Diplodus Vulgaris Research Articles

Do fish gut microbiotas vary across spatial scales? A case study of Diplodus vulgaris in the Mediterranean Sea

BackgroundBiogeography has been linked to differences in gut microbiota in several animals. However, the existence of such a relationship in fish is not clear yet. So far, it seems to depend on the fish species studied. However, most studies of fish gut microbiotas are based on single populations. In this study, we investigated the gut microbiota of fish from three wild populations of the two-banded sea bream Diplodus vulgaris (Geoffroy Saint-Hilaire, 1817) to determine whether its diversity, structure and potential functionality reflect the geographic origin of the fish, at large and small geographical scale. Additionally, we explored the host- and environmental-related factors explaining this relationship.ResultsWe showed that the taxonomy and potential functionality of the mucosa-associated gut microbiota of Diplodus vulgaris differ to varying degrees depending on the spatial scale considered. At large scale, we observed that both the taxonomical structure and the potential functionality of the fish microbiota differed significantly between populations. In contrast, the taxonomical diversity of the microbial community displayed a significant relationship with factors other than the geographic origin of the fish (i.e. sampling date). On the other hand, at small scale, the different composition and diversity of the microbiota differ according to the characteristics of the habitat occupied by the fish. Specifically, we identified the presence of Posidonia oceanica in the benthic habitat as predictor of both the microbiota composition and diversity. Lastly, we reported the enrichment of functions related to the metabolism of xenobiotics (i.e. drugs and 4-aminobenzoate) in a population and we indicated it as a potential target of future monitoring.ConclusionsWith this study, we confirmed the importance of investigating the gut microbiota of wild fish species using multiple populations, taking into account the different habitats occupied by the individuals. Furthermore, we underscored the use of the biodegradation potential of the gut microbiota as an alternative means of monitoring emerging contaminants in Mediterranean fish.

Alizarin Red S Marking in Otoliths: A Study on the Growth Dynamics of Diplodus vulgaris Juveniles

This study investigates the age and growth rates of juvenile Diplodus vulgaris in the Çanakkale Strait, utilizing Alizarin Red S (ARS) marking to analyze otoliths for daily growth increments. The research aimed to validate the daily deposition of growth rings in otoliths as a reliable method for age determination in young fish. A total of 65 specimens were subjected to ARS immersion at varying concentrations to identify the optimal marking conditions that would not adversely affect the survival rates of the juveniles. Post-treatment, the fish were released into controlled environments and monitored over a period to assess the incorporation and visibility of ARS marks in the otoliths. The results demonstrated a clear correlation between fish size and age, with a consistent daily growth rate that supports the hypothesis of daily increment formation in otoliths. The mortality rate associated with ARS treatment was within acceptable limits, confirming the method's viability for non-lethal age and growth studies. This research not only underscores the effectiveness of ARS marking in studying juvenile fish growth patterns but also contributes to a better understanding of the life history of D. vulgaris in the Çanakkale Strait, offering valuable insights for fisheries management and conservation efforts.

Untangling Coastal Diversity: How Habitat Complexity Shapes Demersal and Benthopelagic Assemblages in NW Iberia

Understanding species–habitat relationships is essential for ecosystem-based conservation. This study explores the significance of habitat characteristics and complexity for demersal and benthopelagic communities within a patchwork of coastal habitats, including rocky seabed, macroalgae formations, sandy bottoms, and a combination of rock and sand areas. Species and habitats were surveyed along the north-west (NW) Iberian continental shelf area of Viana do Castelo using baited remote underwater video stations (BRUVS). We found significant differences (p < 0.05) in species assemblages across habitats, with rocky substrates showing the highest diversity and abundance. Sand habitats showed the lowest species richness and abundance, underscoring the importance of habitat complexity to support marine life. Our study also emphasises the role of specific species in shaping the communities, identifying key species such as Trisopterus luscus, Diplodus vulgaris, and Ctenolabrus rupestris as the three most abundant in the region and significant contributors to the observed dissimilarities between habitats. By elucidating the impact of habitat complexity on marine life, our results offer essential baseline data, which serve as a kick-start point to inform sustainable management and conservation strategies for the long-term health and productivity of these vital ecological systems in the North-East Atlantic.

