Marine Biodiversity最新文献

Garfish Belone belone (Linnaeus, 1761) are distributed over a wide area covering all the East Atlantic coasts including the North and Baltic Seas and the entire Mediterranean basin. Researchers have presented different opinions regarding the presence of subspecies and endemic species of garfish due to certain morphological variations found in Mediterranean populations up to the current day. The purpose of this study is to clarify the taxonomic status of Belone euxini Günther, 1866, described as the Black Sea endemic by Günther (1866) and Belone acus Risso, 1827, described as the Mediterranean gar fish population by Risso (1827) with an integrative perspective. B. belone specimens were sampled from 12 localities in the North-Eastern Mediterranean. The congeneric Belone svetovidovi Collette & Parin, 1970, specimens were sampled at different locations in the Eastern Aegean Sea and included molecular analyses in order to determine the interspecific distance between Belone species. Detailed morphological description and genetics are provided for B. belone populations. Based on the results, it can be supported that the differences observed between B. belone populations are within the limits of intraspecific variation thus indicating that there are no distinct populations at the species level in the Mediterranean basin.

Prosorhochmidae, known as smiling worms, are hoplonemerteans of great interest to nemertologists, since some species display viviparity and hermaphroditism, both rare traits in this phylum, and can be found in terrestrial and marine environments. Prosorhochmus is a predominantly marine genus and was never recorded on the Brazilian coast. The present study documents the first record of the oviparous Prosorhochmus belizeanus, along with population genetic diversity analyses. Here, we sequenced cytochrome c oxidase subunit 1 (COI) and 16S ribosomal RNA (16SrRNA) regions from individuals of three localities along the Brazilian Northeast coast. From these analyses, we found moderate genetic diversity, no genetic structuring, and no clear geographical pattern. In addition, migration analysis evidenced some influence of the Brazilian Current in the species’ dispersion. Those findings indicate colonization by a small number of mtDNA lineages followed by population stability and shed light into the importance of deepening the knowledge about those organisms to elucidate genetic and dispersion patterns of oviparous invertebrates of rocky shores.

Cold-water dinoflagellates contribute significantly to spring blooms in temperate coastal waters. In the northern Baltic Sea, Peridiniella catenata, Apocalathium malmogiense, Gymnodinium corollarium, and Biecheleria baltica predominate the dinoflagellate spring blooms. Spring dynamics of cold-water dinoflagellates have been previously studied using cyst sedimentation data. Here, we utilize time-series data based on amplicons of the V4 region of the 18S rRNA gene spanning from autumn 2012 to spring 2013 and describe dynamics and habitat preferences of the relatively most abundant dinoflagellates in the northern Baltic Sea. Our results indicate that these species preferred either sea ice, under-ice water, or deeper water columns during the ice-covered season and that they shifted in temporal dominance during our sampling period.

During the KH-23–5 expedition aboard the RV Hakuho Maru to the Kuril-Kamchatka (KKT) and Japan Trenches (JT) in September 2023, we deployed bottom trawls equipped with plankton nets, resulting in a high number of supra- and epibenthic benthic organisms, particularly of isopod crustaceans (Peracarida, Malacostraca). In total, we sampled 2656 specimens of Isopoda spanning at least 14 families and the suborder Epicaridea across 28 stations. Notably, five families were represented by more than 100 specimens each: Munnopsidae led with the highest number of specimens (1123 individuals), followed by Haploniscidae with 564, Macrostylidae with 430, Ischnomesidae with 245, and Desmosomatidae with 188 individuals. Station C8 yielded the highest number of individuals (502), while only one isopod was retrieved from station F11. Our findings document the efficacy of employing additional plankton nets,and we recommend the increased use of bottom trawls deployed with plankton nets in future expeditions.

Abiotic and biotic stressors are known to trigger reproductive activities in several aquatic organisms. In reef environments, physical contact as a response to competition for space on the benthos is a common stressor among sessile organisms, often leading to severe tissue damage and even mortality due to biological and chemical mechanisms. However, the effect of physical stress on coral reproduction has received less attention. In this study, we observed colonies of the scleractinian coral Siderastrea stellata releasing larvae in response to physical contact with the zoantharian Palythoa caribaeorum. Organisms were collected from reefs in Brazil and taken to the laboratory, where competition through physical contact was simulated in tanks by placing the two species in direct contact for 72 h. During this period, seven out of eight corals that were in physical contact with the zoantharian released larvae, showing tissue discoloration and a marked decrease in photosynthetic efficiency. Only one of the other eight colonies held as a control with no physical contact released larvae, indicating that physical contact may have been the trigger for larval release. This is, to our knowledge, the first report of physical contact-induced larval release in a scleractinian species, providing grounds for further investigating the potential mechanisms involved in this phenomenon.

