Sea-level fluctuations in the marginal seas of the northwestern Pacific Ocean during the Pleistonene have profoundly influenced the genetic structure of marine organisms. Previous phylogeographic studies have mainly focused on fish and molluscs; other taxonomic groups have been poorly studied, which restricts a comprehensive understanding of the geogenetic patterns of marine species in this area. To precisely understand how environmental factors and historical events shape the population structure of the sea pen Cavernularia obesa in the East China Sea, we determined partial nucleotide sequences of the mitochondrial cytochrome oxidase subunit I (COI) gene in 71 individuals from five sites. Results of population Genetic and demographic analyses revealed a low genetic diversity within each population. Moreover, the historical population size change showed that the populations experienced bottlenecks during the Pleistonene. The sea level of the East China Sea decreased by >100 m when the glacial advanced during the Pleistonene, which caused the shrinking of habitats for marine species and eventually resulted in low genetic diversity within the populations in this area.

There are unique reef patches in the Biosphere Reserve Banco Chinchorro reef lagoon that have an unusual formation. They appear to be miniature atolls. These formations are at a depth of 2-6 m; however, a few meters away, presenting flowering microatolls occur while others are strongly impacted. In this context, to define the causality of this phenomenon, an analysis of three of these formations was carried out; to try to relate the structure of the corals that make up these formations to the factors of the environment. Records in nictemeral cycles, twelve environmental parameters, and micronutrients. Despite their closeness, the diversity of these patches is high in two of them and very low in the third. These results show notable differences that typify each of them, according to their position on the reef (leeward and windward), in addition, these patterns relate to the underwater scurry of possible relict water that drains from the lagoon microsystem of the main island of the reef, Cayo Centro, towards the microatolls.

Seagrass ecosystems play a vital role in marine environments, providing essential services, and supporting a diversity of fauna and algae that are critical components in marine trophic structures. However, global and local seagrass declines due to various influences raise concerns about the health of these ecosystems. This study investigated the structural and environmental drivers influencing epifaunal communities associated with the dwarf eelgrass ( Zostera capensis), in a temperate lagoon ecosystem. Variation in epifaunal patterns across phenotypically distinct seagrass populations were observed. Large-leaved morphotypes in deeper intertidal stands near the lagoon mouth exhibited higher species diversity and richness. Conversely, small-leaved populations in higher shore stands supported greater species abundances, notably, two desiccation-resistant gastropods, Assiminea sp. and Siphonaria compressa. Seasonal differences in epifauna were significant, with higher abundances observed during spring and summer, while diversity and richness peaked in autumn and winter. Several key factors influencing epifaunal abundances were identified. The results of structural equation modelling showed seagrass shoot densities and leaf width to have positive direct effects, with light (turbidity) and oxygen levels also playing important roles. Temperature, pH, and exposure indirectly affected epifaunal abundances, however, temperature had a direct effect on seagrass structure and significantly influenced five out of six seagrass metrics measured. Ongoing assessments of seagrass distribution in the lagoon indicate more significant declines in populations near to the lagoon mouth, suggesting a simultaneous reduction in associated epifaunal communities reliant on large-leaved seagrass beds. As climate change-induced warming continues, further declines in seagrass populations are anticipated, particularly in large-leaved varieties. This trend is likely to have adverse consequences for the associated epifaunal communities and other trophic levels within the ecosystem. Given the significance of seagrass habitats for food provision and sustaining livelihoods, the loss of these ecosystems could have far-reaching consequences. Preserving seagrass ecosystems is therefore crucial to ensuring the continued provision of these ecosystem services.

