Assessing the effectiveness of restoration actions for Bryozoans: The case of the Mediterranean Pentapora fascialis

Abstract

Marine ecosystems are highly affected by several human stressors. In this context, beyond passive restoration measures such as the creation of marine protected areas, it is urgent that we explore active restoration measures to enhance and accelerate the recovery of sessile marine species. Bryozoans are among the most common sessile invertebrates in rocky bottom ecosystems and are considered habitat‐forming species that are highly vulnerable to physical disturbances, such as recreational diving, ghost fishing nets, and global warming, which makes them highly vulnerable to other impacts. Despite their ecological importance and vulnerability, to date restoration actions for bryozoans have rarely been explored. In this study, different restoration techniques were developed and tested, with a focus on two types of effective methodologies previously applied to other marine invertebrates: recruitment enhancement and the transplantation of adult colonies, in both cases using the Mediterranean bryozoan Pentapora fascialis as a model species. First, different types of artificial surfaces were installed in different coralligenous habitats to test the enhancement of recruitment, concluding that plastic grids are the best substrate in terms of facilitating the recruitment of new bryozoan colonies. Second, different methodologies were tested for adult transplantation. The most successful was to fix colonies to a suitable substrate with a nylon thread attached to the colony ex situ (i.e. on the boat). Using this technique a trial restoration programme was undertaken, involving transplanting adult colonies collected from a ghost fishing net trapped on the bottom, which showed a high survival rate of ~50% after 6 months. The low economic cost of the implementation of the proposed techniques as well as the successful results obtained highlight the viability of restoring bryozoan populations over long temporal and spatial scales.

From marine deserts to algal beds: Treptacantha elegans revegetation to reverse stable degraded ecosystems inside and outside a No‐Take marine reserve

“…To provide an estimate and comparable costs of the combined restoration techniques carried out in this study, the costs of both techniques (complete sea urchin eradication together with the in situ Treptacantha elegans forestation) were assessed considering the revegetation of a 200 m 2 sea urchin barren ground. We accounted for the transportation and material costs, and the salary of 3 qualified divers and 1 boat skipper following the methods of previous studies (Verdura et al ; Pagès‐Escolà et al ). In terms of time, sea urchin eradication and T. elegans forestation of a single barren ground of 200 m 2 size should be achieved in a single day involving the staff mentioned above.…”

Rehabilitation of Mediterranean animal forests using gorgonians from fisheries by‐catch

“…Despite the role of red algae as bioconstructors, sessile invertebrates (e.g. bryozoans and octocorals) have been the primary targets of marine restoration activities carried out on coralligenous reefs (Montero‐Serra et al 2018; Pagès‐Escolà et al 2020). The octocorals Corallium rubrum (Linnaeus, 1758), Eunicella cavolini (Koch, 1887), Eunicella singularis (Esper, 1791), and Paramuricea clavata (Risso, 1826) form habitat of conservation interest in the Mediterranean (SPA/RAC‐UNEP 2019) and have been reported as species significantly contributing to the aesthetic perception of coralligenous reefs (Tribot et al 2016).…”

Mediterranean rocky reefs in the Anthropocene: Present status and future concerns

“…Concerning rocky habitats, most of these research efforts have focused on the recovery of macroalgal stands (Verdura et al, 2018;Guarnieri et al, 2020;Orlando-Bonaca et al, 2021;Savonitto et al, 2021). Recent efforts have also focused on the restoration of populations of invertebrate species, such as the scleractinian coral Astroides calycularis (Musco et al, 2017), the bryozoan Pentapora fascialis (Pagès-Escolà et al, 2020), and the limpet Patella ferruginea (Ferranti et al, 2021), with many novel technologies and approaches emerging, such as or the use of electro-mineral accretion for enhancing the settlement of the red coral Corallium rubrum (Benedetti et al, 2011). Increasing research has also focused on the bioenhancement of artificial habitats by increasing surface topographic complexity, or by using more environmentally friendly construction materials, with some successful examples but also uncertainties about the consistency of the benefits (Strain et al, 2021).…”