Foraminiferal assemblages in active volcanic areas: two study cases from Azores Archipelago (Atlantic Ocean) and Pantelleria Island (Mediterranean Sea)

Recent studies demonstrated the capability of foraminifers to adapt to a wide range of environmental conditions and to give a response to environmental stress due to natural or human origin as environmental indicators (Alve, 1991; Hess et al., 2005; Carboni et al., 2009; Schönfeld et al., 2012). This work aims to document the benthic foraminiferal response to natural stressed environments in two areas, Azores Archipelago and Pantelleria Island, interested by similar active volcanism. The Azores area has been affected by a recent volcanic activity occurred in 2001, while the last submarine eruption of Pantelleria Island dates at 1891. The different periods of eruption of the two areas allow to investigate on the way and time of the re-colonisation process by foraminiferal assemblages. Petrographic, sedimentological and microfaunistic analyses were conducted on selected samples in order to obtain an environmental characterisation of the two active volcanic areas. The inorganic fraction o

Recent studies demonstrated the capability of foraminifers to adapt to a wide range of environmental conditions and to give a response to environmental stress due to natural or human origin as environmental indicators (Alve, 1991; Hess et al., 2005; Carboni et al., 2009; Schönfeld et al., 2012). This work aims to document the benthic foraminiferal response to natural stressed environments in two areas, Azores Archipelago and Pantelleria Island, interested by similar active volcanism. The Azores area has been affected by a recent volcanic activity occurred in 2001, while the last submarine eruption of Pantelleria Island dates at 1891. The different periods of eruption of the two areas allow to investigate on the way and time of the re-colonisation process by foraminiferal assemblages. Petrographic, sedimentological and microfaunistic analyses were conducted on selected samples in order to obtain an environmental characterisation of the two active volcanic areas. The inorganic fraction of samples collected in both areas is constituted of blackish, sand-sized glass shards, whereas the organic component is mainly constituted by foraminifers. Faunal composition, diversity and density highlight two different structure of the assemblages relatively to the two areas. In fact the foraminiferal assemblages of the Azores area are dominate by opportunistic species (Angulogerina angulosa) and represent the first stage of re-colonisation after the eruption occurred in 2001, while the associations of Pantelleria Island (Globocassidulina subglobosa, Lenticulina rotulata, Lobatula lobatula and miliolids) have to be considered as an advanced stage of resettlement with stable rich and well diversified assemblages. Moreover, in the Azores area many morphological abnormalities were recognised confirming a more stressed environment than Pantelleria bottom. In both areas a lot of specimens showed test alterations probably due to hydrothermal fluids that lead to the dissolution of calcium carbonate.