Search

Native populations of marine invasive species have more than twice as high prevalence and three times higher species richness of parasites compared to introduced populations. Parasites can negatively impact host population density and growth by metabolically reducing host growth, reproduction, and survivorship (directly) and interacting with predation, competition, or both (indirectly).

The feeding ecology of the transparent goby Aphia minuta was examined in spring (May 2003) in the coastal waters off Comacchio, in the northwestern Adriatic Sea. Stomach content analysis indicated A. minuta to be a planktivorous species, feeding exclusively on pelagic invertebrates. The diet composition was dominated by the calanoid copepods Acartia clausi and Temora longicornis, followed in decreasing order of importance by other copepods (especially calanoids and Oncaea spp.) and larvae of decapods, polychaetes and bivalves. A. minuta exhibited a generalistic feeding strategy with a relatively broad niche width. Abundant taxa in the environment, such as A. clausi and T. longicornis, were seldom selected, whereas rare taxa, such as larvae of polychaetes and decapods, were highly selected. According to the observed ontogenetic shift in diet, small-size individuals relied preferentially on juvenile T. longicornis and Oncaea spp., whereas large-sized specimens consumed preferably A. clausi and calanoids. The positive relationship found between prey and fish size may help to mitigate the intraspecific competition for food resources., En el presente trabajo se estudió la dieta del góbido transparente A. minuta durante la primavera (Mayo 2003) en el nor-oeste del Mar Adriático (Comacchio). El análisis del contenido estomacal mostró que A. minuta es una especie planctívora, que se alimenta exclusivamente de invertebrados pelágicos. Los copépodos calanoides Acartia clausi y Temora longicornis constituyeron las presas dominantes seguidas, en orden de importancia decreciente, de otros copépodos (calanoides y Oncaea spp.), larvas de decápodos, poliquetos y bivalvos. A. minuta evidenció una estrategia alimentaria generalista y un nicho trófico amplio. Los taxones abundantes en el medio natural, A. clausi y T. longicornis, fueron raramente seleccionados, en cambio taxones poco frecuentes, como larvas de poliquetos y decápodos, estuvieron seleccionados positivamente. Atendiendo al cambio en la dieta a lo largo de la ontogenia, los ejemplares de talla pequeña se alimentaron preferentemente de juveniles de T. longicornis y Oncaea spp., mientras los ejemplares de talla mas grande consumían preferentemente A. clausi y calanoides. La relación positiva observada entre el tamaño de la presa y del depredador podría contribuir a atenuar la competencia intraespecífica por los recursos alimenticio.

The Norther Adriatic circalittoral is mostly characterized by monotonous seabeds, whose dominant biocoenosis ia the muddy detritic. They are interrupted by precoralligenous detritic bottoms and biogenic formations, such as the rocky outcrops called Tegnue and the reefs of Cladocora caespitosa. These habitats are severely endangered, due to intensive fishery and other environmental disturbances. To manage their protection, the knowledge of their extent and the classification of the habitat type, in agreement with the most recent Directives and International Protocols, is essential. No general consensus exsists on the criteria to categorize the coralligenous and a number of definitions is proposed based on noth-western Mediterranean evidences. The available list of species, as well as the main engineering species, are known from these areas, while they cannot be considered to be constant in the rest of the Mediterranean. This paper represents an up-to-date contribution to the knowledge of compoosition and distribution of circallitoral biocoenoses and to the understanding of coralligenous formations in the Northern Adriatic. The study is based on literature data and on most recent researches carried out on rocky outcrops off the Gulf of Venice and Trieste, and on the circallitoral detritic bottom off the Slovenian coast. Rocky outcrops display a wide range of morphologies that, together with environmental factors and human pressures, influence the habitat complexity and thus biodiversity. They are characterized by a rich biodiversity and different assemblages, not all referable to the coralligenous that distinguish the less disturbed off-shore areas. The contribution of different bioconstructors and a draft list of the main coralligenous taxa recognized are provided. The coralligenous biocoenoses of the Northern Adriatic seem to differ from the Mediterranean ones, mainly for a higher number os suspension feeders and for a lower morpho-functional complexity of the communities. Finally, long-term changes in assemblage composition and species abundances were highlighted.