Use of biodegradable materials to reduce marine plastic pollution in small scale coastal longline fisheries

Pollution from lost, abandoned, or discarded fishing gear is recognized as a global nature conservation concern. Longlining with hooks is a commonly applied fishing method in fisheries around the world. The longline gear consists of a mainline with a number of baited hooks that are attached to it by thinner twine (snoods) which are often made of plastic material such as polyamide (nylon) or polyester that degrades very slowly in the marine environment. During longline fishing, some of the snoods are lost at sea contributing to marine macro- and micro-plastic pollution. The extent of the snood loss is often unknown and can vary between different longline fisheries and fishing grounds. In this study, we estimated and compared the risk for the biodegradable and nylon snood loss in an Adriatic small scale longline fishery. Further, we compared the catch composition and estimated catch efficiency between biodegradable and nylon snoods for capture of common pandora (Pagellus erythrinus), two-banded seabream (Diplodus vulgaris) and axillary seabream (Pagellus acarne). The risk for nylon snood loss in this longline fishery (3 % for each snood for each deployment), demonstrate that the use of more environmentally friendly materials is necessary for nature conservation. No significant differences between the performance of the two materials regarding snood loss rate, hook loss rate, catch efficiency and catch composition were found during short-term usage in the fishery. Based on these results, future long-term testing is encouraged to investigate whether this promising performance of the biodegradable snood material is persistent over longer fishing periods.

Early life traits of the common two-banded seabream, Diplodus vulgaris (Perciformes: Sparidae), inhabiting the shallow waters of Gökçeada Island, Turkey

Daily growth rates and pelagic larval duration were investigated in the common two-banded seabream (Diplodus vulgaris). Fish were sampled using a beach seine from the shallow waters of Gökçeada Island, Turkey, between June 2013 and June 2014. The minimum and maximum daily age estimates were 41 and 339 d, respectively. The mean daily growth rate of young-of-the-year D. vulgaris was 0.330 mm·d–1. Our results showed that D. vulgaris exhibits a Type Ia settlement-mark with a pelagic larval duration of 29 d. The hatching period occurred from November to April. The maximum hatching frequencies were observed in winter, when the water temperature was relatively low. The natural logarithm of young-of-the-year abundance data was plotted against age, and the instant mortality coefficients were estimated. The relationships between total length and otolith morphometric measurements (otolith length [OL], width [OW], and radius [OR]) were defined by linear equations. Furthermore, it was observed that this ratio exhibited a linear relationship with OL, OW, and OR and total length and daily age.

Türkiye’nin Doğu Akdeniz Kıyılarında Yayılım Gösteren İki Diplodus Tür Populasyonunda DNA Barkodlama ve Filogenetik analiz

Since Turkey is surrounded by seas on three sides and has different climatic characteristics, it has an extremely rich biodiversity. Identifying fish species and varieties is of great importance for protecting them from drought conditions seen in recent years and using them as a source of human food protein. The purpose of this study was to identify the genetic diversity of Diplodus, one of the fish species the importance of which is under appreciated, in Turkish seas. To this end, the polymorphism between the populations of two species (Diplodus vulgaris and Diplodus sargus) from the Sparidae (Coral fish) family was determined using the nucleotide sequence of the mitochondrial cytochrome c oxidase I (COI) gene, which is 652 base pairs long. 143 specimens of Diplodus were collected from the locations in the Eastern Mediterranean (İskenderun and Mersin) and Western Mediterranean (Antalya). The COI gene was amplified by PCR, genetic diversity analyses of these loci were carried out, and a phylogenetic tree was created to show the relationships between the isolates with a high difference. In conclusion, based on the haplotype and nucleotide diversity patterns, it was found that the COI gene had a low genetic variation among the populations.

Potential protection effects in a small marine reserve: a demersal community analysis from stereo baited remote underwater video

Monitoring is essential for efficient management of marine protected areas (MPAs) but often limited financially. Using low-cost stereo baited remote underwater video, we evaluated potential protection effects in the demersal assemblage of a marine reserve in European Atlantic temperate waters (southwestern Portugal). Due to a lack of before-MPA data, we compared multiple sites from the reserve inside and outside, investigated time trends, and assessed the potentially confounding effects of physical habitat. We found greater biomass of the legal-sized group (i.e. commercial above legal minimum landing size) inside the reserve than outside in the most recent year as opposed to the first year and a significant time increase in its abundance and biomass inside but not outside, indicating different trends in protection levels. On the contrary, biomass of the non-target group decreased significantly in both protection levels through time. One of the most targeted species, the legal-sized Diplodus sargus, reached significantly higher biomass inside than outside while also manifesting positive protection signs in abundance and length. Two legal-sized taxa showed no (Diplodus vulgaris) and negative (Mugilidae) protection responses, possibly due to low value and mobility of the latter. We detected positive responses in non-target wrasses Labrus bergylta and Symphodus spp., highlighting incidental fishing interest. Habitat did not interfere with protection effects. We suggest that community analysis based on stereo measurements renders sensitive protection indicators and offers a more thorough approach than prevailing abundance-focused analysis. The proposed low-cost monitoring solution can serve as a model to other MPAs.

