The Reef Check (RC) underwater coastal environment monitoring (U-CEM) protocol ensures that the volunteer divers, after a 1-day intensive training course, including verification of their abilities, make independent observations on the presence/absence and abundance of selected taxa.
Taxa were selected by RC scientists based on a combination of criteria including, being easily observable and identifiable underwater and one or more of the following: a Non-Indigenous Species (NIS) or a species protected under European directives or international conventions; sensitive to climate change; an ecosystem engineer; threatened by human activities or commercially exploited. Taken together, these taxa represent key aspects of Mediterranean subtidal habitats, and of the changes they may be undergoing. When it is not easy to discriminate between species, genus level was chosen, as in the case of the two protected Mediterranean seahorses.
During the training, divers are made aware of the importance of their contribution and learn how to search and recognize target taxa. Before diving, each participant chose which and how many of the 43 taxa will be searched for, according to the expected habitat typology and to personal motivations. This freedom of choice ensures greater attention and accuracy by the volunteers, for example, because they can select taxa they are more confident with (probably reducing errors), those they like the most (making the diving experience more satisfactory), or limit themselves to a number of taxa they feel able to handle (which reduces pressure). Underwater, the abundance (using numerical or descriptive classes according to the countability of organisms) and depth range (min and max) of each searched taxon are recorded, along with the type of habitat where they are encountered (picked from a list). Taxa actively searched for, but not encountered, are recorded as absent. A plastic board, bearing identification drawings, is provided to help in the task. Recorded observations, including absence, site name and geographic coordinates, date and time, underwater visibility, survey depth range (min and max), and observation effort in terms of dedicated time, are then fed to the online database through an internet form or a dedicated app for Android smartphones (Reef Check Med App, available on the Google Play Store). Each trained participant is identified by a unique personal code. Data are periodically confirmed through a quality control process based on automatic filters (e.g. consistency among reported species, prevailing habitat, dive and observation depth) and manual procedures (e.g. matching between site name and geographic coordinates), and are then made freely accessible via an online geographic information system (Web GIS). Should the quality control process fail, meaning that issues are found with a given set of data, the volunteer(s) that has/have submitted such data is/are individually contacted in order to try to resolve the issue. Inconsistent data are permanently deleted only when this further step fails.