Changes in Planktivory and Herbivory Regimes in a Shallow South American Lake (Lake Blanca Chica, Argentina) Over the Last 250 Years

CARROZZO, DAVID; MUSAZZI, SIMONA; LAMI, ANDREA; CÓRDOBA, FRANCISCO E.; GONZÁLEZ SAGRARIO, MARÍA DE LOS ÁNGELES

Water

MDPI

Lugar: Basel; Año: 2020 vol. 12

Shallow lakes arevulnerable ecosystems impacted by human activities and climate change. The Cladoceraoccupya central role in food webs and are an excellent paleoecologicalindicator offood web structure and trophic status. We conducted a paleolimnological studyin Lake Blanca Chica (Argentina) to detect changes on the planktivory andherbivory regimes over the last 250 years. Generalized additive models werefitted to the time series of fish predation indicators (ephippial abundance andsize, mucrone size, fish scales, and the planktivory index) and pheophorbidea concentration. The cladoceranassemblage changed from littoral-benthic to pelagic species dominance andzooplankton switched from large-bodied (Daphnia)to small-bodied grazers (Bosmina) ca.1900 due to increasedpredation. The shift in planktivory regime (ca. 1920?1930),indicated by fish scales and the planktivory index, as well as herbivory (ca.1920?1950), was triggeredbyeutrophication.Changes in planktivory affected thesize structure of Bosmina, reducingits body size. This study describesthe baseline for the lake as well as theprofound changes in the composition and size structure of the zooplanktoncommunity due to increased predation and the shiftin the planktivory regime.These findings will providea reference status for future management strategiesof this ecosystem.