Information on the impact of land-use activities on semi-aquatic mammals is limited. Such keystone species are of global conservation concern. Two catchment scale studies of the platypus in Tasmania provide insights into the impact of land-use activities on populations of this species.

A study of platypus population health in a river catchment with a long history of forestry and agriculture took a multidisciplinary approach. Platypuses were found throughout the catchment and were generally in good health. There were no differences in infectious agents between subcatchments and age/sex categories. Higher capture rates and body mass in stream reaches running through cleared agricultural land were attributed to the naturally more favourable habitat in such areas compared to subcatchments with high forest cover (native and forestry combined).

A second study investigated the use of streams by platypuses in a forestry dominated catchment. Surveys in 2000 found that despite the long history of forestry disturbance (since 1934), platypuses were found throughout the catchment, with larger streams used more often than smaller headwaters. Individuals in the headwaters were mainly sub-adults and adults in poor condition and they avoided streams disturbed in the 80’s by logging. However, a follow-up study in 2015 found a similar sized platypus population. Analysis of the combined data indicated that use of streams by platypus was influenced primarily by both local and catchment factors, and to a lesser extent forestry disturbance.

Improved management practices and the resilience of this species to environmental change may explain the findings of these studies.