Anthropogenic processes alter the completeness and resolution of the marine fossil record

The youngest fossil record is an indispensable source of data on long-term human impact on marine ecosystems. However, human actions alter not only marine communities and their habitats but also sedimentary and biotic processes controlling the formation of the stratigraphic archives recording those changes. Based on literature data and our own field studies we provide a conceptual framework for understanding the impact of anthropogenic processes on the completeness and spatiotemporal resolution of the fossil record forming on continental shelves. Such processes are diverse and include, among others, changes in sediment fluxes due to reshaping of alluvial and coastal landscapes, seabed disturbance by bottom trawling and ship traffic, ocean acidification and anoxia, removal of native species, and introduction of invasive ecosystem engineers. These physical, geochemical, and biological disturbances can modify sedimentation rates, depth and intensity of sediment mixing, pore water saturation state, and preservation potential of skeletal remains. The resulting taphonomic and stratigraphic signatures can pinpoint historical changes in ecosystem functioning but can also lead to systematic changes in the quality of the record complicating paleoecological and paleoclimatic reconstructions based on the data from sediment cores and surface death assemblages. We highlight the complex feedbacks between human impacts on the ecosystem processes and their preservation in the marine stratigraphic record and suggest research strategies that can maximize the informative value of the geohistorical data.