Annular Sea Bream Diplodus Annularis Research Articles

Pots vs trammel nets: a catch comparison study in a Mediterranean small-scale fishery.

Passive bottom-set nets are the most widely used fishing gears in Mediterranean small-scale fisheries (SSFs). Trammel nets, in particular, have key advantages such as their ease of use and handling and high capture efficiency for numerous commercial species. However, they entail high discard rates (5–44% of the total catch) connected to high mortality, thus exerting an adverse impact on benthic communities, besides catching individuals of commercial species under the minimum conservation reference size (MCRS) and specimens of protected species. Fish pots are seen as alternative and a more sustainable gear type that allow reducing discards in SSFs. In this study, a collapsible pot was tested at three coastal sites in the north-western Adriatic Sea (GFCM GSA 17) to compare its catch efficiency with that of the local traditional trammel nets. Data analysis demonstrated a similar catch efficiency for the commercial species, both among sites and as a whole. Moreover, the trammel net caught a larger amount of discards, both in terms of species number and of CPUEW. The catch comparison study involved the two most abundant landed species, common cuttlefish Sepia officinalis and annular sea bream Diplodus annularis. The pots were more effective for S. officinalis, whereas the trammel net was more effective for the shorter length classes for D. annularis, which were mostly under the MCRS (12 cm). The innovative pots could provide a valuable alternative to the trammel nets traditionally used in the Adriatic Sea, at least in certain areas and periods. Their main advantages include that they do not require a different rigging and they can be used without bait, while their foldable design allows large numbers to be easily loaded on board SSF vessels. The results of this pilot study indicate that pots can achieve the objectives of reducing discards and bycatch in SSFs without penalizing the catch of commercial species.

-Identification of a novel intestinal phospholipase A2 from annular seabream: Insights into its catalytic mechanism and its role in biological processes

Phospholipase A2 (PLA2) is responsible for the lipid hydrolysis process. Fish PLA2 have warranted renewed interest due to their excellent properties in phospholipid digestion. We report for the first time the catalytic properties of a PLA2 secreted from the intestine of the annular seabream Diplodus annularis (IDaPLA2). The refolded IDaPLA2 was purified to homogeneity and showed a molecular mass of around 15 kDa attested by SDS-PAGE and MALDI-TOF analyses. Interestingly, IDaPLA2 revealed higher thermostability compared to mammal pancreatic sPLA2 as it was active and stable at 55 °C with specific activity of 290 U mg−1 on phosphatidylcholine (PC) as a substrate. Using the lipid monolayer technique, the activity of IDaPLA2 was found to be 21.68, 6.88 and 5.66 mol cm−2 min−1 mM−1 using phosphatidylglycerol (PG), PC and phosphatidylethanolamine (PE) monolayers, respectively, at surface pressures from 20−30 mN m−1. Interestingly, the interfacial activity of IDaPLA2 measured at higher surface pressures may highlight its ability to penetrate into phospholipid monolayers suggesting its involvement in cell lipid membrane degradation which can explain the cytotoxicity potential towards macrophage. The docking simulation data provided insights into the involvement of some key amino-acids in substrate binding and selectivity. The dynamic simulation proved the high stability of IDaPLA2. Overall, these results provide original evidence on the involvement of IDaPLA2 into the lipid hydrolysis suggesting it as a potential target in biotechnological applications.

Genetic Analysis of Annular Sea Bream (Diplodus annularis Linnaeus, 1758) Populations Based on mtDNA Cyt b Gene in Turkey

Considering itsimportance and lack of information on its genetic structure, in this study, population genetic structure and genetic diversity of the annular seabream Diplodusannularis (L.) in the Turkish Seas was determined using the partial sequence of mitochondrial DNA cytochrome b gene (997 bp). Localities where annularseabream samples collected were as follows: the eastern Mediterranean Sea (Adana), the western Mediterranean Sea (Antalya), the Aegean Sea (İzmir), theMarmara Sea (Canakkale and İstanbul), Mid-Black Sea (Sinop) and the Eastern Black Sea (Rize). The population genetic structure was estimated throughpairwise FST, analysis of molecular variance and phylogenetic analyses (NJ, MP, ML and BI). As a result the genetic variability was low among the populationbased on haplotype and nucleotide diversities of cytochrome b gene. However, phylogenetic analyses of the cyt b haplotypes showed up there are two possiblegenetic groups (the Aegean-Mediterranean and Marmara-Black Sea) suggesting that the presence of restricted migration at the Straits of Dardanelles, separatingthe Aegean and Marmara Seas.

