Macroalgal forest restoration: the effect of the foundation species

Abstract

IntroductionActive restoration is the strategy needed to trigger or accelerate the recovery of degraded marine habitats, which provide the goods and services essential for preserving biodiversity and human wellbeing. Ecosystem engineers are generally the target species in the ecological restoration of marine ecosystems, and large-sized brown macroalgae (e.g., the Cystoseira complex) are a priority due to their crucial ecological importance and vulnerability in many regions of the Mediterranean Sea. MethodsHere, we present the results of a successful intervention of ecological restoration of Gongolaria barbata. Results and DiscussionOne year after the restoration intervention, we observed the recovery of the canopy in terms of ca. 15m2 with a significant increase in faunal abundance and biodiversity compared with reference areas. However, despite the high restored macroalgal growth rates, the assemblage structure was still significantly different from that of reference pristine areas. Despite the fast faunal colonization of a new 3D habitat linked to the successful re-introduction of the ecosystem engineers (i.e., macroalgae), the complete restoration of the properties of a habitat can be a much longer process. We conclude that, after 1 year, active restoration of macroalgal forests still results in a partial recovery of ecosystem functions (i.e., rehabilitation) rather than a full ecosystem restoration, thus stressing the need for long-term monitoring of restoration interventions.

Stranded seaweeds (Gongolaria barbata): an opportunity for macroalgal forest restoration

“…The recruits growth rates (on average 0.2-0.7 mm/week) and densities (up to 7 recruits 10/cm 2 ) reported here from the stranded seaweed G. barbata are similar to those previously reported in the Adriatic Sea and in other Mediterranean regions using the standard approaches (Verdura et al 2018;Savonitto et al 2021;Orlando-Bonaca et al 2022). The same applies when we compare the data presented here with previous studies conducted in the same area, that is the Conero Riviera (Central-eastern Adriatic Sea; Bianchelli et al 2023a). Although we need further experiments to ascertain the efficacy of outplanting interventions over the long term and at a large spatial scale, these findings suggest that this approach could represent a promising tool for restoration purposes.…”

“…G. barbata current occurrence along the Conero Riviera has been recently documented (Orfanidis et al 2021). Portonovo is nearby two Sites of Community Importance (SCI IT5230005 "Coast between Ancona and Portonovo" and IT5320006 "Portonovo and calcareous cliff"; Bianchelli et al 2023a).…”

“…G. barbata) was explored in the Adriatic Sea (Savonitto et al 2021;Orlando-Bonaca et al 2022). The restoration of fucalean forests is carried out either using in situ and ex situ (cultivated in mesocosms) recruitment approaches or using hybrid methods (combining cultivation in mesocosm and culture in the natural environment), also coupled with passive restoration measures (Verdura et al 2018;Orlando-Bonaca et al 2022;Bianchelli et al 2023aBianchelli et al , 2023b.…”