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6 M. Angiolillo et al. / Marine Pollution Bulletin xxx (2015) xxx–xxx

Fig. 4. Frequency of occurrence of marine debris items found in each region by debris category. ‘‘n’’ refers to the total number of debris items recorded in each region.

Table 2 star Astrospartus mediterraneus (Risso, 1826) was also observed on
Results of mixed logistic models for presence/absence of damages in each sampling lost nets (Fig. 5C). Differences among regions were observed in the
unit. Results are grouped by damage (outcomes) and the relationship with debris percentage of occurrence of epibiont taxa and species composition.
types is investigated. The larger the Odd Ratio (OR), the stronger the impact of the
debris type on the specific damage. For all tests, p < 0.0001. Besides sessile species, debris was utilized as habitat by numer-
ous fish (e.g. Anthias anthias (Linnaeus, 1758), Callanthias ruber
Damage Debris types OR C.I. 95% 0.0030 (Rafinesque, 1810), Muraena helena Linnaeus, 1758, Scorpaena
Abrasion 2362.8 elongata Cadenat, 1943, Scorpaena scrofa Linnaeus, 1758) and vag-
(Intercept) 0.0011 0.0004 142.9 ile benthic species (such as crustaceans, sea-urchins and octo-
Covering Lines 846.6 303.3 puses) which used their cavities as a refuge or dug in the
Nets 38.7 10.5 0.0027 sediment underneath them.
Hanging 6097.5
(Intercept) 0.0008 0.0003 743.9 The logistic model revealed a significant relationship between
Lying Nets 1756.1 505.7 dead specimens of benthic species and fishing gears as nets
Plastic 128.8 22.3 0.0017 (p = 0.019 and O.R. = 3.13) and lines (p < 0.001 and O.R. = 2.76),
12043 while no significant relationship was found with other types of
(Intercept) 0.0002 1.68E-05 4717 debris (Table 6). Dead specimens were mainly corals, found bro-
Lines 1200 120 ken, detached or buried in the sediments. Others were still
Nets 444 42 0.0030 anchored to the substratum but deprived of branches. Others were
329.9 observed bare, with patches of living tissue or completely covered
(Intercept) 0.0011 0.0004 307.1 by epibiont species. Very few dead specimens were recorded in Sic-
Lines 126.4 48.4 2002.0 ily. In Campania, dead specimens mainly belonging to P. clavata
Nets 98.0 31.3 17911 and E. cavolinii, were recorded in 67% of the explored areas, partic-
Plastic 393.4 77.3 ularly in Ischia (c5) and Amalfi (c1). Sardinia showed the highest
Others 3156 556 incidence of dead specimens, belonging to several species such as
P. clavata, E. cavolinii, C. rubrum, V. flagellum and C. verticillata,
species was the black coral Antipathella subpinnata (Ellis & Soland- and recorded in 90% of the explored areas.
er, 1896) (52%) (Fig. 5F), such as wide meadows of this species
were recorded in some areas. 4. Discussion

Several epibionts settled on the bare branches of impacted cor- This study highlights a massive and widespread occurrence of
als, forming large aggregates. Hydroids were the most common anthropogenic debris in the deep rocky environment of the Tyrrhe-
taxa (29%), followed by serpulids (17%), sponges (16%), other anth- nian Sea, with a substantial inter-regional variability. The lowest
ozoans (13%) and bryozoans (7%). The anthozoan Alcyonium coral- abundance of marine debris, recorded in Sardinia is likely related
loides (Pallas, 1766) was often observed forming large colonies to the small human population living in this region, representing
mainly on E. cavolinii. a minor potential source of litter in comparison to more populated
regions, such as Campania. This point supports the hypothesis that
Debris items also represented a substrate for other organisms. the occurrence of high concentrations of debris, in proximity to
The majority of debris (80%), in fact, was covered by colonial coastal urban areas, is correlated to the size of the surrounding
organisms. Fishing lines showed predominantly moderate coloni- human population (Galgani et al., 1996, 2000; Hess et al., 1999;
zation (59%), while considerable amount of taxa were observed Mordecai et al., 2011).
on nets (Table 5). Sometimes, lost nets still standing in their oper-
ative position and potentially still fishing were observed covered In fact, it is possible to observe a positive relationship of debris
by organisms (Fig. 5A). 40% of other debris types showed no abundance with the average density of human population in the
colonization. three surveyed regions (429, 196, 68 inhabitants per kmÀ2, respec-
tively for Campania, Sicily and Sardinia), suggesting a main land-
The most frequent recorded taxa on debris were hydroids (31%), base origin of the recorded debris.
sponges (22%) and polychaetes (16%), followed by bryozoans,
anthozoans and ascidians. Polychaetes such as Serpulidae species Moreover, the debris abundance estimated in this study are
(Protula sp., Sabella sp.) were often observed growing on metal comparable to the ones determined by other authors from urban-
cans, pots, or sacks (Fig. 5J, K). Among anthozoans, various alcyona- ized areas (Galgani et al., 2000; Watters et al., 2010; Mordecai
ceans (Alcyonium acaule Marion, 1878, Alcyonium palmatum Pallas, et al., 2011; Pham et al., 2013, 2014). Very low values of debris
1766, A. coralloides), actiniarians, scleractinians were commonly abundance were found only in the Artic region, likely due to the
observed in association to lost gears. Some gorgonians, as P. remote nature of this environment (Bergmann and Klages, 2012).
macrospina, and more rarely P. clavata or E. cavolinii, were also
recorded growing as epibiotic organisms on abandoned waste
(nets or hard debris) or on dead portions of other corals. The basket

Please cite this article in press as: Angiolillo, M., et al. Distribution and assessment of marine debris in the deep Tyrrhenian Sea (NW Mediterranean Sea,
Italy). Mar. Pollut. Bull. (2015), http://dx.doi.org/10.1016/j.marpolbul.2014.12.044