First steps toward the knowledge of macrofaunal assemblages in rose gorgonian gardens from Central Chile: opening the door for conservation actions

Abstract

AbstractGorgonian gardens of a new species of the generaLeptogorgiasp. are found in Central Chile. Little is known about these populations including depth distribution, colony abundance, structural attributes, and associated macrofaunal assemblages. Hierarchical sampling was conducted at 20 m depth (maximum colony abundances) in order to assess spatial variability in abundance and colony attributes at two spatial scales (among sites and rocky walls). The abundance and composition of the associated vagile and sessile macrofauna were also examined using univariant (Taxa richness, and Shannon index (H’e)) and multivariant approaches, and were compared with adjacent bare rocky habitats. Our results showed a high abundance of gorgonians (ca. 28.9 to 36.5 colonies m-2) compared to other gorgonian gardens in the world. For structural attributes, our results showed smaller colonies with thicker holdfasts in more exposed sites, suggesting the influence of hydrodynamic forces on the colony morphology. Taxa richness andH’eof vagile fauna showed 3-fold and 2-fold, respectively, higher values in gorgonian gardens compared to bare walls, but no differences were observed for sessile fauna. In addition, PCoA and PERMANOVA evidenced a distinctive assemblages’ composition between habitats for both vagile and sessile fauna. Correlation analyses and dbRDA showed, however, little association between structural attributes and associated faunal assemblages (R2=0.06, and ca. 3 to 9.4 % of the total variation explained, respectively). Our results constitute the first assessment of structural habitat complexity and accompanying fauna in these gorgonian gardens and establish the baseline for understanding possible future changes associated to human activities.