Structure and metabolic potential of the prokaryotic communities from the hydrothermal system of Paleochori Bay, Milos, Greece

IntroductionShallow hydrothermal systems share many characteristics with their deep-sea counterparts, but their accessibility facilitates their study. One of the most studied shallow hydrothermal vent fields lies at Paleochori Bay off the coast of Milos in the Aegean Sea (Greece). It has been studied through extensive mapping and its physical and chemical processes have been characterized over the past decades. However, a thorough description of the microbial communities inhabiting the bay is still missing.MethodsWe present the first in-depth characterization of the prokaryotic communities of Paleochori Bay by sampling eight different seafloor types that are distributed along the entire gradient of hydrothermal influence. We used deep sequencing of the 16S rRNA marker gene and complemented the analysis with qPCR quantification of the 16S rRNA gene and several functional genes to gain insights into the metabolic potential of the communities.ResultsWe found that the microbiome of the bay is strongly influenced by the hydrothermal venting, with a succession of various groups dominating the sediments from the coldest to the warmest zones. Prokaryotic diversity and abundance decrease with increasing temperature, and thermophilic archaea overtake the community.DiscussionRelevant geochemical cycles of the Bay are discussed. This study expands our limited understanding of subsurface microbial communities in acidic shallow-sea hydrothermal systems and the contribution of their microbial activity to biogeochemical cycling

Selfie Drones for 3D Modelling, Geological Mapping and Data Collection: Key Examples from Santorini Volcanic Complex, Greece

In the present work, we tested the use of selfie drones as a tool for 3D modeling, geological mapping, and data collection. The model we used is a 0.300-kg multirotor quadcopter being equipped with a 1/2.3-inch CMOS sensor capable of capturing 12 Megapixel pictures, attached to a 2-axis mechanical gimble and with approximately 16 minutes of flight time. Test sites are located in Santorini and are characterised by different settings: i) the 1570-1573 AD volcanic crater area, in Nea Kameni island, has a mostly horizontal topography; ii) the outcrop along Vlychada beach, showing layers of the Late Bronze Age (also well-known as Minoan) eruption, has mostly vertical topography. By applying the Structure from Motion techniques to pictures collected using the selfie drone, we were capable of: i) reconstructing the two sites with centimetric to sub-centimetric resolution; ii) recognizing geological features on very high-resolution Digital Surface Models and Ortomosaics; iii) mapping vertical cliffs made up of volcanic deposits on 3D Digital Outcrops Models; iv) collect new quantitative data for both sites

Virtual Geosite Communication through a WebGIS Platform: A Case Study from Santorini Island (Greece)

We document and show a state-of-the-art methodology that could allow geoheritage sites (geosites) to become accessible to scientific and non-scientific audiences through immersive and non-immersive virtual reality applications. This is achieved through a dedicated WebGIS platform, particularly handy in communicating geoscience during the COVID-19 era. For this application, we selected nine volcanic outcrops in Santorini, Greece. The latter are mainly associated with several geological processes (e.g., dyking, explosive, and effusive eruptions). In particular, they have been associated with the famous Late Bronze Age (LBA) eruption, which made them ideal for geoheritage popularization objectives since they combine scientific and educational purposes with geotourism applications. Initially, we transformed these stunning volcanological outcrops into geospatial models—the so called virtual outcrops (VOs) here defined as virtual geosites (VGs)—through UAV-based photogrammetry and 3D modeling. In the next step, we uploaded them on an online platform that is fully accessible for Earth science teaching and communication. The nine VGs are currently accessible on a PC, a smartphone, or a tablet. Each one includes a detailed description and plenty of annotations available for the viewers during 3D exploration. We hope this work will be regarded as a forward model application for Earth sciences’ popularization and make geoheritage open to the scientific community and the lay public

Corinth Gulf Story Map: Enhancing Public Awareness in Natural and Anthropogenic Environment using Interactive GIS Applications