The accumulation of information on the geographical distribution range, genetic structure, and host utilization of the symbiont is important for studying how the symbiont spreads its distribution. Pseudocladophora conchopheria is a green alga that grows on the shells of intertidal gastropods distributed in the Japanese Archipelago, the Ryukyu Archipelago, and the southern part of Korean Peninsula. However, we discovered algae similar to P. conchopheria on the shells of gastropods from Vietnam. Therefore, species identification of the algae and the host gastropods was performed based on morphological observations and molecular genetic methods. As a result, the morphological characteristics of the algae were consistent with those of P. conchopheria, and the morphological characteristics of the host gastropods were consistent with those of Lunella granulata. Molecular genetic methods further supported these results of morphological identification. Interestingly, their algae were more closely related to P. conchopheria attached to L. correensis from the Sea of Japan rather than those attached to L. granulata from the Ryukyu Archipelago. These results suggest that P. conchopheria has expanded its distribution by utilizing multiple hosts and are explained on a wider scale than previous findings.

Species richness, defined as the number of species within a specific area, exhibits spatial variation at most spatial scales. The drivers behind these patterns, especially for marine invertebrates, remain a subject of ongoing debate. In this study, we explore the determinants of species richness for shallow-water gorgonians (Cnidaria: Anthozoa) in the Eastern Tropical Pacific, utilizing a comprehensive database of geographic occurrences and generalized linear mixed models analyses to investigate the influence of seven environmental variables in the context of four theoretical frameworks (Species-Energy, Environmental Heterogeneity, Climate Seasonality, and Past Climatic Stability hypotheses). Our methodology aims to account for potential spatial autocorrelation, enhancing the reliability of results. Our findings indicate a robust positive association between sea bottom temperature and species richness, supporting the Species-Energy hypothesis. Temperature, a key factor for marine biodiversity, likely enhances gorgonians’ metabolic, ecological, and mutation rates. Topographic ruggedness, climatic stability, and light availability were significant predictors of species richness, though their effects varied between subsets of analyzed taxa. Consequently, although our analysis supports the Environmental Heterogeneity and Past Climatic Stability hypotheses, their importance appears secondary. Overall, this research highlights the critical role of contemporary factors (predominantly temperature and topographic ruggedness) and historical factors, particularly climatic stability over the last 20,000 years, in influencing the distribution of gorgonian species richness in the Eastern Tropical Pacific.

The sea pen Pteroeides spinosum (Ellis, 1764), belonging to the superfamily Pennatuliodea McFadden, van Ofwegen & Quattrini, 2022, is a little-known anthozoan species well-adapted to inhabit soft bottoms. Similar to other sea pens, it can form aggregations in both infra- and circalittoral zones, significantly enhancing the complexity and biodiversity of these habitats. We present the first in vivo video observation of rolling behaviour of a P. spinosum individual, documented during a Remotely Operated Vehicle (ROV) survey, in the northern Tyrrhenian Sea, at a depth range of 50–58 m. The animal assumed a wheel-like shape, likely by inflating its body with seawater. This led to a rolling motion along the seabed, covering a linear distance of approximately 7 m in just 4 min. The observed mobility of this species adds new information about its behaviour, emphasizing the role of video technology in capturing real-time information.

In the era of climate change-related restructuring of planktonic protist communities, it is especially important to identify possible shifts in their taxonomic composition. While traditional microscopy-based morphological classification is time-consuming and requires experienced taxonomists, metabarcoding seems to substantially accelerate the determination of taxonomic composition. In this study, based on samples collected in summer 2019 from the West Spitsbergen Current, we analysed planktonic protists using both methods. Metabarcoding, based on high-throughput sequencing of the V4 region of the 18S rRNA gene, resulted in a much higher number of operational taxonomic units (OTUs) and sample diversity than microscopy, although the resolution of taxonomic identification ranged from species to phyla. Most morphology-based identification was performed at the species or genus level, additionally allowing us to include information about dominants and size fractions. The highest proportion of 45% shared taxa by both methods was recorded at the class level. The composition of dominant protists differed between the approaches, with most similarities being observed in Bacillariophyceae, for which two genera, Thalassiosira and Eucampia, were found to be the most abundant with both methods. For Dinophyceae, the most abundant representatives identified by microscopy were Gymnodinium spp., Prorocentrum minimum and Gonyaulax gracilis, while in the metabarcoding approach, most dinoflagellates were identified to the class level only. Given the different levels of accuracy of taxonomic determinations and possible biases in results connected to the chosen methodology, we advocate using an integrative taxonomic approach for the classification of planktonic protists based on the combination of microscopy and molecular methods.