Interactive comment on “Seasonal, sub-seasonal and spatial fluctuations in oxygen-depleted bottom waters in an embayment of an eastern boundary upwelling system: St Helena Bay” by G. C. Pitcher and T. A. Probyn

In my opinion, the main handicap of this study is an inadequate dataset used for the stated objectives. The authors are trying to describe a seasonal signal, as well as discern a seasonal signal from short-term intra-seasonal decay events, using data from a single year. The (roughly) bi-monthly sampling regime is inadequate to capture meaningful data on the sub-seasonal events. The records capturing the short-term events are from one CTD device that was moored on the sea floor at a 50 m station for just over a year. That mooring does provide useful insight, however it provides no information on spatial extent of these short-term events (as I would have hoped from the title). The mooring also raises a concern in that it demonstrates the high degree (and magnitude) of short-term variability, which suggests that the bi-monhtly ’seasonal’ samples are potentially biased/distorted by such variability. Description of a ’typical’ seasonal signal would likely require several years of similar data. In summary, having monitored only one year, I would be very careful of describing a ’seasonal’ signal. The authors might look into a larger dataset from this well-sampled area to describe a mean seasonal signal.