Bioconstruction and Bioerosion in the Northern Adriatic Coralligenous Reefs Quantified by X-Ray Computed Tomography

Abstract

The northern Adriatic continental shelf hosts several coralligenous reefs rising from the sedimentary bottom and characterized by three main benthic assemblages, respectively, dominated by algal turfs, encrusting calcareous rhodophyte (ECRs) or erect sponges. Bioconstruction and bioerosion processes have been investigated using recruitment travertine limestone tiles deployed in a random site for each main benthic assemblages off Chioggia, 6.1–14.4 km offshore and 20.2–25.4 m depth. Tiles were retrieved after 3 and 12 years and analyzed by X-ray computed tomography (CT), allowing for non-destructively identifying and quantifying deposited and eroded limestone. The main builders were ECRs, serpulids, bryozoans, barnacles, and the bivalves Anomia ephippium, while the most effective borers were sponges from the genus Cliona and the bivalve Rocellaria dubia. The deposition of limestone after 12 years was greater at the site MR08 dominated by ECRs (12.52 ± 2.22 kg m–2), intermediate at the site P213 dominated by erect sponges (4.20 ± 1.24 kg m–2), and lower in the site P204 dominated by algal turfs (2.20 ± 0.72 kg m–2). At MR08, the deposition rate did not vary much over time (from 1.295 ± 0.270 to 1.080 ± 0.198 kg m–2 a–1), while in the other two sites, it significantly slowed down after the first survey period: from 0.952 ± 0.199 to 0.350 ± 0.103 kg m–2 a–1 at P213, and from 1.470 ± 0.462 to 0.203 ± 0.058 kg m–2 a–1 at P204. The amount of eroded limestone increased with the exposure time, with no significant differences among sites, from 1.13 ± 0.29 to 10.39 ± 1.14 kg m–2 on average at 3 and 12 years, respectively. The bioerosion rate also increased with the exposure time and was slightly higher at MR08 (from 0.682 ± 0.208 to 1.105 ± 0.088 kg m–2 a–1), mostly eroded by Cliona rhodensis in addition to C. viridis, compared to P204 (from 0.267 ± 0.078 to 0.676 ± 0.172 kg m–2 a–1) and P213 (from 0.179 ± 0.065 to 0.816 ± 0.171 kg m–2 a–1). Overall, bioconstruction has overcome the bioerosion processes in 3 years. In 12 years, the estimated net balance was essentially nil at all sites. Combining field experiment and CT analysis, this study provides the first quantification of the bioerosion and bioconstruction processes in the northern Adriatic coralligenous reefs, a fundamental step toward their conservation.

When Scientists and Industry Technologies Mitigate Habitat Loss: The First Bioconstruction Relocation in the Mediterranean Sea

“…On the other hand, the monitoring of the nuclei provided information on fast-growing species that rapidly colonized both the nuclei and the pipeline concrete coating after one year of immersion (i.e., encrusting corallinales, encrusting sponges, Reteporella sp., and serpulids). These taxa have been reported as opportunistic or characteristic of the first stage of community development on coralligenous reefs (Fava et al, 2016;Sartoretto et al, 2017;Casoli et al, 2020b;Turicchia et al, 2021). Albeit not analyzed in the present work, fast-growing species settled on the pipeline sections not interested by nuclei relocation, so we can argue that their settlement was not influenced by the relocation activities.…”

The Bioerosion of Submerged Archeological Artifacts in the Mediterranean Sea: An Overview

“…This new carbonate deposit represents a suitable material used as growth substrate for bioeroders (Spencer and Viles, 2002). Carbonate accretion and bioerosion rate affect the habitat structure of both tropical coral reefs (Hutchings, 1986) and coralligenous reefs in the Mediterranean Sea (Turicchia et al, 2022), with remarkable effects on biodiversity and biogeochemical cycling. Bioerosion acts over a wide range of natural substrates, such as encrusting coralline algal thalli and calcareous skeletons of living and dead organisms (Le Tribollet and Payri, 2001;Hutchings and Peyrot-Clausade, 2002;Bick, 2006;Smith et al, 2015;Meyer et al, 2021;Ramıŕez-Viaña et al, 2021).…”

A 3D Innovative Approach Supporting the Description of Boring Sponges of the Precious Red Coral Corallium rubrum

“…The change in boring behaviour of some species during their growth, the wide range of factors influencing it, and the similar erosive patterns produced by different species make it difficult to attribute a boring pattern to a single species. Throughout the literature, many Entobia have been attributed to different species of clionaids considering the morphological characteristics of the cavities [17]; an example is Entobia cateniformis, ichnospecies firstly attributed to Cliona vermifera (Hancock, 1867) by Bromley and D'Alessandro [17], while Färber et al [13] assigned it to Cliona schmidtii (Ridley, 1881), and more recently, Turicchia et al [27] attributed it to Cliona viridis. Conversely, our results in this study suggested E. cateniformis as a possible trace marker for D. pulchella mediterranea.…”