A Review of the Impact on Aquatic Communities of Inputs from Peatlands Drained for Peat Extraction

Peatlands, which account for 21% of total land area in the Republic of Ireland, have been subjected to large-scale drainage and extraction of peat for fuel since the Industrial Revolution, continuing throughout the twentieth and early twenty-first century. Though the effects of this extraction on the water quality of streams draining peatlands have received extensive study, little research has investigated the direct effects of peat drainage and extraction on the aquatic biota (e.g. fish, macroinvertebrates, macrophytes, phytobenthos) of these streams and no studies have yet been published on these effects in Irish peatland streams. This paper reviewed the available data on the effects of physico-chemical stressors such as ammonia, heavy metals and peat sedimentation associated with drainage and extraction on the aquatic biota of peatland streams. Results suggest that peatland drainage and extraction provide several serious challenges to aquatic life, including increased mortality, reduced richness, behavioural changes, habitat alterations and changes in community structure. This review also details the benefits of peatland restoration via drain-blocking on aquatic biota and highlights the extensive knowledge gaps that exist in understanding the effects of peatland derived stressors on surface water communities. These include the impact of peat sedimentation on aquatic biota, the paucity of information on the effects on phytobenthos communities and a lack of knowledge of how the various peat-derived stressors interact to impact aquatic communities in addition to inadequate knowledge of the responses of stream biota to peatland restoration.