Elucidating food webs in infralitoral rocky coastal habitats invaded by Caulerpa cylindracea (Sonder 1845)

Invasive species including Caulerpa cylindracea affect coastal benthic communities inducing structural changes. To assess effects in rocky ecosystems, food webs have been depicted based on stable isotopic data collected from invertebrates and fishes at invaded and non-invaded coastal areas. Isotopic values of invertebrates were slightly higher in invaded than non-invaded habitats of Lampedusa Island, however no significant differences were found. Invasive fish Siganus luridus and native Sparisoma cretense had similar isotopic signatures indicating similar food sources

Nest-mediated parental care in a marine fish: Are large-scale nesting habitats selected and do these habitats respond to small-scale requirements?

Fishes have evolved various reproductive strategies including mechanisms that involve parental care and demersal eggs laid into nests. Symphodus ocellatus has a seasonal reproduction period during which large, dominant males become territorial and build nests with fragments of algae, where they attract females to spawn and provide care to the developing eggs. Based on the hypothesis that the S. ocellatus males choose the reproductive habitat based on some characteristics of the substrate, here we assessed whether, on a coastal area scale, the distribution of this species changes during the reproductive period because of the selection of some suitable sites or substrates, and whether the nesting microhabitat used by this species responding to certain requirements in relation to different characteristics. From April to September 2010, at four locations and on three substrate types, the fish were counted in three periods related to different stages of reproduction. Furthermore, several physical and biological variables have been recorded around numerous nests to select those with more recurrence. We found that S. ocellatus prefers to live on rocky substrates populated by photophilic algae, regardless of the phases of the reproductive cycle. We identified depth (1.7–3.2 m), the presence of a hole, a 10–20 cm algal canopy, and high algal coverage of Dyctiotales as nest requirements. S. ocellatus is mostly distributed in coastal sites sheltered from the action of waves. This allows the construction and maintenance of nests and the possibility to remain in a water temperature range similar to the reproductive physiological constraints

Historical separation and present-day structure of common dolphinfish (Coryphaena hippurus) populations in the Atlantic Ocean and Mediterranean Sea

The common dolphinfish (Coryphaena hippurus) is an epipelagic, mid-trophic level, highly migratory species distributed throughout the world’s tropical and subtropical oceans in waters greater than 20C. Life-history variables, migratory behaviour, and genetic markers have been used to define major stocks in the central Atlantic Ocean and Mediterranean Sea. Here, we used the mitochondrial DNA gene NADH subunit 1 (688 bp) to test for differences between population groups. A total of 103 haplotypes were detected among 203 fish. Gene diversities in samples were large and similar among populations (mean h ¼ 0.932; range 0.894–0.987), but nucleotide diversities varied widely among samples (range p ¼ 0.004–0.034) and appear to reflect population histories. Principal component analysis revealed two large populations groups, and the analysis of molecular variation and pairwise values of UST resolved population structure within these groups. Populations in the eastern Atlantic and Mediterranean showed the largest amounts of divergence from one another (UCT ¼ 0.331). Adult movement and biophysical barriers to larval dispersal may explain contemporary differences between stocks, but the divergent populations in the Mediterranean Sea are likely due to isolations by cold temperature barriers during Pleistocene glaciations. The geographically large stock groupings require international cooperation in the harvest management and conservation of local dolphinfish populations

Unpublished Mediterranean and Black Sea records of marine alien, cryptogenic, and neonative species

To enrich spatio-temporal information on the distribution of alien, cryptogenic, and neonative species in the Mediterranean and the Black Sea, a collective effort by 173 marine scientists was made to provide unpublished records and make them open access to the scientific community. Through this effort, we collected and harmonized a dataset of 12,649 records. It includes 247 taxa, of which 217 are Animalia, 25 Plantae and 5 Chromista, from 23 countries surrounding the Mediterranean and the Black Sea. Chordata was the most abundant taxonomic group, followed by Arthropoda, Mollusca, and Annelida. In terms of species records, Siganus luridus, Siganus rivulatus, Saurida lessepsianus, Pterois miles, Upeneus moluccensis, Charybdis (Archias) longicollis, and Caulerpa cylindracea were the most numerous. The temporal distribution of the records ranges from 1973 to 2022, with 44% of the records in 2020–2021. Lethrinus borbonicus is reported for the first time in the Mediterranean Sea, while Pomatoschistus quagga, Caulerpa cylindracea, Grateloupia turuturu, and Misophria pallida are first records for the Black Sea; Kapraunia schneideri is recorded for the second time in the Mediterranean and for the first time in Israel; Prionospio depauperata and Pseudonereis anomala are reported for the first time from the Sea of Marmara. Many first country records are also included, namely: Amathia verticillata (Montenegro), Ampithoe valida (Italy), Antithamnion amphigeneum (Greece), Clavelina oblonga (Tunisia and Slovenia), Dendostrea cf. folium (Syria), Epinephelus fasciatus (Tunisia), Ganonema farinosum (Montenegro), Macrorhynchia philippina (Tunisia), Marenzelleria neglecta (Romania), Paratapes textilis (Tunisia), and Botrylloides diegensis (Tunisia).peer-reviewe

Edad y tasa de crecimiento de los juveniles de atún Thunnus thynnus del mar Mediterráneo (Sicilia, Italia)

