The northern Ionian coast of Calabria (Southern Italy) represents a largely unexplored marine region, increasingly impacted by anthropogenic pressures yet lacking a comprehensive environmental assessment. This study combines a critical review of available literature with a five-year (2015–2020) experimental dataset of environmental parameters collected in the Villapiana coastal sector, providing the first integrated characterization of the study area, and extending current knowledge on northern Ionian Calabrian coast. Water samples from three offshore stations and sediment samples from one subcoastal station were analyzed for physico-chemical parameters, nutrients, and contaminants. Results highlight a warming trend in surface waters and a notable rise in pH, contrasting with the general acidification reported across the Mediterranean Sea. Chlorophyll-a peak shifted to greater depths, suggesting a deepening of the photic zone. Nutrient levels remained constantly low across depths and stations, confirming the oligotrophic nature of the area. While most pollutants were below detection limits, lead concentrations in seawater exceeded environmental quality standards in a single time point. These findings underline the need for ongoing and standardized monitoring to support conservation strategies and assess future changes in this sensitive coastal ecosystem.

The common octopus (Octopus vulgaris), among coleoid cephalopods, has evolved the most complex nervous system and sophisticated behaviors. Historically, O. vulgaris was a key animal model for neurophysiology research, and today, it is studied for its genomic innovations. However, unlike other models, there is no octopus farming for research, so specimens must be collected from the wild. This study assessed the impact of fishing on octopuses used in research, considering those caught using artisanal pots in the ‘Regno di Nettuno’ Marine Protected Area, Ischia (NA). To evaluate fishing stress, we identified morphological stress indicators such as chromatophore pattern and posture, and three potential molecular markers, estrogen receptor (ER), catalase (CAT), and heat shock protein (HSP70). We measured the percentage of stress signals shown by fished specimens and analyzed their differential gene expression. The transcriptional levels of octopuses caught using traps were compared to control specimens acclimated in captivity. Results indicated fluctuations in gene expression due to fishing stress. These findings suggest that an acclimation period after the stress event of fishing is crucial for ensuring the welfare of octopuses used in research, thus enhancing the quality of physiological and ethological studies.

Effective species identification is crucial for the conservation and management of marine mammals, particularly in regions such as the Mediterranean Sea, where several cetacean populations are endangered or vulnerable. In this study, we developed and validated a High-Resolution Melting (HRM) analysis protocol for the rapid, cost-effective, and reliable identification of the four representative marine cetacean species that occur in the Mediterranean Sea: the bottlenose dolphin (Tursiops truncatus), the striped dolphin (Stenella coeruleoalba), the sperm whale (Physeter macrocephalus), and the fin whale (Balaenoptera physalus). Species-specific primers targeting mitochondrial DNA regions (cytochrome b and D-loop) were designed to generate distinct melting profiles. The protocol was tested on both tissue and fecal samples, demonstrating high sensitivity, reproducibility, and discrimination power. The results confirmed the robustness of the method, with melting curve profiles clearly distinguishing the target species and achieving a success rate > 95% in identifying unknown samples. The use of HRM offers several advantages over traditional sequencing methods, including reduced cost, speed, portability, and suitability for degraded samples, such as those from the stranded individuals. This approach provides a valuable tool for non-invasive genetic surveys and real-time species monitoring, contributing to more effective conservation strategies for cetaceans and enforcement of regulations against illegal trade.

Climate-induced ocean warming poses a major threat to marine invertebrate reproduction, including the sea urchin Paracentrotus lividus, a species of considerable ecological, economic, and scientific interest. Its gonads, highly valued as a culinary delicacy, support local fisheries and aquaculture industries, making reproductive health a critical factor for both conservation and commercial viability. The present study reported the effects of elevated seawater temperatures, mimicking marine heatwave (MHW) conditions, on gonadal maturation and fertilization success on P. lividus. Here, adult specimens at the mature stage of gametogenesis were exposed to control (18 °C) and elevated temperature regimes (24 °C) over a six-week period, and key reproductive metrics were assessed, including histological analysis. Morphological analysis showed very evident gonadal retraction, nearly devoid of germ cells, both for males and females, with a significant decrease in the gonadal index. In addition, histological analysis revealed consistent damage to the gonads, with a significantly increase in histopathological index in specimens kept at 24 °C. These findings reinforce the temperature sensitivity of P. lividus reproduction, suggesting that recurrent heatwaves could severely impair its reproductive output and population dynamics with potential cascading effects on benthic community structure in a long-term ocean warming predicted to intensify.

