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Abstract The garfish Belone belone represents the only valid endemic Belone species for the Mediterranean Sea and the eastern Atlantic Ocean. It shows a wide global distribution range, with a high commercial value and ecological relevance in the pelagic domain. Despite this, there needs to be more knowledge regarding the otoliths of this species, with the total absence of descriptions regarding asterisci and lapilli from Mediterranean populations and a lack of studies on the reliability of shape analysis on its sagittae. The present paper aims to provide the first main contours description of the three otoliths pairs from a Mediterranean population, providing an accurate investigation of morphology, morphometry, and intra-specific variability of sagittae, lapilli, and asterisci. Results showed (i) the absence of directional bilateral asymmetry and sexual asymmetry for the three otoliths pairs, (ii) a different morphology and morphometry of sagittae, lapilli and asterisci than those described in the literature, and (iii) an enhanced variability between sagittae morphometry and shape between the three investigated size classes. All these data confirmed the reliability of the studied species of shape analysis, showing a geographical and size-related variability of otoliths features probably related to genetics, environmental conditions, and life habits variations.

Improve the knowledge base on the ecomorphological adaptation of teleost species to different environments, trying to reconstruct how habitat can shape sagittae, is essential for conservational purposes, evolutionary evaluations, and population dynamics studies. Here is provided a comparative study between sagittae features, growth rates and age composition of two Scorpaena porcus populations inhabiting the Mediterranean waters, one from the Strait of Messina (Central Mediterranean Sea) and one from the Split area (Adriatic Sea). Additionally, the stomach contents of the Messina specimens have also been analysed to provide some preliminary information on the diet of S. porcus. A total of ninety individuals, half from each area, have been obtained from two extremely different environments. Results showed an overall different morphology, shape, and morphometry of sagittae among the size classes of the two investigated populations. Samples from Messina were characterized by a most elliptical and slender shape, with a more regular serration of margins than those from Split, which exhibited a wider sagitta, with a most enhanced anti-rostrum and longer rostrum. Concerning diet, specimens from Messina showed a preference for Crustacea (especially Brachyura and Amphipoda) and Teleost species, showing some differences with literature data from other geographical areas (Split one included). Results have confirmed the reliability of sagittae to detect the inter-population variability of S. porcus from different geographical areas, an essential tool for stock assessment, population studies and investigation on ecomorphological adaptation of teleost species to different habitats.

One of the most crucial biological indicators in tracking long-term variations in the reproductive cycle is sexual development. Scorpaena porcus (Linnaeus, 1758), commonly known as the black scorpionfish, is a small teleost from the family Scorpaenidae. Much is known about its ecology, but data on its reproductive and defense systems are still lacking. Antimicrobial peptides (AMPs), such as piscidins, are integral components of the innate immune system in fish. These peptides exhibit a wide range of activity against bacteria, fungi, viruses, and protozoa and act as the first line of host defense. This study aims to investigate the primary sexual development stages in male and female gonads of black scorpionfish, providing additional knowledge on the reproductive biology of this teleost while evaluating concomitant changes in the expression of a Piscidin-1 antimicrobial peptide. The results show a histological, morpho-structural change from the immature stage to the developing virgin stage. Immunohistochemical analyses show that germinal and somatic cells are strongly reactive to Piscidin-1 in both gonads at an early ontogeny stage. These data suggest that Piscidin-1 may play a key role in the local defense system of scorpionfish gonads at this delicate stage, which is critical for the continuation and maintenance of the species. The present findings are potentially useful for a better understanding of the reproductive cycle of this fish, improving our knowledge of the interaction between the immune system and reproduction.

