| Seston depletion was measured at five locations along the main current axis of a mussel lease in Ship Harbour, Nova Scotia, Canada. Two Tethered Attenuation Coefficient Chain Sensors (TACCS; Satlantic, Inc.) were used to determine the diffuse attenuation coefficient at 490 nm ( K; m−1 within the stratum where mussels were ultured (4 to 8 m). The values of K were relatively independent of the illumination eometry and were dependent on the concentration of coloured dissolved organic matter CDOM) and chlorophyll-a plus phaeopigments (Chi). The concentration of CDOM was nversely correlated with salinity and exhibited seasonal variations associated with an upwelling event. Chi explained 75% of the variability of K, which was associated with tidal currents suggesting a seaward source and an in-lease sink of Chi. Two methods to calculate seston depletion from K were compared: (1) for the Chl-method, weekly samples were used to develop an empirical algorithm to convert from K to Chl and (2) for the K particles-based method, continuous in situ salinity measurements were used to estimate and correct for CDOM. (Abstract shortened by UMI.)... |
