Detect coastal disturbances and climate change effects in coralligenous community through sentinel stations

species with invasive potential, among other sources of alteration of coastal waters), and in the medium or long term (global warming). Even though the method is able to detect the presence of invasive species, further studies are required to test the reliability of the method for detecting other potential impacts of anthropic origin. Recently, the SBPQ methodology has already been used suc- cessfully in the early detection of exotic species with invasive potential, in particular the invasive seaweed Rugulopterix okamurae [80]. The Fig 2 shows a temporal variation of benthic mean per- cent species coverage at Tarifa Island monitoring by SBPQ method from years 2013 to 2017. It is focused on the management of sensitive indicator target species (benthic and sessile) vs. tolerant species in the Western Mediterranean and can be used in other parts of the world once the native species have been selected. The SBPQ method has been proposed for wide- spread use, not only by scientists, but by sports divers linked to diving clubs or centres that could be involved in underwater environmental monitoring of the coastal environment (Citi- zen Science and “Working with Nature” philosophies). Synthetic adaptation of the SBPQ protocol 1. Choice of vertical walls of pristine rocky bottoms, preferably between 20 and 35 metres deep, biologically structured and of high biodiversity, with the presence of adult-sized target species, sensitive, benthic and sessile indicators, that are visible underwater, preferably colo- nial, with a long life cycle, and abundant compared to the local macrobiota.

2. Selective installation of three to five permanent quadrats of 1x1 m2 (not chosen at random), located on patches of at least one previously selected target species that represents at least 10% of the total coverage per quadrat (Fig 3). The method has recently been updated with the objective of minimizing the degree of intrusion on these fragile habitats. For this pur- pose, a single hole is drilled on the rock and a small plastic bar marks off four 50 x 50 cm detachable monitoring quadrats that are fitted each time monitoring is carried out. This Fig 2. Temporal variation of benthic mean percent species coverage at Tarifa Island monitoring station fixed quadrats from years 2013 to 2017 (1, 2, 3, 4 refer to random sampling times within each year). Species with less than 10% coverage (Alcyonium sp., Aplidium sp., Asparagopsis armata, Crambe sp, Ircinia sp. and Polycitor adriaticum) were grouped under ‘Other species’. Taken from (Garcı´a-Go´mez et al., 2020). https://doi.org/10.1371/journal.pone.0231641.g002 PLOS ONE Detect coastal disturbances in coralligenous PLOS ONE | https://doi.org/10.1371/journal.pone.0231641 May 5, 2020 5 / 23