Unlike adult mammalian cardiomyocytes, cardiomyocytes in teleosts display high proliferative capacity throughout adulthood. This study aimed to identify the immunohistochemical profiles of cardiomyocytes and immune cells in the hearts of Molly fish by assessing the immunolabelling expression of key proteins involved in cell proliferation, differentiation, and tissue protection. The cardiac anatomy of Molly fish includes the atrium, ventricle, and bulbus arteriosus. The expression of SOX9, NF-κB, myostatin, and S100 proteins in myocardial cells indicates the proliferative features of the heart in Molly fish. The bulbus arteriosus is characterized by collagenous chambers and smooth muscle cells that express Ach and iba1. The atrium of Molly fish serves as a storage unit for rodlet cells and immune cells. Rodlet cells displayed immunoreactivity to NF-κB, iba1, Olig2, Ach, and S100 proteins, suggesting their roles in the immune response within the heart. Furthermore, telocytes (TCs) have emerged as a significant component of the atrium of Molly fish, expressing Ach, CD68, S100 protein, and iba1. These expressions indicate the involvement of TCs in multiple signaling pathways that contribute to heart architecture. This study delineates the intricate relationship between cardiomyocytes and innate immune cells in Molly fish.

Abstract Metazoans have several mechanisms of internal defense for their survival. The internal defense system evolved alongside the organisms. Annelidae have circulating coelomocytes that perform functions comparable to the phagocytic immune cells of vertebrates. Several studies have shown that these cells are involved in phagocytosis, opsonization, and pathogen recognition processes. Like vertebrate macrophages, these circulating cells that permeate organs from the coelomic cavity capture or encapsulate pathogens, reactive oxygen species (ROS), and nitric oxide (NO). Furthermore, they produce a range of bioactive proteins involved in immune response and perform detoxification functions through their lysosomal system. Coelomocytes can also participate in lithic reactions against target cells and the release of antimicrobial peptides. Our study immunohistochemically identify coelomocytes of Lumbricus terrestris scattered in the epidermal and the connective layer below, both in the longitudinal and in the smooth muscle layer, immunoreactive for TLR2, CD14 and α-Tubulin for the first time. TLR2 and CD14 are not fully colocalized with each other, suggesting that these coelomocytes may belong to two distinct families. The expression of these immune molecules on Annelidae coelomocytes confirms their crucial role in the internal defense system of these Oligochaeta protostomes, suggesting a phylogenetic conservation of these receptors. These data could provide further insights into the understanding of the internal defense system of the Annelida and of the complex mechanisms of the immune system in vertebrates.

Mesopelagic species are enjoining increasing attention due to the growing impact of fisheries activities on deep marine biocenosis. Improving the knowledge base on mesopelagic species is required to enhance their conservation due to the knowledge gaps regarding many species and families. In this context, otoliths can be fundamental to assessing their life history, ecomorphological adaptation to the deep environment and stock composition. The present paper aims to explore the saccular and utricular otoliths morphology and intra-specific variability of the hatchetfish, Argyropelecus hemigymnus, from the Strait of Messina. Lapilli and sagittae were collected from 70 specimens and separated into four size classes. Morphometric, shape and SEM investigations were performed to describe their morphology, contours, and external structural organization, also studying their intraspecific variability related to sample sizes and differences between otolith pairs. Results showed an otolith morphology different from those reported in the literature with fluctuating asymmetry in sagittae and lapilli belonging to Class IV, and a high otolith variability between all the size classes. Data herein described confirm the otoliths singularity of the population from the Strait of Messina, shaped by a unique marine environment for oceanographic and ecological features.

