart in the turbot genome (>100 kb) was successfully designed and validated using the SNaPshot® method from a new sample set of 154 brill and turbot samples distributed throughout the natural range of both species. Additionally, 10 individuals (two turbot and eight brill) previously genotyped with ddRADseq were genotyped with SNaPshot to check for genotyping accuracy. ddRADseq and SNaPshot genotyping of these 10 markers were identical in the 10 individuals used as controls. Species assignment based on the SNP tool corresponded with phenotypic identification for all samples. Using the SNP tool in a set of 29 unknown samples, all individuals were identified as S. maximus except one identified as a hybrid (heterozygous for all diagnostic SNPs). The methodology (i.e. ddRADseq) has enabled the development of a helpful traceability tool for sustainable management and conservation of turbot and brill resources. Similar approaches could also be applied to other non‐model organisms despite lacking an assembled genome.

Characterization of Aliivibrio fischeri strains associated with disease outbreak in brill Scophthalmus rhombus.

Three bacterial isolates were recovered from a disease outbreak with high mortality affecting brill Scophthalmus rhombus (Linnaeus, 1758). Moribund fish showed no external signs of disease, but plentiful haemorrhages were observed in liver. On the basis of phenotypic and genotypic characterization, the isolates were identified as Aliivibrio fischeri. The phenotypic profile of the isolates was basically similar to that of the type strain of this species, although some discrepancies were observed, mainly in the BIOLOG GN profile. The main cellular fatty acids of strain a591 were also consistent with this species. The highest 16S rDNA sequence similarities were recorded with the type strain of A. fischeri (99.07%); other Aliivibrio species showed similarity values below 96%. The highest sequence similarities with gyrB, rpoD and recA genes were also recorded with A. fischeri type strain (99.31, 98.99 and 95.29% similarity, respectively). DNA-DNA hybridization assays confirmed that these isolates belong to A. fischeri; levels of DNA relatedness were 73.5 to 86.2% with isolate a591 (reciprocal values of 86.9 to 99.04%). Finally, a virulence evaluation of the isolates using Senegalese sole fry was also performed; significant mortalities (100% mortality within 5 d) were recorded by intraperitoneal injection, but only with high doses of bacteria (2 × 106 cfu g-1 body weight).

Molecular characteristics of lysozyme G in Euryglossa orientalis; cDNA cloning, phylogenic analysis, physicochemical properties and tissue gene expression.

Lysozymes are the key molecules of innate immune system against bacterial infections. In the present study, we identified the molecular characteristics, physicochemical properties, antibacterial activity, evolutionary relationship and tissue expression pattern of g-type lysozyme in Euryglossa orientalis (EuOr LysG). The full-length EuOr LysG cDNA is composed of 588 nucleotides and an open reading frame encoding a protein with 195 amino acids with more than 65% identity to g-type lysozyme of Solea senegalensis (73%) and Scophthalmus rhombus (64%). Amino acid sequence alignment showed that EuOr LysG protein possessed a conserved catalytic motif (Glu71-Asp84-Asp101) and one predicted disulfide bond between Cys32 and Cys122. Phylogenetic analysis based on the g-type lysozyme sequences indicated that E. orientalis and other fish of Pleuronectiformes were diverged together in the evolutionary history. The K m and V max values of the recombinant EuOr LysG were 0.266mg/ml of Micrococcus lysodeikticus as substrate and 667U/mg of protein, respectively. The optimum temperature and pH of recombinant EuOr LysG were 45 and 6°C, respectively. Real-time PCR analysis showed that EuOr LysG transcript was most abundant in head kidney and gill and less in muscle. We also showed that the EuOr LysG had potent lytic activity against major fish bacterial pathogens with the highest activity against Bacillus cereus and Aeromonas hydrophila. Bacterial challenge with Vibrio parahaemolyticus could upregulate LysG in immune-related tissues. Our results help to understand the molecular and physicochemical characteristics of g-type lysozyme in E. orientalis which might play an important role in host defense against the bacterial infection.

