Search

The recovery of degraded marine coasts and the improvement of natural habitats are current issues of vital importance for the development of life, both marine and terrestrial. In this sense, the immersion of artificial reefs (ARs) in the marine environment is a way to stimulate the recovery of these damaged ecosystems. But it is necessary to have a multidisciplinary approach that analyses the materials, designs and construction process of artificial reefs in order to understand their true impact on the environment. For this reason, this paper presents the manufacture of artificial reefs by 3D printing, proposing designs with a combination of prismatic and random shapes, with different external overhangs as well as inner holes. For the definition of the artificial reef designs, criteria provided by marine biologists and the results obtained from a numerical simulation with ANSYS were taken into account, with which the stability of the artificial reefs on the seabed was analysed. Three dosages of cement mortars and three dosages of geopolymer mortars were studied as impression materials. The studies included determination of the rheological properties of the mortars, to define the printability, determination of the cost of the materials used, and determination of the mechanical strength and biological receptivity in prismatic specimens that were immersed in the sea for 3 months. To evaluate the environmental impact of the materials used in the production of the mortars, a Life Cycle Assessment (LCA) was carried out. In order to choose the mortars that encompassed the best properties studied, Multi-Criteria Decision Making (MCDM) was applied and the two best mortars were used for the manufacture of the artificial reefs. Finally, the advantages and disadvantages of the 3D printing process used were analysed. The results of the studies carried out in this research show that cement mortars have better characteristics for artificial reef applications using 3D printing, and that the technique applied for the manufacture of the artificial reefs allowed the digital models to be faithfully reproduced. This work has been co-financed by the European Regional Development Fund through the Interreg Atlantic Area Programme, under the project “Artificial Reef 3D Printing for Atlantic Area - 3DPARE” (EAPA_174/2016). Besides, the authors want to thank the following companies for their contribution: Solvay, for supplying the fly ash and sodium hydroxide; BASF, for providing the additives used in the research; Abonomar S.L., for providing the seashells sand; FCC ámbito, for providing the crushed recycled glass and Grupo Cementos Portland Valderribas (Mataporquera plant) for providing the cement.

This paper deals with the evolution monitoring of biomass colonization and mechanical properties of 3D printed eco-materials/mortars immersed in the sea. Measurements of tensile strength, compressive strength, and Young’s modulus were determined on samples deployed along the Atlantic coast of Europe, in France, United Kingdom, Spain, and Portugal. The samples were manufactured using 3D printing, where six mix designs with a low environmental impact binder were used. These mortars were based on geopolymer and cementitious binders (Cement CEM III), in which sand is replaced by three types of recycled sand, including glass, seashell, and limestone by 30%, 50%, and 100% respectively. The colonization of concrete samples by micro/macro-organisms and their durability were also evaluated after 1, 3, 6, 12, and 24 months of immersion. The results showed that both biomass colonization and mechanical properties were better with CEM III compared to geopolymer-based compositions. Therefore, the mixed design optimized according to mechanical properties show that the use of CEM III should be preferred over these geopolymer binders in 3D printed concrete for artificial reef applications. Funding was provided by Interreg Atlantic area through the project EAPA_174/2016- 3DPARE-Artificial Reef 3D Printing for Atlantic area granted to the Faculty of Sciences of the University of Porto; Bournemouth University; ESITC—École Supérieure d’Ingénieurs des Travaux de la Construction de Caen; University of Cantabria; and IPMA—Instituto Português do Mar e da Atmosfera. Other supports were provided by MARE (FCT/MCTES–UIDB/04292/2020), by CIIMAR (FCT/MCTES–UIDB/04423/2020 and UIDP/04423/2020), and by the project LA/P/0069/2020 granted to the Associate Laboratory ARNET.

