Mediterranean Marine Fish Research Articles

Factors Influencing Endangered Marine Species in the Mediterranean Sea: An Analysis Based on IUCN Red List Criteria Using Statistical and Soft Computing Methodologies

The Mediterranean Sea is the second largest biodiversity hotspot on earth, with over 700 identified fish species is facing numerous threats. Of more than 6000 taxa assessed for the IUCN Red List, a minimum of 20% are threatened with extinction. A total of eight key factors that affect vulnerability of marine fish species in the Mediterranean Sea were identified using the scientific literature and expert-reviewed validated databases. A database of 157 teleost fish species with threat status ranging from least concern to critically endangered was compiled. Nominal logistic curves identified the factor thresholds on species vulnerability, namely, age at maturity, longevity, and asymptotic length at 8.45 years, 36 years, and 221 cm, respectively. A second-degree stepwise regression model identified four significant factors affecting the threat category of Mediterranean fish species, namely, overfishing, by-catch, pollution, and age at maturity according to their significance. Predictive analysis using supervised machine learning algorithms was further employed to predict the vulnerability of Mediterranean marine fish species, resulting in the development of a framework with classification accuracy of 87.3% and 86.6% for Support Vector Machine (SVM) and Gradient Boosting machine learning algorithms, respectively, with the ability to assess the degree of variability using limited information.

Scientific progress made towards bridging the knowledge gap in the biology of Mediterranean marine fishes.

The Mediterranean Sea is a renowned biodiversity hotspot influenced by multiple interacting ecological and human forces. A gap analysis on the biology of Mediterranean marine fishes was conducted in 2017, revealing the most studied species and biological characteristics, as well as identifying knowledge gaps and areas of potential future research. Here, we updated this gap analysis five years later by reviewing the literature containing information on the same eight biological characteristics, namely length-weight relationships, growth, maximum age, mortality, spawning, maturity, fecundity and diet, for the 722 fish species of the Mediterranean Sea. The results revealed a considerable knowledge gap as 37% of the species had no information for any of the studied characteristics, while 13% had information on only one characteristic. Out of all the biological characteristics, the smallest knowledge gap was found in the length-weight relationships (studied for 51% of the species, mainly in the eastern Mediterranean), while the least studied characteristic was mortality (studied for 10% of the species). The western and eastern Mediterranean Sea were leading forces in data collection exhibiting the narrowest gaps between current and desired knowledge. The most studied species across the entire region were the highly commercial European hake (Merluccius merluccius), red mullet (Mullus barbatus), European anchovy (Engraulis encrasicolus), European pilchard (Sardina pilchardus), common pandora (Pagellus erythrinus), and annular seabream (Diplodus annularis). The knowledge gap has shrunk by 6% during the last five years, with 40 new species having at least one study on their biology. Moreover, research has slightly shifted towards species that have been traditionally neglected, e.g., sharks, rays and chimaeras (chondrichthyans). It is recommended that research becomes less focused on commercial species and more targeted towards the identified gaps, vulnerable species (e.g., deep-sea species and chondrichthyans) and species that could potentially pose a threat (e.g., non-indigenous species) to the ecosystems of the everchanging Mediterranean Sea.

In Vivo Ultrasound Prediction of the Fillet Volume in Senegalese Sole (Solea senegalensis).

