1,720,981 research outputs found
Morphological and genetic variation in Southern Ocean Echinoderms with main focus on brittle stars (Ophiuroidea)
Full text linkIn recent years, changes to traditional taxonomic methods to incorporate new technologies and techniques have greatly improved the quality of species hypotheses, but more work can be done to improve the speed of new species discovery and documentation. The mitochondrial COI DNA barcode has been successfully used to identify species with high accuracy since the early 2000s and is now currently used in conjunction with morphological examinations to detect and delimit new species. The first aim of this thesis was the definition of a general standard sampling protocol to be applied in remote and extreme areas such as the Southern Ocean to pinpoint new species and the establishment of a procedural approach for samples treatment to obtain and record all the metadata and information associated with the collected organisms that will undergo molecular identification based on DNA barcoding. Distributional information’s regarding the Ross Sea quadrant are still scarce and sparse, despite the continued research that has been held in the area since the 50’s of the past century. To fill this gap, the second objective of the thesis concerns the production of distributional data and species lists of taxa belonging to the phylum Echinodermata from the Terra Nova Bay area (Ross Sea, Antarctica) for which there is still no information in the scientific literature, i.e. the classes Holothuroidea and Crinoidea. To assess this objective, a “Reverse taxonomy” approach was applied to echinoderms samples stored in the permanent biological collections of the Italian National Antarctic Museum (MNA, Section of Genoa). According to this approach, analysis of morphological features (e.g. skeletal elements) was performed only after having obtained molecular data and a robust phylogeny, to assess the congruence between morphological and molecular data. In order to do that, all the available organisms belonging to the phylum Echinodermata suitable for molecular investigation were gathered and analyzed. A collection of cytochrome c oxidase subunit I (COI) sequences amplified from specimen of the MNA collections was produced and used to define species boundaries. DNA sequences were then deposited in permanent databases (BOLD and GenBank). The application of this technique allowed us to increase the available information for the benthic community of the Terra Nova Nay, as well as to re-evaluate the previous knowledge and to correct gross classification mistakes present in literature due to not appropriate approaches in species determination that led to a perpetration of wrong evaluation of biodiversity in the area for more than 50 years. Due to the diversity of the different classes included in the phylum Echinodermata and the specific analyses necessary to assess the correct identification of each taxon, these will be treated and detailed in separate chapters. The Thesis starts with an Introduction, where the most general topics covered by the entire thesis are presented. Each chapter, with the exception of the first one, which has a different structure from the others, has its own specific “Introduction” to the concepts discussed in that study, followed by the sections “Materials and Methods”, “Results” and “Discussion”. Chapters 1 to 4 have already been published as book chapters (Chap. 1 in Marine Genomics - Methods in Molecular Biology), occurrence dataset (Chap. 2, in the Global Biodiversity Information Facility, https://www.gbif.org/) or regular articles in ISI Journals (Chap. 3 and Chap. 4 in Diversity). Considering the specificity of the different chapters, notwithstanding the fact that they pertain to the same, general topic of research, no general Discussion for the entire thesis was produced. Final remarks are instead reported at the end of the whole thesis (“Thesis Conclusions”)
Characterization of Iophon spp. (Porifera, Demospongiae) in association with the brittle stars genus Ophioplinthus (Echinodermata, Ophiuroidea) in the Southern Ocean
No full textSponges represent one of the most important components of the Antarctic zoobenthos, with over 350 known species found on hard and soft substrata, where they increase habitat heterogeneity. Due to hard substrates scarcity in the Antarctic sea bottom, sponges often show peculiar morpho-functional adaptations required to thrive on soft bottoms or to colonize biotic secondary substrates. In these cases, the associations are referred to as ectosymbioses. Symbiotic interactions represent important ecological and evolutionary drivers, often promoting speciation through host shift. Extensive investigations into benthic biodiversity in the Southern Ocean and the ecological role of symbiotic interactions has been recently re-evaluated.