Artificial reefs have been deployed in multiple regions of the world for different purposes including habitat restoration and protection, biodiversity and fish stock enhancement, fisheries management and recreation. Artificial reefs can be a valuable tool for ecosystem protection and rehabilitation, helping mitigate the effects of anthropogenic impacts that we face today. However, knowledge on artificial reefs is unevenly distributed worldwide, with some regions having much more quality information available and published (e.g. European Mediterranean Sea area), while others, for instance the North-East Atlantic area, do not. Here, we provide a characterization of purposely built artificial reefs in North-East Atlantic area based on all available literature (i.e. research papers and reports), highlighting the needs and gaps that are vital for establishing future perspectives for artificial reef deployment and research. In the North-East Atlantic area, sixty-one purposely built artificial reefs have been deployed since 1970, mostly between the years 1990–2009, with Spain being the country with the highest number of artificial reefs. The most reported purpose for their deployment is fisheries productivity and habitat/species protection, although, most artificial reefs are multipurpose in order to maximise the benefits of a given financial investment. The majority of artificial reefs were submerged at < 50 m, mainly between 10 and 20 m of depth. The most used designs were cubic blocks and complex designs made by an array of combined shapes, which mostly consist of concrete (79%). From all the analysed data on artificial reefs, 67% of the cases reported surveys to assess biodiversity after the deployment. However, in 26% of those cases, data was not available. When data was available, only 31% of cases reported long-term biomonitoring surveys (3 years or more). Based upon these findings, we noticed a general lack of scientifically robust data, including records of species and abundance of both fish and invertebrates, as well as macroalgae, preventing an adequate determination of the best balance between shape, construction material and bio-colonization. Critiques and suggestions are discussed in the light of currently available data in order to perform more efficient research, evaluation and functioning of future artificial reefs. info:eu-repo/semantics/publishedVersion

Funding: N.C. was funded by a doctoral grant (SFRH/BD/146881/2019) awarded by Fundação para a Ciência e Tecnologia (FCT). S.S. was supported by Agência Regional para o Desenvolvimento da Investigação, Tecnologia e Inovação (ARDITI) research fellowship in the scope of the H2020 project GoJelly. P.P. was funded by a PhD grant ref. M3.1.a/F/065/2015 by Fundo Regional de Ciência e Tecnologia (FRCT) and the program AÇORES 2020. A post-doctoral research fellowship by ARDITI (ARDITI–M1420-09-5369-FSE-000002) supported J.G.M. F.G. was endorsed by a post-doctoral research fellowship granted by ARDITI in the framework of project RAGES (ARDITI-RAGES-2019-001). R.F. was supported by the funding from project INTERWHALE (PTDC/CCI-COM/0450/2020) by FCT. Doctoral fellowships were financially supported S.C. by ARDITI (ARDITI-M1420-09-5369-FSE-000002). R.S. was supported by a research fellowship in the framework of project PLASMAR+(MAC2/1.1a/347). J.C.-C. is funded by national funds through FCT under the Scientific Employment Stimulus—Institutional Call—[CEECINST/00098/2018]. This work was partially funded by MIMAR+(MAC2/4.6.d/249) in the INTERREG MAC 2014–2020 Programme framework. This study also had the support of Fundação para a Ciência e Tecnologia (FCT), Portugal, through the strategic project (UIDB/04292/2020) granted to MARE UI&IUIDB/04292/2020. Finally, the present paper benefited from underwater surveys during the expedition ‘MARE@Porto Santo 20200 conducted by MARE-Madeira. Current trends in the global climate facilitate the displacement of numerous marine species from their native distribution ranges to higher latitudes when facing warming conditions. In this work, we analyzed occurrences of a circumtropical reef fish, the spotfin burrfish, Chilomycterus reticulatus (Linnaeus, 1958), in the Madeira Archipelago (NE Atlantic) between 1898 and 2021. In addition to available data sources, we performed an online survey to assess the distribution and presence of this species in the Madeira Archipelago, along with other relevant information, such as size class and year of the first sighting. In total, 28 valid participants responded to the online survey, georeferencing 119 C. reticulatus sightings and confirming its presence in all archipelago islands. The invasiveness of the species was screened using the Aquatic Species Invasiveness Screening Kit. Five assessments rated the fish as being of medium risk of establishing a local population and becoming invasive. Current temperature trends might have facilitated multiple sightings of this thermophilic species in the Madeira Archipelago. The present study indicates an increase in C. reticulatus sightings in the region. This underlines the need for updated comprehensive information on species diversity and distribution to support informed management and decisions. The spread of yet another thermophilic species in Madeiran waters provides further evidence of an ongoing tropicalization, emphasizing the need for monitoring programs and the potential of citizen science in complementing such programs. info:eu-repo/semantics/publishedVersion