A melting glacier feeds aquatic and terrestrial invertebrates with ancient carbon and supports early succession

Abstract

ABSTRACTMore than 5000-yr-old organic material was released by a melting glacier in central southern Norway. The ancient carbon was bioavailable and supported early food chains. This was shown through high radiocarbon age in living aquatic and terrestrial invertebrates. Young ponds acted as biological oases, where ancient carbon was assimilated by larvae of various Diptera: mainly Chironomidae, but also Tipulidae and Limoniidae. Within ponds, even predatory diving beetles had a high radiocarbon age. Adult chironomid midges with a radiocarbon age of 1040 yr transported ancient carbon to terrestrial predators among beetles, spiders, and harvestmen. Ancient carbon was also assimilated by chironomid larvae downstream in the glacier-fed river, and radiocarbon dating of chironomid larvae from glacial rivers will thus be an easy way to check whether a given glacier releases bioavailable ancient carbon. Our study indicates that the ancient organic particles were very small. We refer to studies from other countries showing that glaciers collect and release ancient carbon in the form of tiny, long-transported and biodegradable aerosol particles, which stem from the incomplete combustion of radiocarbon-depleted fossil fuels. All our results would fit with this mechanism.