Hurricanes are natural periodic events that disrupt marine ecosystems along their path, altering the distribution and abundance of organisms. In October 2016, Hurricane Matthew struck the Santa Marta region and impacted its coastal zone, yet there have been insufficient studies to measure its effects. The aim of this study was to assess the impact of Hurricane Matthew on the meiofaunal community in the Santa Marta region. To achieve this, sediment samples were collected from the intertidal zone of three beaches five days after the hurricane had passed. The results were compared with previous data on the abundance and diversity of taxonomic groups of intertidal meiofauna, as well as physicochemical variables such as granulometry, organic matter, salinity, and water temperature. Following Hurricane Matthew, the physicochemical variables showed changes due to the effect of the cyclonic surge in the coastal zone. The average organism density on the beaches ranged from 29.3 to 250.8 ind./10cm 2, which were lower values than those recorded before the hurricane. However, the total number of recorded taxa was 13, which is close to the 15 previously registered. The ANOSIM test confirmed differences in the meiofaunal community before and after Hurricane Matthew, with nauplius and copepod being the groups that contributed the most to the dissimilarity between periods. The environmental variables of organic matter and temperature best explained the structure of the meiofaunal community after the natural phenomenon. This study highlights the importance of meiofauna as a monitoring tool for beaches and the effects of environmental disturbances such as hurricanes, which are expected to become more common in coastal areas due to climate change.

The Gulf of Naples as a model system for plankton ecology studiesAdriana Zingone, Domenico D’Alelio and Maria Grazia MazzocchiStazione Zoologica Anton Dohrn, NaplesPlankton play a fundamental role in coastal and oceanic ecosystems as a key element of biogeochemical cycles and pelagic trophic webs and contribute to determine and maintain the health of the oceans. Half of the world’s population leaving along the coasts (Vitousek et al., 1997) relies on services offered by plankton in terms of seafood availability and sea water quality. Therefore, monitoring, quantifying, and understanding the responses of plankton to the variability of the coastal ecosystem represent an urgent challenge to the scientific community, and even more so in an epoch of rapid environmental changes. Yet, because of the prevalently microscopic nature of planktonic organisms and logistic hindrances, research in this field has start developing only in the second half of the XIX century.One of the first marine sites where plankton were studied was the Gulf of Naples (GoN), a coastal embayment of the mid Tyrrhenian Sea in the western Mediterranean. The GoN is in the temperate zone but with subtropical characteristics, under the anthropogenic impacts from one of the most densely populated areas of the Mediterranean Sea contrasted by the influence of the open oligotrophic Tyrrhenian waters. Consequently, the GoN marine ecosystem is a mosaic of areas with different ecological conditions, where highly impacted habitats coexist with relatively pristine localities and marine protected areas. Studies on the plankton of the GoN were fostered by scientists working at the Stazione Zoologica (SZN), the first marine institution in Europe funded in 1872 by Anton Dohrn.Plankton of the GoN were initially analysed to unveil their extraordinary diversity (e.g., Giesbrecht, 1892) and phenology (De Angelis, 1958; Indelli 1944; Issel, 1934). In the second half of the last century, studies also focused on plankton taxonomy, life cycles, and distribution in space and time, until regular monitoring was started in 1984 with a long-term ecological research program at the siteMareChiara (LTER-MC) since 2006 part of the Italian, European and international LTER networks. LTER-MC is located two nautical miles off the coast of the city of Naples in an area that can be alternatively influenced by the eutrophic coastal zone and the oligotrophic waters of the Tyrrhenian Sea. Over the years, LTER-MC has proved to be not only a valuable observatory of the diversity, complexity and temporal variability of plankton but also a precious natural laboratory to test hypotheses that emerged from field observations (reviewed by Zingone et al., 2019).In this Special Issue we have collected the results of the most recent ecological investigations conducted on the plankton of the GoN with the intent to celebrate the 150th anniversary of the SZN