Diet and feeding of juvenile common two-banded sea bream, Diplodus vulgaris (Teleostei: Sparidae), in the eastern central Adriatic Sea

Abstract The diet and feeding of juvenile common two-banded sea bream, Diplodus vulgaris, in the eastern central Adriatic Sea was studied to better understand local ecosystem dynamics in this region. Stomach contents of 140 individuals with total length (TL) between 22 and 106 mm, collected by small beach seines from February to November, were analysed. Food items identified in stomachs belonged to 16 prey groups: Copepoda, Gastropoda, Teleost eggs, Ostracoda, Polychaeta, Bivalvia, unidentified Crustacea, Amphipoda, Decapoda, Cumacea, Echinoidea, Anisopoda, Euphausiacea, Mysidacea, Branchiopoda and Isopoda. Overall, planktonic copepod crustaceans were the most important prey group (percentage index of relative importance, %IRI = 78.9), followed by gastropods (%IRI = 14.9). All other prey groups had much lower %IRI values and thus were of less importance. Fish size was an important factor influencing food composition. Planktonic copepods were the most important prey in juveniles of smaller sizes (up to 76 mm TL), whereas large-sized juvenile individuals (>76 mm TL) mainly consumed benthic prey, such as gastropods, polychaetes and bivalves. Feeding intensity was very high as indicated by the low vacuity index.

İzmir Körfezi’ndeki bazı balık türlerinde biyoişaretçi yanıtlarının metal konsantrasyonları ile birlikte değerlendirilmesi: Bir ön araştırma

Antioxidant related biomarkers (superoxide dismutase, catalase, malondialdehyde) were investigated to evaluate metal (Hg, Cd, Pb, Cr, Cu, Zn, and Mn) bioaccumulation in some organs of fish species (Sparus aurata, Chelon labrosus, Diplodus vulgaris) from the İzmir Bay. Samples were collected at November 2019 from Inner and Outer Bays. Metal and biomarker analyses were carried out by Atomic Absorption Spectrometer and microplate reader, respectively. For metal analyses in organs, higher metal bioaccumulations were found at liver tissues. Higher Hg and Zn concentrations were found in S. aurata, higher Cd, Cr, Cu and, Mn concentrations were detected in C. labrosus and higher Pb concentrations were determined in D. vulgaris. In biomarker results, superoxide dismutase (SOD) and catalase (CAT) activities were generally higher in gills, however, MDA contents were higher at liver. The highest biomarker results were detected at C. labrosus. Statistical analyses were demonstrated that especially MDA content were expressed strong responses for the metal bioaccumulations. Also, Mn levels were considerably correlated with all biomarkers as expected. This study revealed that combined utilization of biomarkers and metal concentrations could be a vital indicator to investigate health status of the marine ecosystems.

Ecological and human health risk assessment of potentially toxic element contamination in waters of a former asbestos mine (Canari, Mediterranean Sea): implications for management

