Microbiotic signatures of the Anthropocene in marginal marine and freshwater palaeoenvironments

Abstract

The term 'Anthropocene' has been proposed to indicate a geological interval characterized by global anthropogenic environmental change. This paper attempts to recognize a method by which the Anthropocene can be defined micropalaeontologically. In order to do this, microfloras and microfaunas (diatoms, macrophytes, dinoflagellate cysts, foraminifera and ostracods) from nearshore waters through to paralic and freshwater aquatic milieux are considered, and biotic variability with an anthropogenic causation identified. Microbiotic change can be related to anthropogenically induced extinctions, pollution-related mutation, environmentally influenced assemblage variability, geochemistry of carapaces/tests, floral change related to lacustrine acidification, faunal and floral correlation to industrial and agricultural signatures and introduction of exotic species via shipping. The influence of humanity on a local scale can be recognized in assemblages as far back as 5000 years BP. However, widespread anthropogenic change took place in Europe and America, particularly in the nineteenth and twentieth centuries, although in Asia (e.g. Japan) it cannot be observed prior to the twentieth century. Profound and global biotic change began in the midtwentieth century and, if the Anthropocene is to be defined in this way, then the period 1940-1945 might encompass the biotic base of the interval.

A stratigraphical basis for the Anthropocene?

“…2). Similarly, changes to land use and land cover, and the resultant increase in soil erosion and transport of sediment into the near-shore setting, result in changes to foraminiferal assemblages considerably earlier than other environmental drivers (Wilkinson et al 2014). The impact of humans on coral reefs was minimal during the early Holocene, with first evidence of decreasing ecological diversity of the large marine herbivores and carnivores beginning around 3.5 ka BP (HoeghGuldberg 2014) (Fig.…”

“…210 Pb may also be useful for dating microfauna and microflora (Wilkinson et al 2014), marine or lacustrine clay sediments and peats. In the more distant future, dating techniques may rely upon more long-lived isotopes, such as 239 Pu and 240 Pu (Table 1), which also bind strongly to soil and sediment particles (Hancock et al 2014).…”

“…Biostratigraphical zones used to recognize chronostratigraphical boundaries are diachronous to some degree as new taxa take time to extend their distribution from a single source origination (Barnosky 2013). Furthermore, there appears to be a time-lag between the onset of anthropogenic activity and the resultant influence upon microbiota (Wilkinson et al 2014). With a deep-time perspective, these diachroneity and time-lag effects fall within the range of error of most radiometric and biostratigraphic dating techniques, and are not considered significant.…”

“…Human impacts on diatom assemblages in lakes, the product of eutrophication and/or alkalization linked to deforestation and introduction of agriculture, extend back at least 5 kyr (Wilkinson et al 2014) (Fig. 2).…”

The Apocalyptic Anthropocene Epoch and Its Management in India.

“…Early human impacts on the land use and land cover started from the great warm period, 3000 years BP (Barnosky, 2008 [24] , Ellis et al 2011Ellis et al , 2012Ellis et al , 2013Ellis et al , 2014 and Wilkinson et al 2014) [29] .Many terrestrial biotic and marine micro biotic changes altered the CO 2 levels due to socio political developments, conversion from hunting to agriculture. continuous formations in the Himalayan range of mountains, undermining of the river Saraswati, desertification of Thar in India, decline of the ancient civilizations, the Mohenjo-Daro and the Harappa are the artifacts of formation of the new epoch.…”