Over the past few decades, demand for sea urchin roe has risen, while wild sea urchin populations have declined. This trend has increased interest in aquaculture techniques and the development of formulated feeds to support ecological restoration and research. Here, we examined the effects of a high-protein formulated feed on gonad development in Paracentrotus lividus, compared to fresh feeds (maize and spinach), across three replicated tanks. We assessed gonad maturation, gamete viability, and larval development, and developed a new histopathological index applicable to both sexes. Formulated feed significantly enhanced gonad maturation, increased gamete production, and led to heavier gonads with higher gonadosomatic indices compared to fresh feeds, which were insufficient to promote maturation within four weeks. Notably, no histological alterations were observed in the gonads. Fertilization trials showed that embryos were produced, but none reached the pluteus stage, indicating decreased embryo viability. Although the formulated feed improved gonad development, it adversely affected water quality, increasing nutrient concentrations and lowering pH. Overall, these findings suggest that high-protein formulated feeds could potentially improve aquaculture production by enhancing gonad maturation and gamete output, but additional measures may be needed to support complete larval development.

Coleoid cephalopods like octopuses, squids, and cuttlefishes have advanced light-sensing systems crucial for visual perception and survival. Previously, it has been demonstrated that the skin of coleoids contains transcripts encoding rhodopsin and retinochrome, exhibiting a dermal light sense. Moreover, chromatophores in the mantle skin of Octopus bimaculoides expand in response to light when completely isolated from the central nervous system and eyes. In our study combining morphology, gene expression, molecular evolution, 3D modeling of protein structures, and phylogenetic analysis, we demonstrated the presence of photosensitive pigment transcripts in Octopus vulgaris, not only in eyes and skin but also in suckers and even optic lobes. In particular, for the first time, the RNA expression of Ov-Rhodopsin, Ov-retinochrome, and Ov-GRK1 was found and quantified in the skin and also localized in different sucker types and the optic lobes. The obtained results suggest that suckers act as extraocular organs. Each of the approximately 1000 suckers contributes to the distributed light perception system, collectively acquiring environmental information that could support eye vision. Our findings could explain octopuses' extraordinary ability to camouflage. Furthermore, the optic lobes, which are part of the central nervous system, could be directly involved in light detection, in addition to their role in the integration of sensory information.

Limited data are available about the coastal ecology of the Calabria region, in the southern Italy. As well, data about the levels of biodiversity and the structure of food webs in these environments are totally missing. However, considering the wide range of physical and ecological conditions distinguishing these ecosystems, a remarkable spread of biodiversity is expected. This review represents a first attempt to describe and estimate the structure of the food webs in a range of shallow stations along the south-western coasts of southern Italy, in the Ionian Sea. They comprise a Special Area of Conservation (Amendolara shoal), an urbanized area (Sibari), a sandy area impacted by industrial installations (Corigliano) and a seagrass meadow (Calopezzati). For each of these stations, we produced ecological simulation models based on the available information in order to estimate the structure of food webs. In particular, the patterns of distribution of trophic resources resulting from literature data were statistically compared to a theoretical model based on the physical and ecological features of coastal ecosystems. The model was responsive and predicted remarkable differences in the compartmentalization of trophic resources among stations, due to the diversity of substrates and the anthropic activities impacting each area. Large availability of resources for omnivores and detritivores characterized most stations. A noteworthy richness of trophic resources for herbivores was forecasted off Amendolara and Calopezzati. In parallel, the model obtained for the urbanized area of Sibari predicted a higher abundance of trophic resources for filter feeders, especially in the deepest station.

Through this collection of papers, we have considered in depth the effects that humans have on invertebrate welfare in a variety of contexts [...]

In the last years biodegradable polymers (BPs) were largely used as real opportunity to solve plastic pollution. Otherwise, their wide use in commercial products, such as packaging sector, is causing a new pollution alarm, mainly because few data reported about their behaviour in the environment and toxicity on marine organisms. Our previous results showed that embryos of the sea urchin Paracentrotus lividus (Lmk) exposed to poly(ε-caprolactone) (PCL), poly(3-hydroxybutyrate) (PHB) and poly(lactic acid) (PLA) showed delay of their development and morphological malformations, also affecting at the molecular levels the expression of several genes involved in different functional responses. In the present work for the first time, we tested the effects of five microplastics (MPs) obtained from BPs such as PBS, poly(butylene succinate), PBSA, poly(butylene succinate-co-butylene adipate), PCL, PHB and PLA, upon grazing activity of the sea urchin revealed by: i. histological analysis seeing at the gonadic tissues; ii. morphological analysis of the deriving embryos; iii. Molecular analyses on these embryos to detect variations of the gene expression of eighty-seven genes involved in stress response, detoxification, skeletogenesis, differentiation and development. All these results will help in understanding how MP accumulated inside various organs in the adult sea urchins, and more in general in marine invertebrates, could represent risks for the marine environment.

