The European Union Marine Strategy Framework Directive requires Member States to monitor and assess the health status of their marine habitats. Belgium put forward that the spatial extent and distribution of the major habitats (sandy mud to mud, muddy sands to sands and coarse-grained sediments), as well as that of gravel beds may only fluctuate within a margin that is limited to the accuracy of the current sediment distribution maps. Due to their ability to provide simultaneous bathymetry and backscatter strength (BS), reflecting seabed nature, multibeam echosounder systems (MBES) provide a time- and costefficient solution to anticipate on this legal obligation. However, as there is no formal quality level scale for the BS and consequently no level of reliability of the final decibel values, evaluating the BS quantitative capabilities to monitor habitat changes remains challenging. In a monitoring context, it is absolutely necessary to investigate to what extent the mean MBES-measured BS variation -from one cruise to another- actually represents a significant change in seabed properties and not only a change in the conditions of the water column (e.g., variation in near-bed suspensions, biological effects, increased occurrence of micro bubbles in the sea surface due to wind) at the time of the measurement. In order to evaluate the relative accuracy and the repeatability of MBES BS and to examine the external sources of variance in acoustic signatures, repeated measurements combining MBES with an Acoustic Doppler current Profiler (ADP) have been performed during tidal cycles on reference areas in the Belgian part of the North Sea. Currents and BS in the water column and vertical profiling of oceanographic parameters have been investigated allowing studying the influence of water column conditions on the BS. Measurements were conducted using two MBES systems to evaluate repeatability between echosounders. Ultimate goal is to arrive at seabed mapping and analyses protocols to obtain harmonized data products from a collaborative seabed mapping community.
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Sexing an adult human skeleton from its fragmented remains is a tremendous challenge in both archaeological and forensic contexts. Although reliable sex estimation methods using the os coxae do exist, as well as the possibility of performing a secondary sexual diagnosis within a funerary assemblage, it is essential in the case of fragmented individuals to set up an alternative sex estimation method based on a skeletal element that is both sexually dimorphic and has a high taphonomic survival rate. This study investigated the sexual dimorphism of the cranial base (occipital and temporal bones), through an exclusively metric approach, in 537 identified western European adults. Using logistic regressions, thirteen predictive models were built up, which yielded up to 86.8% accuracy after cross-validation and with a decision threshold of 0.70. BASE is an R package with a graphic user interface that can be used to apply these predictive models to a target adult individual (https://archive.softwareheritage.org/browse/directory/5e3e3753e1f9c360b0ddbebaa2d2b42e5d7686d9). This paper provides measurement definitions, practical details and user recommendations. BASE is a new sex estimation tool which is free of charge, fast and easy to use, and allows anthropologists to collect biological data from larger numbers of individuals, even when their skeletons are highly fragmented and damaged. This new method can certainly contribute to a better understanding of past populations and will be of considerable value to forensic investigations in today’s context of steadily rising numbers of missing persons. BOUCHERIE A. , POLET C. , MARTINE V., LEFÈVRE P., SANTOS F., 2025. BASE – BAsicranial Sex Estimation: An R package for sexing adult western European individuals from the cranial base morphometry in bioarchaeology and forensic anthropology. , (2) :
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RBINS Staff Publications 2025
