3D Fine-scale Terrain Variables from Underwater Photogrammetry: A New Approach to Benthic Microhabitat Modeling in a Circalittoral Rocky Shelf

The relationship between 3D terrain complexity and fine-scale localization and distribution of species is poorly understood. Here we present a very fine-scale 3D reconstruction model of three zones of circalittoral rocky shelf in the Bay of Biscay. Detailed terrain variables are extracted from 3D models using a structure-from-motion (SfM) approach applied to ROTV images. Significant terrain variables that explain species location were selected using general additive models (GAMs) and micro-distribution of the species were predicted. Two models combining BPI, curvature and rugosity can explain 55% and 77% of the Ophiuroidea and Crinoidea distribution, respectively. The third model contributes to explaining the terrain variables that induce the localization of Dendrophyllia cornigera. GAM univariate models detect the terrain variables for each structural species in this third zone (Artemisina transiens, D. cornigera and Phakellia ventilabrum). To avoid the time-consuming task of manual annotation of presence, a deep-learning algorithm (YOLO v4) is proposed. This approach achieves very high reliability and low uncertainty in automatic object detection, identification and location. These new advances applied to underwater imagery (SfM and deep-learning) can resolve the very-high resolution information needed for predictive microhabitat modeling in a very complex zone.En prens

In-situ growth rate assessment of hexactinellid sponge Asconema setubalense using 3D photogrammetric reconstruction

We describe the first application of a non-invasive and novel approach to estimate the growth rate of Asconema setubalense (Porifera, Hexactinellida) through the use of 3D photogrammetric methodology. Structure-from-Motion techniques (SfM) were applied to videos acquired with the Politolana ROTV in the El Cachucho Marine Protected Area (MPA) (Cantabrian Sea) on three different dates (2014, 2017, and 2019) over six years. With these data, a multi-temporal study was conducted within the framework of MPA monitoring. A complete 3D reconstruction of the deep-sea floor was achieved with Pix4D Mapper Pro software for each date. Having 3D point clouds of the study area enabled a series of measurements that were impossible to obtain in 2D images. In 3D space, the sizes (height, diameter, cup-perimeter, and cup-surface area) of several A. setubalense specimens were measured each year. The annual growth rates recorded ranged from zero (“no growth”) for a large size specimen, to an average of 2.2 cm year�����1 in cup-diameter, and 2.5 cm year�����1 in height for developing specimens. Von Bertalanffy growth parameters were estimated. Taking into account the size indicators used in this study and based on the von Bertalanffy growth model, this sponge reaches 95% maximum size at 98 years of age. During the MPA monitoring program, a high number of specimens disappeared. This raised suspicions of a phenomenon affecting the survival of this species in the area. This type of image-based methodology does not cause damage or alterations to benthic communities and should be employed in vulnerable ecosystem studies and MPA monitoring. Keywords: underwater photogrammetry, Asconema setubalense, Marine ProtectedPostprin

Una experiencia de implementación de infraestructura informática: recorriendo el camino desde lo académico hasta la instalación y puesta en funcionamiento

El propósito de esta investigación surge de la necesidad de instalación de un servidor adquirido por el laboratorio GIDAS. La instalación de esté, nos permitirá disponer de nuestra propia infraestructura IT para dar servicios y centralizar información de los diferentes equipos de investigación. Nos centraremos en el recorrido desde lo académico a las experiencias de instalación y puesta en funcionamiento. La manera propuesta para alcanzar el objetivo planteado y fomentar capacidades para la resolución de problemas, transferencia a las prácticas, trabajo cooperativo, habilidades y la creación de conocimientos por parte de los becarios, es una estrategia de enseñanza denominada método de proyecto. Al ser una estrategia transdisciplinaria tiene relación con una amplia gama de técnicas de enseñanza y de aprendizaje, como lo son el estudio de casos, el debate, el aprendizaje basado en problemas, etc. Se describe detalladamente todos los pasos seguidos en la instalación, así como los problemas que surgieron para llegar a la puesta en funcionamiento.XVII Workshop Arquitectura Redes y Sistemas Operativos (WARSO)Red de Universidades con Carreras en Informátic

Describing Polyps Behavior of a Deep-Sea Gorgonian, Placogorgia sp., Using a Deep-Learning Approach