Between 1948 and 1965, the Canari asbestos mine (Corsica, France) discharged 11 million tonnes of serpentinite rubble into the sea. This study, therefore, aims to assess the environmental and health risks associated with contamination of potentially toxic elements using bioindicators (seagrass and fish) in the areas bordering the former mine within the perimeter of the Cap Corse and Agriate Marine Natural Park. The results and multivariate statistical analyses of the potentially toxic elements, made it possible to identify a concentration gradient, a model of bioaccumulation, and the occurrence of different groups, thus reflecting a spatial variation of the contamination. These results indicate that the former asbestos mine can still be considered, 55years after its closure, as a major source of Co, Cr, and Ni for marine ecosystems and still influences the quality of the coastal area today. Our study, therefore, indicates that the two most polluted sites (Albo and Negru) are the closest stations to the south of the old Canary asbestos mine. According to the Trace Elements Pollution Index (TEPI) values, 6 species were classified as having a high contamination level: Scorpaena notata (1.37), Scorpaena porcus (1.36), Sepia officinalis (1.27), Diplodus vulgaris (1.02), Spicara maena (0.95), and Mullus surmuletus (0.94). Regarding the potentially toxic elements measured in the edible tissues of fish, the concentrations were all below the regulatory thresholds and did not reveal any potential risk to human health (Cd, Cu, Fe, Pb, Se, Sn, Zn). This work provides new and useful information to improve the monitoring of the environmental quality of a region characterized by previous mining activity and to assess the potential risk to human health due to the consumption of fish. Beyond the purely scientific aspects, these results could serve as decision support at the regional level for the definition of long-term public policies.

Breaking the paradigm: Marine sediments hold two-fold microplastics than sea surface waters and are dominated by fibers

We conducted one of the first studies to integrate the quantification and characterization of microplastics (MPs), including fibers, in different habitats (sea surface, seafloor and beach sediments) of a coastal Mediterranean marine protected area, analyzing their ingestion in several marine species. The objectives of the study were to evaluate the distribution of MPs according to shape and polymer, to assess the contribution of fibers to local plastic pollution and to evaluate their ingestion in fish and invertebrates species that inhabit the study area (Pagrus pagrus, Serranus scriba, Spondyliosoma cantharus, Diplodus vulgaris, Oblada melanura, Holothuria forskalii, Holothuria tubularis, Holothuria polis, Arbacia lixula, Paracentrotus lividus, Modiolus barbatus, Mytilus galloprovincialis and Arca noae). A total of 111 environmental samples were analyzed. The mean abundance of MPs (excluding fibers) quantified in beach sediments (13,418.86 ± 28,787.99 MPs/m2) was two orders of magnitude higher than that found in seafloor sediments (76.92 ± 108.84 MPs/m2), which in turn was two orders of magnitude higher than sea surface samples (0.17 ± 0.39 MPs/m2). The fibers were the most abundant shape of MPs identified in all habitats. Variability in MPs ingestion was detected between species, with ingestion rates ranging from 43 % to 100 % for general MPs and ranging from 7 % to 100 % for fibers. The highest ingestion was observed in Holoturians, representing suitable bioindicators for plastic pollution. The composition of the polymer varies weakly depending on habitats and biota, but the result is strongly correlated with the morphology of the plastic. Fibers were mainly composed of cellulose acetate (29 %), styrofoam of polystyrene (18 %), and filaments, films and fragments of polyethylene and polypropylene. The results highlighted the need to expand integrated approaches to effectively study marine plastic pollution and to undertake efficient actions to limit the input of plastics, particularly fibers, into the marine environment.

Some biological aspects and fisheries assessment of Diplodus vulgaris (Geoffrey Saint-Hilaire, 1817) (Teleostei: Sparidae) caught by gillnets (Egyptian Mediterranean waters, Alexandria)

This study was conducted to estimate some biological aspects and fisheries assessment of Diplodus vulgaris caught by gillnets during the period 2018–2020 from the Egyptian Mediterranean waters of Alexandria. From an overall of 1004 individuals of D. vulgaris (10.0 – 24.0 cm TL) examined, lengths from 13.0 to 17.0 cm were representing 82.67% of the total fish number. The length-weight relationships for total and gutted weights of the D. vulgaris were: Log W = −1.7144 + 2.9063 Log L (R2 = 0.9982) and Log W = −1.8508 + 2.9903 Log L (R2 = 0.9967), respectively. The condition factor (k) was found to be fluctuating between 1.268 and 1.534 with an average value of 1.395 ± 0.0597. The overall sex ratio (M: F) was 1.00: 0.63 and the chi-square test revealed highly significant difference (χ2 = 24.80; df = 1; P < 0.01). The spawning season of D. vulgaris was observed from December to February for both sexes. The gonadosomatic index (GSI) reached its highest value in December for both sexes. The age composition of the D. vulgaris catch was estimated to be four years and the first age dominated the population. The present von Bertalanffy growth parameters were calculated as follows: the coefficient of growth (K) = 0.128 yr.-1, the asymptotic length (L∞) = 37.06 cm, and the hypothetical age at zero size (to) = −2.773 yr.-1. The growth performance index (Ф') was: Ф'L = 2.24, and Ф'W = 1.00. The reproductive load (Lm/L∞) was low for males (0.39) and females (0.37). The ratio LmaxD/ LmD was 1.36 and 1.39 for males and females, respectively and it was found to be compatible with the Pauly's Gill-Oxygen Limitation Theory (GOLT). The total mortality coefficient (Z) was 1.79, the natural mortality (M) was 0.39 and fishing mortality (F) was 1.40. The M/K was 3.0615 and Lc/L∞ was 0.371. At the level of the current exploitation rate (Ecur = 0.78), the stock is considered highly exploited by gillnets fishery and only 9.34% of the stock biomass is protected. Fishery management for this wild stock is highly required.