Mucus secretion provides an interface with unique and multifunctional properties between the epithelial cells of many aquatic organisms and their surrounding environment. Indeed, mucus is involved in various essential biological processes including feeding, reproduction, osmoregulation, competition for space, defense against pathogens, xenobiotics, and a multitude of environmental stressors. The ability to produce a functional mucus layer is an important evolutionary step, arising first in Cnidaria that allowed for the development of the mucus-lined digestive cavity seen in higher metazoans. Mucus secretion by cnidarians has been moderately investigated in both corals and jellyfish, which among cnidarians are the ones that have shown the highest secretion rates to date. However, although in corals the production of mucus has received more attention, especially in view of the important ecological role played in coral reefs, in medusozoans the topic is little considered. Although the mucus secreted by corals has innumerable and important immunological, nutritional, and protective responsibilities, it should be remembered that jellyfish too represent a fundamental component of marine trophic web, playing numerous and important roles that are still unclear today. What is certain is that jellyfish are characterized (especially in the era of climate change) by large fluctuations in population density, the ecological implications of which are poorly understood. However, in both cases (Medusozoans and Anthozoans) to date some aspects relating to mucous secretions seem completely obscure, such as the microbiome and its variations as a function of environmental conditions or ontogenetic development, its implications in the field of immunological ecology, the consequent energy costs and finally the role played by the mucus in evolutionary terms. This review summarizes the properties, functions, ecological implications and evolutionary importance of mucus, in cnidarians, mainly focusing its roles in corals and jellyfish. Understanding these aspects relating to the ecological and evolutionary importance played by mucus is of fundamental importance for the ecosystems functioning.

Abstract Otolith features are useful tools for studying taxonomy, ecology, paleontology, and fish biology since they represent a permanent record of life history. Nevertheless, the functional morphology of otoliths remains an open research question that is useful to completely understand their eco-morphology. This study aims to deepen the knowledge of intra- and interspecific variation in sagitta morphology in three congeneric seabreams, to understand how such variability could be related to the lifestyles of each species. Therefore, the sagittae (n = 161) of 24 Pagellus bogaraveo, 24 Pagellus acarne, and 37 Pagellus erythrinus specimens, collected from the south Tyrrhenian Sea, were analyzed using scanning electron microscopy and a stereomicroscope to assess morphometric features, variability between otolith pairs and the external crystalline structure the of sulcus acusticus. Statistical analysis demonstrated that, between the species, variability in sagittal otolith rostral length growth and sulcus acusticus features, correlated with increased fish total length and body weight. Moreover, slight differences between otolith pairs were detected in P. acarne and P. erythrinus (P

The recognition and elimination of invading pathogens are vital for host survival. Macrophages play a central role in host protection and cells functionally reminiscent of vertebrate macrophages are present in all multicellular organisms. A pattern responsible for bacterial recognition found on the surface of macrophages is CD14. These cells possess a repertoire of antimicrobial molecules stored in their granules and lysosomes. Polarization states observed in mammalian macrophages termed M1 and M2 also likely exist in fish macrophages. Markers for macrophage subtypes are slowly but definitively emerging in fish species. In the present study cell markers such as CD14, acetylcholine, alpha 7 acetylcholine nicotinic receptor (nAChR) subtype, the inducible nitric oxidase synthase (iNOS), and the antimicrobial peptide piscidin 1 are reported for the first time in the intestinal macrophages of both catfish Heteropneustes fossilis (Bloch, 1794) and the African bonytongue Heterotis niloticus (Cuvier, 1829) along the anterior and the posterior axis and the concentric muscle layers. Many antimicrobial effector responses of vertebrate macrophages including respiratory burst and NO induction are similar across the diverse animal taxa. Antibodies against calbindin coupled with ones to VAChT and tubulin revealed the localization of myenteric and submucosal plexuses, which are made up of enteric neurons, glial cells, and nerves near macrophages. Current studies allow for the elucidation of multiple roles of macrophages in disease models providing an insight into their in vivo function in fish.

