Dicentrarchus Punctatus Research Articles

Coexisting in the Surf Zone: Age and Feeding Habits of the Spotted Seabass (Dicentrarchus punctatus) and European Seabass (Dicentrarchus labrax) on the Gulf of Cádiz Beaches (Southwest Iberian Peninsula)

Various commercial fish species utilize different coastal habitats as nurseries in their juvenile stages, with surf zones being particularly crucial due to the protection and abundant food resources they offer. Among the species that rely on these areas are the spotted seabass (Dicentrarchus punctatus) and the European seabass (Dicentrarchus labrax). This study aimed to investigate the age and feeding habits of surf zone specimens of these species and explore their environmental adaptations. The average size for D. punctatus was 16.94 ± 4.05 cm, and for D. labrax, it was 23.23 ± 6.30 cm. The length–weight relationship for D. punctatus was TW = 0.013*TL2.885 (parameter a: 95% CI: 0.012–0.014; parameter b: 95% CI: 2.854–2.917), and for D. labrax, it was TW = 0.008*TL3.095 (parameter a: 95% CI: 0.006–0.009; parameter b: 95% CI: 3.040–3.151). In both D. punctatus (79.20%) and D. labrax (75.92%), the predominant age classes were 1+ and 2+. Significant variations in age class abundance were observed in D. punctatus based on the time of day, lunar phase, and season, while D. labrax showed variations only by season. A diet analysis revealed that both species primarily consume mysids and fish, with D. punctatus showing dietary variations related to the time of day, lunar phase, and season, and D. labrax showing variations with the time of day and season.

Reproductive Biology of the Spotted Sea bass, Dicentrarchus punctatus, in Bardawil Lagoon, North Sinai, Egypt

Reproductive Biology of the Spotted Sea bass, Dicentrarchus punctatus, in Bardawil Lagoon, North Sinai, Egypt

Assessing fishery status and sustainable exploitation of spotted seabass (Dicentrarchus punctatus) in Bardawil Lagoon, Eastern Mediterranean, Egypt

The growth and population parameters of spotted seabass (Dicentrarchus punctatus) in Bardawil Lagoon were investigated to assess their fishery status and propose concrete recommendations for sustainable exploitation. The samples (n = 271) were collected from commercial catches during 2021. As revealed by examining the otoliths, D. punctatus has a short life span of a maximum of four years based on the mean lengths of 20.2, 25.3, 29.7, and 33.5 cm for age groups from I to IV, respectively. The total length-weight relationship equations were W = 0.0120TL2.9672 for males, W = 0.0127TL2.9486 for females and W = 0.0124TL2.9563 for the combined sexes. The von Bertalanffy growth function was Lt = 40.50(1-e-0.38(t+0.66)). The study determined the total and natural mortality rates as 1.58 and 0.79 year−1, respectively, with an exploitation rate (E) of 0.49, which was found close to the optimum value (0.5). However, based on management policies, E was greater than the value corresponding to 50% relative biomass per recruit (E0.5), which indicates that the current fishing effort is unsustainable. Therefore, to maintain the biomass of spawning stocks, the study recommends a 22.4% reduction in the current exploitation rate through the application of fishing regulations that decrease fishing efforts. Such recommendations can help ensure the sustainable exploitation of spotted seabass in Bardawil Lagoon.

The contribution of ancient admixture to reproductive isolation between European sea bass lineages.

Understanding how new species arise through the progressive establishment of reproductive isolation (RI) barriers between diverging populations is a major goal in Evolutionary Biology. An important result of speciation genomics studies is that genomic regions involved in RI frequently harbor anciently diverged haplotypes that predate the reconstructed history of species divergence. The possible origins of these old alleles remain much debated, as they relate to contrasting mechanisms of speciation that are not yet fully understood. In the European sea bass (Dicentrarchus labrax), the genomic regions involved in RI between Atlantic and Mediterranean lineages are enriched for anciently diverged alleles of unknown origin. Here, we used haplotype‐resolved whole‐genome sequences to test whether divergent haplotypes could have originated from a closely related species, the spotted sea bass (Dicentrarchus punctatus). We found that an ancient admixture event between D. labrax and D. punctatus is responsible for the presence of shared derived alleles that segregate at low frequencies in both lineages of D. labrax. An exception to this was found within regions involved in RI between the two D. labrax lineages. In those regions, archaic tracts originating from D. punctatus locally reached high frequencies or even fixation in Atlantic genomes but were almost absent in the Mediterranean. We showed that the ancient admixture event most likely occurred between D. punctatus and the D. labrax Atlantic lineage, while Atlantic and Mediterranean D. labrax lineages were experiencing allopatric isolation. Our results suggest that local adaptive introgression and/or the resolution of genomic conflicts provoked by ancient admixture have probably contributed to the establishment of RI between the two D. labrax lineages.