Caviar versus brill eggs: A novel high performance liquid chromatography‐mass spectrometry application for evaluating cosmetic ingredients composition

In this study, raw materials, sturgeon and brill roe, were analyzed and compared as regard their use in cosmetic products. Recently, expensive caviar was largely used in beauty creams as lipids source. We compared lipids from caviar and brill eggs to propose a technological alternative. The fatty acids amount was determined with a new GC‐MS method. The triacylglycerols were identified and characterized by HPLC coupled with high resolution MS (HRMS). Both techniques showed a higher content of fatty acids and triacylglycerols in caviar respect to brill eggs. Some fatty acids, such as linoleic and linolenic acids, which are recognized to enhance skin metabolism, are absent, or show very low concentration, in brill eggs respect to sturgeon ones. It was possible to conclude that brill eggs are not a proper substitute of caviar in the formulation of cosmetic.Practical application: The developed analytical techniques provided a satisfactory analytical characterization of the raw materials. Although the sample preparation for GC‐MS analysis is quite time consuming due to the derivatization of fatty acids, the one for triacylglycerols analyzed by HPLC‐HRMS is very fast, and involves the use of a small amount of organic solvent. Fatty acids and triacylglycerols were identified and characterized.Comparison between Acipenser trasmontanus (caviar) and Scophthalmus rhombus eggs as active ingredient in beauty cream. A fatty acid quantitation and triacylglycerols quantitation, and characterization methods are showed. GC‐MS and HPLC‐HRMS are satisfactory tool to provide a full description of the studied raw materials.

The timing of early life events and growth rate estimates of age‐0 year group brill Scophthalmus rhombus along the west coast of Ireland

The timing of spawning and hatching, larval durations and growth exhibited by juvenile brill Scophthalmus rhombus captured along the Irish west coast were estimated using otolith microstructure analysis. Scophthalmus rhombus were estimated to have hatched between February and May, with fish settling onto nursery grounds between March and June. Fish collected later on in the season exhibited higher otolith growth rates in comparison to earlier collected fish. This is the first study to describe the early life history of a commercially valuable but understudied flatfish species.

Entering uncharted waters: Long-term dynamics of two data limited fish species, turbot and brill, in the North Sea

In the North Sea, turbot (Scophthalmus maximus) and brill (Scophthalmus rhombus) represent highly valuable species in commercial fisheries. Still, available data for both species are limited, making stock assessment difficult. Long-term fisheries data have the potential to improve the understanding of stock dynamics such as long-term distribution changes or development in species' abundances. Historical British otter trawler lpue (landings-per-unit-effort) data from 1923 to 2009, and at the spatial scale of ICES rectangles, revealed that the distribution patterns of turbot and brill were different for most of the 20th century and only became similar in the recent decade. Further, between the 1920s and 1960s, turbot was commonly caught in the northern North Sea and in particular on Turbot Bank, at that time a turbot hotspot off the east coast of Scotland. Within a short time period turbot nearly disappeared from this region. Brill, in contrast, revealed a stable distribution in the southern and central North Sea with a slow expansion into the central North Sea. We used survey cpue (catch-per-unit-effort) from the International Bottom Trawl Survey (IBTS; 1970–2009) and the Beam Trawl Survey (BTS; 1985–2009), as well as British otter trawler lpue, as proxies for the abundance of adult turbot and brill. Commercial lpue suggested for brill and turbot a long-term decrease in abundance. IBTS cpue suggested an increase in abundance for turbot, but this was not confirmed by the BTS. For brill, both surveys did not show a clear trend.

Climate-induced response of commercially important flatfish species during the 20th century

The consequence of elevated ocean temperatures on commercial fish stocks is addressed using time series of commercial landings (1906–2004) and juvenile survey catch data (1904–2006) collected around Denmark. We analyze (i) whether warm-water sole (Solea solea) has increased relative to Boreal plaice (Pleuronectes platessa) and (ii) whether two related warm-water species (turbot, Psetta maxima and brill, Scophthalmus rhombus) show similar responses to increasing temperature or, alternatively, whether turbot (which has a broader juvenile diet) has been favored. Since the early 1980s, both sole and turbot have constituted an increasing part of the commercial landings and survey catches, as compared with plaice and brill, respectively. These changes in species composition were linked to sea surface temperatures, Northern Hemisphere temperature anomalies (NHA) and the North Atlantic Oscillation. NHA was closely related and explained 43% of the observed variation in sole survey catches relative to the plaice catches and almost 38% of the observed variation in the sole landings relative to the plaice landings. For the less common species, turbot and brill, none of the global change indicators explained more than 15% of the variation, although all showed a positive relationship. Survey catch per unit effort increased significantly for both sole and turbot around the early 1980s, whereas catch per unit effort for plaice and brill remained constant. The results indicate that the abundance of warm-water species is likely to increase with increasing temperature but also that species with similar life histories might react differently according to degree of specialization.

