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98 Gianmarco Ingrosso et al.

Fig. 10 Threats to bioconstructions: (A) the negative impact of gosth nets and
(B) anchoring on the coralligenous habitat. (C) The nonindigenous species C. cylindracea
overgrows on colonies of A. calycularis. (D) Plastic litter on M. oculata coral frame. Panel
(A): Photo: Paolo Fossati. Panel (B): Photo: University of Genova. Panel (C): Photo: Fabio
Badalamenti. Panel (D): Photo: University of Cagliari/ISPRA.

degradation of plastic debris generates huge amounts of microplastic fragments
that can be ingested by polyps (Hall et al., 2015) with detrimental conse-
quences for the colonies. Marine debris of anthropogenic origin were also
documented in the coralligenous outcrops using ROVs. Their occurrence
wasmassiveandwidespread(Angiolillo et al., 2015; Cau et al., 2015a,
2017a). Gorgonians were the most commonly affected organisms, followed
by red coral, antipatharians, sponges and other invertebrates. The lowest abun-
dance of marine debris was recorded in Sardinia, representing a minor potential
source of litter in comparison to more populated regions, such as Campania
and Sicily (Angiolillo et al., 2015).

4.1.2 Organic Enrichment
Eutrophication (i.e. excessive nutrient load), mostly related to wastewater
discharge, is a widespread problem in coastal waters (Howarth et al.,
2000), enhancing algal blooms followed by algal death, decomposition
and oxygen depletion leading to mass mortalities (Stachowitsch et al.,
2007). Generally, eutrophication can impact ecosystems directly, causing