Relationships between Opercular Girth, Maximum Girth and Total Length of Six Sparid Fishes from Saros Bay (Northern Aegean Sea, Turkey): An Assessment for Ecosystem-based Fisheries Management

This study was conducted so as to unearth the relationships between opercular girth (Gope), maximum girth (Gmax), and total length (TL) for six sparid fishes (Boops boops, Diplodus annularis, Diplodus puntazzo, Diplodus vulgaris, Lithognathus mormyrus, Oblada melanura) belonging to family Sparidae sampled between April 2015 and July 2016 in Saros Bay (Northern Aegean Sea, Turkey). Gope and Gmax were found to increase linearly with total length for all the species. All r2 values were statistically significant (&gt; 0.82, P &lt; 0.001). This study reports the first information about length-girth relationships (LGRs) of Diplodus puntazzo for the Aegean sea. However, no LGRs estimates existed for Oblada melanura worldwide. These values are important for the selectivity of fishing gear so as to prevent the capture of younger, undersized, and immature individuals, it will assist the development of the ecosystem-based fisheries management.

Heavy metal contamination of Diplodus vulgaris (Sparidae) in the Gulf of Annaba (North-eastern Algeria)

The aim of this work was to evaluate heavy metals (Lead and Cadmium) contamination in the muscles ofa local sea fish species, the black-headed Sar Diploddus vulgaris. We selected two sites in the Gulf of Annabafor this study (Sidi Salem fishing site and the Port of Annaba) and compared results to a reference site (Capde Garde), which is at a valuable distance from any source of pollution, and is considered as a relativelyclean site, while Sidi Salem and Port of Annaba are known to be exposed sites to various sources of industrial,urban and harbor pollution. Analyses have been carried out on 70 samples of dorsal-lateral muscles offishes weighting from 30 g to 280 g and sizing between 11.1 cm to 26.5 cm. The results showed the presenceof both metals in all samples during the 6 months of our study (from November to June) and in the 3 siteswith variable rates. Cadmium levels varied from 0.032 to 0.239 mg/kg/fw. Fish meat from Sidi Salem collectedduring the months of November and February displayed a rate of 0.038-0.074 mg/kg/fw of Cd beforereaching a higher value in March estimated to 0.202 mg/kg/fw of Cd. From April to June, the lateral dorsalmuscles were contaminated by lower Cd contents. Pb concentrations varied from 0.014 to 0.149 mg/kg/fw.The highest value was recorded during the month of March at Sidi Salem. Moreover, Pb concentrations inmuscle tissues increased significantly compared to the other studied sites. Very high significance differenceswere found between Cap de Garde and Port of Annaba and Sidi Salem for both metals (Pb and Cd). Toconclude, the presence of heavy metals in Diplodus vulgaris is due to the diet and the impact of anthropogenicactivities on the biotope of the fish and therefore poses a public health problem linked to frequentconsumption of this fish. Also, D. vulgaris appears to be a suitable sentinel species for the assessment ofecotoxicological risk in the Gulf of Annaba.

