The African west and south coasts suffer from frequent occurrence of Harmful Algal Blooms (HABs). These blooms can have considerable negative impacts on commercial marine concerns such as rock lobster and aquaculture operations, in addition to local marine ecosystems and communities. HAB impacts come about either from the toxicity of some bloom species, or collapse of high biomass blooms through nutrient exhaustion, leading in extreme cases to hypoxia and dramatic mortalities of marine organisms, of which crayfish strandings are the most well known.
The Aquaculture Support Service provides a capability for monitoring and assessing risk of HAB events, based on quantified understanding of bloom dynamics (Pitcher & Nelson, 2006), hypoxic impacts (Pitcher et al 2014), and earth observation. In short, the combined risk is elevated to red=high - indicating imminent danger of a hypoxic event - when the SST is > 13 ℃, the forecast wind for the next three days is low (<5 m s-1), AND there is a persistent high biomass bloom in the critical area.
Earth observation data used in this service:
Chlorophyll-a: derived from 1 km daily Sentinel 3A and 3B Ocean and Land Colour Instrument (OLCI) water-leaving reflectance data using a regional algorithm (Smith et al 2018). The product units are mg m-3
SST (AM): Sea Surface temperature derived from 1 km daily morning (descending) overpasses of the Sentinel 3A and 3B Sea and Land Surface Temperature Radiometer (SLSTR). The product units are ℃
SST (PM): Sea Surface temperature derived from 1 km daily evening (ascending) overpasses of the Sentinel 3A and 3B Sea and Land Surface Temperature Radiometer (SLSTR). The product units are ℃
Reanalysed SST: This is a Level4 gap-free space-time interpolated Foundation Sea Surface Temperature product from the Operational Sea Surface Temperature and Ice Analysis (OSTIA) system run by the UK's Met Office. The product is derived using data from both in-situ and satellite data from infrared and microwave radiometers. It has a spatial resolution of 5km, and is provided at 1 day latency. The product units are ℃
Reanalysed SST Anomaly: This product shows the variation of the daily reanalysed SST product from a daily historical average (calculated with data from 1 Jan 2007 to 31 Dec 2019). The product units are ℃
GlobColour Chlorophyll: This is a level 4 gap-free space-time interpolated chlorophyll product, derived using data from multiple ocean colour sensors. The product is produced by ACRI-ST, obtained from the Copernicus Marine Services, and is provided at 2 day latency. The product units are mg m-3
http://harmfulalgalblooms.freeforums.net/