The microstructural analysis of the sagittal otoliths of juvenile Atlantic bluefin tuna, Thunnus thynnus, can be used to estimate the age and growth rate of young-of-the-year individuals born in the Mediterranean. Samples of juvenile bluefin tuna, obtained as by-catch of the local small-scale pelagic fishery for Atlantic bonito and dolphinfish, were collected off the northern coast of Sicily between late August and early November 2002. Otolith age readings were carried out on 56 specimens ranging between 195 and 400 mm fork length and between 112 and 1266 g total weight. Based on microincrement analysis along a counting path from the otolith core to the antirostrum, juvenile fishes were found to be between 77 days and 153 days old. The estimated growth rate was practically linear over the whole size range, accounting for about 2.0-2.37 mm/day. Derived from the length-weight relationship and the estimated length-at-age data, the mean weight-at-age was 168, 429 and 813 g for 2, 3 and 4 month-old juveniles respectively. Furthermore, the hatching date distribution of bluefin tuna, obtained by means of the back-calculation of ageing data, indicated a spawning period of at least two months, namely from mid-May to mid-July, with a peak in mid-June. Our data indicate that juvenile bluefin tuna have a very high growth rate in the first part of their life, reaching a weight of more than 1 kg in four months.El análisis microestructural de los otolitos sagitta de juveniles del atún Thunnus thynnus, ha permitido estimar la edad y tasa de crecimiento de individuos del primer año de vida, nacidos en el Mediterráneo. Los juveniles de atún, obtenidos como especie acompañante de la pesquería artesanal pelágica del bonito y lampuga, se recolectaron en las costas de Sicilia desde finales de agosto a principios de noviembre de 2002. Las lecturas de edad de los otolitos se realizaron en 56 ejemplares entre 195 mm y 400 mm de longitud de furca y entre 112 g y 1266 g de peso total. En base a los análisis de microincrementos a lo largo del eje de lectura, desde el núcleo del otolito hasta el antirostrum, se determinó que los juveniles tenían entre 77 y 153 días de edad. La tasa de crecimiento estimada era prácticamente lineal a lo largo de todo el rango de tallas, representando alrededor de 2.0-2.37 mm/dia. A partir de las relaciones talla-peso y talla estimada-edad se determinó el peso medio-edad en 168 g, 429 g y 813 g para juveniles de 2, 3 y 4 meses de edad, respectivamente. Además, la fecha de eclosión del atún, estimada a partir del retrocálculo de la edad, indica que el período reproductor se extiende al menos durante dos meses, desde mediados de mayo a mediados de julio con un pico a mediados de junio. Nuestros datos indican que los juveniles de atún presentan una elevada tasa de crecimiento en las fases tempranas de vida, alcanzando un peso de mas de 1 kg en cuatro meses

Unusual presence of Coryphaena hippurus Linnaeus, 1758 (Perciformes: Coryphaenidae) under an offshore oil platform in Southern Brazil

OBJECTIVE: To study the food habits of a sample of the dolphinfish (Coryphaena hippurus) around the Petrobrás PXIV oil platform located off Southern Brazil. Methods: We examined the stomach contents of 28 adult dolphinfish caught around this platform between 2000 and 2001. RESULTS: Results highlighted a diet consisting mainly of pelagic fish, although cephalopods and crustaceans are also present. A large amount of clupeids found in the stomachs could be due to baits used by fishermen that do fish around the platform. CONCLUSIONS: In this research we discuss the possibility of this occurrence being related to trophic opportunistic behavior. This could be a reason why adult dolphinfish are attracted by this platform since the whole structure does act as a fish aggregating device.info:eu-repo/semantics/publishedVersio

Gain or Loss for the Inshore Trawling Ban within Three Miles? Preliminary Data

From 1 June 2010 in the Italian coastal waters of the Northern Adriatic Sea, trawl fishery within three nautical miles became banned. This activity was previously allowed for some species as an exception to legislation. In order to evaluate the consequences both on demersal resources and economic yields of the trawl which will oblige fishermen to trawl beyond three miles, a pilot study was performed. Twenty hauls comparing catch discard and income between hauls within and external to three nautical miles were performed. Results highlighted differences in catch composition both for landing and discard. Landing per unit of effort and discard per unit of effort did not differ in relation to distance from the coast, while income was higher for offshore hauls than inshore ones even if not significantly. Fishery management is a complex task, and the results of this study can contribute to the debate providing new insights into the consequences of the regulation on the trawling within three nautical miles. Considering the high amounts of discard, the habitat damages caused by otter trawling, the presence of juveniles in coastal waters and data regarding fishermen income, this study supports the actual European Community regulation on coastal trawling

Food resource partitioning between two sympatric temperate wrasses

The present study analysed two sympatric wrasses, Thalassoma pavo and Coris julis, with similar sizes and morphologies, that are widespread in the reef habitats of the Mediterranean and the eastern Atlantic coast. Ocean warming has induced the northward movement of T. pavo, whereas C. julis has been moving to deeper habitats. In addition, under conditions of high slope of the sea bottom, T. pavo occupies shallow habitats and C. julis is in greater abundance in deeper habitats. By investigating stomach contents and prey availability in the benthos, we assessed whether the two wrasses exploit food resources by choosing different prey within the same habitat both under co-existence and segregation conditions. The results showed that T. pavo mainly feeds on gammarids and sipunculids, whereas C. julis mainly feeds on Alvania spp. and Paguroidea. The two wrasses also showed an intrinsic partitioning of food resources, independently of the condition of co-existence or segregation and benthic prey availability in the environment. The two wrasses fall in the ‘over dispersion of resource use’ model, in which species share numerous niche dimensions in a variable manner. Our findings may contribute to exclude a greater trophic competition between these labrid species in a projected warming scenario