Search Results (49)

Mesozooplankton were studied monthly (September 2023–August 2024, 12 months) at two coastal stations, at 35 and 90 m water depth, off Punta Blanca, SW Tenerife, Canary archipelago. Sample collection involved 250 and 500 μm bongo nets. This research focused on improving the description of plankton biodiversity and dynamics of the Canary archipelago (Macaronesia area), including its role in the transport of particulate carbon. A total of 156 taxa were identified. Copepoda dominated with 85 taxa, including 72 Calanoida species. They were numerically followed by Appendicularia, Chaetognatha, and Hydrozoa. Mesh sizes varied in collection efficiency, but with a similar pattern during the annual cycle: abundance peaks in early autumn (October–November) and late winter–spring (February–April). The 35 m depth station showed 57 to 3809 ind. m⁻³ (250 μm mesh size) and 10 to 1577 ind. m⁻³ (500 μm). The 90 m depth station showed 22 to 402 ind. m⁻³ (250 μm) and 11 to 170 ind. m⁻³ (500 μm). The present study enhances our understanding of Macaronesia’s mesozooplankton dynamics related to environmental variability, which is crucial for energy transfer assessments in pelagic food webs. It reports new species for the study area, Labidocera acutifrons (Dana, 1849–1852) and Undinula vulgaris (Dana, 1849–1852), highlighting the need for consistent zooplankton monitoring to properly inform conservation and sustainable management actions in the region. Full article

We investigated the biodiversity and spatiotemporal dynamics of benthic hydroids at two contrasting eastern South Adriatic sites: exposed, oligotrophic Lokrum Island and sheltered, nutrient-enriched Bistrina Bay. A total of 54 hydroid taxa were recorded, with substantially higher richness at Lokrum (42 taxa) than at Bistrina (24 taxa). Assemblage composition differed markedly between sites, confirming that local environmental conditions are a primary determinant of community structure, while shallow sublittoral assemblages showed the greatest temporal variability due to seasonally short-lived athecate species. The shared seasonal partitioning at both sites suggests that temperature-mediated life-cycle timing is a key structuring mechanism, and the sharp summer decline in richness underscores the need for multi-seasonal sampling. Laboratory observations of Stylactis inermis from Torre del Serpe near Otranto revealed notable life-cycle plasticity, with detached short-lived eumedusoids reverting to a sessile stolonal stage. This trait may promote persistence under fluctuating conditions while reducing field detectability. Together, these results provide the first seasonal, depth-stratified ecological baseline for monitoring eastern South Adriatic benthic communities under environmental and anthropogenic change. Full article

Sandy beaches are dynamic intertidal ecosystems where ecological interactions play a critical yet often overlooked role in shaping community structure and population dynamics. This study presents a global synthesis of ecological interactions involving mole crabs of the genus Emerita (Crustacea: Decapoda: Hippidae), complemented by new field and laboratory findings. Through a literature review and targeted sampling, we documented multiple interaction types, including predation, parasitism, epibiosis, competition, and symbiosis, highlighting their ecological and potential evolutionary implications. Predation and parasitism were the most frequently reported interactions worldwide. Our new empirical observations revealed, for the first time, the association of Eucheilota (Hydrozoa) and Maritrema sp. (Digenea) with E. rathbunae, as well as annual infection patterns by Profilicollis altmani (Acanthocephala) and algal epibiosis in E. brasiliensis. These interactions influence key biological processes such as burrowing, reproduction, and survival, ultimately affecting species distribution and population structure. Overall, our findings reinforce the central role of ecological interactions in the functioning and conservation of sandy beach ecosystems, particularly under growing anthropogenic pressures. Full article

This study investigates hydroid species distribution across the western Atlantic coastline, focusing on biogeographic patterns, comparing them with Caribbean assemblages, and assess the influence of environmental variables—including salinity, temperature, primary productivity, ocean currents, and chlorophyll—on biogeographic structure. We analyzed 375 species from to 9259 records (1946–2022), spanning the western Atlantic from the Caribbean to southern Argentina (28° N–53° S). Cluster analyses using UPGMA and ordination via nMDS, based on Sorensen-transformed occurrence data. Taxonomic distinctness was assessed with Average Taxonomic Distinctness (Delta+) and Lambda+ variation. UPGMA clustering revealed two main groups: one in the Caribbean and Brazil, and another in southern Brazil, Uruguay, and Argentina. The Amazon River mouth acted as a semi-permeable barrier, with 21.4% species overlap between Caribbean and Brazil. Southeastern Brazil had the highest species richness, likely due to environmental synergy and biodiversity hotspot. Assemblages followed known biogeographic gradients, with lower diversity offshore and on islands. The Río de la Plata showed a distinct, salinity-driven composition. Salinity, chlorophyll, and currents were key distribution drivers. Full article