Simple SummaryThe ability to obtain in vivo information on characteristics related to fish composition is necessary for aquaculture. In addition, there is growing interest in production traits, such as growth, feed efficiency or fillet weight, but it remains difficult to precisely record in vivo individual fish traits that report to these production traits, which can increase edible fish meat production and decrease the environmental impact. In the present study, we performed an ultrasound approach for the in vivo prediction of fillet volume of the Senegalese sole (Solea senegalensis), a species considered a promising flatfish species for marine fish farming. The results show that models based on ultrasound fillet volume measurements explain above 95% of the variation observed in fillet volume. However, for fillet yield estimation, the results were modest. Therefore, further studies are necessary to better understand the potential of the ultrasound approach to this trait. Nevertheless, this work allows us to conclude that the approach with ultrasound is promising for measuring in vivo fish composition traits.Senegalese sole (Solea senegalensis) has been considered a promising new flatfish species for Mediterranean marine fish farming. Accurate prediction of fillet traits in live animals may allow for more efficient control of muscle deposition in fish. In this sense, this study was undertaken to develop a non-invasive method to predict in vivo fish fillet volume and yield using real-time ultrasonography (RTU). The trial was conducted with 44 market weight Senegalese sole (298.54 ± 87.30 g). Fish were scanned with an Aloka SSD 500V with a 7.5 MHz probe. Ten RTU cross-sectional images were taken from the operculum to the caudal fin at regular intervals. These images were analyzed using Fiji software. These data were then used to estimate the partial volumes of the fillet. Actual fillet volume was determined using Archimedes’ principle. Simple and stepwise multiple regression analyses were then used to develop prediction models of fillet volume and yield. The most cranial RTU sections of the fish fillet were the best single predictors of both fillet volume and fillet yield and were the ones included in the best stepwise models. The best RTU slice area explained 82% of the variation observed in fillet volume, but the other RTU slice areas used as predictors of fillet volume showed poor to moderate accuracy (0.035 ≤ R2 ≤ 0.615). Single RTU partial volumes showed poor to very high accuracy (0.395 ≤ R2 ≤ 0.970) as predictors of fillet volume. The best stepwise model based on the RTU slice areas included three independent variables and explained 88.3% of the observed variation. The best stepwise models based on RTU partial volumes (single volumes and/or combinations of single volumes) explained about 97% of the variation observed in fillet volume. Two RTU volume traits, V1–5 + V6–9, and V1+()+9, showed to be practically direct predictors of the actual fillet volume, explaining, respectively, 97% and 96% of the variation observed in the actual fillet volume. The fillet yields show lower correlations with slice areas (r between 0.044 and 0.601) than with volumes (r between 0.288 and 0.637). While further studies are clearly necessary to better understand the potential of RTU for the estimation of fillet yield in fish in general and Senegalese sole in particular, the present results showed that RTU traits can be very good predictors of Senegalese sole’s fillet volume, either used in regression models or as direct predictors.

Mapping the knowledge of the main diseases affecting sea bass and sea bream in Mediterranean.

Good knowledge on the disease situation and its impact on production is a base mechanism for designing health surveillance, risk analysis and biosecurity systems. Mediterranean marine fish farming, as any aquaculture production, is affected by various infectious diseases. However, seabass and seabream, the main produced species, are not listed as susceptible host species for the notifiable pathogens listed in the current EU legislation, which generates a lack of systematic reporting. The results presented in this study come from a survey directly to fish farms (50 hatchery and on-growing units from 10 Mediterranean countries), with data from 2015 to 2017, conducted by the H2020 project MedAID. Seabass showed a higher survival rate (85%) through a production cycle than seabream (80%) in spite of equal mortality due to pathogen infections (10%). The differences in survival may be explained by mortality 'of other causes'. Seabream and seabass have different disease profiles, and the profile is slightly different between geographical regions. Among the most important diseases, tenacibaculosis and vibriosis were identified in seabass and Sparicotyle chrysophrii (a gill fluke) and nodavirus in seabream. Correlating mortality data to management variables showed that increasing density, buying fingerlings from external sources and treatments due to disease are factors that negatively influence mortality rate. Most of the surveyed farms did not keep sufficient quality data to implement good health status reports and perform detailed impact studies, which shows the necessity of updating the current legislative framework to provide the basis for better reporting of relevant pathogens in the Mediterranean basin.

Vaccines and immune protection of principal Mediterranean marine fish species

This review describes and summarizes the knowledge on established and experimental vaccines developed against viral and bacterial pathologies affecting the most important farmed marine finfish species present in the Mediterranean area, namely European seabass Dicentrarchus labrax, sea bream Sparus aurata, turbot Psetta maxima and meagre Argyrosomus regius. The diseases that have been recorded in seabass, sea bream and meagre are caused by bacteria Vibrio anguillarum, Photobacterium damselae, Tenacibaculum maritimum as well as by viruses such as Viral Encephalopathy and Retinopathy/Viral Nervous Necrosis and Lymphocystic disease. The main pathologies of turbot are instead bacteriosis provoked by Tenacibaculum maritimum, Aeromonas sp. and Vibrio anguillarum, and virosis by viral hemorrhagic septicaemia virus. Some vaccines have been optimized and are now regularly available for the majority of the above-mentioned pathogens. A measurable immune protection has been conferred principally against Vibrio anguillarum, Photobacterium damselae sub. piscicida and VER/VNN.

