Recent ecological change in ancient lakes

Abstract

Ancient lakes are among the best archivists of past environmental change, having experienced more than one full glacial cycle, a wide range of climatic conditions, tectonic events, and long association with human settlements. These lakes not only record long histories of environmental variation and human activity in their sediments, but also harbor very high levels of biodiversity and endemism. Yet, ancient lakes are faced with a familiar suite of anthropogenic threats, which may degrade the unusual properties that make them especially valuable to science and society. In all ancient lakes for which data exist, significant warming of surface waters has occurred, with a broad range of consequences. Eutrophication threatens both native species assemblages and regional economies reliant on clean surface water, fisheries, and tourism. Where sewage contributes nutrients and heavy metals, one can anticipate the occurrence of less understood emerging contaminants, such as pharmaceuticals, personal care products, and microplastics that negatively affect lake biota and water quality. Human populations continue to increase in most of the ancient lakes’ watersheds, which will exacerbate these concerns. Further, human alterations of hydrology, including those produced through climate change, have altered lake levels. Co‐occurring with these impacts have been intentional and unintentional species introductions, altering biodiversity. Given that the distinctive character of each ancient lake is strongly linked to age, there may be few options to remediate losses of species or other ecosystem damage associated with modern ecological change, heightening the imperative for understanding these systems.

Ecological Connectivity in Two Ancient Lakes: Impact Upon Planktonic Cyanobacteria and Water Quality

“…The lakes Mikri Prespa and Megali Prespa are of two the oldest lakes on earth, both with an estimated age of 2-5 million years [19]. These two lakes are European endangered monuments hosting high richness of endemic and internationally important endangered species.…”

Impacts of increasing nitrogen:phosphorus ratios on zooplankton community composition and whitefish (Coregonus macrophthalmus) growth in a pre‐alpine lake

“…Therefore, an additional N load would not necessarily be considered to have observable and evident effects on a P-limited lake food web. Recently, N loadings into lakes by groundwater fluxes or airborne wet deposition are increasing on a global scale (Galloway et al, 1995;Hampton et al, 2018;Vitousek, Mooney, Lubchenco, & Melillo, 1997). Phytoplankton growth is, apart from physical (light, temperature, others) and chemical factors (e.g.…”

“…carbon, macroand micronutrients; Lampert & Sommer, 2007), also dependent on the ratio in which nutrients are supplied (Rhee, 1978). Recently, N loadings into lakes by groundwater fluxes or airborne wet deposition are increasing on a global scale (Galloway et al, 1995;Hampton et al, 2018;Vitousek, Mooney, Lubchenco, & Melillo, 1997). However, in European pre-alpine lakes at the same time P depositions are decreasing as a result of effective re-oligotrophication programs (Gerdeaux, Anneville, & Hefti, 2006;Jeppesen et al, 2005).…”

Diatoms diversify and turn over faster in freshwater than marine environments*

“…; Hampton et al. ). The majority of freshwater lakes are geologically recent and have relatively short lifespans, so freshwater planktonic lineages might turn over faster relative to the marine planktonic lineages from environments that have existed continuously since the formation of the oceans.…”

“…First, the age and longevity of most freshwater lakes supporting planktonic communities are linked to Earth's glaciation cycles, with only a few dozen long-lived tectonic basins whose formation predates the last interglacial (ca. 130-115 thousand years ago; Mackay et al 2010;Hampton et al 2018). The majority of freshwater lakes are geologically recent and have relatively short lifespans, so freshwater planktonic lineages might turn over faster relative to the marine planktonic lineages from environments that have existed continuously since the formation of the oceans.…”