The immune system of a fish has cellular and molecular defense mechanisms that are substantially retained throughout the evolution of vertebrates. The innate immune system provides biological processes, such as phagocytosis and mechanical barriers, to implement an efficient defensive response after exposure to chemical or biological contaminants, pollutants, and contact with parasites, germs, and pathogens. Club cells (CCs) are widespread in the skin of Ostariophysi. After a predator attack or exposure to toxins and parasites, these cells can produce alarming substances. Given their effectiveness against viruses, parasites, and common skin lesions, recent studies have suggested that CCs are a component of the immune system. This study aims to immunohistochemically characterize the CCs for the first time in the skin of zebrafish, using mitogen-activated protein kinase (MAPK) p38, Toll-like receptor (TLR)2, Piscidin1, and inducible nitric oxide synthase (iNOS) peptides involved in the function of all types of vertebrate immune cells. According to our analysis, the intermediate layer of the epidermis exhibited rounded, oval, and elongated CCs, with central acidophilic cytoplasm and a spherical basophilic nucleus, that are positive to the antibodies tested. Our results may confirm that CCs could be involved in the immune function, increasing our knowledge of the immune system of teleosts.

Deep Sea environments represent the final collector of anthropogenic debris mainly represented by both plastic and non-plastic materials with different size. This led to potential contamination of deep marine fauna due to direct and indirect ingestion, representing a potential hazard for the species itself and for the final consumer. In this framework, the present study explored the occurrence of anthropogenic debris in the gastrointestinal tract of three Decapoda species of high commercial and ecological value (Parapenaeus longirostris, Aristeus antennatus, and Aristaeomorpha foliacea) from south-western Ionian Sea. After morphometrical measurements and sex determination, the gastrointestinal tract of 136 specimens were extracted and then chemically digested. A total of 230 low density microparticles were isolated, with a high frequency of occurrence in all the analyzed species (76% in P. longirostris, 70% in A. antennatus, and 83% in A. foliacea) mainly represented by fibers (92.6%) with a size between 0.10 and 0.49 mm, and with a dominance of the blue color. The results of the present study report for the first time the anthropogenic debris presence in the studied Decapoda from south-western Ionian Sea, highlighting the necessity to broaden the knowledge about anthropogenic debris pollution status in Mediterranean deep-sea species.

Monitoring the occurrence and distribution of rare fish species is essential, especially in a semi-closed basin such as the Mediterranean Sea. Biologically interesting species often represent fishing waste (being part of the by-catch) and therefore are not retained, leading to a huge gap in data collection. Here we report about the occurrence in the Ionian Sea of a Zu cristatus (Bonelli, 1819) specimen, a mesopelagic fish from the order Lampriformes considered rare in the whole Mediterranean basin. The sample was captured at a depth of 720 m off the coast of Noto (Sicily, Italy) by deep-sea longline fisheries. The biometrics and meristic data were compared with all the available data on specimens previously reported in the Mediterranean Sea. It is interesting to note that, among the few records in the literature, most reports mention a lower depth range for this species. In fact, it is quite known that juvenile specimens of Z. cristatus were frequently found in shallow waters, while information about the biology of the adult stage is scarce, indicating they would seem to prefer much deeper environments. Considering the difficulty to collect data on this rare fish, this contribution can help to improve the knowledge about its distribution.

Lampriformes are circumglobally distributed and contain several families of strictly marine bony fishes that have a peculiar morphology. Lampriformes systematics is affected by limitations in biometric, meristic, and molecular data; for this reason, it underwent several rearrangements in the past. This review aimed to describe the biological and ecological characteristics of the order Lampriformes, summarizing the current taxonomy of the group. The main aim was to clarify what is known about the distribution of the order Lampriformes in the Mediterranean Sea, collecting all the scarce and fragmented reports and notes on their occurrence. Knowledge scarcity is due to their solitary nature, in addition to their low to absent economic value. Despite this, the order Lampriformes represents a taxon of high biological and ecological importance. The high depth range of distribution characterizes their lifestyle. In the Mediterranean Sea, four families are present—Lampridae, Lophotidae, Regalecidae, and Trachipteridae—with the following species respectively, Lampris guttatus (Brünnich, 1788), Lophotus lacepede (Giorna, 1809), Regalecus glesne (Ascanius, 1772), Trachipterus arcticus (Brünnich, 1788), T. trachypterus (Gmelin, 1789), and Zu cristatus (Bonelli, 1819). Data deficiencies affect information on this taxon; the present review, which collected all the reports of the Mediterranean Sea, creates a baseline for depicting the biogeography of these rare and important species.

