The dataset contains annotations made on screenshots of video sequences collected by the TEMPO ecological module from 2012 to 2019 at a frequency from infra-daily to 10 days (base of the Eiffel Tower hydrothermal edifice, Lucky Strike, Mid-Atlantic Ridge, depth of 1695m). A long-term monitoring of the vent fauna dynamics was achieved with the files provided in this DOI that includes: - Annotations of the substratum and of the vent fauna (Bathymodiolus azoricus vent mussel) and microbial mats with polygons; - Annotations of the crab Segonzacia mesatlantica within images; - Count of unidentified zoanthids (manual and automatic; codes are provided). Long-term monitoring of the vent habitat dynamics was made with the following environmental measurements also provided in the DOI: - Yearly measurements made with the CHEMINI and temperatures probes of the underwater vehicle since MoMARSAT2014 - Positions and temperatures measured by iButton® probe in the TEMPO images - Linear regression-based modeling of the vent fluid dilution gradient in order to interpolate the iButton® temperatures over the full set of images The dataset is accompanied with rasters allowing spatio-temporal continuity of the data by masking the portions of the images that do not overlap throughout the image time series. The dataset is also accompanied with a read me to describe the structure of each data.