Chemical and biological trends during lake evolution in recently deglaciated terrain

Abstract

As newly formed landscapes evolve, physical and biological changes occur that are collectively known as primary succession. Although succession is a fundamental concept in ecology, it is poorly understood in the context of aquatic environments. The prevailing view is that lakes become more enriched in nutrients as they age, leading to increased biological production. Here we report the opposite pattern of lake development, observed from the water chemistry of lakes that formed at various times within the past 10,000 years during glacial retreat at Glacier Bay, Alaska. The lakes have grown more dilute and acidic with time, accumulated dissolved organic carbon and undergone a transient rise in nitrogen concentration, all as a result of successional changes in surrounding vegetation and soils. Similar trends are evident from fossil diatom stratigraphy of lake sediment cores. These results demonstrate a tight hydrologic coupling between terrestrial and aquatic environments during the colonization of newly deglaciated landscapes, and provide a conceptual basis for mechanisms of primary succession in boreal lake ecosystems.

Eutrophication of freshwater and marine ecosystems

“…However, recent evidence suggests that this classical pattern of succession from oligotrophic (nutrient-poor) to eutrophic (nutrient-rich) conditions is not necessarily followed in lake basins that are unaffected by human activity. For example, a study of chemical and biological trends in 33 lakes formed after landscape deglaciation in Glacier Bay National Park (Alaska) revealed an opposite trend: these relatively recent lakes grew more dilute and less productive during the past 10,000 yr (Engstrom et al 2000).…”

Postglacial vegetation and climate dynamics in the Seymour‐Belize Inlet Complex, central coastal British Columbia, Canada: palynological evidence from Tiny Lake

“…Hutchinson et al, 2004). The other dates obtained from the Tiny Lake core have probably not been affected by the incorporation of old carbon because this effect becomes negligible approximately 1000 a following lake inception as forest and soil development reduce the exposure and weathering rates of tills (Engstrom et al, 2000;Hutchinson et al, 2004). …”

Major flood disturbance alters river ecosystem evolution

“…facilitation, inhibition, dispersal) and/or abiotic (e.g. temperature, moisture, pH) processes 8 . While glacier retreat driven by climate warming is clearly a strong driver of ecological succession 9 , predicted changes in precipitation can be expected to introduce more stochastic events into flow regimes, the effects of which will be harder to predict.…”