Changes in coastal ecosystems affected by overburden dumping from amber open-cut mining on the Sambia Peninsula (Baltic Sea)

The Sambia Peninsula (Kaliningrad region) is historically well known for its amber mining. The 2019 year was the last year of direct overburden disposal into the Baltic Sea as a part of technological amber mining process. The extremely high-suspended particulate matter concentrations during that disposal were recorded immediately after the discharge of significant volumes of pulp and reached 200 mg/L. The impact of pulp discharge had sequentially suppressed plankton communities development due to the high content of suspended solids and afterwards stimulated plankton development due to the glauconite infusion. Cladocera were the most sensitive group to the effects of suspended matter. According to the preliminary forecast, when the pulp discharge stops, the restoration of plankton communities may take from 1 to 2 seasons to 1 year for different groups. This is due to the timing of the removal of fine suspended particulate matter from sediments and the possibility of secondary entry during resuspension. •Amber open-pit mining causes suspended particulate matter concentration rise in discharge area to extreme level >100 mg/L.•Extreme suspended matter concentrations affect benthos communities negatively in a broader way than plankton communities.•Long-term effect on benthos is more severe, while plankton may benefit from glauconite from overburden discharge.