Bathymetrical distribution and size structure of cold-water coral populations in the Cap de Creus and Lacaze-Duthiers canyons (northwestern Mediterranean)

1. Cold-water coral (CWC) ecosystems are long-lived, slow-growing and fragile, which makes them especially vulnerable to physical damage. In recent decades, CWCs have been severely threatened by fisheries, hydrocarbon extraction, pollution and other human activities.2. In the Mediterranean Sea, some investigations have been carried out on CWC ecosystems, mostly focused on their distributions within the central and eastern basins. 3. Historical reports and fishermen's maps for the eastern Ligurian Sea (NW Mediterranean) from the 1960s document the occurrence of extensive banks of living CWC, mostly Madrepora oculata, between depths of 200 and 500 m. 4. In 2013/2014, multibeam, side scan sonar (SSS) and remotely operated vehicle (ROV) surveys were carried out in that area, specifically in the Levante Canyon, to assess the occurrence, distribution and conservation status of CWC. 5. The SSS and ROV showed numerous trawl tracks and small (10 cm high), dead, buried colonies at 300-500 m. Deeper, between 525 and 575 m, dense populations of living, 1 m high colonies of Madrepora oculata were found on the flanks of Levante Canyon. The deep sites showed colonies overturned or entangled by long-line fishing activities. 6. The discovery of new CWC banks not yet heavily damaged by fishing activities, suggests that urgent measures for conservation should be taken in the Mediterranean and worldwide. The present limitation of trawl-fishing to above 1000 m depth, established by the General Fisheries Commission for the Mediterranean (GFCM) in 2005, seems to be ineffective, since CWCs are mostly located at less than 1000 m depth in the Ligurian Sea. A network of high-seas/deep-sea marine protected areas (MPAs) would favour a better strategy for protecting substantial areas of CWCs. KEYWORDS cold-water coral ecosystems, Levante Canyon, Madrepora oculata, marine protected areas, Mediterranean Sea, remotely operated vehicle, seafloor mapping

Section: Discussionsupporting

confidence: 80%

Cold‐water coral Madrepora oculata in the eastern Ligurian Sea (NW Mediterranean): Historical and recent findings

Fanelli

Delbono

Ivaldi³

et al. 2017

“…Concerning the habitat, this genus seems often associated with the occurrence of scleractinian frameworks or rubble, as demonstrated by the only specimen collected with the base, perfectly covering M. oculata fragment (Figure d, inset). This habitat is present not only in Santa Margherita Ligure, but also in the other localities where Placogorgia was reported; namely, Sicily, Santa Maria di Leuca, Alboran Sea, and Gulf of Lion (Fabri et al, ; Gori et al, ; Hebbeln et al, ; Lo Iacono et al, ; Mastrototaro et al, ; Orejas et al, ; Pardo et al, ; Tursi et al, ; Vertino et al, ). This association is not exclusive, as demonstrated by oceanic records that also describe Placogorgia on rocky bottoms, biogenic detritus, and anthropogenic substrates (Carpine & Grasshoff, ; Grasshoff, ; Thomson, ; Tixier‐Durivault & d'Hondt, ).…”

Section: Discussionmentioning

confidence: 95%

Placogorgia coronata first documented record in Italian waters: Use of trawl bycatch to unveil vulnerable deep‐sea ecosystems

Enrichetti

Bavestrello

Coppari

et al. 2018

1 Despite the pluri-decennial history of bottom trawling monitoring in the Italian Sea, limited attention has been given to the study of cold water corals (CWCs) present in the bycatch. As a result, trawl samples still hold a great potential to reveal information about deep-water biodiversity.2 The rare Mediterranean CWC species Placogorgia coronata was repeatedly found in the bottom trawl discards of the red shrimp fishery in Santa Margherita Ligure (Ligurian Sea). The supposed rarity of this species is strongly biased by taxonomic problems within the genus as well as by the limited exploration of these deep habitats.3 Scientific literature as well as remotely operated vehicle surveys highlighted the presence, in the investigated trawled area, of a dead white coral framework, supporting the hypothesis that the CWC studied, probably thriving on coral rubble, occurs here due to the natural protection to trawling offered by the coral matrix.Trawlers, however, may accidentally affect these secondary hard grounds, as demonstrated by the discard content.4 The long-term monitoring of the catches highlighted a removal rate of up to one colony every two trawling operations; based on the anecdotal fishing effort in this area and the status of the discarded specimens, it is possible to estimate an average catch rate of about 18 live colonies per year per fisherman.5 The occurrence of rare CWC species with low resilience to fishing disturbance is among the required information for the identification of fishing restriction zones designed to protect deep vulnerable marine ecosystems.

“…The filter‐feeding species characterizing these habitats are typical of rocky areas with strong hydrodynamism. The occurrence of cold‐water corals, such as Madrepora oculata , on exposed areas may be related to a compromise between protection from the sediment and exposure to the water flow, which ensures feeding (Gori et al, ). The black coral Leiopathes glaberrima has also been cited as a species that thrives especially on exposed, steep rocky bench terraces or platforms (Bo et al, ; Mytilineou et al, ), or among white coral reefs (Angeletti et al, ; D'Onghia et al, ; Mastrototaro et al, ).…”

Section: Discussionmentioning

confidence: 99%

Benthic habitat modelling and mapping as a conservation tool for marine protected areas: A seamount in the western Mediterranean

Torriente

González-Irusta

Aguilar³

et al. 2019

1. An ecologically representative, well-connected, and effectively managed system of marine protected areas (MPAs) has positive ecological and environmental effects as well as social and economic benefits. Although progress in expanding the coverage of MPAs has been made, the application of management tools has not yet been implemented in most of these areas.2. In this work, distribution models were applied to nine benthic habitats on a Mediterranean seamount within an MPA for conservation purposes. Benthic habitat occurrences were identified from 55 remotely operated vehicle (ROV) transects, at depths from 76 to 700 m, and data derived from multibeam bathymetry. Generalized additive models (GAMs) were applied to link the presence of each benthic habitat to local environmental proxies (depth, slope, backscatter, aspect, and bathymetric position index, BPI).3. The main environmental drivers of habitat distribution were depth, slope, and BPI.Based on this result, five different geomorphological areas were distinguished. A full coverage map indicating the potential benthic habitat distribution on the seamount was obtained to inform spatial management. The distribution of those habitats identified as vulnerable marine ecosystems (VMEs)was used to make recommendations on zonation for developing the management plan of the MPA. This process reveals itself as an appropriate methodological approach that can be developed in other areas of the Natura 2000 marine network.