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Benthic foraminiferal morphological abnormalities Benthic foraminiferal morphological abnormalities from Holocene sediments of the Aegean Sea, from Holocene sediments of the Aegean Sea, Greece: Palaeoenvironmental implications Greece: Palaeoenvironmental implications Dimiza M.D., Koukousioura O., Triantaphyllou M.V. Dimiza M.D., Koukousioura O., Triantaphyllou M.V. University of Athens, Faculty of Geology & Geoenvironment University of Athens, Faculty of Geology & Geoenvironment

Benthic foraminiferal morphological abnormalities from Holocene sediments of the Aegean Sea, Greece: palaeoenvironmental implications

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Page 1: Benthic foraminiferal morphological abnormalities from Holocene sediments of the Aegean Sea, Greece: palaeoenvironmental implications

Benthic foraminiferal morphological abnormalities Benthic foraminiferal morphological abnormalities from Holocene sediments of the Aegean Sea, from Holocene sediments of the Aegean Sea,

Greece: Palaeoenvironmental implicationsGreece: Palaeoenvironmental implications

Dimiza M.D., Koukousioura O., Triantaphyllou M.V. Dimiza M.D., Koukousioura O., Triantaphyllou M.V.

University of Athens, Faculty of Geology & GeoenvironmentUniversity of Athens, Faculty of Geology & Geoenvironment

Page 2: Benthic foraminiferal morphological abnormalities from Holocene sediments of the Aegean Sea, Greece: palaeoenvironmental implications

Morphological abnormalities of recent and fossil benthic foraminiferal tests may be caused by Morphological abnormalities of recent and fossil benthic foraminiferal tests may be caused by environmental stress resulting from anthropogenic pollution and/or natural effects. In the present paper environmental stress resulting from anthropogenic pollution and/or natural effects. In the present paper we document and describe morphological abnormalities of we document and describe morphological abnormalities of Ammonia tepida Ammonia tepida and some additional and some additional foraminiferal species from Holocene sedimentary successions of the Aegean Sea (Alykes Kitros and foraminiferal species from Holocene sedimentary successions of the Aegean Sea (Alykes Kitros and Vravron Attica). The abnormality types are manifested largely by siamese twins, whereas distorted Vravron Attica). The abnormality types are manifested largely by siamese twins, whereas distorted chamber arrangement, overdeveloped or protruding chambers and the presence of multiple apertures chamber arrangement, overdeveloped or protruding chambers and the presence of multiple apertures have also been observed. Our observations on the distribution of abnormal tests in comparison to the have also been observed. Our observations on the distribution of abnormal tests in comparison to the characters of the accompanying fauna suggest that malformation was caused mainly by rapid and characters of the accompanying fauna suggest that malformation was caused mainly by rapid and intense salinity fluctuations.intense salinity fluctuations.

Page 3: Benthic foraminiferal morphological abnormalities from Holocene sediments of the Aegean Sea, Greece: palaeoenvironmental implications
Page 4: Benthic foraminiferal morphological abnormalities from Holocene sediments of the Aegean Sea, Greece: palaeoenvironmental implications
Page 5: Benthic foraminiferal morphological abnormalities from Holocene sediments of the Aegean Sea, Greece: palaeoenvironmental implications

Morphological abnormalities in Morphological abnormalities in the studied specimens were the studied specimens were manifested with certain types as manifested with certain types as siamese twins, distorted chamber siamese twins, distorted chamber arrangement, overdeveloped or arrangement, overdeveloped or protruding chambers and the protruding chambers and the presence of multiple apertures presence of multiple apertures that allow us to characterize that allow us to characterize them as malformed tests. We them as malformed tests. We document morphological document morphological malformation in tests of hyaline malformation in tests of hyaline species (species (A. tepida, Elphidium A. tepida, Elphidium spp., H. germanica, L. lobatulaspp., H. germanica, L. lobatula) ) and of porcellaneous species and of porcellaneous species (miliolids and (miliolids and P. pertususP. pertusus). ).

Page 6: Benthic foraminiferal morphological abnormalities from Holocene sediments of the Aegean Sea, Greece: palaeoenvironmental implications

The interval that bears the abnormal forms in Vravron and Kitros boreholes is The interval that bears the abnormal forms in Vravron and Kitros boreholes is featured by significant changes in the benthic microfauna, supporting featured by significant changes in the benthic microfauna, supporting paleosalinity fluctuations. paleosalinity fluctuations. Rapid and intense salinity changes seem to be responsible for foraminiferal Rapid and intense salinity changes seem to be responsible for foraminiferal assemblages characterized by the presence of malformed tests. assemblages characterized by the presence of malformed tests.

Although most of the studies related to abnormal foraminiferal microfaunas have Although most of the studies related to abnormal foraminiferal microfaunas have been accomplished in recent environments affected by human activity, our been accomplished in recent environments affected by human activity, our results serve as an additional example documenting their presence in the results serve as an additional example documenting their presence in the sediment record, thus correlate them with natural paleoenvironmental changes.sediment record, thus correlate them with natural paleoenvironmental changes.

Page 7: Benthic foraminiferal morphological abnormalities from Holocene sediments of the Aegean Sea, Greece: palaeoenvironmental implications

The interval that bears the abnormal forms in Vravron and Kitros boreholes is The interval that bears the abnormal forms in Vravron and Kitros boreholes is featured by significant changes in the benthic microfauna, supporting featured by significant changes in the benthic microfauna, supporting paleosalinity fluctuations. paleosalinity fluctuations. Rapid and intense salinity changes seem to be responsible for foraminiferal Rapid and intense salinity changes seem to be responsible for foraminiferal assemblages characterized by the presence of malformed tests. assemblages characterized by the presence of malformed tests.

Although most of the studies related to abnormal foraminiferal microfaunas have Although most of the studies related to abnormal foraminiferal microfaunas have been accomplished in recent environments affected by human activity, our been accomplished in recent environments affected by human activity, our results serve as an additional example documenting their presence in the results serve as an additional example documenting their presence in the sediment record, thus correlate them with natural paleoenvironmental changes.sediment record, thus correlate them with natural paleoenvironmental changes.