Bathyal megabenthic assemblages in the SE Iberian Peninsula (Western Mediterranean Sea)

The Iberian SE is an interesting transition and connectivity zone between the Alboran Sea and the Algerian-Balearic basin. It hosts important deep water fisheries targeting mostly red shrimp (Aristeus antennatus). The area comprises a complex system of tectonic canyons (Mazarron Escarpment), seamounts, knolls and hills (Palos, Planazo, Plis-Plas), and pockmark fields (Acosta et al., 2013). Few studies have been conducted on the bathyal megabenthos, unlike in the neighbouring Chella Bank (De la Torriente et al. 2018) and Balearic Islands (Massuti et al. 2022). The LIFE IP Intemares project is filling this gap

Bathyal megabenthic assemblages in the south-eastern Iberian Peninsula (Western Mediterranean)

The SE Iberian sector represents an interesting transition and connectivity zone between the Alboran Sea and the Algerian Balearic basin, and the area comprises a system of tectonic canyons (Mazarron Escarpment), seamounts and pockmarks fields. Despite this, relatively few studies have been conducted on the bathyal zone. During the LIFE IP Intemares A2.2-Mu0820 survey, the continental slope was observed by ROV Liropus-2000, between 183 and 1735m depth following bathymetric mapping using a multibeam echosounder. A combination of multivariate analysis of still imagery and video groundtruthing have been able to discriminate some megabenthic assemblages. On hard bottoms of the upper bathyal horizon: i) Neopycnodonte cochear-Mergelia truncata facies, 193-244m depth; ii) Ellisella flagellum facies, 2441-320m; iii) Antipathes dichotoma facies, 259-270m. Middle horizon: i) Demospongiae facies (Pachastrella, Phakellia, Aaptos…), 241-494m; ii) gorgonian assemblage (Callogorgia, Paramuricea, Placogorgia), 294-624m; iii) Leptometra phalangium facies 293-611m; iv) cold-water corals (Desmophyllum, Madrepora), 516-607m; Antipatharia facies (Antipathella, Leiopathes, Parantipathes), 519-624m. Lower bathyal horizon:; Dicopia antirrhinum facies, 645-1167m. On soft bottoms (mud, sandy-mud) of the upper bathyal horizon: i) Ceriantharia facies, 213-219m depth. Middle horizon: i) Pennatulacea facies (Funiculina, Kophobelemnon, Pteroeides…), 219-541m; ii) Thenea muricata facies, 418-814m; iii) Isidella elongata facies, 462-681m. Lower horizon: i) Pelosina fields, 235-1321m. The results reveals that the bathyal zone of the SE Iberian Peninsula is topographically complex and harbours diverse benthic assemblages, some of which fall within the category of Vulnerable Marine Ecosystems; and some species are listed in annex II of the RAC/SPA list of endangered or threatened species

Vulnerable Marine Ecosystems found in a bathyal zone off the SE Iberian Peninsula (Western Mediterranean)

The Spanish Intemares LIFE IP project contemplates the creation of Special Areas of Conservation within the Natura 2000 Network. During its August 2019 cruise, a series of towed sledge transects were conducted on two seamounts (“Planazo” and “Plis Plas”) and a muddy field of pockmarks, both located in areas off the SE Iberian Peninsula (Western Mediterranean), between 220 and 694m depth. The prospected area has a significant pressure from bottom trawl (directed towards Aristeus antennatus, Nephrops norvegicus, Plesionika spp.) and, to a smaller extent, of bottom longline fisheries (focused on Merluccius merluccius and Pagellus bogaraveo). Some of the observed bathyal habitats fall into the category of Vulnerable Marine Ecosystems (VME), according to FAO (2009, 2016), since they present at least one of the following characteristics: i) uniqueness or rarity; ii) functional significance of habitat; iii) fragility; iv) life history traits of component species that make recovery difficult; and/or v) structural complexity. Among them, “gorgonian gardens” (of Paramuricea hirsuta, Callogorgia verticillata, Bebryce mollis, Swiftia pallida, and Ellisella flagellum) and the yellow tree coral (Dendrophyllia cornigera) highlight rocky bottoms; while on muddy substrates, sea-pen fields (Funiculina quadrangularis and Kophobelemnon stelliferum) and “bamboo coral gardens” (Isidella elongata) do so. These habitats, along with fields of the crinoid Leptometra phalangium, are also considered Essential Habitats for target species of fishing interest. The location, mapping and characterization of these habitats are necessary to establish “no-take” zones within the future management plan for the area studied

Vulnerable Marine Ecosystems found in a Bathyal Zone off the SE Iberian Peninsula (Western Mediterranean)

Description of VMEs (gorgonian and bamboo coral gardens) found in two seamounts during one of the INTEMARES surveys using a towed camera