Pleistocene marine fish invasions and paleoenvironmental reconstructions in the eastern Mediterranean

Marine bioinvasions affect ecosystems in irreversible ways, creating socio-economic problems worldwide. In particular, eastern Mediterranean marine fish faunas today are significantly disturbed due to overfishing, habitat deterioration, the Lessepsian invasion, and climate change. Isolating the impact of each parameter is difficult, because pre-anthropogenic activity data are lacking. In this study, we use the paleontological record to infer the causes and mechanisms behind marine fish invasions, focusing on the Mediterranean basin, which is a restricted basin and a biological hotspot, where the effects of climatic and oceanographic changes are amplified. Therefore, the Mediterranean Sea is an ideal area to study marine biological invasions in relation to abrupt climate changes. Furthermore, we focus on the Pleistocene, which was a period of intense glacial–interglacial changes. Thus, we investigate the effect of climate changes on the fish fauna of an eastern Mediterranean shelf, by identifying the fish otoliths in the Early–Middle Pleistocene marine sediments of Rhodes (Greece). We offer a synthesis of the Mediterranean marine fish from the Tortonian until today and hypothesize on the conditions that drove marine fish distribution range shifts during the Pleistocene. We reconstruct the paleobathymetric evolution of the study areas based on fish otoliths, and we consider taphonomy in our interpretations. The Pleistocene climatic variability induced periodic and gradual replacements of fish taxa. Episodic invasions of cold-water North Atlantic mesopelagic species are correlated with intervals of climatic deterioration, specifically during marine isotope stages 50, 44, 36, 20, and 18.

Location and morphological identification of Myxosporida and evaluation of the effect of freezing and Giemsa staining on the spore length

Enteromyxum leei, Ceratomyxa spp., Polysporoplasma spans are myxosporea usually found in cultured Mediterranean marine fish. The present study refers to the evaluation of the seasonality and prevalence caused by myxosporea infections in cultured sharpsnout seabream (Puntazzo puntazzo C.) and gilthead seabream {Spams aurata L.). The main target organ of all infected fish was the intestine and some-times the gallbladder and the kidney were also target organs. The highest prevalence was observed during summer in cultured sharpsnout seabream. P. sparis has been observed in gilthhead seabream, which proved to be the main host of this parasite, but it was also observed in cultured sharpsnout seabream. The main target organ in all infected fish was the kidney. The highest prevalence was observed during summer in cultured gilthead seabream. Mature spores of Ceratomyxa diplodae were observed in sharpsnout seabream. The main target organ of the parasite in cultured fish was the gallbladder. The morphology and size observations of myxosporeans mentioned above were also studied. Freezing in -20 °C (for 1 and 6 months) and the effect of Giemsa staining in myxosporean mature spore's size were evaluated. According to the results, 6 months freezing and Giemsa staining reduced significantly the size of mature spores. Finally, the protocol for Giemsa staining for the three different myxosporea species, usually found in cultured mediterranean marine fish, was standardized. Fresh smears were stained by Giemsa, according to protocol used for fresh smears. For E. leei the best results were obtained after immersing the smears in the stain for 20 min, for C diplodae after immersing the smears in the stain for 30 min and for P. sparis after immersing the smears in the stain for 24 min.

Gap analysis on the biology of Mediterranean marine fishes.