Ontogenetic variation in the diet of Engraulis encrasicolus (L.) was examined in the northern Adriatic Sea, off the River Po delta, by stomach contents analysis. Anchovy (10 to 130 mm total length) were collected during a 1 wk cruise in October 2002. Feeding activity was mainly diurnal in all the length classes: stomach fullness, calculated for each 10 mm size class, was always higher during the day than at night, with maximal values measured for the 40 to 49 and 50 to 59 mm. size classes. All analysed life stages of E. encrasicolus had a strictly zooplanktivorous diet based on a few species of copepods. The principal prey of E. encrasicolus were small-sized copepods, measuring about 0.2 to 0.3 or 0.5 to 0.6 mm in prosoma length. The copepods Euterpina acutifrons and Oncaea spp. dominated anchovy diet during the day, both in terms of frequency, number and biomass, in all anchovy size classes. During the night, bivalve larvae were also important dietary items, with Oncaea spp. and E. acutifrons making up >69% of total prey number for all anchovy size classes. Within the considered size range, the dimensions of particles does not seem to be a limiting factor in food selection, and no relationship was found between anchovy length and the maximal dimension of ingested prey. Ivlev's electivity index confirmed that European anchovy was able to select specific food items and preferred small copepods such as E. acutifrons and Oncaea spp., and bivalve and decapod larvae.

This Collective Article presents information about 27 taxa belonging to five Phyla (one Ochrophyta, one Cnidaria, three Arthropoda, two Mollusca and twenty Chordata) and extending from the Western Mediterranean Sea to the Levantine Sea and the Black Sea (Sea of Marmara). The new records were reported from 11 countries as follows: Algeria: occurrence of the African striped grunt Parapristipoma octolineatum; Spain: new records of eight uncommon fish species (Gadella maraldi, Hypleurochilus bananensis, Lobotes surinamensis, Parapristipoma octolineatum, Selene dorsalis, Sphoeroides marmoratus, Tetragonurus cuvieri, and Trachyrincus scabrus) from the Spanish Mediterranean; Italy: new record of the football octopus Ocythoe tuberculata from the Southern Tyrrhenian Sea; a rare sighting of a juvenile phase of a moray eel of the genus Gymnothorax, tentatively identified as Gymnothorax cf. unicolor in the Ligurian Sea; first record of adult Facciola’s sorcerer Facciolella oxyrhynchus in the Adriatic Sea; occurrence of the tope shark Galeorhinus galeus in the Northern Adriatic Sea; Libya: first confirmed record of the pen shell Pinna rudis; first documented record of the palaemonid shrimp Brachycarpus biunguiculatus; first record of the fish Sudis hyalina; Malta: new records of Grant’s rockling, Gaidropsarus granti; multiple concomitant reports of the rare hydro-medusan species Aequorea forskalea; Croatia: a record of the skipjack tuna Katsuwonus pelamis in the Southern Adriatic Sea; Albania: new record of the bigeye thresher shark Alopias superciliosus; Greece: confirmation of the rare brown alga Sargassum flavifolium occurrence in the Eastern Mediterranean Sea; first record of the scaleless dragonfish Bathophilus nigerrimus; Turkey: first occurrence of the calanoid copepod Pteriacartia josephinae in the Aegean Sea; first documented record of the Cremona’s sea slug Placida cremoniana for the easternmost Mediterranean Sea; new record of the yellow-headed goby Gobius xanthocephalus in the Sea of Marmara; Cyprus: first record of the Liechtenstein’s goby Corcyrogobius liechtensteini; an individual of the Yellow-fin tuna Thunnus albacares captured with handline by an artisanal fisher; Lebanon: an individual of the Black marlin Istiompax indica captured in a gill net., peer-reviewed