Population genetic studies of genus Dicentrarchus reveal loss of genetic diversity in Egyptian waters

Genus Dicentrarchus includes two closely related, and commercially important species, Dicentrarchus labrax and Dicentrarchus punctatus. These species have similar morphological features in early developmental stages, nevertheless, they have noticeably different growth rates. The molecular differentiation between these species is therefore of interest. Moreover, the assessment of genetic diversity within and among populations is a primary step towards investigating the population structure and proper conservation of wild stocks of these species in Egypt. For these purposes, in total 141 samples of both species were collected from three locations along the Mediterranean Sea (Maadia, Damietta and Bardawil Lagoon), in Egypt. The samples were sorted according to their external features into 87 D. labrax samples and 54 D. punctatus samples. A partial sequence of cytochrome oxidase subunit I (COI) gene was used to barcode the two species and to assess the genetic diversity of the collected samples. For population differentiation comparisons, D. labrax COI sequences representing six European countries (France, Spain, Sweden, Turkey, the UK and Germany) were retrieved from the NCBI database and used in the analysis. Among the Egyptian D. labrax populations, only six haplotypes were identified, with low haplotype diversity and nucleotide diversity (average Hd=0.2214, average π=0.001), suggesting possible reduction in population size. Eleven haplotypes were identified in D. punctatus populations, with moderate haplotype diversity and low nucleotide diversity (average Hd=0.469, average π=0.002). The recorded overexploitation of both species could be a reason for the reduced genetic diversity. The studied populations of both species exhibited low inter-population differentiation (average FST=0.035 and 0.065 for D. labrax and D. punctatus, respectively). However, high FST values were recorded between the Egyptian D. labrax populations and the European populations (FST=0.626–0.962, p<0.01) except for Turkey (FST=0.037, p<0.05). Special attention should be directed to proper protection and management of the existing diversity of the two Dicentrarchus species in Egypt.

Studies on Prevailing Parasitic Trematodiasis Affecting Some Cultured Marine Fishes in Ismailia Governorate

This study was carried out to detect the trematodes affecting some marine fishes. Fish species collected were 100 Dicentrarchus labrax and 100 Dicentrarchus punctatus from private farms at Ismailia provinces. There were no pathognomonic signs in infested fishes except marbling of gills in fishes with gill monogenean infestations. Other signs and P. M. lesions were haemorrhages, abrasions on skin, sluggish movement, abdominal distension and emaciation, pale liver, congesion intestine with entritis in some cases. The higher infestation rate was in D. punctatus (52%) followed by D. labrax (35%). The isolated parasites in D. labrax and D. punctatus were monogenetic trematodes (Diplectanum bocqueti) and Digenetic trematodes (Acanthostomum sp.and Allostomachicolina secundus). Detection of Acanthostomum sp. using molecular biology (PCR) was recorded. Seasonal prevalence in relation to fish sex, body weight, body length and infestation, statistical analysis and histopathological picture was also recorded.

Feeding Habitats, Connectivity and Origin of Organic Matter Supporting Fish Populations in an Estuary with a Reduced Intertidal Area Assessed by Stable Isotope Analysis