Ultrastructure and phylogeny of Ceratomyxa diplodae (Myxosporea: Ceratomyxidae), from gall bladder of European seabass Dicentrarchus labrax.

The myxosporean parasite Ceratomyxa diplodae Lubat et al. 1989 sensu Sitjà-Bobadilla & Álvarez-Pellitero, 1993, originally described from the annular seabream Diplodus annularis in the Adriatic Sea, has subsequently been reported from several other sparid hosts, and also a moronid fish, the European seabass Dicentrarchus labrax from the Mediterranean Sea. Here, molecular identity and additional morphological data are given for this parasite infecting the gall bladder of D. labrax in a southern Portuguese fish farm. In the bile, disporic plasmodia were spherical to subspherical with a smooth surface membrane. Most myxospores were crescent-shaped, 5.1 ± 0.5 (4.8-6.7) µm long (mean ± SD) and 21.9 ± 1.0 (20.4-23.9) µm thick; a few were more arcuate, 5.7 ± 0.4 (5.3-6.3) µm long and 17.3 ± 1.0 (16.3-19.1) µm thick. The wall consisted of 2 symmetrical valves united along a slightly curved suture line, with moderately tapering to rounded ends. Two spherical polar capsules, measuring 2.9 ± 0.3 (2.5-3.4) µm in diameter, contained a polar filament forming 8 to 9 coils organized in 2 rows. Host species, tissue tropism, and myxospore morphology supported species identification. Phylogenetic analyses of the small subunit ribosomal RNA sequence positioned the parasite among most sparid-infecting Ceratomyxa spp., suggesting the existence of a common ancestor for these species. The acquisition of molecular data from infections of C. diplodae in its original host and in other sparids is essential in order to ascertain if the morphological and biological variations found among reports of this parasite are intra- or inter-specific.

Seasonal Variation of the Chemical Composition, Fatty Acid Profiles and Mineral Elements of Diplodus Annularis (Linnaeus, 1758) Caught in the Tunisian Coastal Water

The present study investigated the seasonal variation of the chemical composition and fatty acid profiles of Annular sea bream Diplodus annularis from the Gulf of Gabes (Tunisia). Moisture, protein, fat and ash contents of the fish muscle were examined as a function of season and sex. Protein, fat and ash average contents were 18.65, 6.47 and 2.20 g/100 g, respectively. The major fatty acids in D. annularis lipids were palmitic acid, oleic acid, eicosapentaenoic acid, docosahexaenoic acid and myristic acid. Palmitic acid was the most abundant saturated fatty acid ranging from 26.38 to 32.79 % of the total fatty acids. Oleic acid was the main monounsaturated fatty acid ranging from 26.28 to 35.76 %. The high amounts of saturated and monounsaturated fatty acids in the investigated species are almost in agreement with other studies. Interestingly, omega-3 fatty acids were present at high level in spring (18.04 %). Moreover, the fish muscle contained appreciable concentrations of essential elements (Ca, K, Na and Mg). The present work suggests that this fish could be used as a source of healthy diet for humans.

Short-term residence and movement patterns of the annular seabream Diplodus annularis in a temperate marine reserve

The short-term movements of a small temperate fish, the annular seabream Diplodus annularis (Linnaeus 1758), were examined using standard tag-recapture and passive acoustic telemetry in Palma Bay (NW Mediterranean), a marine protected area (MPA). The study aimed to provide valuable information for assessing the recreational fishery and its results suggest that MPAs can be used to protect the adult stock of D. annularis. All the fish tagged with standard tags were recaptured near the release locations, with a maximum distance of ∼300 m. The maximum time between release and recapture was 185 d. Two different arrays of acoustic receivers were deployed, one in 2008 and another in 2009, within the MPA. Twenty adults were surgically tagged with acoustic transmitters. Fish monitored in 2008 ( n = 12) were translocated from the point of capture to analyse the movement behaviour after artificial displacement. Upon release at displaced locations, 67% of the fish moved towards the original capture location using a time of return that ranged from 0.75 to 15.25 h. Fish monitored in 2009 ( n = 8) were released at the point of capture. They showed high site fidelity with a maximum period of 27 d between the first time and the last time they were detected.

