A 700‐year record on the effects of climate and human impact on the southern cape coast inferred from lake sediments of eilandvlei, wilderness embayment, south africa

Abstract

The southern Cape coast, South Africa, is sensitive to climate fluctuations as it is influenced by different atmospheric and oceanic circulation systems. Palaeoecological evidence of Holocene climate variations in this region is presently limited. Here, we present a lake sediment record spanning approximately the last 670 years from Eilandvlei, a brackish coastal lake situated mid‐way between Cape Town and Port Elizabeth. The results from geochemical and sedimentological analyses point to an increase in minerogenic sediment input from the catchment starting around ad 1400. Changes in the seasonal distribution of rainfall during the Little Ice Age may have altered river discharge and increased erosion rates and fluvial sediment transport in pre‐colonial times. A rising mean lake level, possibly associated with an altered water balance or relative sea‐level rise, may offer an explanation for the deposition of finer sediments. After ad 1450, reduced burial flux of elements associated with autochthonous sediment formation may have resulted from ecological changes in Eilandvlei. Enhanced sedimentation rates, increasing carbon, nitrogen, phosphorous and biogenic silica concentrations, as well as high concentrations of proxies for allochthonous sediment input (e.g. aluminium, titanium, zirconium) point to increasing sediment and nutrient flux into Eilandvlei from the late nineteenth century onwards. The most likely factor involved in these recent changes is land‐use change and other forms of human impact.

Understanding Late Quaternary change at the land–ocean interface: a synthesis of the evolution of the Wilderness coastline, South Africa

“…1). The lakes preserve evidence for past fluctuations in marine influence inundation (Martin, 1968) and more general palaeoenvironmental conditions (Irving,1998;Reinwarth et al, 2013). It is currently unclear whether they persisted when sea-levels were lower or whether they were drained and replaced by river systems at such times.…”

“…Cowell and Thom, 1994). A fuller understanding of sedimentation history within the lakes/back-barrier lagoons is also relevant to ongoing work seeking to use these archives of palaeoenvironmental and palaeoecological change (Reinwarth et al, 2013).…”

Holocene sea level and environmental change at the southern Cape – an 8.5 kyr multi-proxy paleoclimate record from lake Voёlvlei, South Africa

“…Eilandvlei (Kirsten et al, 2018a;Kirsten et al, 2018b;Quick et al, 2018;Reinwarth et al, 2013;Wündsch et al, 2018;Wündsch et al, 2016b), Groenvlei (Martin, 1959(Martin, , 1968Wündsch et al, 2016a) and Swartvlei (Birch et al, 1978;Haberzettl et al, 2019) has yielded multiple paleoenvironmental records (Fig. 1 B).…”

Late Holocene Marine Radiocarbon Reservoir Correction for the Southern and Eastern Coasts of South Africa

“…Kirsten and Meadows, 2012) and sedimentological parameters (e.g. Reinwarth et al 2013) from wetland and lake sediments, as well as novel evidence, including a range of biological and chemical characteristics of rock hyrax middens (e.g. Chase et al, 2013).…”