foundation, an important occasion that has been widely celebrated (Boero et al., 2023). This special issue focuses on phyto- and zooplankton and their environment studied in both field and lab investigations, with classical methods as well as taking advantage of advanced technologies such as the recent developments of molecular approaches. With this collection, we gather the most updated knowledge on the plankton of the GoN, with a special attention to features that may shed light on general aspects going beyond the local scale of the sampling site.The topics investigated in this Special Issue span over different temporal scales. Some studies took into consideration a large period of the LTER-MC time-series and examined trends of environmental variables (Kokozska et al., 2023; Romillac et al., 2023), revealing that, in the case of plankton, hydrographic changes including inshore–offshore exchanges, the residence time of freshwater and the shallowing of the mixed layer depth are more important than simple temperature increase recorded in summer. The response of plankton is seen in the increased contribution over the years of the autumnal blooms deriving from a lengthening of the stratification period, and in significant trends in specific elements of the phyto- and meso-zooplankton (Saggiomo et al., 2023; Mazzocchi et al. 2023). Interestingly the observed environmental changes are contrasted by the overall stability of the whole mesozooplankton community (Mazzocchi et al., 2023), which parallels the resistance to interannual variation recently highlighted for phytoplankton (Longobardi et al., 2022). When it comes to individual key taxa, the need emerges to consider different aspects of their life cycle, such as fecundity and egg hutching success, to understand the important role played by biology in shaping the observed seasonal and long-term trends in copepod populations (Carotenuto et al., 2023).At the seasonal scale, the annual patterns of seven different and stable phytoplankton associations, identified by leveraging the multiannual data on species distribution from the LTER-MC time series, showed a close relationship with variables related to astronomical factors (Zingone et al., 2023). Their functional diversity varied across the seasons, with divergent or convergent traits within each association reflecting the variable strength of the environmental filtering. A high seasonal signal was also found in dinoflagellate communities investigated in a three-year metabarcoding dataset, along with the identification of a species-rich winter community, so far neglected by the current views of dinoflagellate preference for stable and warm summer conditions (Mordret et al., 2023).A whole range of classical and advanced approaches were used to address plankton variability, including the analysis of physical-chemical, biological and diversity data from the natural environment (Kokozska et al., 2023; Mazzocchi et al., 2023; Romillac et al., 2023; Zingone et al., 2023), laboratory experiments (e.g., Carotenuto et al., 2023; René et al. 2023; Traboni et al., 2023) and more sophisticated chemotaxonomic (Saggiomo et al., 2023) and biomolecular approaches (Di Capua et al., 2023; Mordret et al., 2023; Russo et al., 2023). The latter studies have addressed temporal trends in groups of species hardly detected by morphological studies, unveiling, for example, a high amount of dinoflagellate diversity not assigned to any described taxa (Mordret et al., 2023). This unknown diversity may reveal novel species to be discovered and described, but may also be the effect of massive gaps in reference datasets, i.e., the dictionaries that allow translating the environmental DNA data into biologically meaningful information. In this respect, the delivery of novel reference sequences from several crustacean zooplankters of the GoN represents a relevant contribution to help interpret metabarcoding data and decipher the hidden diversity of plankton communities and their role in the ecology of the system (Di Capua et al., 2023).Molecular approaches are also proven useful and usable to address interspecific relationships of different natures. Co-occurrences derived from a three-year metabarcoding time-series coupled with background biological information on size and trophic habits of their components revealed a trophic hierarchy and modularity in the network, which would allow quick food-web re-arrangements under shifting hydrographic conditions that are typical of the coastal area of the GoN (Russo et al., 2023). The same three-year time series was also explored in the first investigation on diatom parasites of the GoN, where incubation