We estimated the current level of knowledge concerning several biological characteristics of the Mediterranean marine fishes by carrying out a gap analysis based on information extracted from the literature, aiming to identify research trends and future needs in the field of Mediterranean fish biology that can be used in stock assessments, ecosystem modeling and fisheries management. Based on the datasets that emerged from the literature review, there is no information on any biological characteristic for 43% (n = 310) of the Mediterranean fish species, whereas for an additional 15% (n = 109) of them there is information about just one characteristic. The gap between current and desired knowledge (defined here as having information on most biological characteristics for at least half of the Mediterranean marine fishes) is smaller in length-weight relationships, which have been studied for 43% of the species, followed by spawning (39%), diet (29%), growth (25%), maturity (24%), lifespan (19%) and fecundity (17%). The gap is larger in natural mortality for which information is very scarce (8%). European hake (Merluccius merluccius), red mullet (Mullus barbatus), annular seabream (Diplodus annularis), common pandora (Pagellus erythrinus), European anchovy (Engraulis encrasicolus), European pilchard (Sardina pilchardus) and bogue (Boops boops) were the most studied species, while sharks and rays were among the least studied ones. Only 25 species were fully studied, i.e. there was available information on all their biological characteristics. The knowledge gaps per characteristic varied among the western, central and eastern Mediterranean subregions. The number of available records per species was positively related to total landings, while no relationship emerged with its maximum reported length, trophic level and commercial value. Future research priorities that should be focused on less studied species (e.g. sharks and rays) and mortality/fecundity instead of length-weight relationships, as well as the economy of scientific sampling (using the entire catch to acquire data on as many biological characteristics as possible) are discussed.

DNA barcoding for species assignment: the case of Mediterranean marine fishes.

BackgroundDNA barcoding enhances the prospects for species-level identifications globally using a standardized and authenticated DNA-based approach. Reference libraries comprising validated DNA barcodes (COI) constitute robust datasets for testing query sequences, providing considerable utility to identify marine fish and other organisms. Here we test the feasibility of using DNA barcoding to assign species to tissue samples from fish collected in the central Mediterranean Sea, a major contributor to the European marine ichthyofaunal diversity.Methodology/Principal FindingsA dataset of 1278 DNA barcodes, representing 218 marine fish species, was used to test the utility of DNA barcodes to assign species from query sequences. We tested query sequences against 1) a reference library of ranked DNA barcodes from the neighbouring North East Atlantic, and 2) the public databases BOLD and GenBank. In the first case, a reference library comprising DNA barcodes with reliability grades for 146 fish species was used as diagnostic dataset to screen 486 query DNA sequences from fish specimens collected in the central basin of the Mediterranean Sea. Of all query sequences suitable for comparisons 98% were unambiguously confirmed through complete match with reference DNA barcodes. In the second case, it was possible to assign species to 83% (BOLD-IDS) and 72% (GenBank) of the sequences from the Mediterranean. Relatively high intraspecific genetic distances were found in 7 species (2.2%–18.74%), most of them of high commercial relevance, suggesting possible cryptic species.Conclusion/SignificanceWe emphasize the discriminatory power of COI barcodes and their application to cases requiring species level resolution starting from query sequences. Results highlight the value of public reference libraries of reliability grade-annotated DNA barcodes, to identify species from different geographical origins. The ability to assign species with high precision from DNA samples of disparate quality and origin has major utility in several fields, from fisheries and conservation programs to control of fish products authenticity.

Age at maturity of Mediterranean marine fishes

In this review we collected data on the age at maturity (tm) and maximum reported age (tmax) for 235 stocks of Mediterranean marine fishes, belonging to 82 species, 37 families, 12 orders and 2 classes (Actinopterygii and Elasmobranchii). Among Actinopterygii (mean tm ± SD = 2.20 ± 1.43 y, n = 215), tm ranged from 0.3 y, for the common goby Pomatoschistus microps, to 12 y, for dusky grouper Epinephelus marginatus, while among Elasmobranchii (mean tm ± SD = 5.94 ± 2.47 y, n = 20), tm ranged between 2.7 y, for brown ray Raja miraletus, and 12 y for picked dogfish Squalus acanthias. Overall, the tmax ranged between 1 y, for transparent goby Aphia minuta, and 70 y, for wreckfish Polyprion americanus. The mean tmax of Actinopterygii (tmax ± SD = 10.14 ± 9.42 y) was lower than that of Elasmobranchii (tmax ± SD = 14.05 ± 8.47 y). The tm exhibited a strong positive linear relation with tmax for both Actinopterygii (logtm = 0.58 ´ logtmax – 0.25, r2 = 0.51, P < 0.001) and Elasmobranchii (logtm = 0.67 ´ logtmax – 0.006, r2 = 0.51, P = 0.007). The mean tm/tmax did not differ significantly with sex within Actinopterygii (ANOVA: F = 0.27, P = 0.60, n = 90; females: mean ± SD = 0.276 ± 0.143; males: mean ± SD = 0.265 ± 0.138) and Elasmobranchii (ANOVA: F = 1.44, P = 0.25, n = 10; females: mean ± SD = 0.499 ± 0.166; males: mean ± SD = 0.418 ± 0.133). Finally, the dimensionless ratio tm/tmax was significantly lower (ANOVA: F = 31.04, P < 0.001) for Actinopterygii (mean ± SD = 0.270 ± 0.135, n = 180) than for Elasmobranchii, (mean ± SD = 0.458 ± 0.152, n = 20), when stocks with combined sexes were excluded from the analysis.

