Benthic foraminifera and mollusks from La Maddalena Harbour (Sardinia, Italy): A proxy for recent environmental changes

Roberta DESSÌ

Primo

;Riccardo RACIS;Sandro DEMURO;Daniela BASSO;Valentina BRACCHI;Andrea PREDA;Carla BUOSI

Ultimo

2024-01-01

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Abstract

Benthic foraminifera and mollusks are useful tools for palaeoenvironmental reconstructions due to their ubiquitous presence across marine habitats and their sensitivity to environmental changes induced by natural and anthropogenic events. Their community structures offer valuable insights into habitat characteristics, with certain species acting as bio-indicators of specific environmental conditions. This study delves into the micro- (benthic foraminifera) and macropaleontological (mollusks) analysis of a sediment core drilled from the shallow seabed (maximum depth ∼15 m) in the Ex-military arsenal of the La Maddalena harbour located on the southern coast of La Maddalena island (Sardinia, Italy). In this site, a naval arsenal worked for nearly one century with heavy impact on the coastal zone. By examining changes in species composition, abundance, and diversity, the research aims to elucidate the environmental history and ecological trajectory of the marine ecosystem in the area. Through the identification of over 90 species of foraminifera and 101 mollusk species, the study reveals a decline in diversity indices with depth, accompanied by shifts in foraminiferal assemblages indicative of different coastal settings. The most frequent foraminiferal species were Elphidium crispum, Ammonia tepida, Planorbulina mediterranensis and Spiroloculina ornata. These results, supported by statistical analyses, allowed identification of distinct assemblages corresponding to varying marine environments. Similarly, mollusk analysis underscores changes in habitat preferences, reflecting a transition from infralittoral vegetated bottoms to more complex substrates, possibly linked to colonization of the area during the last centuries and harbour renovation activities. Collectively, the integration of mollusk and foraminifera data provides a comprehensive understanding of past environmental dynamics, offering valuable insights into the evolution of marine ecosystems in the La Maddalena harbour.