Cnidarian defensive strategies are commonly associated with the toxins they synthesize. Because toxins have negative, sometimes lethal, effects on humans, research has focused on them for medical and biotechnological applications. However, Cnidaria possess a variety of defensive systems complementing toxins. In recent decades, ecological and biotechnological studies have shed light on these systems, particularly in Anthozoa, while the knowledge of defensive systems different from toxins has remained limited in Medusozoa (Cubozoa, Hydrozoa, Scyphozoa and Staurozoa). In this review, we collected the scattered information available in the literature and organized it into four main topics: UV-light protection compounds, antioxidants, antimicrobial peptides, and endosymbionts. Within the topics, we found the largest amount of data refers to antimicrobial activities, which suggests this line of research as a potential exploitation of this group of organisms often appearing in large aggregates. We also found that some Medusozoa have been studied in detail as model organisms, although the close phylogenetic relationship among classes suggests that some defensive strategies may be common to other members of different classes. Indeed, an integrated understanding of defensive systems has the potential to inform not only ecological and evolutionary frameworks, but also biotechnological applications—from the identification of novel antioxidants or antimicrobial agents to the valorization of Medusozoan biomass. Full article

Cnidarian jellyfish (Medusozoa) comprise approximately 3800 known species which play important roles for marine ecosystem. This study aimed to understand the diversity of cnidarian jellyfish and symbiosis among marine organisms. The taxonomy of the family Zancleidae (Hydrozoa, Anthoathecata) has been problematic because of the limited differences in morphological characteristics between species. This family comprises approximately 40 species belonging to four genera: Apatizanclea, Halocoryne, Zanclea, and Zanclella. In this study, we describe a new species of hydromedusa belonging to the family Zancleidae found in Japanese waters. Zanclea innocens sp. nov. can be distinguished from other Zanclea species by the presence of nematocyst clusters on the exumbrella, slightly thickened apical projection, four narrow exumbrellar nematocyst pouches on ridges often reaching the umbrella apex, four marginal bulbs, and two tentacles. Additionally, Zanclea medusopolypata was recorded for the first time in Japanese waters. This paper provides taxonomic keys for the identification of species in the genus Zanclea. Full article

The phylum Cnidaria comprises five main classes—Hydrozoa, Scyphozoa, Hexacorallia, Octocorallia and Cubozoa—that include such widely distributed and well-known animals as hard and soft corals, sea anemones, sea pens, gorgonians, hydroids, and jellyfish. Cnidarians play a very important role in marine ecosystems. The composition of their fatty acids (FAs) depends on food (plankton and particulate organic matter), symbiotic photosynthetic dinoflagellates and bacteria, and de novo biosynthesis in host tissues. In cnidarian lipids, besides the common FA characteristics of marine organisms, numerous new and rare FAs are also found. All Octocorallia species and some Scyphozoa jellyfish contain polyunsaturated FAs (PUFAs) with 24 and 26 carbon atoms. The coral families can be distinguished by specific FA profiles: the presence of uncommon FAs or high/low levels of common fatty acids. Many of the families have characteristic FAs: Acroporidae are characterized by 18:3n6, eicosapentaenoic acid (EPA) 20:5n3, 22:4n6, and 22:5n3; Pocilloporidae by 20:3n6, 20:4n3, and docosahexaenoic acid 22:6n3 (DHA); and Poritidae by arachidonic acid (AA) and DHA. The species of Faviidae show elevated concentrations of 18:3n6 and 22:5n3 acids. Dendrophylliidae, being azooxanthellate corals, have such dominant acids as EPA and 22:5n3 and a low content of DHA, which is the major PUFA in hermatypic corals. The major and characteristic PUFAs for Milleporidae (class Hydrozoa) are DHA and 22:5n6, though in scleractinian corals, the latter acid is found only in trace amounts. Full article

This study provides a detailed analysis of the community of hydrozoan epibionts of Acanthophora spicifera in La Paz Bay, Baja California Sur. The investigation was carried out in two season periods, corresponding to the warm and cold seasons on the pier of the Autonomous University of Baja California Sur (UABCS) Pichilingue research station. The percentage of epibiont coverage was calculated and analyzed. The average length of the thalli was 7.8 ± 4.6 cm. Eleven taxa of hydrozoans were recorded; the hydrozoan Obelia cf. dichotoma had the highest coverage percentage, and in summer, there was a higher taxa richness. It is recommended to monitor this macroalga and its epibionts for its wide distribution in the bay, although in UABCS, Pichilingue Pier has not seen epibionts that threaten biological diversity. Full article