Stable isotopes (δ13C and δ15N) were used to analyse the food web downstream of the largest estuary on the French coast: the Gironde. The different sources of organic matter supporting the most abundant and commercially important fish species were determined, as well as habitat connectivity for fish. Stable isotope analysis was performed in different producers (marine, freshwater and local sources), primary consumers (zooplankton and macrozoobenthos) and nine fish species (Alosa alosa, Engraulis encrasicolus, Sprattus sprattus, Liza ramada, Pomatoschistus minutus, Platichthys flesus, Solea solea, Dicentrarchus punctatus and Argyrosomus regius) in three habitats of the downstream area of the estuary in June–July 2012. All sources and invertebrates had significantly different isotopic signatures in different habitats. Only sole, S. solea, presented distinct dual isotopic signatures, indicating a higher feeding location fidelity, no other fish species showed significant differences in isotopic signatures. This overlap was interpreted as evidence that fish had not been feeding exclusively in the habitat where they were collected, instead ingesting food with different isotopic signatures, reflecting high habitat connectivity for these fish. As the base of the fish food web significantly differed among habitats, the present study indicated the suitability of stable isotopes in tracing fish movements and their fidelity/connectivity for habitats separated by less than 10 km, particularly estuarine habitats without salinity differences but located on opposite banks. The SIAR mixing model estimations of organic matter contribution to fish diets in the Gironde estuary were quite similar for the fish species investigated. The major organic source was marine-derived POM, with contributions >75 % for each species. Freshwater and local POM (generally indicated as the sources structuring estuarine food webs) contributed little to the overall fish food webs in the Gironde estuary. Only flounder, P. flesus, and shad, A. alosa, migratory amphihaline species, utilised freshwater POM in greater proportion than marine. The observed low freshwater POM-high marine POM contribution to the fish food web seems to be explained by the reduced intertidal surface of the system. This characterization of the trophic base and habitat connectivity for the most important Gironde estuary fish provides a novel insight for future management of the estuary, especially in the current context of global change.

A phylogeny of the temperate seabasses (Moronidae) characterized by a translocation of the mt‐nd6 gene

The entire mitochondrial genome of the striped bass Morone saxatilis was sequenced together with the mitochondrial (mt) control regions of the white bass Morone chrysops, white perch Morone americana, yellow bass Morone mississippiensis, spotted seabass Dicentrarchus punctatus, European seabass Dicentrarchus labrax and the Japanese seabass Lateolabrax japonicus. The resultant 17 580 base pair circular genome of M. saxatilis contains 38 genes (13 proteins, 23 transfer RNAs and two ribosomal RNAs) and a control region bordered by the proline and phenylalanine mitochondrial tRNAs. Gene arrangement was similar to other vertebrates, except that the mt-nd6 gene was found within the control region rather than the canonical position between the mt-nd5 and mt-cyb genes. This translocation was found in all the Morone and Dicentrarchus species studied without functional copies or pseudogenes in the ancestral position. In L. japonicus, the mt-nd6 gene was found in the canonical position without evidence of an mt-nd6 gene in the control region. A Bayesian analysis of these and published mt-nd6 sequences from 45 other Perciformes grouped the Morone and Dicentrarchus species monophyletically with a probability of 1·00 with respect to L. japonicus and all other perciforms, and placed the Dicentrarchus species in the basal position. These data reinforce current placement of L. japonicus outside the Moronidae and provide a clear evolutionary character to define this family. The phylogeny of the Moronidae presented here also supports the hypothesis of an anadromous common ancestor to this family that gave rise to the North American estuarine and freshwater species. A series of tandem repeats previously reported in M. saxatilis was found in the control region of all Morone species between the mt-nd6 and mt-rnr1 genes, but not in either Dicentrarchus species, which reinforces the continued use of these two separate genera.

The impact of extreme turbidity events on the nursery function of a temperate European estuary with regulated freshwater inflow

Estuaries are used as nursery grounds by numerous marine species despite being usually subject to strong anthropogenic disturbances. Abundances of marine recruits (fish and crustacean decapods) and their main prey (mysids) were monitored by monthly sampling, from June 1997 to February 2009, in the lower reaches of the Guadalquivir estuary (SW Spain). During that period, unusually high and persistent turbidity events (HPTEs) were observed twice. Both HPTEs started with strong and sudden freshwater discharges after relatively long periods of very low freshwater inflow. Data from this time-series were used to test the hypothesis that HPTEs may negatively impact the nursery function of estuaries either by decreasing prey availability or by decreasing survival/arrival of marine recruits. During HPTEs, the commonest mysid ( Mesopodopsis slabberi), a key species in the estuarine food web, showed a significant decrease in abundance. Likewise, some marine recruits that prey on M. slabberi and whose peaks of abundance within the estuary occur in summer–autumn ( Engraulis encrasicolus and Pomadasys incisus) were less abundant during HPTEs. It is also suggested that HPTEs might have triggered a shift in the distribution of the most euryhaline prey ( Neomysis integer) and predator ( Dicentrarchus punctatus and Crangon crangon) species, towards more saline waters. This could have contributed to an increase in the inter-specific competition (for food/habitat) within the estuarine nursery area. The results discussed in this study call attention to the need to reduce as much as possible the anthropogenic pressures that may stimulate the occurrence of high and persistent turbidity events (HPTEs) in order to preserve the nursery function of temperate estuaries.