experiments were combined with microscopy observations and contextual metabarcoding analyses (Renè et al., 2023). This multi-approach study revealed that chytrid fungi (Chytridiomycota) are a common component of the protist community in the GoN and would deserve quantification with specific techniques to assess their role in the mortality of their hosts. Besides metabarcoding, another special technique, the stable isotope analysis, provided relevant details of trophic interactions to unveil the complexity of planktonic food webs, which can buffer the environmental variability due to the specific hydrographic features of the GoN (Merquiol et al., 2023). Finally, laboratory experiments conducted with microplastics, which are presently one of the most concerning threats for marine organisms, have revealed that copepod daily intake of food was not significantly affected by their presence, likely because of their ability to avoid those particles and flexible feeding habits (Traboni et al., 2023).The studies presented in this Special Issue have provided many new pieces to the complex puzzle of the plankton ecosystem in the GoN, at the same time opening new questions and providing indications for new studies to be developed in the future. Mainly the topic of trophic and non-trophic interactions has only started to be explored. The discovery of a high amount of parasitic Syndiniales and highly dynamic chytrid fungi populations highlights the need to take into consideration all levels of the network that connects the existence of marine planktonic organisms. While trends are observed in some components of the system, it is necessary to go beyond descriptions and take into consideration the life cycles and reproductive traits of plankton species along with other functional aspects that allow unveiling the mechanism underlying those trends, thus opening the way to the forecast of future scenarios under changing environmental conditions. In this respect, results from both classical, laboratory studies and extensive molecular information obtained from natural populations, interpreted in the light of background knowledge, are expected to provide a formidable new asset to understand plankton and predict their changes in the coming years.In addition to the contribution to the knowledge of the GoN ecosystem, the studies collected in this Special Issue shed light on several aspects of the plankton ecology that go beyond the local scale, emphasizing the specificity of the area and pointing to the pivotal role of long-term investigation sites as testbeds for wide-ranging ecological questions.REFERENCESBoero, F., Groeben, C., & Passariello, A. (2023). La vita del mare. Il mare per la vita: 150 anni di ricerca alla Stazione Zoologica Anton Dohrn . Firenze: Giunti.Caracciolo, M. R., Berney, C., Alric, B., Piredda, R., Zingone, A., Sarno, D., . . . Henry, N. (submitted). Insight into diatoms diversity at two European coastal sites (LTER-MC in the Mediterranean Sea and SOMLIT-Astan in the Western English Channel) using a DNA Metabarcoding approach. Marine Ecology .Carotenuto, Y., Di Capua, I., Di Pinto, M., Palumbo, F., Percopo, I., Uttieri, M., . . . Ianora, A. (2023). Twenty-year trends ofCentropages typicus (Copepoda, Calanoida) reproduction, feeding, population abundance and structure in the Gulf of Naples (Western Mediterranean Sea). Marine Ecology, 44 (3), e12739. doi:10.1111/maec.12739De Angelis, C. M. (1958). Seasonal variation of plankton collected in the Gulf of Naples during 1954-1955. Rapp. Comm. int. Mer Médit., 14 , 245-254.Di Capua, I., Piredda, R., D’Angiolo, R., Minucci, C., Montalbano, A., Boero, F., . . . Uttieri, M. (2023). Is integrated taxonomy useful to study diversity and ecology? An example from crustacean zooplankton at the Long-Term Ecological Research site Marechiara (LTER-MC).Marine Ecology, 44 (3), e12752. doi:10.1111/maec.12752Giesbrecht, W. (1892). Systematik und Faunistik der pelagischen Copepoden des Golfes von Neapel und der angrenzenden Meeres-Abschnitte(Vol. 19): R. Friedlander & sohn.Indelli, E. (1944). Il microplankton di superficie del Golfo di Napoli.Acta Pontificia Academia Scientiarum, 8 , 91-100.Issel, R. (1934). Ciclo annuale del microplancton di superficie nel golfo di Napoli (golfo interno) (Introduzione illustrata all’indagine ecologica). Pubblicazioni Stazione Zoologica Napoli, 14 , 1-50.Kokoszka, F., Le Roux, B., Iudicone, D., Conversano, F., & Ribera d’Alcalá, M. (2023). Long‐term variability of the coastal ocean stratification in the Gulf of Naples: Two decades of monitoring the marine ecosystem at the LTER–MC site, between land and open Mediterranean Sea. Marine Ecology, 