Gorgonians play a fundamental role in the deep sea (below 200 m depth), composing three-dimensional habitats that are characterized by a high associated biodiversity and playing an important part in biogeochemical cycles. Here we describe the use of a benthic lander to monitoring polyps activity, used as a proxy of gorgonian feeding activity of three colonies of Placogorgia sp. Images cover a period of 22 days with a temporal resolution of 30 min. In addition, this seafloor observatory is instrumented with oceanographic sensors that allows continuous monitoring of the hydrographic conditions in the site. Deep-learning is used for automatic detection of the state of the polyps registered in the images. More than 1000 images of 3 large specimens of gorgonians are analyzed, annotating polyps as extended or retracted, using the semantic segmentation algorithm ConvNeXt. The segmentation results are used to describe the feeding patterns of this species. Placogorgia sp. shows a daily pattern of feeding conduct, depending on the hours of day and night. Using a Singular Spectrum Analysis approach, feeding activity is related to currents dynamics and Acoustic Doppler Current Profile (ADCP) return signal intensity, as proxy of suspended matter, achieving a linear correlation of 0.35 and 0.11 respectively. This is the first time that the behavior of the Placogorgia polyps, directly related to their feeding process, is described

Semi-automatic method of fan surface assessment to achieve gorgonian population structure in Le Danois Bank, Cantabrian Sea

This study presents a semi-automatic method to estimate fan surface of a Placogorgia sp. octocoral assemblage using 3D point clouds in El Cachucho MPA at 550 m of depth. The presence of gorgonian forests and deep-sea sponge aggregations in Le Danois Bank was the cause of its declaration as ‘El Cachucho’ Marine Protected Area (MPA), being included in the Natura 2000 network. The Placogorgia sp. is a structuring species of the deep Cantabrian Sea; parameters such as population structure and morphology inform on the overall health of this vulnerable habitat, but the estimation of gorgonian metrics often requires destructive sampling. The use of non-invasive methodology, which does not cause damage or alterations on benthic communities, is particularly necessary in vulnerable ecosystem studies and Marine Protected Areas (MPA) monitoring. This study proposes a semi-automatic methodology to assess gorgonian morphometries fitting planes to colonies. Video transects acquired in Le Danois Bank, during the ECOMARG- 2017 survey using the Politolana underwater towed vehicle were used. Using Pix4D Mapper Pro and Cloud Compare software, size and morphometry of fan-shaped gorgonians and forest population structure were assessed. RMS of fitting planes shows that the geometrical figure chosen is suitable to retain the morphometric characteristics of the specimens of this species. The adjustment of semi-automatic values with a sample of digitized surfaces manually is validated (R2=0.97). The results show that gorgonian population was mostly dominated by small colonies. The population structure distribution shows a high proportion (~22%) of recruits (< 0.05 m2) ce.The authors would like to thank the crew and scientific team aboard the RV Ángeles Alvariño from the Spanish Institute of Oceanography, for their help with the objectives of the ECOMARG 2017 survey. We are especially grateful to the pilot, Luis Armada, and eDronica team, responsible for the Politolana towed sled. This study was funded by the Spanish Institute of Oceanography (IEO) and was included in the ECOMARG Project

3D modeling of Rio Miera wreck ship merging optical and multibeam high resolution points cloud

3D reconstruction and virtual reality (VR) technology provide many opportunities for the documentation and dissemination of underwater cultural heritage. Advances in the development of underwater exploration technology have allowed for the first time to accurately reconstruct a complete 3D model of the cargo Río Miera in the Cantabrian Sea. Sunk on December 6, 1951 after a strong collision, the cargo ship Río Miera rests on a sandy bottom about 40 meters deep, very close to the Cantabrian coast. Located in an area of strong currents is a classic objective of the region for the most experienced divers. The survey was carried out this summer in R/V Ramón Margalef of the IEO, acquiring acoustic data with multibeam echo sounders and hundreds of images acquired by a remotely piloted underwater vehicle. The campaign is part of the PhotoMARE project - Underwater Photogrammetry for MArine Renewable Energy. This work describes the workflow regarding the survey, images and acoustic data acquisition, data processing, optic 3D point cloud color enhancement and acoustic and optic dataset merging procedure to obtain a complete 3D model of wreck Río Miera in Cantabrian Sea. Through this project, Spanish Institute of Oceanography - IEO have advanced - combining acoustic and image methods - in the generation of 3D models of archaeological sites and submerged structures.Survey funded by PhotoMARE Project. PhotoMARE - Underwater Photogrammetry for MArine Renewable Energy, was selected as part of the call for grants of the Program I + C = + C 2016, Support for R & D projects in cooperation in Marine Renewable Energies by SODERCAN (Sociedad para el Desarrollo Regional de Cantabria). The authors would like to thank the crew and scientific team aboard the RV Ramón Margalef from the Spanish Institute of Oceanography, for their help with the objectives of the PhotoMARE2018 survey. Thanks to COMPLUTIG for its contribution to the achievement of project objectives