Environmental Engineering Techniques to Restore Degraded Posidonia oceanica Meadows

Abstract

Seagrass planting techniques have shown to be an effective tool for restoring degraded meadows and ecosystem function. In the Mediterranean Sea, most restoration efforts have been addressed to the endemic seagrass Posidonia oceanica, but cost-benefit analyses have shown unpromising results. This study aimed at evaluating the effectiveness of environmental engineering techniques generally employed in terrestrial systems to restore the P. oceanica meadows: two different restoration efforts were considered, either exploring non-degradable mats or, for the first time, degradable mats. Both of them provided encouraging results, as the loss of transplanting plots was null or very low and the survival of cuttings stabilized to about 50%. Data collected are to be considered positive as the survived cuttings are enough to allow the future spread of the patches. The utilized techniques provided a cost-effective restoration tool likely affordable for large-scale projects, as the methods allowed to set up a wide bottom surface to restore in a relatively short time without any particular expensive device. Moreover, the mats, comparing with other anchoring methods, enhanced the colonization of other organisms such as macroalgae and sessile invertebrates, contributing to generate a natural habitat.

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

“…This study shows the feasibility of using fertile thalli stranded on the beach to obtain recruits for restoration, without damaging natural populations and habitats (Ferretto et al 2021). In this regard, stranded stems of Posidonia oceanica are also used for its restoration (Piazzi et al 2021). This approach has the double advantage of obtaining recruits without causing any damage to the natural populations, and promoting a sort of “circular economy” through the reuse of the stranded seagrass/macroalgae that would otherwise be lost.…”

Restoration performance of Thalassia hemprichii and Enhalus acoroides at Gaolong bay and Xincun lagoon, Hainan Island, China

“…The transplanting unit was laid out in regular patterns, with the distance was 50 cm. We called this "single-plant-fixed-distance transplantation", which was easy to conduct and less damage to surrounding habitats (Piazzi et al, 2021).…”

Feasibility of the Sabellarid Reef Habitat Restoration

“…3 So far, some efforts have been made to restore degraded and threatened marine habitats (e.g., Boström-Einarsson et al, 2020;Cebrian et al, 2021;Montseny et al, 2021). In the Mediterranean Sea, several studies focused on the restoration of coralligenous formations (Fava et al, 2010;Forcioli et al, 2011;Montero-Serra et al, 2017;Topçu et al, 2018;Montseny et al, 2019;Pagès Escolà et al, 2020;Casoli et al, 2021), seagrass meadows (Pirrotta et al, 2015;Alagna et al, 2019;Da Ros et al, 2021;Mancini et al, 2021;Piazzi et al, 2021;Ventura et al, 2021), macroalgal forests (De La Fuente et al, 2019;Tamburello et al, 2019), and other vulnerable habitat-forming species (Baldacconi et al, 2010;Musco et al, 2017). Despite their ecological role and fragility, sabellarid reef habitats have been neglected in restoration studies so far.…”