AUTHOR=Wiik Emma , Bennion Helen , Sayer Carl D., Davidson Thomas A., Clarke Stewart J., McGowan Suzanne , Prentice Stephen , Simpson Gavin , Stone Laura TITLE=The coming and going of a marl lake: multi-indicator palaeolimnology reveals abrupt ecological change and alternative views of reference conditions JOURNAL=Frontiers in Ecology and Evolution VOLUME=3 YEAR=2015 URL=https://www.frontiersin.org/journals/ecology-and-evolution/articles/10.3389/fevo.2015.00082 DOI=10.3389/fevo.2015.00082 ISSN=2296-701X ABSTRACT=
Eutrophication is the most pressing threat to highly calcareous (marl) lakes in Europe. Despite their unique chemistry and biology, comprehensive studies into their unimpacted conditions and eutrophication responses are underrepresented in conservation literature. A multi-indicator palaeolimnological study spanning ca. 1260–2009 was undertaken at Cunswick Tarn (UK), a small, presently eutrophic marl lake, in order to capture centennial timescales of impact. Specific aims were to (1) establish temporal patterns of change (gradual/abrupt) across biological groups, thereby testing theories of resistance of marl lake benthic communities to enrichment, and (2) compare the core record of reference condition with prevailing descriptions of high ecological status. Analyses of sediment calcium (Ca), phosphorus (P), pigments, diatoms, testate amoebae, cladocerans, and macrofossils, revealed three abrupt changes in ecosystem structure. The first (1900s), with biomass increases in charophytes and other benthic nutrient-poor indicators, supported ideas of resistance to eutrophication in