Large-scale Posidonia oceanica restoration in a Site of National Interest using an innovative bio-plastic transplant system

Abstract

Along the Italian coasts there are many areas affected by industrial activities defined as "Sites of National Interest" (SNI), which require urgent and effective remediation and restoration actions. In the framework of TETIDE project (PON01_03112 www.progettotetide.it)a restoration program was developed in SNI Priolo(Sicily) in response to a dramatic decline and regression of Posidonia oceanicameadow, caused byseveral years of petrochemical industries dumping. In particular, a large scale P. oceanicarestoration plan was carried out in four steps: (1) habitat selection, by calculation of the Preliminary Transplant Suitability Index (PTSI); (2) field assessments and test-transplanting, to evaluate the site suitability; (3) identification of suitable restoration sites, by calculation of the Transplant Suitability Index (TSI); (4) finally, according to TSI results, a large P. oceanicatransplant was performed. Cuttings were anchored by using an innovative system (patented by Biosurvey Srl, Spin-off University of Palermo) made of a new generation bio-plastic (Mater-Bi), totally biodegradable after 5 -10 years in the field, maintaining the same physical characteristics of plastics.This system consists of a radial structure that can be anchored on the seabedby a picket. The structure is modular with five arms on which a variable number of clips for fixation of P. oceanicacuttings occurs. A total of 20’000 cuttings corresponding to about 70’000 shoots, were anchored at a depth of 12 m over 2’500 m2 of P. oceanicadead matte. After six months of monitoring, cuttings survival was 93.3 % with visible roots production, while mortality and detachment were about 1.7% and 5% respectively with a consequent slight decrease of shoot density. These results suggested that the modular bio-plastic system can be successfully employed for restoring damaged meadows allowing the natural anchoring of plants before structure degradation, without realising harmful residues in the environment.