2.2. Sedimentation rates
Sedimentation rates were measured using a nested experimental design. Sediment traps, consisting of a PVC tube of 5 cm internal diameter, 11.5 cm length and sealed at one end (English et al., 1997), were deployed in groups of three at three different locations (about 20 m away from each other) at each study site. The sediment traps were 20 cm above the substrate and left in situ for 4–6 weeks, depending on weather conditions and logistical considerations, and were replaced after they were retrieved. Sediment trap deployment was conducted in 2004, 2006, 2008 and 2010. The sediment and water within the traps were filtered through a pre-weighed Whatman quantitative filter, dried at 60 °C until reaching a constant weight and subsequently weighed. Sedimentation rates are expressed as mg dry weight cm−2 day−1