Although the ecological importance, along with economic relevance, upper bathyal seabed habitats are not widely investigated. In this work we propose a case of multidisciplinary study for habitat mapping. Geomorphological investigation using Multibeam, Subbottom CHIRP and 500J Sparker surveys was carried out on shelfbreak sea bottoms located 12 nm offshore San Pietro island (south-western Sardinia). Moreover, the geophysical dataset constituted the base for a Biodiversity ROV survey carried out in Summer 2011, Images collected were analyzed with CPCe software (Coral Point Count with Excel extensions) in order to investigate different species and coverage.. The Sardinian western continental margin is characterized by the setting of high-angle fault system ( Oligo-Miocene ), which borders the Sulcis shelfbreak on southwestern side and gives rise to escarpment and intra-platform basin. On top of the Pliocene sequence, between upper slope and the distal platform, lies the prograding sedimentary prism. The prism is composed by different system tracts characterized by various types of clinoform pattern, laterally associated to four falling-low stand system-tracts related to as many glacio-eustatic oscillations which occurred between Middle Pleistocene and Holocene. The continuity of the prograding sedimentary prism is interrupted only by an undifferentiated tertiary basement outcrop, a tectonically isolated monoclinal “Cuesta” relief where hard bottom anthozoans corals (L. glaberrima) are located. At the base of the isolated relief the seabottom sediment stock is composed of plastic silty.sands and sandy silts with high water content slipping structures and creeps are detectable all over the soft bottom. On the soft bottom different facies of the biocoenosis “detritique du large” (DL) were examinated, recognizing ecologically important species (Isidella elongata,Esper 1788, Leptometra phalangium, Clark 1908 ).
Habitat mapping in upper bathyal seabed: target species in soft sediments (Isidella elongata,Esper 1788) and hard surfaces (Leiopathes glaberrima,Pallas 1766) (SW Sardinian margin – West Mediterranean Sea).
Cau A;FOLLESA, MARIA CRISTINA;ORRU', PAOLO EMANUELE;Deiana G;PALIAGA, ENRICO MARIA
2013-01-01
Abstract
Although the ecological importance, along with economic relevance, upper bathyal seabed habitats are not widely investigated. In this work we propose a case of multidisciplinary study for habitat mapping. Geomorphological investigation using Multibeam, Subbottom CHIRP and 500J Sparker surveys was carried out on shelfbreak sea bottoms located 12 nm offshore San Pietro island (south-western Sardinia). Moreover, the geophysical dataset constituted the base for a Biodiversity ROV survey carried out in Summer 2011, Images collected were analyzed with CPCe software (Coral Point Count with Excel extensions) in order to investigate different species and coverage.. The Sardinian western continental margin is characterized by the setting of high-angle fault system ( Oligo-Miocene ), which borders the Sulcis shelfbreak on southwestern side and gives rise to escarpment and intra-platform basin. On top of the Pliocene sequence, between upper slope and the distal platform, lies the prograding sedimentary prism. The prism is composed by different system tracts characterized by various types of clinoform pattern, laterally associated to four falling-low stand system-tracts related to as many glacio-eustatic oscillations which occurred between Middle Pleistocene and Holocene. The continuity of the prograding sedimentary prism is interrupted only by an undifferentiated tertiary basement outcrop, a tectonically isolated monoclinal “Cuesta” relief where hard bottom anthozoans corals (L. glaberrima) are located. At the base of the isolated relief the seabottom sediment stock is composed of plastic silty.sands and sandy silts with high water content slipping structures and creeps are detectable all over the soft bottom. On the soft bottom different facies of the biocoenosis “detritique du large” (DL) were examinated, recognizing ecologically important species (Isidella elongata,Esper 1788, Leptometra phalangium, Clark 1908 ).
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