Further insights into the responses of macroinvertebrate species to burial by sediment

Abstract

The impact of fine sediments on both habitat quality and macroinvertebrate communities of riverine systems has been well documented over recent years. However, there is a paucity of studies examining the mechanisms that relate macroinvertebrate sensitivity and responses of individual macroinvertebrate species to burial by sediment. Laboratory-based burial experiments were undertaken to study the response of some EPT species including Baetis rhodani, Ecdyonurus insignis, Rhithrogena semicolorata, Hydropsyche siltalai, Rhyacophila dorsalis and the amphipod Gammarus duebeni to burial. A range of burial conditions were studied which included five sediment fractions at two burial depths. Responses were variable across species and, overall, the ranking of the determinants that impacted on species responses to burial was burial depth > sediment class > species source, with no detectable effect linked to body size. Increased burial depth had the most marked effects on emergence times, while slower escape times were also observed from the finer sediment classes. Species source also influenced responses with some upland species taking longer or failing to emerge from burial. Further mechanistic studies, based on EPT species, are required to enhance our understanding of how and at what level sediment affect species, an essential step in developing pressure-specific biological metrics.