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Mediterranean Bioconstructions Along the Italian Coast 97

4.1.1 Pollution
Chemicals introduced in the marine environment from land-based (agricul-
tural runoff, industrial and urban waste) and sea-based (oil spills, shipping)
sources of pollution could result in severe impacts on bioconstructions by
impeding growth and reproduction of building organisms, and causing
diseases or mortality in sensitive species. Several studies have correlated gra-
dients of increasing pollution to increasing impacts on bioconstructions, in
particular for those in the intertidal or superficial waters, such as L. byssoides
and vermetid reefs, which are primarily exposed to coastal sources of pollu-
tion. Such species are highly sensitive to chemical pollution (Blanfun eet al.,
2016; Verlaque, 2010), and large concretions are present only in condition
of high environmental quality (Ballesteros et al., 2007; Chemello, 2009; Di
Franco et al., 2011).
Bioconstructors inhabiting the shallow subtidal may be strongly affected
as well. For instance, the presence of coastal industries has been associated
with an increased spatial heterogeneity and decreased diversity of cor-
alligenous assemblages (Bevilacqua et al., 2012, 2018). The decline of
C. caespitosa reefs has been observed in relation to industrial discharge
(El Kateb et al., 2016), and chemicals are likely to have detrimental effects
also on A. calycularis as on other corals (Wear and Thurber, 2015). Toxic
substances may induce metabolic changes, decrease rates of growth and
reproduction or reduce viability of corals (Pastorok and Bilyard, 1985).
Domestic detergents may cause high coral mortality and reduced tissue
growth (Shafir et al., 2014), whereas inorganic pollutants have harmful
effects on fertilization and embryo development (Humphrey et al., 2008)
and on early-life history stages of coral species (Humanes et al., 2017). Prod-
ucts such as sunscreen UV filters containing benzophenone-2 induce defor-
mity in coral planulae (Downs et al., 2014) and, by promoting viral
infection, potentially play an important role in coral bleaching (Danovaro
et al., 2008). Pharmaceuticals have negative ecological consequences on
aquatic invertebrates even at very low concentration (Brodin et al., 2014)
by affecting spawning, larval release, locomotion and fecundity (Fong and
Ford, 2014).
Plastic litter is increasingly recognized as a potential threat to bio-
constructions, even for deep-water corals (Fig. 10D). In a recent study,
Savini et al. (2014) documented plastic bags and debris to be the most repre-
sented type of marine litter in CWC banks in the northern Ionian Sea. In this
case, the major effects are due to the entanglement of debris on colonies,
causing impediments for normal polyp activities (e.g. feeding). Moreover,