Hydromorphological assessment of Polish lakes: Elaborating the Lake Habitat Survey for Polish Lakes (LHS_PL) method and determining ecologically based boundary values for lake classification.

The Lake Habitat Survey for Polish Lakes (LHS_PL) is a method for the hydromorphological investigation of lakes employed for the assessment of the ecological status of surface water bodies in Poland. It was developed based on the British Lake Habitat Survey method. In 2015, after almost a decade of work on the adaptation, the LHS method was finally adjusted to Polish conditions, and since 2016, it has been implemented in the State Environmental Monitoring programme. This paper presents the assumptions and evolution of the method and the approach for determining boundary values for the high/good (H/G) and good/less than good (G/LTG) ecological status classes. The method involves the assessment of the morphological features of the lake and anthropogenic pressures at 10 observation plots as well as the analysis of hydrological alterations and anthropogenic activities within the lake basin and the entire catchment area. The data collected in the field are used to calculate the index of lake hydromorphological alteration, that is, the Lake Habitat Modification Score for Polish Lakes (LHMS_PL). The LHMS_PL values range from 0 to 144, where 0 means no modification and 144 refers to a hydromorphologically highly modified state. The boundary values for the H/G and G/LTG status classes have been determined using the quartile method based on the relationship between hydromorphological modifications of lakes and the condition of the phytoplankton and macrophyte communities therein. [ABSTRACT FROM AUTHOR]