Increased sedimentation in surface waters due to anthropogenic activities can lead to the deterioration of salmonid spawning habitat through infiltration of excessive fine sediment into redds. This study assessed the effects of sediment on salmonid reproductive habitat on Prince Edward Island, Canada by evaluating egg survival and fry length using brook trout egg in situ incubations. In-stream egg incubators were buried in the substrate of streams in three watersheds with between 10 and 69% agricultural land-use during 2012-2013 and 2013-2014. Accumulated incubator sediment load and associated particle size, incubator organic matter and stream parameters temperature, velocity, bed sediment and particle size were measured over the period of study. There was no significant difference in embryo survival among watersheds. Survival was not related to fine sediment; instead, it increased with higher average temperature that was in turn associated with the presence of groundwater upwelling in the stream. The size of the fry was also not significantly different between watersheds with varying agricultural activity. Fry length was most strongly related to sediment organic matter content. Brook trout are widespread in PEI rivers, including in many rivers that have high sediment loads due to intensive agricultural land use. This species may avoid the adverse effect of fine sediment through their natural adaptation of using groundwater upwelling for spawning.
Ashley Alberto, Simon C. Courtenay, Andre St-Hilaire and Michael R. van den Heuvel