Story maps are widespread as an interactive tool used for science and spatial data communication, information and dissemination. A web-based application using story mapping technology is presented here to highlight places of interest around Corinth Gulf (Greece), a new addition in Natura 2000 areas. A tailored story map that combines thematic webmaps and scenes (3D webmaps) generated through a Geographic Information System (GIS) having a great impact on web-based visual presentations with narrative text and multimedia content was created to highlight the geological and cultural environment of the area around Corinth Gulf

Novel Virtual Reality Solutions for Captivating Virtual Underwater Tours Targeting the Cultural and Tourism Industries

The underwater environment beyond its natural unique beauties has a great scientific interest as it pertains all fields of marine research; despite this, it has not been adequately exploited for cultural and tourism purposes. Virtual and augmented reality technologies have advanced considerably in re-producing and representing unreachable large-scale environments. To this end, this work presents an integrated interactive framework for exploring the underwater world such as submerged cities, shipwrecks, sunken harbors, diving and marine parks, either in situ via augmented reality, or remotely via virtual reality. Firstly, the designed solution exploits high-resolution visual and range data acquired with state-of-the-art technologies (swath mapping systems, underwater vehicles, unmanned aerial vehicles) and processed through novel approaches to create a synthetic topographic relief basemap and to analyze its geomorphology, as well as the anthropogenic interventions. Secondly, this framework allows to write narrative scenarios and produce interactive VR experiences, through a set of custom tools for multimedia content management. The developed framework, named VIRTUALDIVER, will enable domain experts to design immersive xReality experiences and users to experience environments that are typically accessed only by underwater vehicles in cost-intensive, scientific missions. This will promote the underwater cultural heritage, and natural environment through the development of innovative research, teaching, tourism and creative products

Regional mapping and characterisation of shallow submarine hydrothermal system (Milos)

International audienc

Shallow-water hydrothermalism at Milos (Greece): Nature, distribution, heat fluxes and impact on ecosystems

International audienc

Shallow-water hydrothermalism at Milos (Greece): Nature, distribution, heat fluxes and impact on ecosystems

Submarine hydrothermal activity is responsible for heat and chemical exchanges through the seafloor. Shallow-water hydrothermal systems (SWHS), while identified around the globe, are often studied in a way that is less comprehensive than their deep-ocean counterparts (e.g., along ridges), where systematic optical and acoustic mapping is more prevalent and coupled to in situ observations and sampling. Using aerial drones, an AUV, and temperature measurements at 10-40 cm subseafloor, we investigated in 2019 one of the most extensive SWHS known to date, in Paleochori and nearby Spathi and Agia Kyriaki Bays (south of Milos, Greece). Hydrothermal venting, found from the shore to water depths of almost 500 m, shows emissions of gases and high-temperature fluids, often associated with bacterial mats and/or hydrothermal mineral precipitates. This study provides extensive drone mapping coupled with local AUV surveys for seafloor characterization and ground-truthing from the shore to similar to 20 m water depth. Seafloor photomosaics also provide a detailed context to samples, measurements and observations carried in situ. We interpret the photomosaics to define distinct seafloor types, linked to this hydrothermal activity. White hydrothermal patches (WHPs) often show a clear polygonal organization, together with outflow areas that are both more dispersed and distributed. Polygonal patterns likely result from fluid convection in a sandy porous medium heated from below. These WHPs display elevated subseafloor temperatures, typically >50 degrees C, with maximum values of similar to 75 degrees C. Photomosaics also display textures of biological origin, including seagrass and bioturbation patterns. Widespread bioturbation by burrowing shrimps is often associated with WHPs, bounding them, but also occurs on sandy seafloor away from hydrothermal patterns. Subseafloor temperatures at these bioturbated areas are of similar to 30-40 degrees C, and are thus transitional between hot WHPs and sedimented seafloor unaffected by hydrothermal activity (similar to 24 degrees C). In addition to linking subseafloor temperature data and interpreted seafloor photomosaics, our results provide a comprehensive general overview of this SWHS, of the organization of its hydrothermal outflow through the seafloor, and of the underlying subseafloor fluid circulation. This paper also gives the first perspectives on the heat fluxes of the system, and constitutes a background for other studies on the nature and distribution of microbial communities, controlled by this hydrothermal activity