44 (3). doi:10.1111/maec.12725Longobardi, L., Dubroca, L., Margiotta, F., Sarno, D., & Zingone, A. (2022). Photoperiod-driven rhythms reveal multi-decadal stability of phytoplankton communities in a highly fluctuating coastal environment.Scientific reports, 12 (1), 3908.Mazzocchi, M. G., Di Capua, I., Kokoszka, F., Margiotta, F., Ribera d’Alcala’, M., Sarno, D., . . . Licandro, P. (2023). Coastal mesozooplankton respond to decadal environmental changes via community restructuring. Marine Ecology, 44 (3), 12746. doi:10.1111/maec.12746Merquiol, L., Mazzocchi, M. G., & D’Ambra, I. (2023). The planktonic food web in the Gulf of Naples (western Mediterranean Sea) based on the analysis of carbon and nitrogen stable isotope ratios. Marine Ecology, 44 (3).Mordret, S., Piredda, R., Zampicinini, G., Kooistra, W. H. C. F., Zingone, A., Montresor, M., & Sarno, D. (2023). Metabarcoding reveals marked seasonality and a distinctive winter assemblage of dinoflagellates at a coastal LTER site in the Gulf of Naples.Marine Ecology, 44 (3), 12758. doi:10.1111/maec.12758Reñé, A., Timoneda, N., Sarno, D., Piredda, R., Zampicinini, G., Zingone, A., . . . Garcés, E. (2023). Vertical and temporal distribution of chytrids infecting diatoms in the Gulf of Naples (Italy, Mediterranean Sea). Marine Ecology, 44 (3), e12726. doi:https://doi.org/10.1111/maec.12726Romillac, N., Abagnale, M., Kokoszka, F., Passarelli, A., Saggiomo, V., Ribera d’Alcalà, M., & Margiotta, F. (2023). Interplay among anthropogenic impact, climate change and internal dynamics in driving nutrient and phytoplankton biomass in the Gulf of Naples. Marine Ecology, 44 (3), e12754. doi:10.1111/maec.12754Russo, L., Bellardini, D., Zampicinini, G., Jordán, F., Congestri, R., & D’Alelio, D. (2023). From metabarcoding time series to plankton food webs: The hidden role of trophic hierarchy in providing ecological resilience. Marine Ecology, 44 (3), 12733. doi:10.1111/maec.12733Saggiomo, M., Bolinesi, F., Brunet, C., Passarelli, A., Margiotta, F., Saggiomo, V., & Mangoni, O. (2023). A CHEMTAX-derived phytoplankton community structure during 12-year observations in the Gulf of Naples (LTER-MC). Marine Ecology, 44 (3), e12745. doi:10.1111/maec.12745Traboni, C., Sarno, D., Ribera d’Alcala’, M., & Mazzocchi, M. G. (2023). Microplastics in the menu of Mediterranean zooplankton: insights from the feeding response of the calanoid copepod Centropages typicus Marine Ecology, 44 (3), 12760. doi:10.1111/maec.12760Vitousek, P. M., Aber, J. D., Howarth, R. W., Likens, G. E., Matson, P. A., Schindler, D. W., . . . Tilman, D. G. (1997). Human alteration of the global nitrogen cycle: Sources and consequences. Ecological Applications, 7 , 737-750. Ddoi: 10.1890/1051-0761(1997)007[0737:HAOTGN]2.0.CO;2Zingone, A., D’Alelio, D., Mazzocchi, M. G., Montresor, M., Sarno, D., & ’LTER-MC Team’. (2019). Time series and beyond: multifaceted plankton research at a marine Mediterranean LTER site. Nature Conservation, 34 , 273. doi:10.3897/natureconservation.34.30789Zingone, A., Tortora, C., D′Alelio, D., Margiotta, F., & Sarno, D. (2022). Assembly rules vary seasonally in stable phytoplankton associations of the Gulf of Naples (Mediterranean Sea). Marine Ecology, 44 (3), 12730. doi:10.1111/maec.12730

Marine bacterial species contribute to a significant part of the oceanic population, which substantially produces biologically effectual moieties having various medical and industrial applications. The use of marine-derived bacterial pigments displays a snowballing effect in recent times, being natural, environmentally safe, and health beneficial compounds. Although isolating marine bacteria is a strenuous task, these are still a compelling subject for researchers, due to their promising avenues for numerous applications Due to their beneficial properties, including anticancer, antibacterial, antioxidant, and cytotoxic actions, marine-derived bacterial pigments were desirable in the food, pharmaceutical, textile, and cosmetic industries. Marine bio-pigments are preferred over synthetically produced colored compounds due to their biodegradability and higher environmentally friendly nature. Besides that, hazardous effects associated with the consumption of synthetic colors further substantiated the use of marine dyes as color additives in industries as well. Herein, we have reviewed the potential of different bacterial species isolated from the marine environment in diverse studies that produce bioactive pigments with potential commercial applications, in addition to the biosynthesis and physiological roles of associated pigments. The chemical structures of the bioactive compounds are also discussed.