First Record of Pempheris rhomboidea (Kossmann &amp; Räuber, 1877) Harvested from Aquaculture Fish Cages

An individual of Pempheris rhomboidea species was detected in a cage where sea bream was grown in the Mersin Dana Island region. P. rhomboidea is a species of the Pempheridae family distributed in the Indo-Pacific and West Atlantic and is a nocturnal species that inhabit coral reefs and rocky waters. It is known that different wild fish species enter into the aquaculture fish cages where marine fish are grown and grow together with the aquaculture species. There is no previous record of this species obtained from aquaculture cages. The total length and weight of the individual in the cage were 12.6 cm and 23.938 g. Considering the mesh size of the cage, it is estimated that this individual entered the cage in the juvenile period. At the end of the 11-month aquaculture period, it was determined that the individual reached a length close to the maximum length that the species can reach in its natural habitat. It was determined that some morphometric characteristics of the individuals harvested from the cage were similar to individuals caught in nature. The ability of the nocturnal species to grow in aquaculture cages indicates strong adaptability. Other wild species harvested from the cage at the same time were Oblada melanura, Scomber japonicus, Liza ramada, Diplodus vulgaris, Alosa fallax nilotica, Siganus rivulatus, Trachurus mediterranus, Lichia amia, Argyrosomus regius, Spicara smaris, Coryphaena hippurus. The proportional increase of wild species in aquaculture fish cages may cause economic losses for the companies in the future.

Species diversity of gillnet catches along the Egyptian Mediterranean coast of Alexandria

The present work deals for the first time with the species diversity of gillnets operated on the fisheries coasts of Alexandria City from El-Montazah to Sidi Kirayr. A total of 6161 specimens of about 427 kg were collected during periods from Feb 2018 to Jun 2018 and from Dec 2019 to Nov 2020 using two types of gillnets: the demersal and the pelagic gillnets. All samples were identified and photographed. A total of 108 species were identified in the catch of gillnets (99 fish species; 1 molluscan species and 8 crustacean species). From that, 28 lessepsian species were recognized. The catch was dominated by Family Sparidae (25 species) and Family Scombridae (8 species). The results showed that the species and size composition of gillnets catch were depending on the type of the gillnet and its mesh size. The catch of the demersal gillnets represented 63.27% of the total production by number and 84.72% by weight of the total catch of gillnets, while the catch of pelagic gillnets represented 36.73% and 15.28% by number and weight of the total catch, respectively. Eighty nine fish species were caught by the demersal gillnets and 36 fish species were caught by pelagic gillnets. Diplodus vulgaris was the main species caught by the demersal gillnets and Boops boops and Sardinella aurita were the main species caught by the pelagic gillnets. On the other hand, according to mesh number, which is defined as numbers of meshes in half-meter length of net, the gillnets with mesh number 17–18 followed by gillnets with mesh number 20 were the main meshes for the demersal gillnets. As for the pelagic gillnets, they were restricted to mesh number 33–34. In addition, only mesh numbers 11, 14, 17–18, 20 and 25–26 (demersal gillnets) and mesh numbers 33–34 (pelagic gillnets) were operated all over the year. Only 7 fish species from the target production were represented in all seasons namely: D. vulgaris, B. boops, Diplodus levantinus, Diplodus sargus, Umbrina cirrosa, Lithognathus mormyrus, and Trachurus mediterraneus. The seasonal diversity index of fish species was H' = 1. 3652 and the large numbers of fish species recorded were in spring (61 species) followed by autumn (58 species), summer (47 species), and winter (27 species). Further biological studies are needed to identify the most dominant species caught by the gillnets operated in Alexandria.

Ciguatoxin Detection in Flesh and Liver of Relevant Fish Species from the Canary Islands.

The Canary Islands are a ciguatoxin (CTX) hotspot with an established official monitoring for the detection of CTX in fish flesh from the authorised points of first sale. Fish caught by recreational fishermen are not officially tested and the consumption of toxic viscera or flesh could lead to ciguatera poisoning (CP). The objectives of this study were to determine the presence of CTX-like toxicity in relevant species from this archipelago, compare CTX levels in liver and flesh and examine possible factors involved in their toxicity. Sixty amberjack (Seriola spp.), 27 dusky grouper (Epinephelus marginatus), 11 black moray eels (Muraena helena) and 11 common two-banded seabream (Diplodus vulgaris) were analysed by cell-based assay (CBA) and Caribbean ciguatoxin-1 (C-CTX1) was detected by liquid chromatography mass spectrometry (LC-MS/MS) in all these species. Most of the liver displayed higher CTX levels than flesh and even individuals without detectable CTX in flesh exhibited hepatic toxicity. Black moray eels stand out for the large difference between CTX concentration in both tissues. None of the specimens with non-toxic liver showed toxicity in flesh. This is the first evidence of the presence of C-CTX1 in the common two-banded seabream and the first report of toxicity comparison between liver and muscle from relevant fish species captured in the Canary Islands.

