Abstract
Climate change models predict an increase in the frequency of extreme rainfall and thus the supply of terrigenous sediments to coastal waters. Understanding how this supply affects coastal ecosystems has become important for coastal managers worldwide. Here we describe an experiment designed to investigate how thin surface deposits of terrigenous clay affect settlement decisions of benthic juvenile recruits. This experiment builds on previous studies that revealed evidence for a link between bacterial activity in the sediment underlying terrigenous clay deposits and the behaviour of the recruits on the surface of the deposit: reduced end products of the anaerobic microbial decomposition of organic matter diffuse upwards across the terrigenous clay deposit informing the recruit about poor substrate suitability. This effect results from an increase in the diffusive distance for the transport of oxygen from the seawater into the clay-underlying sediment, that is, a reduced supply of oxygen to the sediment. To test this model, we will study the behaviour of juvenile Macomona liliana in a laboratory flume. We hypothesize that juveniles that reject the surface of terrigenous clay deposited onto organic-rich coastal sediment will not reject the surface of the same clay if it was deposited onto sterile coastal sediment.
