Evidences of human impact on megabenthic assemblages of bathyal sediments in the Alboran Sea (western Mediterranean)

Abstract

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Healthy assemblages of Isidella elongata unintentionally protected from trawling offshore of Asinara Island (northwestern Sardinia, NW Mediterranean Sea)

“…Bo et al 13 reported the presence of I. elongata with healthy, tall (up to 36 cm), highly branched colonies, and an average density of 0.5 ± 0.04 col. m −2 and maximum values of 2.7 col. m −2 . These density values are comparable to those found in this study and with those reported by Grinyó et al 42 for bathyal soft bottoms in the Alboran Sea, where I. elongata reached a maximum density of 7 col. m −2 . Other data from the Mediterranean Sea acquired by ROV-imaging showed that in the Balearic Sea, different values of density were reported when comparing untrawled and trawled bottom areas: 0.23–0.27 col. m −2 and 0.0053–0.0062 col. m −2 , respectively 21 .…”

“…According to Pérès and Picard 15 , I. elongata is associated with compact mud. Further studies are needed to clarify whether potential differences in the physical, geological, and geochemical characteristics of sediments (e.g., grain size, porosity, water content, composition, and organic content) can contribute to driving the distribution of Isidella facies 42 . www.nature.com/scientificreports/ and fly-tipping.…”

“…The portions of the video not relevant (i.e., ascent and descent ROV phases, ROV far from the seafloor, recording close-up images, and frames with poor visibility or out of focus) were not considered in the analyses. Each cleaned ROV video transect was divided into 5 m long sampling units (SUs; 5 m long and 1 m wide; estimated from the laser beam distance), according to previous studies of Pierdomenico et al 7 , Enrichetti et al 72 , and Grinyó et al 42 . All the observed colonies of I. elongata were counted in each SU and divided into two size classes, using laser beams as a metric scale, following Pierdomenico et al 7 and Ingrassia et al 43 : small colonies (< 20 cm www.nature.com/scientificreports/ height) and large colonies (> 20 cm height).…”

Environmental Status and Geomorphological Characterisation of Seven Black Coral Forests on the Sardinian Continental Shelf (NW Mediterranean Sea)

“…Very few studies have focused on assessing the actual environmental status of mesophotic ecosystems and, thus, on collecting the quantitative information needed to determine the baseline for developing appropriate conservation policies and future monitoring activities. The increase of human impacts, mainly due to fishing pressures and uncontrolled litter disposal, is leading to the severe degradation of these important mesophotic ecosystems [1,51,52], stressing the need to enforce control and surveillance measures to improve and preserve the "Good Environmental Status" of mesophotic coral forests under European marine legislations. While shallower ecosystems, such as coastal mangroves and seagrasses, as well as deeper, cold-water coral reef habitats, are currently under several monitoring and protection measures for the maintenance and restoration of these ecosystems [53,54], only a few conservation initiatives are explicitly aimed at the protection of deep circalittoral assemblages from destructive practices, such as fishing activities [28,30].…”

Monitoring global fishing activity in proximity to seamounts using automatic identification systems

“…However, this also results in high levels of bycatch that can account for up to 65% of total catch including the exploitation of juvenile and undersized individuals (Maynou et al, 2021; Tsagarakis et al, 2014). Indiscriminate trawling practices have also resulted in substantial alterations in benthic community composition in this region with many VME indicator species now largely absent from these areas (De la Torriente Diez et al, 2022; Grinyó et al, 2020; Pierdomenico et al, 2018). Seamounts in this region have also been shown to serve focal roles for a diverse range of threatened top predators that are vulnerable to capture in trawl nets, and so these features deserve increased attention in future marine spatial planning discussions (Bo et al, 2021; Vassallo et al, 2018).…”