The planktonic foraminiferal species Globorotalia truncatulinoides is widely used as a biostratigraphic proxy for the Quaternary in the Mediterranean region. High-resolution quantitative studies performed on sediment cores collected in the central and western Mediterranean Sea evidence a significant abundance of G. truncatulinoides during the Middle Holocene. The robust chronological frame allows us to date this bio-event to 4.8–4.4 ka Before Present (BP), very close to the base of the Meghalayan stage (4.2 ka BP). As a consequence, we propose that G. truncatulinoides can be considered a potential marker for the Middle–Late Holocene chronological subdivision. G. truncatulinoides is a deep-dwelling planktonic foraminifer and their distributional pattern in the central and western Mediterranean Sea provides a tool to monitor the onset of the regional deep vertical mixing of the water column. During the Holocene, the significant increase in the abundance of this species is in phase with the end of African Humid Period, which marks the transition from a more humid climate to the present-day semi-arid climate.
28 December 2024 in Communications Earth & Environment
One debated scenario for the termination of the Messinian salinity crisis 5.33 million years ago is cataclysmic refilling of the Mediterranean Sea through the Zanclean megaflood. Here we present a clear line of onshore-to-offshore evidence for this megaflood spilling over a shallow-water marine corridor in south-east Sicily into the nearby subaqueous Noto Canyon: (i) >300 asymmetric and streamlined erosional ridges aligned with the megaflood direction, (ii) poorly-sorted breccia deposited between the Messinian and Lower Zanclean Trubi Formations, (iii) soft-sediment deformation structures and clastic injections in the breccia and underlying units, and (iv) a 20 kilometre wide erosional shelf channel connecting the ridges with Noto Canyon. Numerical modelling results support the modulation of flow velocity and direction by the excavation of the channel and Noto Canyon. Our findings demonstrate that the Messinian salinity crisis was terminated through a cataclysmic flood, which implies pronounced Mediterranean sea-level drawdown prior to the flooding.
Amphistegina lobifera, a symbiont-bearing benthic foraminifera native to the Indo-Pacific, is expanding its distribution range in the Mediterranean Sea due to ysian migration through the Suez Canal. This study investigates the colonization dynamics and ecological impact of A. lobifera on Pantelleria Island, which is located in the Central Mediterranean. Nine samples were collected from various substrates at different depths (−4 to −20 m) and analysed for composition, abundance, and ecological diversity. Results reveal a significant dominance of A. lobifera, especially in shallow unvegetated substrates, with relative abundances exceeding 50%. Conversely, more vegetated substrates host more diverse and balanced assemblages. Diversity indices are consistently lower where A. lobifera is dominant, indicating reduced biodiversity. Comparison with similar studies in Malta, Linosa, and Corfu confirms a 20% relative abundance threshold for A. lobifera as indicative of potential ecological imbalance. The results suggest that it represents a growing threat to native microbenthic biodiversity and reinforce its usefulness as a bioindicator species. Pantelleria represents a key transition zone for monitoring the dynamics of invasive species in the Mediterranean, and this study highlights the urgent need for long-term surveillance of benthic biodiversity.
Amphistegina lobifera, a symbiont-bearing benthic foraminifera native to the Indo-Pacific, is ex-panding its distribution range in the Mediterranean Sea due to Lessepsian migration through the Suez Canal. This study investigates the colonization dynamics and ecological impact of A. lobifera on Pantelleria’ island, located in the central Mediterranean. Nine samples were collected from various substrates at different depths (-4 to –20 m) and analysed for composition, abundance, and ecological diversity. Results reveal a significant dominance of A. lobifera, especially in shallow un-vegetated substrates, with relative abundances exceeding 50%. Conversely, more vegetated sub-strates host more diverse and balanced assemblages. Diversity indexes are consistently lower where A. lobifera is dominant, indicating reduced biodiversity. Comparison with similar studies in Malta, Linosa, and Corfu confirms a 20% relative abundance threshold for A. lobifera as indicative of potential ecological imbalance. The results suggest that it represents a growing threat to native microbenthic biodiversity and reinforce its usefulness as a bioindicator species. Pantelleria represents a key transition zone for monitoring the dynamics of invasive species in the Mediterranean, and this study highlights the urgent need for long-term surveillance of benthic biodiversity.