Harmful algal blooms (HAB), defined by the rapid development of a toxic or non desirable phytoplankton species in a water body, impact both economy and water environment. Their monitoring is then one of the main duty of water quality managers. HAB monitoring is generally based on punctual water sampling and analysis which is time consuming. To support HAB monitoring, optical remote sensing as been used, providing information on total phytoplankton biomass with chlorophyll-a concentration (Chl-a). However, Chla is only partially informative as it does not allow to distinguish between phytoplankton species. Here, we show that the newly developed autonomous hyperspectral radiometry systems (PANTHYR and HYPSTAR) primary dedicated to the validation of water reflectance data from satellite can be very useful for HAB monitoring. On a first example, we show how Phaeocystis globosa bloom can be monitored with a PANTHYR system in the Southern North Sea. Although not toxic, this specie produces foam which accumulates on the beach impacting touristic and economical activities. On a second example, toxic cyanobacteria blooms are monitored in a water reservoir at Blankaart (Belgium). In both cases, HAB indexes are developed based on the specificity of pigment composition of the harmful phytoplankton species compared to other local species using the analysis of second derivatives of the water reflectance spectra. We hence show that HYPSTAR and PANTHYR technology associated with local HAB indexes will allow for an improvement of HAB monitoring with real time alerts at daily scale.

Primary Presenter: Héloïse Lavigne, Royal Belgium Institute of Natural Sciences (hlavigne@naturalsciences.be)

Authors:

Clémence Goyens, RBINS  (cgoyens@naturalsciences.be)

Kevin Ruddick, RBINS  (kruddick@naturalsciences.be)

Quinten Vanhellemont, RBINS  (qvanhellemont@naturalsciences.be)