Bioactive natural products from marine invasive species may dramatically impact native communities, while many synthetic pharmaceutical drugs are released into the marine environment and have long-lasting harmful effects on aquatic life. Sometimes metabolites from alien species and synthetic compounds share similar mechanisms of action suggesting comparable ecotoxicological impacts. This applies to the alkaloid caulerpin (CAU) from the green alga Caulerpa cylindracea, highly invasive in the Mediterranean Sea, and to the synthetic lipid-lowering drug fenofibrate (FFB), both acting as agonists of peroxisome proliferator-activated receptors (PPARs). Analogies with FFB, which is widely considered hazardous to the aquatic environment, have led to concerns about the ecotoxicological potential of CAU. The problem has implications for public health as CAU is well known to enter the food web accumulating in fish of commercial importance. Here, we compared the effects of FFB and CAU through biochemical and histopathological analysis on a relevant bioindicator molluscan species, the mussel Mytilus galloprovincialis. Mussels were fed with food enriched with CAU or FFB. After treatments, biochemical markers were analyzed revealing metabolic capacity impairments, cellular damage, and changes in acetylcholinesterase activity in mussels fed with FFB-enriched food. NMR-based metabolomic studies also showed significant alterations in the metabolic profiles of FFB-treated mollusks. In addition, dietary administration of FFB produced morphological alterations in the mussels’ gills and digestive tubules. Obtained results confirm that FFB is harmful to aquatic life and that its release into the environment should be avoided. Conversely, dietary treatment with CAU did not produce any significant alterations in the mussels. Overall, our results pave the way for the possible valorization of the huge biomass from one of the world’s worst invasive species to obtain CAU, a natural product of interest in drug discovery.

In recent years, scientists have made exceptional achievements that have led to major advancements in the fast-growing field of Aquatic Physiology. This editorial initiative, led by Prof. Andreas Fahlman, the previous Specialty Chief Editor of the Aquatic Physiology Section, is focused on the new insights, novel developments, current challenges, latest discoveries, and future perspectives in the field of Aquatic Physiology. Distinguished and active researchers have been invited to identify the greatest challenges in the sub-disciplines of Aquatic Physiology and offer solutions to address those challenges. This article Research Topic covers the basic mechanisms of osmoregulation, acid-base regulation, respiration, the nervous system, endocrines, behaviors, and digestion at the molecular, cellular, and biochemical levels, and further extends the discussion to aspects of evolutionary physiology. These articles will inspire, inform, and provide new direction to researchers in the field. Aquatic animals must maintain ionic and acid-base homeostasis in their body fluids to ensure the normal operations of cellular activities and physiological processes. This mechanism is a basic platform for studying environmental adaptation, pollution toxicology, stress biology, and evolutionary physiology of aquatic animals, and further provides important information to improve management of aquaculture practice. Life in fresh water (FW) is osmotically and energetically challenging for living animals because they need to continuously take up Na (and other ions) from a salt-dilute environment. Our understanding of Na uptake mechanisms in invertebrates is much poorer than that in fishes. To this end, Lee et al. proposed the Na/H antiporter (NHA) as a possible candidate for the Wieczorek Exchanger in many crustaceans and insects, which is hypothetically driven by apical proton pump V-type H ATPase (VHA). More studies are awaited to explore the Na uptake of NHA and other potential Wieczorek Exchangers. In the case of teleosts, which are the most studied fish group, Shih et al. reviewed the recent progress and clarified the related debates in their Na uptake mechanisms. FW teleosts absorb Na from the environment mainly via Na/H exchanger 3 (NHE3)-mediated and Na-Cl co-transporter (NCC) mediated mechanisms in gill/skin ionocytes, and they rely on NHE for amajority of Na uptake, probably due to a favorable NH4 + gradient that efficiently drives NHE. NHEs are considered themajor acid-secreting transporters in seawater (SW) fishes as well as in FW ones. NHE3 is the most studied NHE isoform, while NHE2 and its function has never been clarified. According to Liu et al., NHE2 is localized at the basolateral membrane of fish ionocytes and appeared to facilitate acid and salt secretion in sea water (SW)medaka, providing a new insight into the role of NHE2 in SW osmoregulation. Gill (or skin) ionocytes are important sites for fish OPEN ACCESS