The Use of Histological Techniques to Study the Reproductive Biology of the Hermaphroditic Mediterranean Fishes Coris julis, Serranus scriba, and Diplodus annularis

AbstractThe usefulness and importance of histological techniques in reproductive studies have been widely discussed for gonochoristic fish species. In the case of hermaphroditic fishes, histology is a particularly important tool for the proper identification of sexual pattern (i.e., sequential, simultaneous, or nonfunctional hermaphroditism). We used a histological approach to describe hermaphroditism, dynamics of follicle development, and spawning patterns in three species from the northwestern Mediterranean Sea (Balearic Islands, Spain): the Mediterranean rainbow wrasse Coris julis (sequential hermaphrodite), painted comber Serranus scriba (simultaneous hermaphrodite), and annular sea bream Diplodus annularis (nonfunctional hermaphrodite). Development of secondary growth follicles was asynchronous in all three species, and similar peaks in spawning activity occurred between May and July. However, notable differences in sexual cycle and egg production were found. For the painted comber, hydrated follicles were present in ovarian tissue almost every day during the peak of the spawning season, suggesting daily spawning and increasing the chances of autofertilization unless a mechanism to avoid this action is present in this species. Intersexual Mediterranean rainbow wrasses were identified, and the size and age at sex change were estimated to be 132 mm total length and 4 years, respectively. Previous investigators have concluded that the annular sea bream is a protandric hermaphrodite, but our results indicate nonfunctional hermaphroditism. These three species are of little commercial interest and are considered to be bycatch by the artisanal fleet, but they are vulnerable to the impacts of some recreational angling activities. Currently, no specific management plan has been developed for these species. We address the importance of describing sexual pattern and its implications for future conservation efforts.

Biology of the annular seabream, Diplodus annularis (Sparidae), in coastal waters of the Canary Islands

The biology of the Canary Islands annular seabream Diplodus annularis (Linnaeus 1758) was studied from samples collected between January and December 1998. Fish ranged from 82 to 209 mm total length in size and from 8.7 to 137.1 g in weight. The mean length showed an increase with increasing water depth. Males showed a negative allometric growth and females isometric growth. The species was characterized by protandric hermaphroditism. The overall sex ratio was unbalanced in favour of males (1 : 0.79). The reproductive season extended from January to May, with a peak in spawning activity in March–April. Males reached maturity at a smaller length (103 mm, 1-year-old) than females (128 mm, 2-year-old). Fish aged 0–6 years were found. The von Bertalanffy growth parameters for all individuals were: L∞=247.9 mm, k=0.268 years–1, and t0=–0.879 years.

Age and growth of the annular seabream, Diplodus annularis (Pisces: Sparidae), from the Canarian archipelago (central-east Atlantic)

Age and growth of the annular seabream Diplodus annularis off the Canary Islands (Central-east Atlantic) were studied. The length range of fish was between 82 and 209 mm in total length. Otoliths showed clear growth rings. Two rings, one opaque and one translucent, were laid down each year on the otoliths. Seasonal growth cycles were related to physiological changes produced by the influence of temperature and reproductive cycle.The opaque ring was deposited during the summer months and the translucent one during the winter months. Individuals aged 0 to 6 years were found. After the first year, the annual growth rate droped rapidly as a consequence of the sexual maturity. The difference in size between males and females was not considered as evidence of an intersexual difference in growth rates since they are the same specimens at different stages of sexual succession. The parameters of the von Bertalanffy growth equation for all individuals were: L∞ = 248.5 mm, k = 0.259 year–1, and t0 = –0.871 year. The backcalculation method demonstrated the validity of using otoliths for estimating age and growth.

Biology of the annular seabream, Diplodus annularis (Sparidae), in coastal waters of the Canary Islands

Summary The biology of the Canary Islands annular seabream Diplodus annularis (Linnacus 1758) was studied from samples collected between January and December 1998. Fish ranged from 82 to 209 mm total length in size and from 8.7 to 137 1 g in weight. The mean length showed an increase with increasing water depth. Males showed a negative allometric growth and females isometric growth The species was characterized by protandric hermaphroditism. The overall sex ratio was unbalanced in favour of males (1 : 0.79). The reproductive season extended from January to May, with a peak in spawning activity in March-April. Males reached maturity at a smaller length (103 mm, 1-year-old) than females (128 mm, 2-year-old). Fish aged M years were found. The von Bertalanffy growth parameters for al1 individuals were: L, = 247.9 mm, k = 0.268 years-l. and t0 =-O.879 years.