Craspedacusta sowerbii is an invasive hydrozoan found globally in freshwater habitats. C. sowerbii has a complex life cycle that includes benthic, pelagic, dispersal and dormant stages. The distribution of the medusa (jellyfish) stage has been well documented, but little is known about the other life cycle stages, which are suggested to be more widespread. In addition, the conditions required for growth, reproduction and dispersal of the different life cycle stages, as well as the environmental cues that regulate life cycle transitions, are not fully understood. The aim of this study was to determine laboratory conditions for growth of, and transition to, different life cycle stages in order to improve our ability to culture all life cycle stages of C. sowerbii. In addition, insight into the environmental triggers that promote life cycle transitions will enable us to better predict the potential negative effects C. sowerbii could impose on freshwater ecosystems. Full article

Stylasterid corals are known to be fundamental habitat-formers in both deep and shallow waters. Their tridimensional structure enhances habitat complexity by creating refuges for a variety of organisms and by acting as basibionts for many other invertebrates, including sponges. Porifera represent crucial components of marine benthic assemblages and, in Antarctica, they often dominate benthic communities. Here, we explore the sponge community associated with thanatocoenosis, mostly composed of dead stylasterid skeletons, collected along the Western and Northern edges of the Ross Sea continental shelf. Overall, 37 sponge species were identified from 278 fragments of the stylasterid Inferiolabiata labiata, of which 7 are first records for the Ross Sea, 1 is first record for Antarctic waters and 2 are proposed as new species. Despite the high biodiversity recorded in this and previous studies on Antarctic deep-sea communities, we are still far from capturing the true richness of Antarctic benthic assemblages. Long-term research programs designed to improve the knowledge of the deep-sea fauna inhabiting Antarctic waters are needed to support successful management and conservation plans, especially in this area, considered one of the main marine diversity hotspots worldwide. Full article

The characteristics of zooplankton communities and the relationships with the aquatic environment in the shallow waters of northern Liaodong Bay were investigated. Spot sampling surveys were carried out in April, June, September, and November 2018 to assess zooplankton species composition and diversity, abundance, biomass, and dominant species, and the associated relationships with environmental factors. A total of 45 species of zooplankton were recorded in the survey, comprising 18 Copepoda, 2 Amphipoda, 1 Mysidacea, 1 Decapoda, 1 Chaetognatha, 7 Hydrozoa, 1 Tunicate, and 14 planktonic larvae. Overall, the most dominant species was Aidanosagitta crassa (Tokioka, 1938), with copepods and planktonic larvae also dominating the zooplankton community. However, there was a seasonal alternation of species dominance. A cluster analysis showed that the zooplankton community in spring differed from other seasons and was mostly influenced by suspended particulate matter. Bioenv analysis indicated the main environmental factor affecting the zooplankton community in spring was suspended particulate matter. In summer, the determining variables were temperature, dissolved inorganic nitrogen (DIN), nitrate, and sediment pH. In autumn, temperature, DIN, and nitrate were determining variables, and dissolved oxygen (DO) and DIN in winter. Zooplankton abundance and biomass were influenced by salinity, suspended particulate matter, chemical oxygen demand (COD), chlorophyll, and water and sediment pH. In general, the shallow sea area north of Liaodong Bay is rich in zooplankton species and exhibits significant seasonal variations. Human activities have disturbed the biological community to a certain extent, and the environmental factors in this area are closely related to the diversity of zooplankton species. Full article

Owing to global climate change or the ever-more frequent human activities in the offshore areas, it is highly probable that an imbalance in the offshore ecosystem has been induced. However, the importance of maintaining and protecting marine ecosystems’ balance cannot be overstated. In recent years, various marine disasters have occurred frequently, such as harmful algal blooms (green tides and red tides), storm surge disasters, wave disasters, sea ice disasters, and tsunami disasters. Additionally, overpopulation of certain marine organisms (particularly marine faunas) has led to marine disasters, threatening both marine ecosystems and human safety. The marine ecological disaster monitoring system in China primarily focuses on monitoring and controlling the outbreak of green tides (mainly caused by outbreaks of some Ulva species) and red tides (mainly caused by outbreaks of some diatom and dinoflagellate species). Currently, there are outbreaks of Cnidaria (Hydrozoa and Scyphozoa organisms; outbreak species are frequently referred to as jellyfish), Annelida (Urechis unicinctus Drasche, 1880), Mollusca (Philine kinglipini S. Tchang, 1934), Arthropoda (Acetes chinensis Hansen, 1919), and Echinodermata (Asteroidea organisms, Ophiuroidea organisms, and Acaudina molpadioides Semper, 1867) in China. They not only cause significant damage to marine fisheries, tourism, coastal industries, and ship navigation but also have profound impacts on marine ecosystems, especially near nuclear power plants, sea bathing beaches, and infrastructures, posing threats to human lives. Therefore, this review provides a detailed introduction to the marine organisms (especially marine fauna species) causing marine biological disasters in China, the current outbreak situations, and the biological backgrounds of these outbreaks. This review also provides an analysis of the causes of these outbreaks. Furthermore, it presents future prospects for marine biological disasters, proposing corresponding measures and advocating for enhanced resource utilization and fundamental research. It is recommended that future efforts focus on improving the monitoring of marine biological disasters and integrating them into the marine ecological disaster monitoring system. The aim of this review is to offer reference information and constructive suggestions for enhancing future monitoring, early warning systems, and prevention efforts related to marine ecological disasters in support of the healthy development and stable operation of marine ecosystems. Full article

