TEMPO

MONITORING OF POSIDONIA MEADOWS IN THE FRENCH MEDITERRANEAN

TEMPO is the network for monitoring the ecological status of Posidonia meadows in two characteristic sectors of this key Mediterranean ecosystem : the lower limit (deepest extension limit) and the intermediate depth (-15 meters ; representative depth of the meadow in the Mediterranean ; Gobert et al., 2009). This network is operated since 2011 by Andromède Océanologie with the support of the Rhone Mediterranean and Corsica Water Agency. It covers the entire French Mediterranean coastline bordered by the three regions : Corsica, SUD region, and Occitania. The objectives are to collect descriptive data on the state and functioning of Posidonia meadows and to monitor their evolution over time and space.

TEMPO currently includes 73 sites located at the lower limit of the meadows (between 5 and 40 m) and 52 sites located at the intermediate depth (around -15 m). Each year, a region is monitored in late spring (May-June) in order to cover the entire coastline every three years. Some TEMPO sites are also monitored for fish (PISCIS network), temperature (CALOR network) and acoustic listening (CALME network).

TEMPO includes 73 sites located at the lower limit of the meadows (between 5 and 40 meters deep) and 52 sites located at the intermediate depth (around -15 m).

Descriptive data on the health and dynamics of P. oceanica meadows are collected on two characteristic areas : at the lower limit (LI) and, since 2014, at the intermediate depth of -15 meters (PI). A descriptive leaflet (Material and methods) of this monitoring network is available on the website.

• In LI, vitality measurements (density and unraveling of the clusters, type and depth of the boundary) are carried out, surveys of the pressures observed, as well as a mapping of the meadow. Two methods are used : acoustic telemetry (many lower limits of meadows have already been mapped using this method ; Descamp et al., 2009, 2011 ; Deter et al., 2010, 2012), and photogrammetry. These data can be used to calculate an EQR (Ecological Quality Ratio) and thus determine the ecological status of each lower limit site.
• At the IP, three indicators are used to characterize the state of health of seagrass beds and thus assess the ecological quality of coastal water bodies : the PREI (Posidonia oceanica Rapid Easy Index ; Gobert et al., 2009), established according to WFD requirements and integrated into the TEMPO network in 2014 ; the BiPo (Biotic index based on P. oceanica ; Lopez y Royo et al., 2010) and the EBQI (Ecosystem-Based Quality Index ; Personnic et al., 2014), which were integrated in 2015. These sites are in line with existing TEMPO sites at the lower edge of the meadow.

Acoustic telemetry mapping. The diver uses a pointer equipped with a mini keyboard and a screen to precisely position the limits of the meadow. (Andromède océanologie ©)

According to the PREI protocol, two characteristic sectors of the meadow are monitored (five parameters are measured) : the lower limit (existing TEMPO site) and the intermediate depth. PREI requires sampling of seagrass clusters in situ, which are then analyzed in the laboratory. Very similar to PREI, the BiPo2 index allows the ecological status of each site to be determined by taking into account four parameters based on the health of the P. oceanica plant itself. The EBQI is based on a model of ecosystem functioning that takes into account its different compartments (= “boxes”) : posidonia, algae, herbivores, organic matter, small fauna, small and large predators, seabirds, and the interactions between these compartments. This index requires the in situ sampling of posidonia leaves that are then analyzed in the laboratory.

 By clicking on the button “Access the maps” just below, you will find more details on the indicators used at intermediate depth, links to the different scientific publications : PREI indicator (Gobert et al., 2009), BiPo indicator (Lopez Y Royo et al., 2010) and EBQI indicator (Personnic et al., 2014) and two scientific publications by Descamp et al. (2005 and 2010) concerning the acoustic telemetry method.

You will also find the different TEMPO sites located at the lower limit or at the intermediate depth (dark green and light green triangles) and a comparison tool.

Contact : Gwenaëlle Delaruelle (gwenaelle.delaruelle@andromede-ocean.com)

Project leader : Andromède Océanologie   –  andromede-ocean

Update frequency : Annual monitoring by region (each region, Occitanie/PACA West, PACA East and Corsica, is monitored every three years).

Partners : Rhone Mediterranean and Corsica Water Agency

Study reports