First records, rediscovery and compilation of deep-sea echinoderms in the middle and lower continental slope of the Mediterranean Sea

Abstract

Summary:This study provides a compilation of all available information on deep-sea echinoderms from the middle and lower slopes of the Mediterranean Sea, with the aim of providing a unified source of information on the taxonomy of this group. Previous records of species are updated with new data obtained from 223 trawl hauls conducted in 11 cruises within the northwestern Mediterranean Sea between 800 m and 2845 m depth. Valid names, bathymetric ranges and geographic distributions are given for all species. The new data report, for the first time, the presence of the Atlantic echinoid Gracilechinus elegans (Düben and Koren, 1844) in the Mediterranean Sea. We also report the presence of the endemic holothurians Hedingia mediterranea (Bartolini Baldelli, 1914), dredged only once previously in 1914 in the Tyrrhenian Sea, and Penilpidia ludwigi (von Marenzeller, 1893), known previously only from three samples, two in the Aegean Sea and one in the Balearic Sea. Additionally, the deeper limits of the bathymetric distribution of four species have been expanded: the asteroid Ceramaster grenadensis (Perrier, 1881) to 2845 m; the echinoid Brissopsis lyrifera (Forbes, 1841) to 2250 m; and the holothurians Hedingia mediterranea and Holothuria (Panningothuria) forskali Delle Chiaje, 1823, to 1500 m and 850 m, respectively.Keywords: deep-sea echinoderms; Mediterranean Sea; Gracilechinus elegans; submarine canyons; taxonomy; bathymetric range. Primera cita, redescubrimiento y recopilación de los equinodermos de profundidad en el talud continental medio e inferior del MediterráneoResumen: Este estudio presenta una recopilación de toda la información disponible sobre los equinodermos de profundidad en el talud continental medio e inferior del mar Mediterráneo, con el fin de proporcionar una fuente de información unificada sobre la taxonomía de este grupo. Se han actualizado los registros anteriores mediante nuevos datos provenientes de 223 pescas de arrastre de 11 campañas oceanográficas realizadas en el noroeste Mediterráneo entre 800 y 2845 m de profundidad. Se ha actualizado el nombre de las especies, sus rangos batimétricos y sus distribuciones geográficas. Los nuevos datos presentan, por primera vez, la presencia del equinoideo Atlántico Gracilechinus elegans (Düben and Koren, 1844) en el mar Mediterráneo. También se cita la presencia en el noroeste Mediterráneo de dos especies de holoturias endémicas del Mediterráneo, Hedingia mediterranea (Bartolini Baldelli, 1914)

Increasing sediment accumulation rates in La Fonera (Palamós) submarine canyon axis and their relationship with bottom trawling activities

“…Remotely operated vehicle images collected along La Fonera deep canyon axis seafloor evidenced a large presence and densities of the burrowing sea urchin Brissopsis lyrifera [ Mecho et al ., ]. This species is known to be a very active burrower capable of substantially reworking fine‐grained marine sediments [ Widdicombe and Austen , ; Hollertz and Duchêne , ] and, as such, is plausibly responsible for the scolicia and intense bioturbation observed in the upper layers of the 2011 sediment core.…”

Comparison between ROV video and Agassiz trawl methods for sampling deep water fauna of submarine canyons in the Northwestern Mediterranean Sea with observations on behavioural reactions of target species

“…Notes were also made on other abundant crawling invertebrates of ecological relevance in the area, such as irregular sea urchins (Mecho et al, 2014).…”

“…Knowledge of reaction behaviour is highly relevant to evaluate species vulnerability to commercial trawling (Lorance and Trenkel, 2006), which is of great relevance for the management of fisheries (Aguzzi et al, 2014;Bahamon et al, 2009). However, the behaviour of deep-sea fauna is still poorly understood (Lorance and Trenkel, 2006) and is a potential source of bias in stock assessments.…”

“…This species performs displacements in large groups(Hollertz and Duchêne, 2001;Hollertz, 2002;Ramirez -Llodra et al, 2008;Pawson and Pawson, 2013) and it is known to be highly abundant in submarine canyons(Mecho et al, 2014). We also sampled living specimens by Agassiz trawling in all three investigated canyons.The large amounts of B. lyrifera carcasses forming the observed thanatocenoses are probably the result of the transport of dead individuals from up-canyon, which is favoured by the oceanographic processes acting in these canyons and subsequent dynamics (cf.…”

Identification and protection of terrestrial global biodiversity hotspots: progress and challenges

“…Although at present 36 biodiversity hotspots have been identified, there are still many biodiversity-rich regions on Earth that have an immense contribution in global species diversity and associated economy, 20 especially the marine ecosystems such as the coral reefs and deep sea megabenthos. 21,22 These aquatic ecosystems probably harbor the highest concentration of biodiversity and endemic species; they also represent some of the highly threatened ecosystems that have not been considered in the present concept of biodiversity hotspots. Recent work in marine biodiversity has resulted in identification of heretofore unknown regions of aquatic biodiversity 23 which due to the lack of access and immense distribution across the earth (three-fourth of the earth surface) that can harbor even greater biodiversity than the terrestrial ecosystems.…”