First genetic linkage map for comparative mapping and QTL screening of brill (Scophthalmus rhombus)

Genetic maps constitute valuable tools to detect genomic regions associated with complex traits and to go forward to understand their genetic basis. Flatfish include several species of great commercial value for which increasing genomic resources are available including genetic maps and EST databases. Application of comparative mapping strategies to flatfish is relevant to obtain genetic information associated with productive traits. The brill (Scophthalmus rhombus) is a flatfish species closely related to turbot (S. maximus) whose meat is highly appreciated in the Spanish market. The Junta de Andalucía local Government has begun a program to adapt this species to captivity for its future production. In this study, we developed the first genetic map of brill using the current turbot genetic map as starting point. This strategy enabled us to select a number of homogeneously distributed markers in the turbot map and to apply cross-species microsatellite amplification to obtain informative markers. Nearly two hundred microsatellites from the framework turbot map were used for validation, and 100 markers were finally informative for mapping. The parents and offspring of the two families (54 and 88, respectively) used to construct the genetic map were genotyped with this panel. All markers, except eleven, were successfully grouped and ordered in 24 linkage groups. Linkage groups and order of markers were highly consistent with the previous turbot genetic map. Linkage map information was used to carry out a preliminary study on growth-related QTL for body weight, length and Fulton's condition factor in the two families, as the main phenotypic traits of interest in this species.

Sperm production and quality in brill Scophthalmus rhombus L.: relation to circulating sex steroid levels

The aims of the present study were to characterize sperm quality and to quantify seasonal changes in sexual hormone (testosterone [T], 11-ketotestosterone [11-KT] and 17,20β-dihydroxypregn-4-en-3-one [17,20β-P]) levels in male brill (Scophthalmus rhombus) plasma, as well as to test a more intensive sampling strategy to establish relationships between sex steroid levels and sperm production parameters. Sperm concentration ranged from 0.5 to 3.1 × 10(9) spermatozoa mL(-1), and changes in sperm quality parameters depending on sampling date were observed. Plasma sexual steroid levels remained high and changed in parallel during the spawning season and afterwards decreased to very low levels in summer. The analysis of annual changes of 11-KT and T ratios suggests that 11-KT can be the main circulating androgen for stimulating spermatogenesis in S. rhombus and that T could be involved in the beginning of spermatogenesis through the positive feedback on brain-pituitary-gonad axis. Finally, daily 11-KT and T levels showed similar patterns of variation in males sampled, whereas 17,20β-P amounts showed somewhat opposite trends. These differences could be related with the different role of androgens and progestin during the spermatogenesis.

Changes in lipid classes, fatty acids, protein and amino acids during egg development and yolk-sac larvae stage in brill (Scophthalmus rhombusL.)

Brill (Scophthalmus rhombus L.) is a flatfish considered of special interest for aquaculture diversification, but the high mortality observed during the early larval rearing is the main obstacle to commercial culture. The objective of this study was to contribute to the knowledge of nutrient utilization of early-hatched larvae, characterizing the changes in lipid and protein contents during embryogenesis and the yolk-sac larval stage of S. rhombus. Total lipid, lipid classes and fatty acid contents remained constant during embryogenesis and yolk-sac larval development, except for phosphatidylethanolamine and phosphatidylinositol, which increased in quantity during the yolk-sac larval stage. On the other hand, total protein (including non-protein nitrogen) and amino acids decreased their contents in both periods, especially at hatching. The decrease only in the serine, glutamic acid, proline and lysine contents during embryogenesis suggests a selective use of amino acids during this phase. Unlike embryogenesis, amino acids loss during hatching appears to be non-selective, and almost all amino acids (essential and non-essential) decreased. Our results suggest that there is higher catabolism of protein vs. lipid during embryogenesis and the yolk-sac larval stage of S. rhombus.

