Novos métodos para restauração marinha através dos “SAR” (simbiotic artificial reefs)

Abstract

Artificial reefs (ARs) are a tool used for several decades to actively restore marine-coastal ecosystems and fisheries resources. However, RAs have been implemented without planning, causing several environmental impacts and suspicion of their use in restoration programs. This thesis aimed to determine the optimal characteristics for ARs to be successful in restoring marine and coastal ecosystems. This mainly relates to SDGs 13 (climate action) and 14 (life below water). Thus, the study was divided into three chapters. The first chapter addresses a discussion on ARs in Brazil, exploring their history, key scientific knowledge and future perspectives, thus providing from an ecological perspective a decision-making tool on the use of ARs to avoid several environmental impacts that have already occurred in the country (i.e., introduction of exotic species, use of polluting materials, etc.). In the second chapter, a systematic literature review (SLR) was carried out on the state of the art of ARs in the world between xx-xx, including a meta-analysis on the effectiveness of ARs in resembling natural reefs (NRs), with the Bray-Curtis similarity index as a measure of success in restoring marine and coastal ecosystems. Important information gaps are highlighted regarding socioeconomic aspects; design, materials and layout in the selected habitats; legal, management and planning aspects considering long-term monitoring. Regarding efficacy, few articles (n=13) allowed appropriate comparisons between ARs and NRs, highlighting the need to apply adequate reference sites in these implementations. The meta-analysis showed that ARs are not similar to reference NRs (p=0.03 and p=0.05 for common and random effect models, respectively). A high level of heterogeneity (88%) indicates that this relationship may be influenced by factors other than the nature of the reef. However, some ARs that were successful in resembling NRs provided more accurate directions in this regard. In the third chapter, an experimental study was carried out in the city of Porto Cesario, Italy, between October 2019 and September 2021. The effectiveness of organic materials known to provide nutrients, degrade pollutants and reduce the risk of pathogens in terrestrial ecosystems was tested. Experimental plates of biochar, bioferment and concrete (control) were photographed at different times during the study period. The coverage of taxonomic groups was estimated using Photoquad software and analyzed with univariate and multivariate PERMANOVA using material and time as factors. Significant differences were detected between material, time and their interaction, showing an ecological succession with changes in community composition through the colonization periods. Biochar achieved a higher coverage of marine organisms in a shorter colonization time, compared to bioferment and the control, which is required in restoration programs, as well as being an optimal material for submersion. Degraded reef ecosystems have opportunities to be restored through ARs, whenever a scientific and logical planning with space-time specificity is applied.