The fish intestine operates as a complicated interface between the organism and the environment, providing biological and mechanical protections as a result of a viscous layer of mucus released by goblet cells, which serves as a barrier against bacteria, viruses, and other pathogens, and contributes to the functions of the immune system. Therefore, goblet cells have a role in preserving the health of the body by secreting mucus and acting as sentinels. The ancient jawless fish broadgilled hagfish (Eptatretus cirrhatus, Forster, 1801) has a very basic digestive system because it lacks a stomach. By examining the presence, localization, and co-localization of 5-HT, TLR2, iNOS, and Piscidin1, this study intends to provide insight into the potential immune system contributions arranged by the gut goblet cells of broadgilled hagfish. Our results characterize intestinal goblet cells of broadgilled hagfish, for the first time, with the former antibodies, suggesting the hypothesis of conservation of the roles played by these cells also in primitive vertebrates. Moreover, this study deepens the knowledge about the still little-known immune system of hagfish.

Dendritic cells (DCs) are antigen-presenting cells (APCs) that regulate the beginning of adaptive immune responses. The mechanisms of tolerance to antigens moving through the digestive tract are known to be regulated by intestinal DCs. Agnatha and Gnathostoma are descendants of a common ancestor. The Ostracoderms gave rise to Cyclostomes, whereas the Placoderms gave rise to Chondrichthyes. Sarcopterygii and Actinopterygii are two evolutionary lines of bony fishes. Brachiopterygii and Neopterygii descend from the Actinopterygii. From Neopterygii, Holostei and Teleostei evolved. Using immunohistochemistry with TLR-2, Langerin/CD207, and MHC II, this study aimed to characterize intestinal DCs, from myxines to teleosts. The findings reveal that DCs are positive for the antibodies tested, highlighting the presence of DCs and DC-like cells phylogenetically from myxines, for the first time, to teleosts. These findings may aid in improving the level of knowledge about the immune system’s evolution and these sentinel cells, which are crucial to the body’s defense.

Merluccius merluccius is one of the most important Mediterranean benthopelagic predators. It represents a key species for the ecosystem’s functioning due to its fundamental role in the energy transferal between different domains and depth strata. The aim of this study was to explore the feeding habits of European hakes in the southern and central Mediterranean Sea, and also to analyze timescale variations and ontogenetic shift in five size length classes. A total of 411 stomachs collected from 2018 to 2020 were analyzed to assess diet and feeding habits. Results confirmed hakes’ role as a generalist benthopelagic predator, preying both in the suprabenthic layer and in the entire water column. Concerning the ontogenetic diet shift, juvenile hakes prefer zooplanktonic prey, while larger hakes have a diet mainly based on teleosts and decapods. The variations in diet composition between years, characterized by a fluctuation of cephalopods, bioluminescent teleost species and mesopelagic crustaceans, have highlighted the ability of European hake to model its diet to the geographical and prey availability. These features make analysis of the diet of M. merluccius essential to understanding the trophic dynamic existing in bentho-meso-pelagic environments, to improve ecosystem conservation in accordance with ecosystem-based fishery management.

