Impact assessment of fish cages on coralligenous reefs through the use of the STAR sampling procedure

Abstract

The study aimed at contributing to the development of methods to assessing the effects of human disturbance on coralligenous reefs. The effects of the presence of a fish farm on coralligenous reefs were evaluated using the STAR (STAndaRdized coralligenous evaluation procedure) sampling procedure. An asymmetrical sampling design was used to compare the aquaculture site with two reference sites in areas unaffected by human pressure. The response of different ecological indices (ESCA, Ecological Status of Coralligenous Assemblages; ISLA, Integrated Sensitivity Level of coralligenous Assemblages; COARSE, COralligenous Assessment by Reef Scape Estimate) and descriptors (α-diversity, β-diversity and Sensitivity Level) of this kind of disturbance was compared. Results indicate that coralligenous reefs are vulnerable to aquaculture fish cages, and differences in the structure of coralligenous assemblages between the disturbed and the reference sites were mostly due to the decrease in β-diversity. On the contrary, no significant differences in the number of taxa/groups were highlighted. Encrusting Corallinales, erect Rhodophyta, Dictyotales, Fucales and Halimeda tuna were more abundant in reference sites than in disturbed site, while Peyssonnelia spp. and algal turfs had the opposite trend. Conversely, no significant differences between conditions were found in the abundance of sessile invertebrates. The study supports the suitability of the STAR approach to be employed in impact evaluation assessments, such as in monitoring programs. The present study is a first attempt to combine three different ecological indices (ESCA, ISLA and COARSE) within a unified approach, in order to assess the status of coralligenous reefs subjected to a moderate human-induced disturbance. The inconsistent response of the different indices highlights the advantage of applying different indices and descriptors to evaluate the variable human pressures on natural systems.

Coralligenous cliffs: distribution and extent along the Tuscany coasts and spatial variability of the associated assemblages

“…Continental sites clearly differ from the island counterpart, probably because they are more exposed to the coastal pressures (Holon et al, 2015). In areas subjected to sedimentation, eutrophication and pollution (Balata et al, 2005;Piazzi et al, 2011Piazzi et al, , 2019cPiazzi et al, , 2021b, coralligenous assemblages tend to be dominated by tolerant and opportunistic organisms, such as algal turf and encrusting sponges. However, the two continental sites were significantly different, which induces one to consider other causes of variability (Holon et al, 2014) to explain these differences.…”

Impacts of Marine and Lagoon Aquaculture on Macrophytes in Mediterranean Benthic Ecosystems

“…of depth, at about 30 m of cages, there is a decrease in βdiversity, encrusting Corallinales, erect Rhodobionta, Dictyotales, Fucales (Phaeophyceae) and Halimeda tuna (Ulvophyceae) and an increase in Peyssonnelia spp. (Rhodobionta) and algal turfs (Piazzi et al, 2019). Unfortunately, most authors focus on the impact of fish farming on P. oceanica meadows, but pay little attention to other macrophyte assemblages.…”

NAMBER: A biotic index for assessing the ecological quality of mesophotic biogenic reefs in the northern Adriatic Sea

“…Several methods have been proposed to assess the ecological quality status of coralligenous assemblages for both banks and rims. Coralligenous rims can be effectively surveyed by scuba diving (Teixidó et al, 2013; Piazzi et al, 2019a), whereas banks, which are generally at greater depths, are often surveyed by unmanned vehicles such as remotely operated vehicles (ROVs) (Bo et al, 2014; Casoli et al, 2017; Ferrigno et al, 2018; Piazzi et al, 2019c; Rossi et al, 2021). Ecological quality indices have been developed for both coralligenous rims (Deter et al, 2012; Gatti et al, 2012; Cecchi et al, 2014; Ruitton et al, 2014; Gatti et al, 2015a; Montefalcone et al, 2017; Sartoretto et al, 2017; Valisano et al, 2019; Piazzi et al, 2019b; Piazzi et al, 2021) and banks (Cánovas‐Molina et al, 2016a; Ferrigno, Russo & Sandulli, 2017; Enrichetti et al, 2019) occurring in the north‐western Mediterranean Sea.…”