A wide variety of substances have been used to anaesthetise invertebrates, but many are not anaesthetics and merely incapacitate animals, rather than preventing pain. Much is now known about the mode of action of modern clinical and veterinary anaesthetics because of their use on human beings and other vertebrates. In essence, the role of an ideal general anaesthetic is to act as a muscle relaxant, an analgesic, an anaesthetic and an amnesic. To achieve all these properties with a single substance is difficult and various adjuvants usually need to be administered, resulting in a cocktail of drugs. In a clinical setting, the vast majority of patients are unaware of surgery being carried out and have no memory of it, so they can claim to have felt no pain, but this is much more difficult to demonstrate in invertebrates. Here we show that 1% MgCl2, a muscle relaxant, is a useful adjuvant for the clinical anaesthetic isoflurane on Octopus vulgaris when applied for 10 minutes before the clinical anaesthetic. After this, full anaesthesia can be achieved in 5 minutes using only 1% isoflurane and from which full recovery takes place rapidly in about 10 to 15 minutes. This reduces stress on the animal and minimises the quantity of anaesthetic used.

The bisindolic alkaloid caulerpin (CAU) is a bioactive compound isolated from green algae of the genus Caulerpa that are highly invasive in the Mediterranean Sea. On the other side, the purine alkaloid caffeine (CAF) is one of the most globally consumed psychoactive substances and a widespread anthropogenic water pollutant. Both compounds display a large panel of biological properties and are well known to accumulate in the tissues of aquatic organisms and, in certain circumstances, co-occur in the human diet. On this premise, the present study aimed to investigate possible synergistic interactions between CAU and CAF by using the bivalve Mytilus galloprovincialis as a model organism. Mussels were exposed to CAF via medium while they were fed with food enriched with CAU. After treatments, biochemical analysis confirmed the toxic potential of CAF, with increased AChE activity and lipid peroxidation. Also, histopathological alterations were observed in the gills and digestive tubules. The NMR-based metabolomics analysis detected higher levels of free amino acids under CAF treatments. Conversely, the food administration of CAU did not affect the above toxicological biomarkers. In addition, we did not observe any cumulative effect between CAF and CAU toward increased cellular damage and neurotoxicity. On the other hand, a possible action of CAU in decreasing CAF toxicity could be hypothesized based on our results. This hypothesis is supported by the activity of CAU as an agonist of peroxisome proliferator-activated receptors (PPARs). PPARs mediate xenobiotic detoxification via cytochromes P450, which is involved in CAF metabolism. Overall, the results obtained not only rule out any cumulative adverse effects of CAF and CAU but also encourage further research to evaluate the possible use of CAU, a compound easily obtained through the valorization of biomass from invasive species, as a food additive to improve the clearance of xenobiotics.

A considerable amount of coastal contamination is caused by wastes deriving from household and the degradation and the metabolism of plants and animals, even if our attention is commonly focused on industrial pollutants and contaminants. Waste pollutants are mainly represented by highly diluted soluble compounds and particles deriving from dead organisms. This complex combination, consisting of suspended particles and dissolved nutrients, has a significant impact on coastal planktonic and benthic organisms, also playing an active role in the global cycles of carbon. In addition, production practices are nowadays shifting towards recirculated aquaculture systems (RAS) and the genic responses of target organisms to the pollution deriving from animal metabolism are still scarcely addressed by scientific investigations. The reservoir of organic matter dissolved in the seawater is by far the least understood if compared to that on land, cause only a few compounds have been identified and their impacts on animals and plants are poorly understood. The tendency of these compounds to concentrate at interfaces facilitates the absorption of dissolved organic compound (DOC) onto suspended particles. Some DOC components are chemically combined with dissolved metals and form complexes, affecting the chemical properties of the seawater and the life of the coastal biota. In this research, we compared the reproductive performances of the common sea urchin Paracentrotus lividus cultured in open-cycle tanks to those cultured in a recirculating aquaculture system (RAS), where pollution progressively increased during the experiment due to animal escretions. Sea urchins were cultured for 7 months under these two conditions and their gametes were collected. Embryos resulting by in vitro fertilization were analyzed by Real Time qPCR to identify possible effects of pollution-induced stress. The fertility of sea urchins was evaluated, as well as the gonadosomatic indices and the histological features of gonads. Our results indicate that pollution due to excess of nutrients, event at sub-lethal concentrations, may hardly impact the reproductive potential of this key species and that chronic effects of stress are revealed by the analyses of survival rates and gene expression.