This study aims to evaluate some biochemical parameters and serum electrolytes in cultured rainbow trout Oncorhynchus mykiss (Walbaum, 1792) to evaluate a potential correlation with biometric parameters (weight and length). For this purpose, 100 cultured trout (300–700 g weight range, 25–38 cm length range) bred on a fish-farm were used for the study. Physico-chemical characteristics of water were measured on the farm. Blood samples were collected from each fish to analyze the following parameters: glucose, triglycerides, cholesterol, aspartate aminotransferase (AST); alanine aminotransferase (ALT), calcium (Ca2+), chlorine (Cl−), iron (Fe2+), phosphorus (P), magnesium (Mg2+), potassium (K+), sodium (Na+) and urea. Statistical data analysis showed a significant correlation between size and glucose and cholesterol. No correlation was found between size and other parameters studied. These results represent a contribution to the study of fish size leading to better understanding some biochemical parameters and serum electrolyte profiles in cultured rainbow trout. This research contributes to understanding the intra-individual variability of some blood parameters in cultured rainbow trout O. mykiss offering reliable information on chronic stress status, metabolic disorders and deficiencies in relation to different sizes. These could help in improve the health monitoring in trout fish farms.

The present paper represents the first description of abnormal hermaphroditism in Galeus melastomus (Rafinesque, 1810). The black mouth cat shark specimen, collected in summer from southern Tyrrhenian Sea at the entrance of Salerno gulf, showed a basic intersexuality characterized by the presence of male secondary and female primary sexual characters. The reproductive system has been described with an accurate morphological analysis, also including a histological assessment of oocytes. Results showed the presence of only right clasper, not exceeding the pelvic fin in length, with the absence of internal males’ sexual organs. Concerning the female primary characters, the analysis of histological assessment showed the structure of mature oocyte, confirming the maturity stage of a mature female in active extruding stage, as highlighted by the macroscopic morphological analysis. Despite in many marine organisms’ hermaphroditism is a physiological condition showed by specimens during their lifecycle, in Elasmobranchs this is considered an abnormal condition, with some exceptions. The lack of information on hermaphroditism in elasmobranchs form the Mediterranean Sea requires an increase of scientific community’s attention, improving the knowledge on the reproductive biology of this sensitive taxon. This is essential to enhance the conservation of elasmobranchs populations in the entire Mediterranean basin.

In fish, the spleen is the prime secondary lymphoid organ. It has a role in the induction of adaptive immune responses, in addition to its significance in the elimination of immune complexes. This study was conducted on 18 randomly obtained adult molly fish (Poecilia sphenops) of both sexes using histological, immunohistochemical, and ultrastructural studies to highlight the cellular components of the spleen and their potential role in the immune system. The spleen of molly fish was characterized by the presence of well-distinct melanomacrophage centers, and other basic structures present in higher vertebrates including red and white pulps, blood vessels, and ellipsoids. Some mitotic cells could also be identified in the red pulp. Mast cells with characteristic metachromatic granules could be seen among the splenic cells. Rodlet cells were randomly distributed in the spleen and were also observed around the ellipsoids. The white pulp of the spleen expressed APG5. The expressions were well distinct in the melanomacrophages, leukocytes, and macrophages. Myostatin was expressed in leukocytes and epithelial reticular cells. IL-1β showed immunoreactivity in monocytes and macrophages around the ellipsoids. NF-κB and TGF-β were expressed in macrophages and epithelial reticular cells. Nrf2 expression was detected in stem cells and rodlet cells. Sox-9 had a higher expression in epithelial reticular cells and stem cells. The high frequency of immune cells in the spleen confirmed its role in the regulation of both innate and adaptive immunity, cell proliferation, and apoptosis.

Antimicrobial peptides (AMPs) are found widespread in nature and possess antimicrobial and immunomodulatory activities. Due to their multifunctional properties, these peptides are a focus of growing body of interest and have been characterized in several fish species. Due to their similarities in amino-acid composition and amphipathic design, it has been suggested that neuropeptides may be directly involved in the innate immune response against pathogen intruders. In this review, we report the molecular characterization of the fish-specific AMP piscidin1, the production of an antibody raised against this peptide and the immunohistochemical identification of this peptide and enkephalins in the neuroepithelial cells (NECs) in the gill of several teleost fish species living in different habitats. In spite of the abundant literature on Piscidin1, the biological role of this peptide in fish visceral organs remains poorly explored, as well as the role of the neuropeptides in neuroimmune interaction in fish. The NECs, by their role as sensors of hypoxia changes in the external environments, in combination with their endocrine nature and secretion of immunomodulatory substances would influence various types of immune cells that contain piscidin, such as mast cells and eosinophils, both showing interaction with the nervous system. The discovery of piscidins in the gill and skin, their diversity and their role in the regulation of immune response will lead to better selection of these immunomodulatory molecules as drug targets to retain antimicrobial barrier function and for aquaculture therapy in the future.

