The criterion was evaluated as a spatial extent of permanent alteration of hydrographical conditions (changes in wave action) to the seabed and water column, associated in particular with physical loss of the natural seabed as per Decision 2017/848/ЕU. In compliance with Directive 2017/845/ЕC and Decision 2017/848/ЕU the changes in hydrographical conditions were assessed using newly developed methodology and indicator, which are based on comparison of pressures on the marine environment estimated for a selected reference period (reflecting the earliest available shore state unaffected by human interference) with that of the reporting period 2012-2017. As a reference year was adopted 1983, while evaluation periods are 1983-2017 and 2012-2017. The assessment outcome contributes to assessment of D7C2.

Spatial extent of each benthic habitat type adversely affected (physical and hydrographical characteristics and associated biological communities) due to permanent alteration of hydrographical conditions. Threshold values for adverse effects: EQR M-AMBI(n) ≥ 0.68 Extent threshold not required. The outcomes of assessment of criterion D7C2 (an estimate of the extent of adverse effect per habitat type in each assessment area) contribute to the assessment of criterion D6C5.

The spatial extent of macroalgal and seagrass habitats adversely affected (physical and hydrographical characteristics and associated biological communities) due to permanent alteration of hydrographical conditions.