Size at maturity of Mediterranean marine fishes

In this review we collected data on the length at maturity (Lm) and maximum reported total length (Lmax) of 565 Mediterranean marine fish stocks, representing 150 species, 68 families, 24 orders and 3 classes. Overall, Lm ranged from 2 cm, for the males of the toothcarp Aphanius fasciatus, to 350 cm, for the females of the bluntnose sixgill shark Hexanchus gris- eus .L m was positively linearly related with Lmax for Actinopterygii (logLm =- 0.123 ? 0.92 9 logLmax; r 2 = 0.87, n = 471, P \ 0.001) and Elasmobranchii (logLm =- 0.008 ? 0.922 9 logLmax; r 2 = 0.90, n = 92, P \ 0.001) with the two slopes being signif- icantly different (ANCOVA: F = 2,904, P \ 0.001). The reproductive load (Lm/Lmax) ranged between 0.23 (sand steenbras Lithognathus mormyrus) and 0.94 (angular roughshark Oxynotus centrina and thornback ray Raja clavata). The mean Lm/Lmax was signifi- cantly (ANOVA, F = 34.14, P \ 0.001) lower for Actinopterygii (mean = 0.59, SD = 0.122, n = 471) compared to Elasmobranchii (mean = 0.70, SD = 0.132, n = 92) and Holocephali (mean = 0.77, SD = 0.077, n = 2). The Lm/Lmax was significantly (ANOVA, F = 43.80, P \ 0.001) higher for species providing some form of parental care, i.e. guarders, bearers, nesters (mean Lm/Lmax ± SD = 0.68 ± 0.141, n = 111) compared to non-guarders (mean Lm/Lmax ± SD = 0.59 ± 0.123, n = 454). The mean Lm/Lmax displayed a remarkable constancy with longi- tude (northern and southern Mediterranean coastline: ANOVA, F = 0.01, P = 0.93), latitude (western, cen- tral and eastern regions: ANOVA, F = 1.25, P = 0.29) and habitat (ANOVA, F = 0.85, P = 0.51).

Proteomic evaluation of potentiated sulfa treatment on gilthead sea bream (Sparus aurata L.) liver

Potentiated sulfa drugs are a combination of sulfonamide and pyrimidine potentiators. They are currently used against fish bacterial pathogens in Mediterranean marine fish farming. The present work aimed studying the potential hepatotoxicity of a combination of sulfadiazine (SDZ) and trimethoprim (TMP) in gilthead sea bream juveniles after oral administration, at the recommended ratio of 5:1 (SDZ/TMP), equivalent to a dose of 30mgkg−1fishday−1, for 10days at 19°C temperature. Electrophoresis (DIGE) technology coupled with MS was used to identify possible markers of hepatotoxicity of this treatment. The results obtained show significant changes in the expression of 41 proteins by treatment (p≤0.02). Among these proteins, 14 increased in abundance, and 27 decreased with respect to the control group. Proteins showing differential expression with respect to the control were identified by PMF and/or LC-MS/MS and database research. Proteins like apolipoprotein A-I and fatty acid binding protein (lipid metabolism and transport, and antioxidant role), phosphoglucomutase 1 (carbohydrate metabolism), elongation factor 1-alpha (protein biosynthesis and antioxidant role), mitochondrial aldehyde dehydrogenase (oxidation regulation activity and antioxidant role) and ypbc-32-D06 (aminotransferases), were differentially expressed in treated fish. These proteins have not been associated before with potentiated sulfa effect in farmed fish. However, they are frequently found differentially expressed as a characteristic cellular/tissue stress response under different experimental conditions, making difficult their use as specific biomarkers for this treatment.

