The export of mercury (Hg) and the neurotoxin, methylmercury (MeHg), from wetland dominated catchments is common throughout the boreal region. However, wetlands vary significantly in their degree of minerotrophy related to their hydrogeomorphic setting, which has previously been shown to affect wetland MeHg import/export. In this field study, we use a series of wetland dominated catchments with varying degrees of minerotrophy (poor fen, moderate fen, channel fen, and extreme rich fen) to assess how their hydrogeomorphic setting impacts seasonal (June–October) total mercury (THg) and MeHg export or import. Streamwater from the headwater poor and moderate fens had the highest MeHg yield (13 and 19 mg km-2, respectively) and percent MeHg, while THg yield was greatest from the channel fen (410 mg km-2). Conversely, the extreme rich fen was a net THg (-740 mg km-2) and MeHg (-140 mg km-2) importer. Deceases in MeHg concentrations and export from the extreme rich fen coincide with increased total dissolved manganese, suggesting that manganese redox chemistry may be important in regulating MeHg cycling and/or mobility to higher-order rivers. This work extends previous studies showing swamps to be net MeHg importers to include extreme rich fens as another wetland type that removes Hg from streams and provides another possible mechanism, manganese reduction, that influences MeHg cycling. We highlight how hydrogeomorphic setting plays an important role in controlling Hg export to rivers in the Canadian Western Boreal Plain.