Analysis of three multigene families as useful tools in species characterization of two closely-related species, Dicentrarchus labrax, Dicentrarchus punctatus and their hybrids

By analyzing three multigene families, two closely related and commercially important species, Dicentrarchus labrax and Dicentrarchus punctatus, were characterized by cytogenetic and molecular methods. The interspecies hybrid Dicentrarchus labrax (♀) × Dicentrarchus punctatus (♂) was also analyzed. The multigene families studied were the 5S rDNA, 45S rDNA and the U2 snRNA. A microsatellite GTT motif was found within the non transcribed spacers (NTS) of the 5S rDNA from the two species. However, hexanucleotide duplication next to this microsatellite was observed in the D. labrax and hybrid clones, but not in D. punctatus. The U2 snRNA appeared to be linked to the U5 gene and showed two variant sequences, in both D. labrax and D. punctatus. They differed in one insertion/deletion of 7 nucleotides. The first internal transcribed spacer (ITS-1) region showed higher nucleotide variability in D. punctatus than in D. labrax. Nucleotide polymorphism within species and also nucleotide divergence between species were determined in the different gene regions. In a FISH analysis we obtained three chromosomal markers, because the 5S rDNA, 18S rDNA and U2 snRNA probes hybridized each in three different chromosome pairs. Hence none of them was co-localized. The 5S rDNA cluster and U2 snRNA were localized in acrocentric chromosome pairs, while the 18S rRNA gene probe hybridized in a subtelocentric pair. Finally, the usefulness of the results in developing tools for phylogenetic analysis and species identification are discussed in relation to other fish species.

Putative transcription factor binding sites and polymorphisms in the proximal promoter of the PRL‐A gene in percomorphs and European sea bass (Dicentrarchus labrax)

AbstractThere is an increasing interest in exploring how the mechanisms that regulate gene expression might generate diversity in phenotypes as a function of habitat utilisation (at both inter‐ and intra‐specific levels). Prolactin (PRL) is the main hormone involved in adaptation to low salinity in teleosts. Several mechanisms regulating PRL‐A gene expression have been described. The main mechanisms involve Pit‐1 binding sites and length polymorphism of a short sequence repeat (SSR) located in the proximal promoter (PP) of the gene. Together, these processes may generate phenotypes with potentially distinct physiological responses to salinity. To gain insight into their relative roles and importance, we sequenced the PP of the PRL‐A gene in the euryhaline European sea bass (Dicentrarchus labrax) and in the stenohaline sister species, Dicentrarchus punctatus. Then, we assessed the presence of both SSR and binding elements in PP among several teleost lineages, by checking available data from the literature and GenBank. The sequence of PRL‐A PP was completely distinct between the percomorphs and other lineages such as salmoniform, siluriform and cypriniform, except for short stretches of nucleotides that were highly conserved across all species, also including mammals. Most of them were identified as putative cis‐regulatory elements, including Pit‐1, but also δEF1, c‐ETS, CEBP, and GATA binding factor 2, previously unreported as regulating PRL‐A transcription in teleosts, but involved in gene regulation in mammals. This result suggests that there is greater conservation of PRL‐A regulatory mechanisms across vertebrate lineages than previously thought, and offers new perspectives for future studies. The presence and homology of an SSR in the PP of PRL‐A gene of percomorphs was demonstrated, but no SSR polymorphisms were found amongst the two Dicentrarchus species, or within natural D. labrax populations covering the known range of natural genetic variation, including marine, brackish water and freshwater populations.

FISHERIES REGULATIONS BASED ON YIELD PER RECRUIT ANALYSIS FOR THE SPOTTED SEABASS DICENTRARCHUS PUNCTATUS (MORONIDAE) AT BARDAWIL LAGOON, MEDITERRANEAN COAST OF SINAI, EGYPT

