species” by the Scientific Advisory Committee of the General Fisheries Commission
for the Mediterranean (General Fisheries Commission for the Mediterranean. 2009).
9.7.3 Cold Seeps
Cold seeps are outstanding components of some slope areas of the Alboran Sea and
even more so in the adjacent Gulf of Cádiz, where they are more widespread and
diverse due to the geological past and wide availability of fluid-enriched sediments
(Vanreusel et al. 2009). In the Alboran Sea, cold seeps are mainly represented by
mud volcanoes (seafloor edifices formed by mud and fluid extrusion) and pockmarks
(seafloor depressions formed by fluid extrusion and further seafloor collapse)
(Comas et al. 2003; Sautkin et al. 2003). These cold seeps are mostly located in
the West Alboran Basin between 350 and 1600 m depth. Most studies have been
performed on specific mud volcanoes (e.g. Perejil, Kalinin) and pockmarks
(e.g. Crow’s foot pockmark field) of the southern field on the Moroccan margin
(Comas et al. 2003; Hilário et al. 2011; Rodrigues et al. 2011; López-Rodríguez et al.
2014). Cold seep communities of the Alboran Sea have been poorly studied in
comparison to those of the Gulf of Cádiz or the western Mediterranean Sea, and
the available information is only based on the presence of some chemosymbiotic
species. Initially, Comas et al. (2003) detected chemosynthetic communities with
“pogonophorans” (now considered siboglinid polychaetes) in Kalinin mud volcano,
beneath few centimetres of pelagic drape. Later on, Hilário et al. (2011) collected
four fragments of stiff-walled tubeworms in a cluster of NE–SW pockmarks, named
“Crow’s foot” pockmarks. One of them contained the anterior part of a vestimentiferan or siboglinid tubeworm that was assigned to the genus Lamellibrachia. This
represented the first record of a vestimentiferan polychaete in the western Mediterranean and indicated some fluid venting activity in these pockmarks because
Lamellibrachia is typically associated with the presence of carbonates and sulphide
at the sediment surface. Furthermore, Rodrigues et al. (2011) indicated the occurrence of two chemosymbiotic bivalves (Myrtea sp., Lucinoma sp.) and two
siboglinids (Lamellibrachia sp., Siboglinum sp.) in cold seeps of the Alboran Sea.
López-Rodríguez et al. (2014) also found bivalves of the genus Acharax at ca. 10 cm
depth in the mud breccia of the flank of Perejil mud volcano, where methane bubbles
were also detected as well as abundant vestimentiferan tubeworms at the top.
Together with the preliminary characterization of the chemosymbiotic communities,
different studies on the micro-paleontological communities (mainly foraminifera) of
these mud volcanoes have been done for characterizing and dating the mud breccia
sediments (Sautkin et al. 2003; Gennari et al. 2013). The presence of
chemosymbiotic fauna on some mud volcanoes (e.g. Perejil, Kalinin) indicates
that current methane/hydrocarbon seeping in some of them still occurs (Hilário
et al. 2011). Nevertheless, the majority of the Alboran Sea mud volcanoes seem to
be inactive or maybe just dormant, so it is very unlikely that chemosynthesis-based
communities will develop on them (Comas et al. 2010).
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J. L. Rueda et al.
for the Mediterranean (General Fisheries Commission for the Mediterranean. 2009).
9.7.3 Cold Seeps
Cold seeps are outstanding components of some slope areas of the Alboran Sea and
even more so in the adjacent Gulf of Cádiz, where they are more widespread and
diverse due to the geological past and wide availability of fluid-enriched sediments
(Vanreusel et al. 2009). In the Alboran Sea, cold seeps are mainly represented by
mud volcanoes (seafloor edifices formed by mud and fluid extrusion) and pockmarks
(seafloor depressions formed by fluid extrusion and further seafloor collapse)
(Comas et al. 2003; Sautkin et al. 2003). These cold seeps are mostly located in
the West Alboran Basin between 350 and 1600 m depth. Most studies have been
performed on specific mud volcanoes (e.g. Perejil, Kalinin) and pockmarks
(e.g. Crow’s foot pockmark field) of the southern field on the Moroccan margin
(Comas et al. 2003; Hilário et al. 2011; Rodrigues et al. 2011; López-Rodríguez et al.
2014). Cold seep communities of the Alboran Sea have been poorly studied in
comparison to those of the Gulf of Cádiz or the western Mediterranean Sea, and
the available information is only based on the presence of some chemosymbiotic
species. Initially, Comas et al. (2003) detected chemosynthetic communities with
“pogonophorans” (now considered siboglinid polychaetes) in Kalinin mud volcano,
beneath few centimetres of pelagic drape. Later on, Hilário et al. (2011) collected
four fragments of stiff-walled tubeworms in a cluster of NE–SW pockmarks, named
“Crow’s foot” pockmarks. One of them contained the anterior part of a vestimentiferan or siboglinid tubeworm that was assigned to the genus Lamellibrachia. This
represented the first record of a vestimentiferan polychaete in the western Mediterranean and indicated some fluid venting activity in these pockmarks because
Lamellibrachia is typically associated with the presence of carbonates and sulphide
at the sediment surface. Furthermore, Rodrigues et al. (2011) indicated the occurrence of two chemosymbiotic bivalves (Myrtea sp., Lucinoma sp.) and two
siboglinids (Lamellibrachia sp., Siboglinum sp.) in cold seeps of the Alboran Sea.
López-Rodríguez et al. (2014) also found bivalves of the genus Acharax at ca. 10 cm
depth in the mud breccia of the flank of Perejil mud volcano, where methane bubbles
were also detected as well as abundant vestimentiferan tubeworms at the top.
Together with the preliminary characterization of the chemosymbiotic communities,
different studies on the micro-paleontological communities (mainly foraminifera) of
these mud volcanoes have been done for characterizing and dating the mud breccia
sediments (Sautkin et al. 2003; Gennari et al. 2013). The presence of
chemosymbiotic fauna on some mud volcanoes (e.g. Perejil, Kalinin) indicates
that current methane/hydrocarbon seeping in some of them still occurs (Hilário
et al. 2011). Nevertheless, the majority of the Alboran Sea mud volcanoes seem to
be inactive or maybe just dormant, so it is very unlikely that chemosynthesis-based
communities will develop on them (Comas et al. 2010).
342
J. L. Rueda et al.