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Marine Protected Areas (MPAs) and Key Biodiversity Areas (KBAs) are important tools for preserving species, habitats and ecological-geological-oceanographical processes. Nowadays, more than 10% of the Alboran Sea is under some protected figure or is on its way to be protected. This chapter presents the current state of the MPAs and KBAs of the Alboran Sea. Most of the habitats included in the Annex I of the Habitats Directive or the Barcelona Convention are represented in MPAs-KBAs of the Alboran Sea. More than 290 threatened species are also occurring in these MPAs-KBAs, but some of them have experienced a strong decline even within them (e.g. Zostera marina, Pinna nobilis). Although important progress in the protection of the Alboran Sea has been made in the last decades, there is still much to be done for effective conservation of the habitats and species. The main efforts may focus on improving (1) knowledge of the habitats and species; (2) the surveillance and mitigation against current impacts; (3) the coordination between local, national and international agencies; and (4) the measures for improving habitats and threatened species populations, among others. A deep change in the socio-economic model is then needed for preserving the Alboran Sea natural heritage, promoting then a sustainable use of its resources.

Bottom trawling activity, commercial species and benthic and demersal assemblages were studied integrating Vessel Monitoring System data (VMS), fishing logbook data and otter trawl samples in a mud volcano (MV) field of the Spanish margin of the Gulf of Cadiz (GoC) in 2011. High trawling activity was detected around Anastasya MV and between the Cadiz and Guadalquivir diapiric ridges, and low trawling activity around Gazul MV and in the deepest areas (Huelva Channel and southwards). A total of 11 938 individuals from 126 benthic and demersal species were collected in the samples. Multivariate analyses mainly grouped samples according to depth and sediment type and 3 different assemblages were detected. The Stratum 1 assemblage (Gazul MV, 441–470 m depth, muddy sand, low trawling activity and high near-bottom current speed) was dominated by Parapenaeus longirostris, Leptometra phalangium and Plesionika antigai, among others, and displayed high species richness and abundance. The Stratum 2 assemblage (Anastasya and Tarsis MVs, Triangle, and the External zone, 528–622 m, mud/sandy mud, medium to high trawling activity and low near-bottom current speed) was dominated by P. longirostris, Plesionika martia, Nezumia aequalis and small chondrichthyans (mainly sharks), among others, and displayed low species richness, abundance and biomass. The Stratum 3 assemblage (Huelva Channel > 700 m, sand, low trawling activity and high near-bottom current speed) was dominated by similar species to Stratum 2, but also included large demersal sharks (Centrophorus granulosus, Galeorhinus galeus, Dalatias licha) that resulted in a high biomass. Depth and near-bottom current speed showed strong relationships with the benthic and demersal assemblages in Principal Component Analyses. The occurrence of medium to intense trawling activity in and around some MVs (Habitat 1180, Council Directive 92/43/ECC-Habitats Directive) should imply an effective regulation that allows a balance between sustainable fisheries and habitat conservation.

The Gulf of Cádiz represents an important seepage area with ca. 70 mud volcanoes (MV), of which one third are located in European waters (Spain and Portugal). Previous projects and expeditions resulted on a large amount of information on different aspects of MV of the Moroccan margin, which seem to have a higher seepage activity than those of the Iberian margin. Those studies mainly focused on their geological characteristics, whereas others offered novel information on their associated biota, especially the endosymbiont-bearing invertebrates as well as non-previously described species (Vanreusel et al. 2009). In 2014, the MV of the Spanish margin of the Gulf of Cádiz were included in the Natura 2000 network (Site of Community Importance - SCI "Volcanes de fango del golfo de Cádiz" - ESZZ12002) under the framework of the Life + project INDEMARES. Nowadays, the LIFE IP PAF INTEMARES project represents an opportunity for improving the knowledge on the biodiversity of this SCI.

The Gulf of Cádiz (GoC) represents an area of ecological importance within the northeastern Atlantic Ocean due to the presence of Mediterranean and Atlantic water masses, a heterogeneous seafloor and a biological confluence. Nevertheless, information on the presence of vulnerable deep-sea habitats is still very scarce and it is of importance for further habitat monitoring within the context of the Habitats and Marine Strategy Framework Directives and for improving conservation and resource extraction management. From 2010 to 2012, fluid migration and emission related edifices (e.g., mud volcanoes, diapirs) from the Spanish continental margin of the GoC have been explored using a remotely operated vehicle (ROV; Liropus 2000) and an underwater camera sled (UCS; APHIA 2012) as well as several devices for collecting sediment and fauna. Different vulnerable deep-sea habitats have been observed, including anoxic bottoms with bacterial mats, sea-pen communities, sponge aggregations, antipatharian and gorgonian communities and also cold-water coral banks. Some of these habitats are included in conservation lists of the habitat directive and in international conventions (OSPAR, RAC/SPA), however some of them are located in areas of the GoC that are exposed to intense trawling. The diversity of habitats detected in the Spanish continental margin of the GoC highlights the importance of seepage related edifices as inducers of seabed and habitat heterogeneity in deep-sea areas. En prensa