Understanding the factors that affect species’ distributions is a central topic of ecology and biogeography. However, the majority of research about this topic has focused on species inhabiting terrestrial environments. At broad scales, abiotic variables consistently serve as the primary determinants of species’ distributions. In this study, we investigate the explanatory power of different abiotic variables in determining the distributional patterns of sea snakes on a global scale. Additionally, as the boundaries of realized thermal niches have significant implications for the ecology of the species and their geographic distributions, we also evaluated the asymmetry of realized thermal limits (i.e., differences in variances between upper and lower limits of the realized thermal niche). We obtained global environmental variables and occurrence data for each species across their entire known geographic range. Using this data, we employed a correlative ecological niche modeling procedure to analyze the influence of individual variables in explaining species’ distributions. To estimate the realized thermal limits of each species, we extracted the mean, minimum, and maximum values of temperature at four depths (superficial, mean benthic, minimum benthic, and maximum benthic) for each occurrence record of the species. We then evaluated the asymmetry of the realized thermal niche by measuring and comparing the variances of the upper and lower limits. Both analyses (the importance of variables and realized thermal limit asymmetry) were performed at three taxonomic levels (sea snakes as a lineage of marine-adapted elapids [true sea snakes + sea kraits], subfamily, and genus) and at two spatial resolutions. Overall, we found that temperature, phosphate, nitrate, salinity and silicate concentrations were the most influential factors in explaining the spatial distribution patterns of sea snakes, regardless of the taxonomic level or spatial resolution. Similarly, we observed that the realized thermal limits were asymmetric with higher variance in the lower limits, and that this asymmetry decreases as the taxonomic level and spatial resolution increased. Finally, our results align with previous findings regarding patterns of asymmetry in realized thermal limits and the significant influence of abiotic variables in explaining the distribution of marine species.

Ostreobium comprise endolithic algae commonly seen in conjunction with scleractinian corals. In the past, it was solely recognized as a coral skeleton bioeroder. Yet, their relationship with corals is critical because they give photosynthetic byproducts and help the coral when it loses its primary symbionts due to stress. The variety of these algae among coral species of the genus Porites in the tropical easter Pacific and western Atlantic was investigated here. We extracted Ostreobium samples from seven Porites species including two from the Tropical Easter Pacific-TEP ( P. panamensis, P. lobata) and five from the Caribbean (P . furcata, P. porites, P. colonensis, P. branneri, and P. astreoides). We also compared the new rbcL sequences from algae found within various coral species from other parts of the world. A biogeographic analysis and two methodologies, PTP (Poisson tree process) and GMYC (General Mixed Yule-Coalescent), were used to delineate the different species. The findings revealed a significant degree of genetic diversity within Ostreobium, with more than 15 groups of no more than three individuals and 40 individual lineages. Its origins date back to the Ordovician, 500 Ma, and it does not appear to preserve host-specificity. The sampled locations include a wide variety of Ostreobium still, biogeographically, varied patterns were confirmed, making it impossible to pinpoint the precise origins of most clades. The ancestry analyses revealed convergent events for the emergence of Ostreobium in a few genera of local corals, but the phenomenon also occurred in genera from far-off places.

The two-toned pygmy squid ( Idiosepius pygmaeus, Streenstrup, 1881) is a small, tropical cephalopod that inhabits seagrass meadows and is known to attach to blades of seagrass using a specialised adhesive organ. A global decline in seagrass habitat due to anthropogenic disturbances may threaten the species that rely on seagrass meadows for shelter, foraging and other crucial activities. It is unclear if I. pygmaeus can utilise alternative habitats in the absence of seagrass. Here, we test the effect of habitat type, material and composition type, and the presence of conspecifics on the settlement preferences of I. pygmaeus. Individuals each underwent three separate experiments: 1) testing the preference between their known habitat, Zostera muelleri subsp. Capricorni and potential substitute, Sargassum, 2) testing the preference to attach to a natural or artificial structure of similar shape and size, and 3) testing the preference of identical habitats, one with a conspecific adhered to and one without. We found that I. pygmaeus did not have a strong preference for either Zostera or Sargassum. However, a strong preference was found for attachment to the natural structure over the artificial one. There was also strong evidence for the use of conspecific cues in habitat choice, with 75% of individuals selecting the habitat that contained a conspecific. As habitat loss is the leading cause of species extinction, the knowledge of habitat preferences for I. pygmaeus is vital in order to assess their risk of population decline. The findings of this study suggest that I. pygmaeus could utilise an alternative habitat in the presence of seagrass meadow reduction, which is under threat from human activity.