Species specificity in the magnitude and duration of the acute stress response in Mediterranean marine fish in culture

The aim of the present study was to examine the species-specific stress response for seven Mediterranean fishes in culture. Also, to evaluate the method of measuring free cortisol concentration in the rearing water as a non-invasive and reliable indicator of stress in marine species, of aquaculture importance. Gilthead sea bream, Sparus aurata (Sparidae); common dentex, Dentex dentex (Sparidae); common Pandora, Pagellus erythrinus (Sparidae); sharpsnout sea bream, Diplodus puntazzo (Sparidae); dusky grouper, Epinephelus marginatus (Serranidae); meagre, Argyrosomus regius (Sciaenidae) and European sea bass, Dicentrarchus labrax (Moronidae) were subjected to identical acute stress (5–6 min chasing and 1–1.5 min air exposure) under the same environmental conditions and samples were analyzed by the same procedures. Results indicated that there was a clear species-specificity in the magnitude, timing and duration of the stress response in terms of cortisol, glucose and lactate. European sea bass showed a very high response and dusky grouper and meagre a very low response, except plasma glucose concentrations of dusky grouper which was constantly high, while sharpsnout sea bream presented a protracted stress response, up to 8 h. The present study confirmed that free cortisol release rate into the water can be used as a reliable stress indicator.

Spawning period of Mediterranean marine fishes

We collected all available information (i.e. international and local journals, conference proceedings, theses, technical reports) on the spawning season (n = 511 stocks, 168 species), gonadosomatic index (n = 237 stocks, 81 species) and sex ratio (n = 97 stocks, 68 species) of Mediterranean marine fish. The 511 stocks represented 20 orders (most were Perciformes, 283 stocks) and 65 families (most were Sparidae: 17 species and 63 stocks). Overall, 346 stocks (128 species) spawned between April and August, 139 stocks (60 species) between September and March, while the remaining 26 stocks (13 species) were all-year-round spawners. In addition, 174 stocks (34.1%) were characterised by an extended (>4 months) spawning season, but, for most stocks (332 stocks, 64.4%), spawning duration ranged from 2 to 4 months inclusive. Regardless of the onset and the duration of spawning, the spawning period of 284 and 287 stocks included June and July, respectively, indicating that most Mediterranean species are summer spawners. Female gonadosomatic index ranged between 0.06 and 37 (mean ± SE = 8.55 ± 0.647, n = 95) and was significantly higher (t-test: t = 5.58, P < 0.001) than the corresponding male one, which ranged between 0.06 and 30 (mean ± SE = 4.21 ± 0.431, n = 95). Congeneric species that occupied the same area and share the same requirements exhibited successive and non-overlapping spawning (e.g. Sparidae in the Adriatic Sea, Mugilidae in the Ionian Sea and Tunisian waters). The knowledge of the spawning period coupled with information on spawning and nursery grounds and detailed knowledge of mating systems, social interactions, maturity and fecundity may be very useful for fisheries management.

Muscular cholinesterase activities and lipid peroxidation levels as biomarkers in several Mediterranean marine fish species and their relationship with ecological variables

Muscular cholinesterase activities, as potential markers of neurotoxic exposure, and lipid peroxidation levels, indicative of oxidative stress damage, both currently used in early-warning pollution monitoring, were characterised in eighteen fish species of ecologic and/or economic importance. These species comprise five orders and eleven families of teleosts and two species of elasmobranchs, feed using different strategies (benthic, epibenthic, endobenthic and pelagic), belong to different trophic levels and express different swimming behaviour. Their habitat ranges from 50 to 60 m (shallow or continental shelf) and 600 to 850 m (middle continental slope). Sampling took place in front of the Barcelona coast (NW Mediterranean) during four seasonal cruises in 2007. In the summer sampling, another site potentially exposed to a different pollution load (Vilanova) was included for comparison. Species, seasonal and site differences were tested and discussed in relation to chemical analysis of the local sediment, systematic position, habitat depth, feeding strategy, trophic level and swimming activity. Greater inter species differences rather than seasonal or site trends were seen in accordance to little pollution fluctuations. Higher cholinesterase activities were recorded in suprabenthos feeders, regardless of depth habitat, whereas LP levels were similar in all species except for the shark Scyliorhinus canicula in which they were consistently elevated. This study confirms and broadens former observations carried out with a more reduced number of fish species (Solé et al., 2008a).

