In this study, we present a framework for seagrass habitat mapping in shallow (5–50 m) and very shallow water (0–5 m) by combining acoustic, optical data and Object-based Image classification. The combination of satellite multispectral images-acquired from 2017 to 2019, together with Unmanned Aerial Vehicle (UAV) photomosaic maps, high-resolution multibeam bathymetry/backscatter and underwater photogrammetry data, provided insights on the short-term characterization and distribution of Posidonia oceanica (L.) Delile, 1813 meadows in the Calabrian Tyrrhenian Sea. We used a supervised Object-based Image Analysis (OBIA) processing and classification technique to create a high-resolution thematic distribution map of P. oceanica meadows from multibeam bathymetry, backscatter data, drone photogrammetry and multispectral images that can be used as a model for classification of marine and coastal areas. As a part of this work, within the SIC CARLIT project, a field application was carried out in a Site of Community Importance (SCI) on Cirella Island in Calabria (Italy); different multiscale mapping techniques have been performed and integrated: the optical and acoustic data were processed and classified by different OBIA algorithms, i.e., k-Nearest Neighbors’ algorithm (k-NN), Random Tree algorithm (RT) and Decision Tree algorithm (DT). These acoustic and optical data combinations were shown to be a reliable tool to obtain high-resolution thematic maps for the preliminary characterization of seagrass habitats. These thematic maps can be used for time-lapse comparisons aimed to quantify changes in seabed coverage, such as those caused by anthropogenic impacts (e.g., trawl fishing activities and boat anchoring) to assess the blue carbon sinks and might be useful for future seagrass habitats conservation strategies.

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The Pilot Project “SeaCleaner” is a citizen science and educational project, developed by the Institute of Marine Sciences of the Italian Research Council (CNR-ISMAR). Since 2013, it has involved environmental nongovernmental organizations (NGOs), volunteers, five Italian Marine Protected Areas surrounding the Pelagos Sanctuary, and so far more than 50 high school students within the Italian program for “work-related learning internships.” The project aims to overcome the lack of current data on marine litter—a gap of knowledge that cannot be ignored any longer, according to the last European Union's ambitious Marine Strategy Framework Directive (MSFD)—by building an app for Android devices, which is easy to use and, at the same time, methodologically sound and comprehensive. This should enable a continuous census (in time and space) for supporting the proper management and removal of solid waste (through scheduled campaigns, etc.). The project has multiple effects: (1) to prompt students to broaden their scientific knowledge on topics not strictly related to scholastic curricula, making them aware of current environmental problems and teaching them how to solve them; (2) to engage an increasing number of volunteers in marine litter monitoring activities; and (3) to contribute to a common protocol for data acquisition, useful for both environmental and scientific purposes, helping scientists to overcome the lack of current data on marine litter.

The reproductive phenology of three species of Gelidiales, Gelidium canariense, Gelidium arbuscula and Pterocladiella capillacea, was analysed seasonally for a period of one year in two localities on the West coast of Tenerife (Atlantic Ocean, Canary Islands, Spain). Considerations are provided on sex ratio, maximum length and branch order of uprights and on the length of the thalli for each sexual and asexual phase of the Canary Islands populations. The three species were characterized by a high percentage of tetrasporophytes, while female and male gametophytes have been observed only in little proportion. Only G. canariense showed gametophytes in all seasons while the occurrence of gametophytes in G. arbuscula and Pterocladiella capillacea demonstrated a clear seasonality.

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