Is artificial habitat diversity a key to restoring nurseries for juvenile coastal fish? Ex situ experiments on habitat selection and survival of juvenile seabreams

Abstract

Man‐made infrastructures have become ubiquitous components of coastal landscapes, leading to habitat modification that affects the abundance and diversity of marine organisms. Marine coastal fish have a complex life cycle requiring different essential habitats. One of these habitats is known as a nursery, a place where juveniles can settle in large numbers, survive, and grow to contribute to the adult population. Nurseries are mainly found in shallow, sheltered zones and are thus particularly impacted by urbanization, notably by harbors. The vertical featureless structure of docks is very unlikely to be used by juveniles, which need complex habitats to find food and shelter from predators. Recent attempts to rehabilitate the nursery function in such environments by using artificial habitats have proven efficient in increasing juvenile densities. However, nothing is known about the survival of juveniles in these habitats, preventing any conclusions on the effectiveness of this means of restoration from being drawn. Here, we set up tank experiments to test the relationship between habitat preferences and the survival rate of two species of seabream when facing stalk‐attacking combers. Habitat choice was consistent with survival results, indicating that artificial habitats might not represent unintended ecological traps for juveniles. However, the artificial habitats' effect on survival was variable between species. Therefore, our results suggest that habitat diversity might be of prime importance to sustain juveniles of different species and stress the need for the development of diverse artificial habitats to counteract the effects of seascape homogenization.

Shoreline infrastructure degradation and increasing littoral naturalization accommodates juvenile fish and crab assemblages in heavily urbanized Upper New York Harbor

“…For other species, a pattern was much more difficult to discern because of temporal variation. This is consistent with findings in manipulative laboratory experiments that microhabitat diversity should lead to higher species diversity in shallow marine nurseries (Mercador et al ).…”

All shallow coastal habitats matter as nurseries for Mediterranean juvenile fish

“…Habitat and seascape tri-dimensional structure can be qualified by its heterogeneity and complexity 90 , 91 . Generally high quality habitats for juvenile fishes are recognized to be associated with high degrees of three-dimensional structuration 92 , in terms of both complexity 51 , 53 , 93 , 94 and/or heterogeneity 42 . Natural rocky habitats (RS) presented a high structural and biological complexity due to different macrophytes assemblages, and indeed supported the highest mean species richness and abundance of juvenile fishes in the two sampling period (cold and warm).…”

The Three-Dimensional Structure of Mediterranean Shallow Rocky Reefs: Use of Photogrammetry-Based Descriptors to Assess Its Influence on Associated Teleost Assemblages

“…Complexity can play a part in interactions such as predatorprey dynamics. Prey can use these shelters to escape predators (Hixon, 1991;Cheminée et al, 2017b), which improves their chances of survival, while predators can use habitat complexity to their advantage as hiding places to search or pursue prey, depending on their predation tactic (Thiriet et al, 2014;Chacin and Stallings, 2016;Mercader et al, 2019). Prey could be disadvantaged by complexity since it could reduce their visual field and therefore force them, to either risk predation by feeding outside their refuge or to remain in their shelter and risk starvation, and have difficulty in finding reproductive partners (Rilov et al, 2007).…”