Community Structure of Gurnards in Relation to Different Environmental Variables in Antalya Gulf

Fish assemblages have not been studied at the family level using comprehensive environmental variables. Ecological studies focusing on spatiotemporal density (abundance and biomass) and morphometry (size and inter-traits relationships) of fish species have been highly limited in the Mediterranean Sea, particularly in the Turkish Levant coast. Gurnards (Family: Triglidae) have received little attention in ecological research. In the present study, in order to outline the spatiotemporal dynamic of density and morphometry in space (region and bottom depth) and time (season) alongside environmental parameters, gurnards collected seasonally from a study conducted on shelf/shelf break of the Antalya Gulf in 2014-2015 (de Meo et al. 2018) were studied. A total of 79 stations were sampled in year period (22 stations in May, 17 in August, 21 in October and 19 in February). Of the total stations, occurrence of the gurnards in stations varied between 4 (Trigla lyra) and 34 (Lepidotrigla cavillone). The gurnards were represented by six species in Antalya Gulf. In general, the small-sized specimens (L. cavillone and L. dieuzeidei < 15 cm) outnumbered the larger specimens (Chelidonichthys lucerna, C. cuculus, C. lastoviza and T. lyra) in the gurnard population. The species were significantly differentiated by the bottom depth, followed by the depth-gradient environment. Shallow water, middle shelf and deeper water species were distinguished among the six species. The gurnards avoided the seagrass meadows. Only Chelidonichthys lastoviza was found close to the meadow beds. Small-sized species had more abundance than large-sized species on bare bottoms. Large-sized species exhibited greater sizes in eutrophic areas compared to those in oligotrophic areas, whereas small-sized species had similar sizes in both trophic states, leading to differences in their growth types. Overall, females outnumbered the males for all species and the species exhibited a size-dependent sexual dimorphism with the females being longer and heavier than the males. Assemblage of six gurnard species was correlated with depth, thus bottom type (coarse to fine material of sediment from coast to open water) and chl-a and fine bioseston. With respect to fish-epibenthic fauna relation, the gurnard community was correlated primarily with Decapoda and Holothuroidea and secondarily with Crinoidea, followed by Ophiuroidea. The gurnards were distributed specifically at different depths of the shelf/break, preferring bare bottoms in general with depth-graded environment in space and time.