Assessing biotic response to anthropogenic forcing using mollusc assemblages from the Po–Adriatic System (Italy)

Abstract

Preserving adaptive capacities of coastal ecosystems in the Anthropocene requires an understanding of their natural variability prior to modern times. We quantified responses of nearshore molluscs assemblages to past environmental changes using 101 samples (∼57300 specimens) retrieved from the subsurface Holocene succession and present-day seabed of the Po-Adriatic System (Italy). Present-day assemblages shifted in their faunal composition with respect to their mid-late Holocene counterparts. Major differences are observed in lower nearshore settings, where present-day samples show higher heterogeneity, reduced standardised richness, reduced relative abundance of Lentidium mediterraneum , and increased relative abundance of Varicorbula gibba , scavengers (genus Tritia ), and deposit feeders (nuculid bivalves). A dominance of infaunal opportunistic species and shifts towards detritus-feeding and scavenging are often associated with disturbed benthic habitats. Our results suggest that the ongoing anthropogenic stressors (mainly bottom trawling and non-native species) are currently shifting benthic communities into novel states outside the range of natural variability archived in the fossil record. Supplementary material at https://doi.org/10.6084/m9.figshare.c.6351348

A sea of change: Tracing parasitic dynamics through the past millennia in the northern Adriatic, Italy

“…host and parasite biodiversity (Wood et al, 2018). Our findings are consistent with other studies that show a decrease in the equitability of C. gallina-dominated communities and a reduction of the targeted bivalve over time in the Adriatic Sea (Scarponi et al, 2023;Carlucci et al, 2024), raising concern about the nearfuture status of C. gallina.…”

Marine conservation palaeobiology: What does the late Quaternary fossil record tell us about modern-day extinctions and biodiversity threats?

“…Similarly, sedimentary cores from the coastal Adriatic habitats indicated that shifts in mollusc communities during the ice ages over the last 125,000 years were much less dramatic than changes in relative species abundance that took place in the last centuries (Kowalewski et al, 2015). These data also demonstrated that those mollusc communities were spectacularly resilient to major climate and sea-level changes in the late Quaternary (Kowalewski et al 2015;Scarponi et al, 2022) but not to late Holocene human impacts (Scarponi et al, 2023). These examples highlight the unique value of geohistorical estimates in assessing if a given human-induced ecosystem shift is a truly significant event or falls within the natural range of long-term ecosystem variability.…”

“…See Supplementary Material for additional information. Cybulski et al, 2020;Dillon et al, 2021;Hong et al, 2021;Rivadeneira and Nielsen, 2022;Meadows et al, 2023;Scarponi et al, 2023) ecosystems. The above citations are only a fraction of novel studies aimed at establishing pre-Anthropocene baselines or improving the management and restoration of natural habitats by employing geohistorical data.…”

A natural history of networks: Modeling higher-order interactions in geohistorical data

“…Exploring various time scales to reveal finer or coarser partitions allows connecting time scales of the dynamics to the structural scales present in the network (Lambiotte et al 2014). Recently, varying Markov time models were used to explore larger-scale modular patterns of the Holocene succession and present-day nearshore seabed of the Adriatic Sea (Scarponi et al 2022). In networks representing the deep-time fossil record, the specific relationship between the Markov time and time scales of the evolution of the Earth-Life system has not been explored.…”