Data on the biology and ecology of Galeus melastomus are old/absent for the Southern Tyrrhenian Sea, despite there being numerous studies in the wider area. A total of 127 specimens of G. melastomus from the southern Tyrrhenian Sea, collected in 2018–2019 using trawling nets, were analyzed to investigate size at sexual maturity, sex ratio, length–weight relationships, and feeding habits. To our best knowledge, this is the first time in which all these features were investigated in the Southern Tyrrhenian Sea for G. melastomus. The stomach content analysis showed that G. melastomus had intermediate feeding habits, preying on a great variety of species, especially Cephalopoda, Osteichthyes, and Crustacea. The Levin’s index value (Bi) was 0.53. Sex ratio was 0.92:1, with females slightly more abundant and bigger than males. The results also showed a decrease (33.7 cm for females, 31.1 cm for males) in length at 50% maturity (L50). This could be a result of anthropogenic stressors, such as overfishing and/or and environmental changes, which can induce physiological responses in several species. Our results highlighted the differences related to sexual maturity, growth, and feeding habits of the blackmouth catshark in the studied area, providing reference data to allow comparison with future studies on this species adaptations to this and other deep-sea areas in the Mediterranean Sea.

In the present study, it has been evaluated how 10 µm of polyethylene microspheres can be ingested by Artemia salina (Linnaeus, 1758) larvae within the first 7 days of the life cycle, and the impact on their health. Twelve A. salina larvae (instar I) groups were exposed to different microplastics (MPs) concentrations (0-1-10-102-103-104 MPs/mL), with and without Dunaliella salina as a food source. The results highlighted that A. salina larvae ingest MPs in relation to the exposure times in a dose-dependent manner and are significantly influenced by food availability. The highest contamination found was 306.2 MPs/individual at 104 MPs/mL exposure without a food source. No MPs were found in the presence of the food source from 1 to 102 MPs/mL, while contamination was detected at all concentrations of MPs without a food source. The worst effect on the developmental stages was evaluated at 168 h with a food source, with a delay compared to the control of I and II instars at 103 and 104 MPs/mL, respectively. Furthermore, microalgal feeding was significantly reduced for about 50% in the presence of 104 MPs/mL. These results highlight that aquatic microplastics pollution could affect the A. salina’s feeding behavior and life cycle.

The environmental monitoring of chemical toxicants has been a widely studied topic in the last few decades. The main aim of the present study was to determine the total concentration of nine elements (Cd, Cr, Pb, Ni, Al, Cu, Fe, Mn, and Zn) in the fish species grey mullet (M. cephalus) and in the coastal marine waters collected from various sampling points along the Black Sea (Bulgaria) and the Ionian Sea (Italy). Further, those results were applied to predict the pollution degree in those coastal marine environments. The fish samples were subject to acid digestion followed by appropriate analytical determination. The metal concentrations in marine water samples collected from the Black Sea (Bulgaria) and the Ionian Sea (Italy) were also analyzed. Unpaired Student’s t-test and the one-way ANOVA were applied for the statistical analysis of the data. The statistical results revealed a significant variation (p < 0.0001) in the concentration of various fish tissues. The accumulation of toxic and essential elements differs significantly in grey mullet species caught from the Black Sea (Bulgaria) and the Ionian Sea (Italy). The results from this study may serve as a convenient approach during marine pollution programs set by both countries (Italy and Bulgaria).

