Benthic foraminifera as indicators of tsunami and extreme-wave sediment transport on Mediterranean rocky coasts: Evidence from Menorca Island

The transport and deposition of overwash sands on the rocky shores of Menorca Island (Balearic Islands, Spain) were investigated to evaluate the effects of extreme wave events, including tsunamis and storms. Samples were collected from sands interspersed between boulders at two sectors: Punta Nati (NW) and Sant Esteve (SE). Benthic foraminiferal analyses and bathymetric reconstructions indicate that the sands originated from inner-shelf environments at water depths ranging from 14 to 31 m. The dominance of epiphytic benthic foraminifera (>98%) suggests transport from vegetated substrates, most likely Posidonia oceanica meadows, whose present-day depth range coincides with the inferred source depths. Differences in epiphytic morphotype distribution and planktic/benthic (P/B) ratios indicate sector-specific transport energy. The SE sector exhibits higher abundances of robust morphotype A* ( Miniacina miniacea , Nubecularia lucifuga ), lower diversity, and reduced P/B ratios, reflecting transport under higher-energy wave conditions. In contrast, the NW sector shows lower A* abundances, higher diversity, and higher P/B ratios, consistent with lower-energy transport. Depth of Closure analyses confirm that extreme waves are capable of mobilizing sediments from source depths in both sectors, however wave energy is greater in the SE sector. Combined with geomorphological and numerical modeling evidence, results suggest that tsunamis primarily impacted the SE sector, while local events may have influenced the NW sector. This study demonstrates that both tsunamis and extreme waves contributed to overwash sand deposition, with sector-specific forcing controlling the severity of impact. The integrated benthic foraminiferal and paleobathymetric approach provides a robust framework for identifying sediment sources and evaluating past coastal hazards in Mediterranean environments.