The feeding ecology of 0 year-group turbot Scophthalmus maximus and brill Scophthalmus rhombus on Irish west coast nursery grounds

On sandy beach nursery grounds along the west coast of Ireland, 0 year-group turbot Scophthalmus maximus were found to consume six types of crustaceans, in addition to polychaetes. The 0 year-group brill Scophthalmus rhombus fed almost exclusively on mysids, even though nine taxonomic prey groups were identified in the sediment across the investigated beaches. Both species avoided non-motile organisms such as gastropods and bivalves, which were present in high abundances in the sediment and their growth and condition was not significantly related to the quantity or type of prey consumed, temperature or salinity. A high incidence of feeding was detected for both species over the duration of the study, suggesting that food was not limiting on west of Ireland nursery grounds. Temporal partitioning of settlement was detected between S. maximus and S. rhombus, indicating that inter-specific competition for food does not occur between these two flatfish species on west of Ireland nursery grounds.

Diet and niche overlap of southern populations of brill Scophthalmus rhombus and turbot Scophthalmus maximus

The diets of adult brill Scophthalmus rhombus and turbot Scophthalmus maximus from the Portuguese coast relied mostly on fishes. There was a higher diversity of food items compared to their northern counterparts, and several of the identified prey are the first records of these species, including a brown alga, echinoderms, nematodes, oligochaetes, gastropods, bivalves and various fish species. The diet of the two species was significantly different and niche overlap was low.

Effects of two diets on lipid composition and reproductive performance of brill (Scophthalmus rhombus) eggs

The effects of two diets with different lipid composition (squid Loligo gahi and one commercial pellet for breeders) on reproductive performance and egg lipid composition of brill (Scophthalmus rhombus) were compared. A total of 36 adult brill weighing 1482 ± 432 g were randomly distributed in the experimental tanks. A flow-through system composed of four tanks with 4.2 m2 of bottom area (5.0 m3 × 1.2 m water depth) was used. The experiment lasted for approximately 5 months (168 days). From the four mature females fed squid, three ovulated. Five females fed pellets matured and ovulated. Total ovulations were of 10 and 44, by the three females fed squid and the five ovulating female fed pellets respectively. Egg viability was higher, although not significantly, for females fed pellets. This indicates that pellets could be a better food for breeding females. In general, the egg total lipid content and the lipid classes composition did not seem to be affected by diet. In contrast, results indicate that not only diets but also individual females, regardless of the diet consumed, are determinant for egg fatty acid composition, clearly modulating their composition.

Reduction of flatfish habitat as a consequence of the proliferation of an invasive mollusc

Coastal bays provide habitats for juveniles and adults of many marine species. Mont Saint-Michel Bay (MSMB, France) hosts a highly diversified fish community and constitutes one of the most important nursery grounds for many commercially exploited marine species, such as sea bass, flatfish, clupeids and rays in the English Channel. Besides, MSMB also suffers from the massive invasion of an exotic mollusc, the American slipper-limpet ( Crepidula fornicata, L.). This species arrived four decades ago and now represents the main filter-feeder biomass in the bay (150 Mt), an order of magnitude larger than local farmed and natural shellfishes. Recent analyses underlined the impact of this small gastropod on the trophic structure of this bay and its negative influence on juvenile sole densities in the nursery grounds. The present study uses a geostatistical approach to explore the effect of the extension of the slipper-limpet on flatfish (common sole Solea solea, L.; plaice Pleuronectes platessa, L.; brill Scophthalmus rhombus, L. and flounder Platichthys flesus, L.) spatial distribution. Data collected during survey of the MSMB at the end of the 1970s and three decades later have been used to build interpolated maps of (1) slipper-limpet and (2) flatfish spatial distributions. Slipper-limpets were concentrated in a small area, in the western part of the MSMB, in the 1970s while today they occupy half of the bay. This rapid proliferation led to the decrease of available surface for flatfishes, which previously occupied the whole bay and are now restricted to its eastern part. The present study highlighted that the negative influence on fish habitat in MSMB is apparently more related to changes in the substratum than to trophic interactions. This invasion has possible consequences on flatfish population renewal at a large scale and may also damage other benthic or demersal species, such as rays.