MEPS 492:199-210 (2013)  -  DOI: https://doi.org/10.3354/meps10494

ABSTRACT: By moving between habitats, mobile link organisms serve as vectors of material and energy transport between ecosystems. Additionally, if these mobile species are key organisms, their movement patterns can have profound consequences on the functioning of the ecosystems they link. The Mediterranean herbivorous fish Sarpa salpa has been defined as a key organism in seagrass and rocky macroalgal habitats. Our objective in this study was to evaluate the potential of this species to be considered a mobile link by: (1) assessing its capacity to connect different habitats, the strength of these connections, and the habitat use; and (2) determining whether the patterns observed were consistent on a diel basis and over an annual period. We used the recently developed Brownian bridge movement models (BBMM) framework to analyse the movement patterns of 18 fish tracked with passive acoustic telemetry (mean tracking duration: 103 ± 22 d) and a time-frequency analysis to assess their temporal patterns. Our results showed that S. salpa performed trips between different and distant habitats (on the order of km) with large home ranges (overall mean: 134 ± 10 ha). Despite its high mobility, S. salpa used seagrass more intensively rather than rocky habitats. In addition, our results confirm the existence of diel patterns for this species, mostly observed in the seagrass habitat, with fish moving from shallow areas during the day to deeper areas at night. These patterns were visible for most of the year. Taken together, these results suggest that S. salpa may act as a mobile link by connecting shallow and deep areas of the meadow on a daily basis and linking different and distant habitats over longer temporal scales.

KEY WORDS: Brownian bridge movement models · BBMM · Seascape · Spatial patterns · Sarpa salpa · Temporal patterns