Novel molecular data for monogenean parasites of sparid fishes in the Mediterranean and a molecular phylogeny of the Microcotylidae Taschenberg, 1879

During a study of the monogeneans of four sparid fishes (Diplodus vulgaris, Pagellus bogaraveo, Pagrus pagrus and Sparus aurata) from the Western Mediterranean off Algeria, a large collection of parasites was characterised molecularly (28S rRNA and cox1 genes). A total of 46 partial sequences (23 for each gene) were generated from 38 isolates of monogeneans which included four species (Atrispinum acarne, Microcotyle erythrini (sensu stricto), Sparicotyle chrysophrii and Prostatomicrocotylinae gen. sp.) of the family Microcotylidae, two putative species of the family Capsalidae (Encotyllabe spp.), and one species (Choricotyle chrysophryi) of the family Diclidophoridae. Our study provides (i) the first molecular data for the Capsalidae in the Mediterranean; (ii) the first record of a member of the Prostatomicrocotylinae in the Mediterranean and in a sparid fish (D. vulgaris); (iii) the first cox1 sequences for A. acarne; (iv) the second record of M. erythrini (s.s.) from P. pagrus; and (v) the second confirmed by molecular data record of S. chrysophrii in wild populations of S. aurata. The first phylogenetic hypotheses for the family Microcotylidae developed here, revealed the monophyly of the subfamily Prostatomicrocotylinae and the genus Microcotyle but the relationships among the subfamilies were still largely unresolved with the best represented subfamily Microcotylinae being polyphyletic. Our results highlight the importance of molecular methods in the assessment of monogenean diversity and the need for a thorough taxon-sampling approach to increase the accuracy of phylogenetic reconstruction of the relationships of the large and taxonomically complex polyopisthocotylean family Microcotylidae.

Diel Variability in the Bottom-Trawl Catch Rates of Sparid Fishes in İzmir Bay (Central-Eastern Aegean Sea)

Time of day may affect the availability, distribution and behaviour of many fishes, at least in the depths that the light penetrates. Changes in the activity and position of the demersal fish as a response to the changing light levels during a diel (24 h) cycle may affect their catchability or vulnerability to the bottom trawl. Diel variability in the bottom-trawl catch rates of five sparid fish species, namely Boops boops, Diplodus annularis, Diplodus vulgaris, Pagellus acarne and Pagellus erythrinus, were investigated during seven experimental bottom-trawl surveys conducted within the same locality in İzmir Bay. All trawl haulings were performed using the same operation and sampling procedure and carried out for each seasonal survey at different periods day, including the morning, noon, afternoon, dusk, early-night, midnight, late-night and dawn. Percentage contribution by weight of the sparid fishes to the total catch varied according to the sampling season between 23-79%. Catch rates of the sparid fishes usually did not show significant diel periodicity except D. vulgaris. Daylight catch rates of D. vulgaris were significantly higher than twilight and night periods (Daylight&gt;Twilight&gt;Night). Information on diel variations obtained in this study could be fundamental in understanding the distribution dynamics of the five sparid fishes and developing future management approaches.

Otolith Fingerprints and Tissue Stable Isotope Information Enable Allocation of Juvenile Fishes to Different Nursery Areas

Integrated otolith chemistry and muscle tissue stable isotope analyses were performed to allocate juvenile Diplodus puntazzo and Diplodus vulgaris to nurseries in the Adriatic Sea. Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) was used to quantify the concentrations of chemical elements in the otoliths. Fish muscle samples were analysed for δ13C and δ15N. In general, Ba/Ca and Sr/Ca ratios and isotopes varied between sites and species. Values of δ13C and δ15N were significantly different between species and sites. Multivariate analysis detected a significant difference in the element signature between species while there was no evidence for a significant interaction for sites. A clear pattern across the four groups of interest, D. puntazzo_Estuary &gt; D. vulgaris_Estuary &gt; D. puntazzo_Coastal &gt; D. vulgaris_Coastal, following decreases in δ13C, and increases in δ15N were found. It seems that these species are feeding on the same local food web within more productive estuarine site while at costal site, feeding segregation among investigated species is evident. Both species were re-allocated correctly to the estuarine waters based on the otolith chemistry and stable isotopes information and higher value of δ15N. Combining otolith chemistry with tissue isotope ratios of juvenile fish provided complementary information on nursery habitat use at different spatial scales and elucidated ecological and environmental linkages.