The majority of Hydrozoa is represented by not readily noticeable, small species. In recent decades, however, taxonomic knowledge of the group has increased worldwide, with a significant number of investigations focused on the Mediterranean Sea. Over more than two decades, 115 species of hydrozoans were recorded from coastal waters along nearly 300 km of the Salento Peninsula (Apulia, Italy). For each species, records from different collections were merged into single sheets of a general database.

<p>ARMS-MBON is a network of more than 25 partners who deploy Autonomous Reef Monitoring Structures (ARMS) settlement units in the vicinity of marine stations and Long-term Ecological Research sites in European coastal waters and Ant/arctica. After a few months the units are brought up, and visual, photographic, and genetic assessments are made of the lifeforms that settled on them. The collected data are published (see the related datasets and GitHub links listed in this record) and the omics data analysed.-nbsp;</p><p>In this record we include the outputs of our analysis of the 18S data from 2018-2020. The analysis used the PEMA bioinformatics software, and the resulting taxonomics inventory has been submitted as DwCA to (Eur)OBIS. In addition, all the PEMA inputs and outputs can be found on the ARMS-MBON GitHub site (see links in this record), and the subset of the sampling data to which these 18S results are linked can also be found on the ARMS-MBON GitHub site.</p>

<p>ARMS-MBON is a network of more than 25 partners who deploy Autonomous Reef Monitoring Structures (ARMS) settlement units in the vicinity of marine stations and Long-term Ecological Research sites in European coastal waters and Ant/arctica. After a few months the units are brought up, and visual, photographic, and genetic assessments are made of the lifeforms that settled on them. The collected data are published (see the related datasets and GitHub links listed in this record) and the omics data analysed.-nbsp;</p><p>In this record we include the outputs of our analysis of the ITS data from 2018-2020. The analysis used the PEMA bioinformatics software, and the resulting taxonomics inventory has been submitted as DwCA to (Eur)OBIS. In addition, all the PEMA inputs and outputs can be found on the ARMS-MBON GitHub site (see links in this record), and the subset of the sampling data to which these ITS results are linked can also be found on the ARMS-MBON GitHub site.</p>

<p>ARMS-MBON is a network of more than 25 partners who deploy Autonomous Reef Monitoring Structures (ARMS) settlement units in the vicinity of marine stations and Long-term Ecological Research sites in European coastal waters and Ant/arctica. After a few months the units are brought up, and visual, photographic, and genetic assessments are made of the lifeforms that settled on them. The collected data are published (see the related datasets and GitHub links listed in this record) and the omics data analysed.-nbsp;</p><p>In this record we include the outputs of our analysis of the COI data from 2018-2020. The analysis used the PEMA bioinformatics software, and the resulting taxonomics inventory has been submitted as DwCA to (Eur)OBIS. In addition, all the PEMA inputs and outputs can be found on the ARMS-MBON GitHub site (see links in this record), and the subset of the sampling data to which these COI results are linked can also be found on the ARMS-MBON GitHub site.</p>

The hypothesis that, temporal variation in nematode abundance, community composition and trophic structure is coupled with changes in the quantity and quality of their potential food sources was tested.

The direct or indirect influence of a river plume on meiofaunal abundance and community composition was investigated in the North Adriatic Sea (NW Mediterranean Sea).

The meiofaunal abundance, biomass, community structure and nematode diversity were investigated in relation to the spatial distribution of the potential food sources in the Atacama trench and open slope (South Pacific Ocean).