A 1100-year multi-proxy palaeoenvironmental record from Lake Höglwörth, Bavaria, Germany

Anthropogenic activities have exerted strong influence on ecosystems worldwide, particularly since 1950 CE. The local impact of past human activities often started much earlier and deserves detailed study. Here, we present an environmental record from a 278 cm long sedimentary core from Lake Höglwörth (Bavaria, Germany). Sedimentological and geochemical parameters indicate that the organic-rich bottom sediments of the record consist of peat that formed prior to inline-formula $M1inlinescrollmathml{\mathrm{normal\; 870}}_{-\mathrm{normal\; 160}}^{+\mathrm{normal\; 140}}$ 39pt17ptsvg-formulamathimg82944dc0b29bd4229010117534751a7a egqsj-72-219-2023-ie00001.svg39pt17ptegqsj-72-219-2023-ie00001.png  CE, when lake sediments started to accumulate. After inline-formula $M2inlinescrollmathml{\mathrm{normal\; 870}}_{-\mathrm{normal\; 160}}^{+\mathrm{normal\; 140}}$ 39pt17ptsvg-formulamathimgf27da962661dbefe38095b9143ff3f8f egqsj-72-219-2023-ie00002.svg39pt17ptegqsj-72-219-2023-ie00002.png  CE, distinct shifts in lithology, elemental composition, and the biological record are visible and are interpreted to result from the construction of a monastery on the lake peninsula in 1125 CE and/or the damming of the lake. From inline-formula1120±120 to inline-formula $M4inlinescrollmathml{\mathrm{normal\; 1240}}_{-\mathrm{normal\; 120}}^{+\mathrm{normal\; 110}}$ 45pt17ptsvg-formulamathimg1f0a22960501e0f2fcf022ab05d541a2 egqsj-72-219-2023-ie00003.svg45pt17ptegqsj-72-219-2023-ie00003.png  CE, the lake environment was relatively stable. This period was followed by enhanced deforestation that led to a more open landscape and soil erosion, visible in increased allochthonous input from inline-formula $M5inlinescrollmathml{\mathrm{normal\; 1240}}_{-\mathrm{normal\; 120}}^{+\mathrm{normal\; 110}}$ 45pt17ptsvg-formulamathimg0864c09116df22be3e6e3052404dfadd egqsj-72-219-2023-ie00004.svg45pt17ptegqsj-72-219-2023-ie00004.png to inline-formula $M6inlinescrollmathml{\mathrm{normal\; 1380}}_{-\mathrm{normal\; 110}}^{+\mathrm{normal\; 90}}$ 45pt17ptsvg-formulamathimgd8ba1a1009a04f576c1ccaa884746c17 egqsj-72-219-2023-ie00005.svg45pt17ptegqsj-72-219-2023-ie00005.png  CE. This was accompanied by high aquatic productivity and bottom or interstitial water anoxia from inline-formula $M7inlinescrollmathml{\mathrm{normal\; 1310}}_{-\mathrm{normal\; 120}}^{+\mathrm{normal\; 100}}$ 45pt17ptsvg-formulamathimg932f124d529599d28f7f6fbd431b8011 egqsj-72-219-2023-ie00006.svg45pt17ptegqsj-72-219-2023-ie00006.png to inline-formula $M8inlinescrollmathml{\mathrm{normal\; 1470}}_{-\mathrm{normal\; 100}}^{+\mathrm{normal\; 90}}$ 45pt17ptsvg-formulamathimg6413ee01c35affec33c38d03ce32cf9d egqsj-72-219-2023-ie00007.svg45pt17ptegqsj-72-219-2023-ie00007.png  CE, possibly triggered by increased nutrient availability. Enhanced allochthonous input and a substantial shift in the aquatic community can be assigned to the construction of a flour mill and related rerouting of a small creek in 1701 CE. High aquatic productivity and bottom or interstitial water anoxia after inline-formula1960±10 CE correspond to recent eutrophication resulting from accelerated local anthropogenic activities. The sedimentary record from Lake Höglwörth exemplarily demonstrates that anthropogenic activities have had substantial environmental impacts on aquatic environments during the past millennium.