Porpita porpita is a colonial polymorphic hydrozoan distributed in temperate and tropical zones. This species, like most hydrozoans, possesses a metagenetic life cycle with alternating life forms: medusa stage, polypoid colony, and planula larva. However, a characterization of its early stages of development is still lacking. For this study, an integrative description of the larval stages and the hydroid colony was performed using molecular and histologic tools. The results show that P. porpita develops through three larval stages: preplanula, planula, and premetamorphic planula. The preplanula is distinguished by an absence of polarity, the planula by differentiation of the oral–aboral poles, and the premetamorphic stage by cellular differentiation. Furthermore, two morphologies of young hydroids with different developmental patterns of gonozooids and dactylozooids were observed; notably, it was not possible to observe the gastrozooid in either. Taxonomic identification was confirmed using mitochondrial (COI) and ribosomal (18S and 28S) markers. Our analysis indicates that the COI gene exhibits higher intraspecific variability compared to the 18s and 28s rDNA ribosomal genes. The presented results support the future identification of P. porpita based on morphological characteristics, regardless of the stage of development. Specifically, they shed light on the diversity of mesozooplankton in reef communities. Full article

The family Eirenidae is one of the major taxa of the order Leptothecata, comprising approximately 80 species from ten genera. In this study, taxonomic investigations, including morphological observations and molecular 16S phylogenetic analyses, were conducted on unknown Eirenidae specimens collected off the coast of Iwaki, Fukushima Prefecture, eastern Japan, in June 2022. The specimens had the following morphological characteristics: marginal warts and tentacular bulbs with lateral cirri and without adaxial papillae, a mouth with simple lips, four simple radial canals, and eight statocysts common to the genus Eutima. However, this species can be distinguished from other species of Eutima by the number of tentacles, number and shape of marginal warts, position of the gonads, and gastric peduncle length. Moreover, the monophyly of the species was evident in the 16S rRNA phylogenetic tree (as indicated by the high bootstrap value of 100%), thereby supporting the validity of the new species. Based on these results, we describe it as a new species, Eutima onahamaensis, for taxonomic stabilization. We also made detailed observations of the morphology and molecular phylogenetic analyses of one of the species newly recorded in Japan: Eutima diademata. A comparative table of the primary diagnostic characteristics of Eutima has been provided. This study provided taxonomic keys for identifying species in the genus Eutima. Full article

Olindiid freshwater jellyfishes of the genus Craspedacusta Lankester, 1880 are native to eastern Asia; however, some species within the genus have been introduced worldwide and are nowadays present in all continents except Antarctica. To date, there is no consensus regarding the taxonomy within the genus Craspedacusta due to the morphological plasticity of the medusa stages. The species Craspedacusta sowerbii Lankester, 1880 was first recorded in Italy in 1946, and until 2017, sightings of the jellyfish Craspedacusta were reported for 40 water bodies. Here, we shed new light on the presence of the freshwater jellyfishes belonging to the genus Craspedacusta across the Italian peninsula, Sardinia, and Sicily. First, we report 21 new observations of this non-native taxon, of which eighteen refer to medusae sightings, two to environmental DNA sequencing, and one to the finding of polyps. Then, we investigate the molecular diversity of collected Craspedacusta specimens, using a Bayesian analysis of sequences of the mitochondrial gene encoding for Cytochrome c Oxidase Subunit I (mtDNA COI). Our molecular analysis shows the presence of two distinctive genetic lineages: (i) a group that comprises sequences obtained from populations ranging from central to northern Italy; (ii) a group that comprises three populations from northern Italy—i.e., those from the Lake Levico, the Lake Santo of Monte Terlago, and the Lake Endine—and the single known Sicilian population. We also report for the first time a mtDNA COI sequence obtained from a Craspedacusta medusa collected in Spain. Full article