Bioactive natural products from marine invasive species may dramatically impact native communities, while many synthetic pharmaceutical drugs are released into the marine environment and have long-lasting harmful effects on aquatic life. Sometimes, metabolites from alien species and synthetic compounds share similar mechanisms of action, suggesting comparable ecotoxicological impacts. This applies to the alkaloid caulerpin (CAU) from the green algae Caulerpa cylindracea, highly invasive in the Mediterranean Sea, and to the synthetic lipid-lowering drug fenofibrate (FFB), both acting as agonists of peroxisome proliferator-activated receptors (PPARs). Analogies with FFB, which is widely considered hazardous to the aquatic environment, have led to concerns about the ecotoxicological potential of CAU. The problem has implications for public health as CAU is well known to enter the food web accumulating in fish of commercial importance. Here, we compared the effects of FFB and CAU through biochemical and histopathological analysis on a relevant bioindicator molluscan species, the mussel Mytilus galloprovincialis. Under laboratory conditions, mussels were fed with food enriched with CAU or FFB. After treatment, biochemical markers were analyzed revealing metabolic capacity impairments, cellular damage, and changes in acetylcholinesterase activity in mussels fed with FFB-enriched food. NMR-based metabolomic studies also showed significant alterations in the metabolic profiles of FFB-treated mussels. In addition, dietary administration of FFB produced morphological alterations in the mussels' gills and digestive tubules. Obtained results confirm that FFB is harmful to aquatic life and that its release into the environment should be avoided. Conversely, dietary treatment with CAU did not produce any significant alterations in the mussels. Overall, our results pave the way for the possible valorization of the huge biomass from one of the world's worst invasive species to obtain CAU, a natural product of interest in drug discovery.

Octopuses, which are among the most intelligent invertebrates,1,2,3,4 have no skeleton and eight flexible arms whose sensory and motor activities are at once autonomous and coordinated by a complex central nervous system.5,6,7,8 The octopus brain contains a very large number of neurons, organized into numerous distinct lobes, the functions of which have been proposed based largely on the results of lesioning experiments.9,10,11,12,13 In other species, linking brain activity to behavior is done by implanting electrodes and directly correlating electrical activity with observed animal behavior. However, because the octopus lacks any hard structure to which recording equipment can be anchored, and because it uses its eight flexible arms to remove any foreign object attached to the outside of its body, in vivo recording of electrical activity from untethered, behaving octopuses has thus far not been possible. Here, we describe a novel technique for inserting a portable data logger into the octopus and implanting electrodes into the vertical lobe system, such that brain activity can be recorded for up to 12 h from unanesthetized, untethered octopuses and can be synchronized with simultaneous video recordings of behavior. In the brain activity, we identified several distinct patterns that appeared consistently in all animals. While some resemble activity patterns in mammalian neural tissue, others, such as episodes of 2 Hz, large amplitude oscillations, have not been reported. By providing an experimental platform for recording brain activity in behaving octopuses, our study is a critical step toward understanding how the brain controls behavior in these remarkable animals.

Paracentrotus lividus gonads, often referred to as “roe” or “uni” for gastronomical purposes, are among the most appreciated seafood delicacies in the Mediterranean area and worldwide. However, the increasing demand for human consumption has caused a growing pressure on its wild stocks, prompting the need to develop efficient aquaculture systems for its production. The set-up of effective feeds for various life stages and optimal procedures for breeding post-larvae and adult sea urchins still need to be improved. Here, for the first time, we aim at developing artificial feeds for the post-larvae of P. lividus because a critical step to improve our productive skills is post-larval growth. We tested various natural and prepared components to speed up the growth and enhance the survival rates of post-larvae, while taking into account the abiotic and biotic factors influencing the culture conditions in three replicate sets of tanks, characterized by different volumes. We tested formulated feeds and compared them with the effect of fresh foods in the frame of canonical culture practices. Our results indicated the efficiency of a feed composed of spirulina and Ulva rigida. Statistical analyses demonstrated the positive impact of this diet on the growth of post-larvae, behavior and survival rates. In addition, we demonstrated the efficacy of prepared feeds in the sea urchin aquaculture system, because they facilitated manipulation and control of the culture procedures for the satisfactory growth of P. lividus post-larvae.