20 pages, 9 figures, 5 tables, supplementary data https://doi.org/10.12681/mms.25306, The Mediterranean Sea has a long-lasting history of fishery exploitation that, together with other anthropogenic impacts, has led to declines in several marine organisms. In particular, elasmobranch populations have been severely impacted, with drastic decreases in abundance and species diversity. Based on their experience, fishers can provide information on marine species occurrence, abundance and behavioural traits on a long-term scale, therefore contributing to research on the poorly studied biological aspects of elusive or rare elasmobranch species. In this study, for the first time, the use of the Local Ecological Knowledge (LEK) of fishers was applied to study the behavioural traits of sharks, rays and skates in 12 FAO-GFCM geographical sub-areas (GSAs) of the Mediterranean Sea. This study found both new insight and proved the reliability of LEK-based catch seasonality, reflecting seasonal movements, by comparing LEK-based findings and available literature on five elasmobranch taxa (Mustelus spp., Squalus acanthias, Raja spp., Myliobatis aquila and Scyliorhinus stellaris) in the Adriatic Sea and 7 taxa (Mustelus spp., Raja spp., Prionace glauca, Scyliorhinus canicula, Torpedo spp., Pteroplatytrygon violacea and Isurus oxyrinchus) in the remaining Mediterranean GSAs. In addition, LEK provided new insights into a novel comprehensive representation of species aggregations (Mustelus spp., S. acanthias, M. aquila and S. canicula) in the sampled GSAs and supplied the first descriptions of the size, number of individuals and sex composition of the aggregations. When the limits and shortcomings of LEK-based research are considered, this methodology can be a complementary and cost-effective tool used to study elasmobranchs in either a data-poor scenario or a scenario in which a baseline is missing. LEK can also be useful for the evaluation and inclusion of fishers’ perceptions on bottom-up management and to provide important evidence for conservation plans, This work was supported by funding of Ministero dell’Istruzione, dell’Università e della Ricerca (MIUR) to CM, With the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)

Ontogenetic variation in the diet of Engraulis encrasicolus (L.) was examined in the northern Adriatic Sea, off the River Po delta, by stomach contents analysis. Anchovy (10 to 130 mm to- tal length) were collected during a 1 wk cruise in October 2002. Feeding activity was mainly diurnal in all the length classes: stomach fullness, calculated for each 10 mm size class, was always higher during the day than at night, with maximal values measured for the 40 to 49 and 50 to 59 mm size classes. All analysed life stages of E. encrasicolus had a strictly zooplanktivorous diet based on a few species of copepods. The principal prey of E. encrasicolus were small-sized copepods, measuring about 0.2 to 0.3 or 0.5 to 0.6 mm in prosoma length. The copepods Euterpina acutifrons and Oncaea spp. dominated anchovy diet during the day, both in terms of frequency, number and biomass, in all anchovy size classes. During the night, bivalve larvae were also important dietary items, with Oncaea spp. and E. acutifrons making up >69% of total prey number for all anchovy size classes. Within the considered size range, the dimensions of particles does not seem to be a limiting factor in food selection, and no re- lationship was found between anchovy length and the maximal dimension of ingested prey. Ivlev's electivity index confirmed that European anchovy was able to select specific food items and preferred small copepods such as E. acutifrons and Oncaea spp., and bivalve and decapod larvae.

The temporal dynamics of microphytoplankton, microzooplankton and mesozooplankton were monitored over 37 months in the Adriatic Sea in order to identify alterations in the plankton structures, which can lead to, or enhance the production of macro-aggregates, that affected the entire northern basin in summers 2000 and 2002, and to assess any negative effects of mucilage on plankton temporal patterns. Samples were collected monthly, from June 1999 to July 2002, on three transects at 9 stations across the northern and central Adriatic Sea. Besides the high year – to – year variations in abundances and taxonomical composition, plankton communities only showed a clear seasonal succession during 2001, when since April a grazing food web developed and was able to control large sized phytoplankton increase. In spring-summer 2000 and 2002 consumer abundances remained quite low and the dominant mesozooplankton summer species (Penilia avirostris) did not reach its usual summer maximum. The lack of an efficient top control was more evident on the northernmost transect, where generally grazing food web prevails over the microbial one. A large part of the microphytoplankton blooms, although not particularly intense, was exported to the bottom in the particulate phase, where it was processed by bacteria, enhancing the production of refractory dissolved material.