## 8 Conclusions  
The provided literature review allows us to formulate the following conclusions and identify the following areas for future development:* Numerical modeling is used mainly for wave simulation. There is a large potential to also use the modeling process for other purposes, such as the prediction of development, particularly of species or ecosystem growth.
* Nowadays, different additive manufacturing technologies are used for designing and manufacturing coral reefs. The most effective seems to be joining several of them in one project, which gives new possibilities for reef restoration.
* Currently, the most reliable seems to be the use of cementitious materials for artificial reef production using additive manufacturing technology; however, the usage of other materials, including biopolymers from biomass waste, seems to be a valuable option for the future.
* A lot of research confirms the benefits connected with artificial reefs for the restoration of ecosystems; however, the problems connected with potential \"ocean sprawl\" and the wide spreading of invasive species should be taken into consideration during planning the research.
* Still, a lot of challenges exist in the area of artificial reefs, which are connected with materials, additive technology, investigated ecosystems, and other areas. The exemplary challenges are a lack of previous research connected with the usage of 3D printing technologies for designing freshwater artificial reefs and the small number of investigations about the long-term function of artificial reefs.
* There a several areas that seem to be crucial for the further development of artificial reefs, including multifunctionality, digitalization, and the design of advanced materials. This topic seems to have a huge potential in further research, but it also requires joining competences form several scientific disciplines.  
Conceptualization, K.K. and P.D.; methodology, K.K. and A.Z.; validation, S.G. and W.-T.L.; formal analysis, K.O.; investigation, K.K., S.G. and A.Z.; resources, K.K.; data curation, W.-T.L. and A.Z.; writing--original draft preparation, K.K., K.O., P.D. and A.Z.; writing--review and editing, S.G. and W.-T.L.; visualization, K.O.; supervision, K.K. and P.D.; project administration, K.K.; funding acquisition, K.K. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the project entitled: \"Development of water treatment systems that counteract the eutrophication process of lakes based on zeolites obtained from industrial by-products\", which is financed by the Polish National Center for Research and Development under the M-ERA.NET 3 program, grant number M-ERA.NET3/2023/67/CleanLake/2024.  
The original contributions presented in the study are included in the article; further inquiries can be directed to the corresponding author.  
The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.  
The following abbreviations are used in this manuscript:  
DLP Digital Light Processing  
FDM Fused Deposition Modeling  
FFF Fused Filament Fabrication  
PLA polylactic acid  
PHB polyhydroxybutyrate  
SCA Selective Cement Activation  
SLA Stereolithography