Beachrock can be found in intertidal marine environments worldwide even though the knowledge about its ecological value in Messina's strait is still quite scarce. In this study, six tidal ponds of Messina's Beachrock were sampled from October 2016 to October 2017 to investigate the ecological status of the area, biotic and abiotic factors that can influence the faunal assemblage and the relationships among the communities inhabiting the various pools examined. A total of 13399 organisms, belonging to 5 Phyla, were identified by Visual Census. The surveyed stations showed biodiversity values and evenness that depend, above all, from the edaphic features and water exchange of the different tidal ponds. Tidal ponds characterized by a lower water exchange showed a faunal assemblage characterized by the presence of species tolerant to a wide temperature and salinity range, as Mugil cephalus, Clibanarius erythropus and Phorcus turbinatus. The pools with the most water exchange showed the highest abundance and evenness values; while the ponds characterized by hard bottom showed this feature as strong influence on the species composition. A preliminary mathematical study was also carry out to describe, qualitatively, the main mechanisms ruling the interaction between the Clibanarius erythropus and Phorcus turbinatus.

The phylum Cnidaria is one of the most important contributors in providing abundance of bio- and chemodiversity. In this study, a comprehensive chemical investigation on the nutritional and nutraceutical properties of Mediterranean jellyfish Pelagia noctiluca was carried out. Also, compositional differences between male and female organisms, as well as between their main anatomical parts, namely bell and oral arms, were explored in an attempt to select the best potential sources of nutrients and/or nutraceuticals from jellyfish. With the exception of higher energy densities and total phenolic contents observed in females than males, no statistically significant differences related to the specimen’s sex were highlighted for the other compound classes. Rather, the distribution of the investigated chemical classes varied depending on the jellyfish’s body parts. In fact, crude proteins were more abundant in oral arms than bells; saturated fatty acids were more concentrated in bells than oral arms, whereas polyunsaturated fatty acids were distributed in the exact opposite way. On the other hand, major elements and trace elements demonstrated an opposite behavior, being the latter most accumulated in oral arms than bells. Additionally, important nutraceuticals, such as eicosapentaenoic and docosahexaenoic acids, and antioxidant minerals, were determined. Overall, obtained data suggest the potential employment of the Mediterranean P. noctiluca for the development of natural aquafeed and food supplements.

Enormous marine biodiversity offers an endless reservoir of chemicals for many applications. In this scenario, the extraction of seaweeds represents an interesting source of compounds displaying antimicrobial activity. In particular, among the different red algae, Gracilaria gracilis plays an important role due to the presence of important bioactives in its composition. In spite of these features, an efficient culture system is still absent. In the present study, a novel algal culture method was developed and compared to another more common cultural practice, widely reported in literature. A higher efficiency of the new method, both for daily growth rate and biomass, was assessed. Furthermore, the growth inhibitory activity of five extracts, obtained using ethanol, methanol, acetone, chloroform or diethyl ether as a solvent, from the cultured G. gracilis was tested against Gram-positive and Gram-negative pathogens. Algal extracts exhibited a considerable inhibitory activity against B. subtilis strains, while a slight inhibition was observed against V. fischeri. The different extracts showed significant differences in bacterial growth inhibition, with the highest activity that was recorded for the ethanol extract, followed by that of methanol. Based on the chemical characterization, these findings could be related to the antimicrobial activity played by the combination of total carbohydrates and polyphenols, which were determined at high levels in ethanol and methanol extracts, as well as by the highest number and levels of single polyphenols. Conversely, the lower growth inhibitory activities found in chloroform and diethyl ether extracts could be related to the isolation of minor lipid classes (e.g., neutral and medium polar lipids) composed by fatty acids, such as stearic, oleic and arachidonic acids, typically characterized by antimicrobial activity. In consideration of the results obtained, the present study has a double implication, involving both the field of cultural practices and the exploitation of natural sources for the isolation of antimicrobial agents useful both in pharmaceutical and food applications.