**Preface to "Larval Settlement on Marine Surfaces: The Role of Physico-Chemical Interactions"**

This reprint is a collection of 11 scientific articles (8 research papers, 1 communication and 2 reviews) published in the *Journal of Marine Science and Engineering* on the topic of "Larval Settlement on Marine Surfaces: The Role of Physico-Chemical Interactions".

I proposed the above-mentioned topic because advancing our understanding of larvae–surface interactions will certainly be greatly beneficial with respect to addressing the challenges of future innovative eco-engineering designs, yielding the best solutions for industrial biofouling protection and coastal ecosystem preservation. Biofouling occurs when sessile aquatic organisms rapidly settle on artificial hard substrata, which poses a large problem worldwide since their growth often causes severe damage to submerged structures. Accordingly, international efforts are being exerted toward the development of anti-fouling systems because biofouling not only increases static and hydrodynamic loading, but also affects corrosion characteristics and impedes underwater inspection and maintenance.

On the other hand, biofouling leads to the formation of a well-structured community on natural hard substrata characterised by ecological succession and can be considered an important source of biodiversity, whose long-term preservation controls the trophic chain of coastal ecosystems.

In all cases, there is a very close relationship between larval settlement and the type of substratum in question since the ecological succession of the fouling community in coastal marine ecosystems directly depends on interactions between organisms and surfaces. Due to their texture, microstructure, roughness, colour, and chemical composition, the various types of hard substrata affect organisms' settlement by favouring dominant species or preventing the settlement of biofouling organisms. The impact on the ecosystem biodiversity of the resident community caused by the extensive use of anthropogenic substrata requires attention due to the various unpredictable effects that can occur. Under some conditions, artificial substrata can enhance biodiversity and productivity at a local scale in depauperated areas and can positively contribute to regional productivity overall, but they can also lead to the recruitment and selection of invasive species by acting as a collector for larvae that negatively affect the local biodiversity. Therefore, the influence of a substratum's physico-chemical interactions on the settlement of various organisms in the macrofouling community represents an essential factor in choosing an appropriate artificial surface for application in a variety of coastal marine ecosystems. For this reason, I selected studies that focus on various aspects of the evaluation of marine larval settlement on both natural and artificial surfaces, including pro-fouling and anti-fouling systems.

> **Francesca Cima** *Editor*