Reference biochemical values for three cultured Sparid fish: striped sea bream, Lithognathus mormyrus; common dentex, Dentex dentex; and gilthead sea bream, Sparus aurata

The aim of the present study was to set up reference intervals for biochemical parameters in new candidate species of Mediterranean marine fish culture—striped sea bream, Lithognathus mormyrus and common dentex, Dentex dentex as well as traditionally cultured species—gilthead sea bream, Sparus aurata. The reference biochemical values were assessed for plasma cortisol, glucose, Ca, inorganic P, Na, K, Cl, C-reactive protein, hematocrit, and prothrombin time. The biochemical reference values established may allow important physiological decision in adaptation process of striped sea bream and common dentex as well as provide contribution to our present knowledge on gilthead sea bream physiology.

Comparative analysis: a tool for studying monogenean ecology and evolution

The comparative approach has been used widely in evolutionary ecology during the last 10 years. In the first part of this study, taking monogeneans of Mediterranean marine fishes as an example, we highlight the pitfalls that may arise in interspecific studies. In the second part, the independent contrast method is used to control for phylogenetic effects in order to evaluate the determinants of monogenean species richness and their specificity. Our results show the importance of controlling data for both host sample size and phylogeny to avoid confounding effects. Thereafter, taking into account both sampling effort and phylogenetic effects, our results show that host size is the main factor affecting monogenean species richness and specificity.

Determinants of parasite species richness in Mediterranean marine fishes

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 149:61-71 (1997) - doi:10.3354/meps149061 Determinants of parasite species richness in Mediterranean marine fishes Sasal P, Morand S, Guégan JF Data on parasites of Mediterranean Sea fishes, collected from previous published surveys, were used to test 5 hypotheses concerning the determinants of parasite species richness. A total of 170 parasite species belonging to 5 distinct taxonomic groups (nematodes, acanthocephalans, digeneans, monogeneans and crustaceans) were identified from 79 marine fish species (3904 individuals) collected at a regional scale. Five independent variables concerning host life traits (body size, diet, range, abundance and schooling) were investigated and controlled for host sampling effort. A comparative analysis using the independent contrasts method was conducted in order to avoid phylogenetic confounding effects. We demonstrate the importance of taking host sampling effort into account when investigating the determinants of parasite species richness. Monogeneans were the only group for which the species richness showed a significant correlation with some of the variables studied. Parasite species richness of monogeneans was positively correlated with host body size and negatively correlated with host species abundance. The positive relationship between fish body size and the number of parasite species on a regional scale may be explained by the hypothesis that larger host body size increases host vagility which in turn enhances exposure to more and more parasite species. Our findings disagree with previous studies that did not take either phylogenetic confounding effects or geographic scale into account. We demonstrate the importance of using phylogenetic information in comparative analyses by showing that fish body size was not correlated with geographical range when using phylogenetic independent contrasts. We also suggest that studying parasites of host species from the same geographical region avoids the problem of confounding various assemblages of hosts with distinct histories. Parasite · Marine fish · Species richness · Independent contrasts · Sampling effort · Body size · Fish abundance Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 149. Publication date: April 10, 1997 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1997 Inter-Research.

Larviculture of Mediterranean Marine Fish Species: Current Status and Future Trends

AbstractThe larviculture of Mediterranean marine fish species has focused on the production of Spurus auruta and Dicentrarchus labrar. European fry production of these species has increased from 12 million in 1987 to 28 million in 1989 and is expected to rise to nearly 40 million fry in 1990.Within differing hatchery systems, larval survival has been improved through the use of commercially available w3‐HUFA rich live food enrichment diets. This combined with the use of surface cleaning techniques has led to a standardization of larval rearing procedures enabling mass production of quality fry. Increased concern with larval hygiene has resulted in larger larval rearing batch production and regular sterilization periods in most European units.Market pressure is stimulating established producers to diversify their species range and industrial quantities of Puntazzo puntuzzo, and Pagrus major are already being produced. Work has started on the larval culture of Dentex dentex, Pagrus pagrus and Seriola dumerilli.