Many coastal environments are suffering increasing levels of organic nutrients deriving from anthopogenic and microbial activities and this will affect the natural communities of these environments. In addition, the importance of phosphorus as a nutrient that is limiting primary productivity in these areas is also coming to light. Likewise, in recent years, incidences involving Ostreopsis ovata blooms in temperate coastal zones have been reported with increasing frequency, intensity and distribution. So it was decided to investigate a potential link between these actualities. Studies of O. ovata ‘success’ have covered many aspects of its ecology, however, to date there has been no information given about its possible use of organic substrates as nutrient source. Yet there are many reports in the literature on diverse algal groups that can maintain ‘normal’ activity by making use of organic substrates. In this preliminary study, the phosphatase assay was used as convenient and rapid method to assess possible organic nutrition. Phosphatases are a group of enzymes that hydrolyse simple organic compounds and release inorganic phosphate. Evidence has shown that the bulk of enzyme activity is associated with the cell wall or its immediate surroundings, leading to the release of inorganic phosphate external to the cytoplasmic membrane and the subsequent uptake of much of this into the cell.
Here we report on the phosphatase activities of O. ovata cultured in media containing inorganic or organic phosphate and natural samples. Primarily the results show that O. ovata could utilise organic P compounds as growth continued unimpeded in organic P only media and the occurrence of high surface phosphatase activity associated with the cells. The results also highlight what seems to be a high constitutive phosphatase activity. This signifies that even when experiencing high ambient nutrient levels, that rates of activity can continue to supply ‘luxury’ levels of P to the cells. It is likely that O. ovata would thrive under high nutrient conditions and have a competitive edge over other groups of organisms that may have product repressible phosphatases
