Human impact on freshwater environments in Norse and early medieval Iceland

Preliminary data from fish bone assemblages preserved in middens at Norse and early medieval farm sites in Mývatnssveit, northern Iceland, suggest that the pattern of fish exploitation changed during the first few centuries following the settlement. Freshwater taxa become less common in deposits at some sites between the 9th and 12th centuries AD, replaced by saltwater species such as cod or by domestic mammals. Within the freshwater fish taxa, the proportion of lake (e.g. arctic charr) to river fish (e.g. brown trout) tends to increase over the same period. One possible interpretation of these patterns is that fish stocks in rivers and, perhaps to a lesser extent, lakes declined in response to degradation of freshwater environments following the settlement. Here we examine palaeolimnological data which suggest that increased sedimentation rates, increased nutrient status, and increased algal and chironomid production in some lakes occurred in concert with clearance of woodland and destabilisation of soils following landnám. These changes are unlikely to have had a negative impact on the food supply for freshwater fish, so an alternative explanation must be sought for the patterns in the archaeofaunal data