In this context, particularly intriguing is the ectosymbiontic relationships established between brittle-stars of the genus Ophioplinthus Lyman, 1878 and the demosponge genus Iophon Gray, 1867. Even though this interaction is widely reported in the Antarctic scientific literature, detailed information regarding the partners is still limited. In this work we analysed the samples available at the Italian National Antarctic Museum (MNA, Section of Genoa) to classify the partners of the association at the finest possible level. Thanks to these new materials we report the first record of I. flabellodigitatum Kirkpatrick, 1907 on O. brevirima (Mortensen, 1936) and of I. unicorne Topsent, 1907 on O. gelida (Koehler, 1901). Out of the 166 Ophioplinthus specimens examined in this work, the significant proportion of 57.8% were found to be engaged in symbiotic associations, highlighting the importance of this interactions within the Antarctic brittle star population. In the specimens studied, the presence of Iophon has different degrees of development but numerous specimens of O. gelida did not exhibit this association, while all the O. brevirima specimens present the symbiosis. Our analysis also reported a difference between the external morphology of the two Iophon sponge compared to the original description by Kirkpatrick of 1907
A Beacon in the Dark: Grey Literature Data Mining and Machine Learning Enlightening Historical Plankton Seasonality Dynamics in the Ligurian Sea
Full text linkThe Mediterranean Sea, as one of the world’s most climate-sensitive regions, faces significant environmental changes due to rising temperatures. Zooplankton communities, particularly copepods, play a vital role in marine ecosystems, yet their distribution dynamics remain poorly understood, especially in the Ligurian Sea. Leveraging open-source software and environmental data, this study adapted a methodology to model copepod distributions from 1985 to 1986 in the Portofino Promontory ecosystem using the Random Forest machine learning algorithm to produce the first abundance and distribution maps of the area. Five copepod genera were studied across different trophic guilds, revealing habitat preferences and ecological fluctuations throughout the seasons. The assessment of model accuracy through symmetric mean absolute percentage error (sMAPE) highlighted the variability in copepod dynamics influenced by environmental factors. While certain genera exhibited higher predictive accuracy during specific seasons, others posed challenges due to ecological complexities. This study underscores the importance of species-specific responses and environmental variability in predictive modeling. Moreover, this study represents the first attempt to model copepod distribution in the Ligurian Sea, shedding light on their ecological niches and historical spatial dynamics. The study adhered to FAIR principles, repurposing historical data to generate three-dimensional predictive maps, enhancing our understanding of copepod biodiversity. Future studies will focus on developing abundance distribution models using machine learning and artificial intelligence to predict copepod standing crop in the Ligurian Sea with greater precision. This integrated approach advances knowledge of copepod ecology in the Mediterranean and sets a precedent for integrating historical data with contemporary methodologies to elucidate marine ecosystem dynamics
New distributional records of Southern Ocean Isopoda based on vouchers from the Italian National Antarctic Museum (MNA, Section of Genoa)
Full text linkThe order Isopoda Latreille, 1816 consists of species occurring in terrestrial, marine and freshwater environments. In the Southern Ocean (SO), this group is amongst the most speciose and occur at all depths. Isopoda biogeography, despite being studied since the first Antarctic expeditions, is still poorly known from a geographical point of view and shows large occurrence gaps for some groups in specific sectors of the SO. In this paper, we update the isopod checklists of the Ross Sea (RS) and of some peri-Antarctic areas, such as the South Orkney Islands (SOI) and the South Sandwich Islands (SSI), based on the study of museum vouchers curated by the Italian National Antarctic Museum (MNA, Section of Genoa).A total of 279 MNA samples from 15 different expeditions were studied. From this material, consisting of 419 specimens, 41 accepted species distributed in 24 families and 51 genera were identified. Comparing this newly-obtained information with the GBIF (Global Biodiversity Information Facility) and OBIS (Ocean Biodiversity Information System) portal, 15 species are here reported for the first time in the Ross Sea, with five new records in the Ross Sea Marine Protected Area. All records are new for the Terra Nova Bay area, for which a checklist of this group has never been produced before
Cymbulia parvidentata Pelseneer, 1888 (Mollusca, Cymbuliidae) in the Ligurian Sea: further evidence of Atlantic species incursions in the Mediterranean area
Full text linkWe report the first record of a stranded specimen of Cymbulia parvidentata, a pteropod species of Atlantic origin, in the Ligurian Sea. On 27 February 2022, six C. peronii and one C. parvidentata were collected on Borgio-Verezzi Beach (Savona, Italy - 44.16° N, 8.304633° W). Specimens were examined morphologically and biometrically. Measurements (length, width, height and wet weight) separated the two taxa, C. peronii being larger than C. parvidentata. The finding of C. parvidentata, which has only occasionally been reported in southern Italy, is remarkable and may be due to ascending Atlantic water (AW) pulses that reach the Ligurian Sea. This finding adds to the previous knowledge of other pelagic species of Atlantic origin that were found in the Ligurian Sea, suggesting the possibility of major on-going changes and a general "Atlantification". In order to determine the frequency of such events, it will be highly desirable to design specific citizen-science campaigns
Stranding of Porpita porpita (Cnidaria, Hydrozoa) in Ligurian coast: sampling bias or evidence of a warming sea?
Full text linkOn September 1st, 2023 three specimens of the blue button Porpita porpita (Linnaeus, 1758) (Cnidaria, Hydrozoa) were found stranded along the store of the Genoa metropolitan area (northwest Mediterranean Sea, Ligurian Sea) as a result of a citizen science contribution. This record represents the second observation of the species in this area after the first one, occurred in 2019. The general increase in observations of P. porpita in the Mediterranean basin, from 2010 on, may suggest a higher abundance of specimens in the sea, likely due to climate change, an intensified effort in reporting sightings of citizens scientist (whose data accounts for more than 85% of total available records), or a combination of both factors. The analysis of environmental data related to this latest stranding event suggests that this occurred under specific meteorological conditions. Since monitoring the spread of non-indigenous species is fundamental to study global warming effects on marine biodiversity, the understanding of the precise environmental settings under which they may occur might reduce observational biases and contribute to the acquisition of sound data less linked to fortuitous observations
Sponges (Porifera) from the Ross Sea (Southern Ocean) with taxonomic and molecular re-description of two uncommon species
No full textPorifera are one of the dominant components of the marine benthic communities in the Antarctic Sea (44% of the total species are endemic). Despite these data and the various studies on marine biodiversity, the abundance and diversity of sponges on shallow Antarctic reefs and in the deep sea are likely significantly underestimated. In this context, our work deals with the description of Antarctic sponges inhabiting Tethys Bay (Ross Sea). A total of 46 sponge specimens were collected at different depths during three separate Italian Antarctic Expeditions and identified into 15 species within the Demospongiae and Hexactinellida classes. More importantly, we report on finding two species, i.e. Haliclona scotti and Mycale (Aegogropila) denticulata, for the first time after 114 and 16 years, respectively, from their original description. More details are also given on their taxonomic re-description and molecular characterization. © 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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