Transplantation assessment of degraded Posidonia oceanica habitats: site selection and long-term monitoring

Abstract

A model developed for Zostera marina was adapted and used to select suitable areas for Posidonia oceanica transplantation in the Gulf of Palermo, where recent rehabilitation programmes have reduced human pressure. This model consists of three steps: (1) habitat selection, by calculation of the Preliminary Transplant Suitability Index (PTSI); (2) field assessments and test-transplanting, to evaluate the site suitability and to estimate the effects of tearing on transplant units (about 50%); (3) identification of suitable restoration sites, by calculation of the Transplant Suitability Index (TSI). A new parameter was added to the literature model: the number of grids detached, which is linked to factors (hydrodynamic regime, anchoring, fishing) that have a potentially great effect on the final outcome of the transplant. Only one site (TSI = 16) in the Gulf of Palermo was indicated as potentially suitable for restoration with P. oceanica. In this site, a transplant of 40 m2 was implemented. From 2008 to 2014, transplant effectiveness was evaluated in terms of establishment, detachment and mortality of cuttings and shoot density. The long-term monitoring (6 years) allowed us to detect changes in the structural conditions of the transplanted meadow and to identify the possible turning point in P. oceanica recovery (2 years after transplanting). Moreover, 6 years after transplantation the P. oceanica meadow has exceeded the transplant shoot density of about 16%, with a mean and a maximum value of 11.6 and 17 shoots per cutting, respectively.

Restoration of Seagrass Meadows in the Mediterranean Sea: A Critical Review of Effectiveness and Ethical Issues

“…A recurring issue with regard to the literature dealing with seagrass restoration in the Mediterranean Sea is that the bulk of the literature deals with techniques, describes experiences on a very local scale, and only concerns the short term [125]: one year [106,125,208,215,222,234,236,241,270], two years [22,209,217,223,224,231,232], three years [124,210,235,256], four years [55,183,242,274], or five years [194], rarely longer [211,212]. The longest monitoring survey (17 to 24 years) does not concern a restoration operation but rather a scientific study of the morphological characters of strains coming from 11 Mediterranean regions (mainland Spain, Balearic Islands, French Catalonia, French Riviera, Corsica, Italy, Malta, Greece, Turkey, and Algeria) and transplanted at the same site in the Port-Cros National Park (Provence) [211].…”

“…Wire or plastic grids, laid flat on the bottom and retaining P. oceanica cuttings, have been used in Provence, the French Riviera, Corsica, Tuscany, and Sicily [203][204][205][206][207][208][209][210][211][212]. Wire grids were fixed at the corners with 20-70 cm long steel bars [206].…”

“…As concerns the transplanting of P. oceanica, the only habitat where such an operation would be justified, from an ecologically ethical point of view (taking into consideration the above-mentioned caveats), is dead matte resulting from human impact, which is exemplified by attempts in Provence [211] and Sicily [43,212,271,273]. The case of trenches opened in a meadow to place a pipeline, then filled with rubble, should be considered; natural recolonization seems relatively rapid [135,[161][162][163]; however, if this were not the case, transplanting would be justified [217].…”

“…It is regrettable to note that almost no replanting project has used this decision tree, which might be because the answer was obviously "no"? From this point of view, the strategy for selecting P. oceanica transplantation sites implemented in the Gulf of Palermo (Sicily) by Pirrotta et al [212] is almost unique in the Mediterranean and therefore deserves to be highlighted and praised.…”

Predicting the response of nekton assemblages to seagrass transplantations in the Venice lagoon: An approach to assess ecological restoration

“…The loss of seagrass beds has induced scientists and practitioners in many countries to directly intervene with restoration programmes (van Katwijk et al, ). However, there are still few examples of seagrass transplantations in the Mediterranean (Jahnke, Serra, Bernard, & Procaccini, ; Pirrotta et al, ; Pranovi, Curiel, Rismondo, Marzocchi, & Scattolin, ). In the Venice lagoon (northern Adriatic Sea, Italy), a seagrass restoration programme (Seagrass RESTOration, ‘SeResto’; http://www.lifeseresto.eu; Facca et al, ) was started in 2014 in order to restore the status of the northern lagoon sub‐basin, which was subject to extensive loss of Zostera marina and Zostera noltei (Curiel, Checchin, Miotti, Pierini, & Rismondo, ; Sfriso, Facca, Ceoldo, & Marcomini, ).…”