Temporal partitioning of microhabitat use among four juvenile fish species of the genusDiplodus(Pisces: Perciformes, Sparidae)

Abstract

Timing, microhabitat selection and behavior from the onset of settlement to recruitment to the adult population of juvenile fishes of the genus Diplodus (Pisces: Sparidae) were investigated along a rocky coastline in the Central Mediterranean Sea. The settlement periods in Diplodus sargus and Diplodus annularis were concentrated in spring, between late May and early June, and the recruits leave the nursery grounds in late September–October. Juvenile fishes of Diplodus puntazzo and Diplodus vulgaris showed a partial time overlapping, sharing the same zones in winter and early spring, from February to May. Multiple correspondence analysis showed that sea breams settle in well‐defined habitats. The smallest juveniles of D. sargus and D. puntazzo settled primarily in the shallowest sheltered pebbly areas, located in sciaphilous crannies covered by red algae. Diplodus vulgaris settlers were observed on a wider range of substrata: rock on sand, gravel and pebbles without algal cover or large boulders, generally in deeper waters. The intermediate‐size juveniles of D. sargus, D. puntazzo and D. vulgaris showed a preference for rocky substrata with substantial algal cover, with arborescent structures (Phaeophyceae). Diplodus annularis juveniles showed high fidelity to seagrass beds (Posidonia oceanica). The home range increased over time in all species, highlighting a loss of substrate specificity: larger juveniles were even observed in deeper and different microhabitats outside nursery grounds. This study suggests that shallow infra‐littoral rocky communities with photophilic algae play a key role in recruitment of sparid fishes, affecting the distribution and abundance of juvenile fishes and therefore determining the renewal of populations and the structure of adult assemblages.

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

“…Juvenile Diplodus spp. are known to undergo ontogenic shifts in habitat use, enlarging their niche by vertical (for D. vulgaris ) or horizontal (for D. sargus ) migration (Ventura et al ). Those shifts have also been observed on the AH within harbors (Bouchoucha et al ), and during experiments, most juveniles were observed under the AH, which seems to be the same in situ (authors' unpublished data).…”

Mapping and Classification of Ecologically Sensitive Marine Habitats Using Unmanned Aerial Vehicle (UAV) Imagery and Object-Based Image Analysis (OBIA)

“…From the orthomosaic generated by 160 overlapping images the high heterogeneity over the whole extent of the mapped area was clearly visible. Along this jagged coastline we identified two small coves (Figure 7a) were the presence of particular natural features such as sandy patches, pebbles and large boulders made such area suitable for settlement of juvenile sparid fish [42,65,66]. In fact, thanks to the high resolution (3 cm/pix) of the imagery after a visual inspection we were able to identify the most suitable habitats for juvenile fish of the genus Diplodus.…”

Potential use of marinas as nursery grounds by rocky fishes: insights from four Diplodus species in the Mediterranean

“…They are highly abundant in both natural and artificial rocky coastal areas (Tortonese 1965) and their juveniles are present in high abundances inside marinas, at least along the internal side of peripheral breakwaters (Clynick 2006). Natural settlement patterns are fairly well described for all four species: D. annularis, D. puntazzo and D. sargus all settle in one pulse, in June-July, October-November and May-June respectively, while D. vulgaris settles in two pulses, in November-December and in January-February, the first pulse being the more predominant (García-Rubies & Macpherson 1995, Harmelin-Vivien et al 1995, Cheminee et al 2011, Ventura et al 2014. In Diplodus species, physical habitat characteristics (substrate, depth, level of protection from the prevailing winds, etc.)…”