III International Conference on Island Evolution, Ecology and Conservation - La Réunion 8-13 JulyPrevious studies on lacustrine sedimentary sequences in the Azores show that climate variability
and vulcanism along with the arrival of humans played a signi#12;cant role in the recent development of
these insular Azorean ecosystems. However, the timing and rate of anthropogenic impacts on these
lakes is poorly constrained. Paleoecological research allows us to reconstruct ecological conditions prior
to and after human settlement, thereby contributing to our understanding of how species and island
ecosystems responded to both natural and anthropogenic disturbances. To assess both types of impacts
over the last 1000 years, we analysed the elemental geochemistry on bulk organic matter, diatoms, and
chironomid remains in a 994 cm-long sediment core recovered from Lake Funda (Flores Island, Azores)
in 2017. Preliminary results from Lake Funda show that human colonization was the main driver
of ecological changes. We identi#12;ed three major ecological phases: (1) 950-1350 yr AD, a pristine
lake ecosystem with mesotrophic diatom taxa, including benthic and tychoplanktonic life-forms, and
free-living chironomids species representing an undisturbed environment; 2) 1350-1450 yr AD, the release
of cattle and gradual forest clearance lead to an increase in nutrient inputs and the start of the
human-impacted phase; and, (3) after Portuguese settlement, from 1450 yr AD to present, a second
human-impacted phase resulted in lake eutrophication and the development of an anoxic hypolimnion
due to an increase of nutrient loading. The #12;rst anthropogenic phase resulted in a drastic 50% decline of
the overall biodiversity with a shift to planktonic diatom species and free-living chironomids, while the
second was characterised by a substantial reduction in the density of chironomids and diatom assemblage
shifts towards the dominance of Aulacoseira granulata and A. ambigua suggesting a shift in lake
trophy. Other external drivers like major climate oscillations likely play a role within these phases as
well. Our study demonstrates the sensitivity of aquatic ecosystems in remote islands to anthropogenic
impacts that have the ability to overtake natural forces of variability (i.e., climate).This research is funded by FCT (SFRH/BPD/99461/2014), and through the funded research projects PaleoNAO(CGL2010-15767), RapidNAO (CGL2013-40608-R), PaleoModes (CGL2016-75281-C2), DISCOVERA-ZORES (PTDC/CTA-AMB/28511/2017) and the Luso-America
