Phytoplankton are key elements of marine ecosystems supporting all higher trophic levels. However, a few species are directly responsible for major economic losses, due to their impact on the exploitation of marine resources, and on human health. The coast of Portugal is regularly affected by blooms of some of these species (HABs), in particular by the dinoflagellates Dinophysis acuta and D. acuminata, responsible for the diarrhetic shellfish poisoning syndrome, and Gymnodinium catenatum, responsible for the paralytic shellfish poisoning syndrome. HABs are natural phenomena and part of the diet of the shellfish they toxify. So far the only way to safeguard public health is by harvest closure of the toxified resource. This has serious social-economic implications and there is an urgent need for new science driven technological approaches that help minimize or mitigate these events.
The ultimate objective of HabWAVE is the development of new forecasting capabilities to allow for timely management decisions that may reduce the impact of HABs on the emerging aquaculture industry in Portugal. To achieve this goal, we have put together a multidisciplinary consortium, joining marine biologists, physicists, geologists and modelers, with a long track record of research in HABs and coastal oceanography, to investigate the conditions leading to bloom initiation, in particular, species such as G. catenatum that produce in their life- cycle a benthic resting cyst. In most areas affected by HABs the origin of the inoculum for bloom initiation is still an open question. In cyst producing species, these may represent seed-beds that once the conditions are favourable for their germination, inoculate the overlaying waters. However, these cysts need physical mechanisms that allow their (or their germlings) transport from bottom sediments to the euphotic zone. In HabWAVE, an inventory of benthic cyst beds will be done, considering both bottom sediments and the adjacent benthic nephloid layer (BNL). Physical processes, responsible for bottom particulate matter dynamics will be identified by in situ observations (ADCP 300 looking up and a 1200 looking down coupled with a LISST200x, multiple thermistor vertical chain), and satellite data (SAR, SST and ocean colour). The environmental and physiological traits of Gymnodinium catenatum cysts and other potentially toxic species will be investigated and a germination model will be developed. Finally, a state-of-the-art hydrodynamic model will be developed to assess transport mechanisms of resting cysts that may explain the initiation of HABs. Observational results of the viability of cysts from natural cyst beds will be used to test hypothesis on bloom initiation using lagrangian individual based experiments. In the end, we expect to produce a conceptual model that will contribute to the operationalization of a predictive system for HABs, based on a combination of satellite observations, and modelling information.