he spotted seabass Dicentrarchus punctatus in Bardawil Lagoon was assessed using Beverton and Holt relative yield per recruit model. A total of 879 specimens were collected during two fishing seasons between April 2004 and December 2005. The maximum life span was four years for length range of 13.8 – 35 cm TL. The parameters of the von Bertalanffy growth function were K = 0.581 year -1 , L∞ = 37.476 cm and t0 = -0.227 years. The rates of total mortality Z and natural mortality M were 1.32 and 0.40 year -1 respectively. Rates of fishing mortality F = 0.92 year -1 and exploitation E = 0.70 indicate that the population of this species is being heavily exploited. The estimated total length at first capture Lc was 14.8 cm, while the total length at 50% maturity was 25.13 cm. Reproductive activity of spotted seabass took place between November and February, with the greatest intensity in December. Yield per recruit analysis revealed over-fished stock conditions particularly because small fish are effectively unprotected by current minimum size regulations. Based on the analysis it is recommended that the commercial fishery of Bardawil Lagoon should be subjected to a total allowable catch, bag limits should be lowered and a maximum size limit be implemented.

Discards of the beach seine fishery in the central coast of Portugal

The beach seine fishery is performed regularly along the Portuguese coast in shallow water sandy areas. The catches and discards of this fishery were studied from March until November 1999, on the coast south of Lisbon. Fishing operations were monitored weekly and estimates of the weight of catches and discards per species were determined for each haul. A total of 60 fish species was identified in the catches but Scomber japonicus, Trachurus trachurus and Diplodus bellottii represented approximately 90% of the catches. For most of the species the percentage of discarded fish was extremely high (ca. 100%). The species for which the estimates of discards were lower than 25% of the catches were Sardina pilchardus, Merluccius merluccius, Dicentrarchus labrax, Dicentrarchus punctatus, T. trachurus, several Sparidae species, Spicara maena, S. japonicus, Solea senegalensis, and Solea solea. Most of the species exhibited a marked seasonal abundance pattern that varied according to the species. Discards also varied considerably within and between seasons. The relationships between discards and total catch, species catch, mean length of fish and percentage of fish above minimum legal size were different according to species. For S. japonicus and S. pilchardus discards were negatively correlated with their catch, mean length of fish and percentage of fish above minimum legal size, while for T. trachurus significant correlations were obtained only for the last two variables.

Analyse comparée de la structure génétique de deux espèces de poissons marins apparentées et sympatriques Dicentrarchus labrax et Dicentrarchus punctatus

We present here the genetic structure existing among five samples of the spotted sea bass Dicentrarchus punctatus, and we compare it to what prevails in the common sea bass D. labrax, a congeneric species sampled on almost the same geographical range. A genetic distance tree inferred from the polymorphism at six microsatellite loci shows a distinct pattern for the two species. D. labrax samples appears to be genetically more homogeneous with a global Fst of 3% as compared to the 10% observed at D. punctatus, indicating a lesser level of gene flow in the latter species. While appearing more differentiated, D. punctatus presents no clear geographical organisation of its genetic variability in opposition to D. labrax samples. This allows us to propose this pair of closely relative species as a good candidate for the study by comparative analysis of the biological and/or historical factors affecting genetic differentiation in marine environment.

Karyotype analysis, nucleolar organizer regions(NORs), and C-banding pattern of Dicentrarchus iabrax(L.) and Dicentrarchus punctatus(Block, 1792)(Pisces, Perciformes) with evidence of chromosomal structural polymorphism.

Chromosomes of Dicentrarchus labrax and Dicentrarchus punctatus collected from the Gulf of Palermo are examined from kidney cells. The diploid chromosome number in both species is 2n=48. Ag-NOR and C-banding analyses revealed the presence of structural chromosomal polymorphism involving pair 1.A comparative analysis among the Giemsa, NOR- and C-banded karyotypes suggests that a close phylogenetic relationship between D. labrax and D. punctatus occurs. There are evidences for a conservative evolutionary trend in this genus.

Sea basses, Dicentrarchus labrax (Linne) and D. punctatus (Bloch) (Pisces, Serranidae), a control fish in fresh water

Dicentrarchus labrax and Dicentrarchus punctatus is able to thrive and grow in fresh water ponds. In all experiments there was successful controlling of young Tilapia aurea in the experimental ponds in comparison to the control ones. The number of young T. aurea per female and per pond was significantly lower in the experimental ponds than in control ponds. In 1973 the average number of young T. aurea per female was 80 in the experimental ponds and 287 young in the control ponds. In 1974 the average number of T. aurea young per female was 48 in the experimental ponds and 586 young in the control ponds. The growth rate of D. punctatus and D. labrax was higher in fresh water ( S = 0.5‰) than in nature (salt water).