###### Abstract
Research on the hydrodynamics of artificial reefs is primarily based on insights obtained within experimental and numerical modeling of different reef types, individual or as a combination of various geometries, and to date, based on the authors' knowledge, the main scope was to identify characteristics and changes of upwelling and eddy currents induced by these artificial structures [8; 28; 29; 30; 31; 32; 33; 34; 35; 36; 37; 38]. However, there is a paucity of studies related to the turbulence around these artificial reefs. Turbulence represents the most effective mixing factor that can be met in nature on small as well as large scales [39]. In coastal areas, turbulence structures affect the chemical and physical interaction between the reefs and the surrounding features [40], and they have a strong impact on the typology of different aquatic organisms that may have dissimilar preferences for either high or low turbulent flow conditions. Therefore, turbulence is considered to be an extremely important factor affecting the larval survival and recruitment of pelagic fish [41; 42]. Previous studies on the turbulent characteristics of natural coral reefs confirm that turbulent mixing controls the vertical coupling between the implantation layer and the overlying water, and it determines the vertical transport of heat, food, pollutants, larvae, or nutrients from the seabed community [43; 44; 45; 40]. At the same time, an improved understanding of turbulent processes on coral reefs is crucial for the prediction of momentum, energy, and scalar transport, and from an understanding of these basic fluxes, it could be possible to learn more insights about the physics that shape reef ecosystem processes [46; 47], sediment suspension and transport [48], and larval settlement on reefs [49]. Many mollusc veligers change their behavior in response to turbulence, and variations in these responses provide clues to whether or how adult habitat structure shapes larval behavior [50]. A study conducted by [PERSON] et al. [50] has shown that Oyster larvae (Crasostexa virginica) could enhance their settlement success by moving toward the seafloor in the strong turbulence areas associated with coastal habitats, and the speeds that larvae propelled themselves downward rose steadily with turbulence intensity to several times the terminal fall velocity in still water [50]. Turbulence mixing is the major driver to change the physicochemical characteristics of water column, and it can, for example, not only facilitate oxygen transport from water to surface sediment, but it can also enhance sediment suspension, which is one of the key processes affecting water turbidity and indirectly influencing eutrophication in shallow lakes [51; 52]. A previous study completed by [PERSON] et al. [53] confirmed that turbulence intensity plays an important role in internal phosphorus release: the results presented demonstrated that strong turbulence caused a reduction of phosphate in the overlying water, oxygen delivery was enhanced under moderate turbulence mixing, and turbulence induced high suspended sediment adsorption, contributing more intensively to phosphorous (P) inactivation [53]. Recent studies [54; 55; 56] have shown that turbulence may also affect the feeding of marine organisms such as plankton and other fish. Furthermore, turbulent motions in the surrounding flows can be important also for the encounters of aquatic microorganisms and their prey by bringing predators and prey close from time to time and thereby enhancing the probability of capture even without relying on self-induced motions [57; 58; 59; 60; 61]. Nevertheless, sometimes, turbulence can also provide organisms with hydrodynamic signals that may be wrongly interpreted as generated by an approaching predator, which may affect their behavior and the energetic cost of swimming [62]. In addition, the presence of turbulence can change the particles' settling velocity, which subsequently alters the concentration within the suspension layer.