Microalgae in marine and brackish waters of Europe regularly cause «harmful effects», considered from the human perspective, in that they threaten public health and cause economic damage to fisheries and tourism. Cyanobacteria cause similar problems in freshwaters. These episodes encompass a broad range of phenomena collectively referred to as «harmful algal blooms» (HABs). They include discoloration of waters by mass occurrences of microalgae (true algal blooms that may or may not be «harmful») to toxin-producing species that may be harmful even in low cell concentrations.
A broad classification of HAB distinguishes three groups of organisms: 1) the toxin producers, which even with low biomass can contaminate seafood, causing sickness and death in humans eating the seafood, or sickness and death in the shellfish and fin-fish themselves; 2) the high-biomass toxin producers (cyanobacteria), which can have similar harmful effects; and 3) the high-biomass bloom species, which can cause either anoxia that indiscriminately kills off marine life, or unpleasant foam or gelatinous masses that are a nuisance for tourists who may develop allergic skin reactions after bathing.
For adequate management of these phenomena, monitoring of microalgae is required. However, the effectiveness of monitoring programmes is limited by the fact that it is time consuming and morphology as determined by light microscopy may be insufficient to give definitive species and toxin attribution. Once cell numbers reach a threshold level, then shellfish are selected to toxin analysis by the mouse bioassay. The mouse bioassay is continued on a daily basis until no more toxin is detected. In Spain, however, it is used continually even when there is no toxin present in the samples. Molecular and biochemical methods are now available that offer rapid means of both species and toxin detection.
In this project we will target rapid species identification using rRNA genes as the target. rRNA genes include regions that are so variable that they are species or even strain specific. These regions can be targeted for probe design to recognize species or even strains. We are also including antibody reactions to specific toxins produced by these microalgae because even when cell numbers are very low, the toxins can be present and can be accumulated in the shellfish. Microarrays are the state of the art technology in molecular biology for the processing of bulk samples for detection of target RNA/DNA sequences. Existing rRNA probes and antibodies for toxic algal species/strains and their toxins will be adapted and optimized for microarray use to strengthened the EU`s ability to monitor for toxic algae. The purpose of MIDTAL is to support the common fisheries policy to aid the national monitoring agencies by providing new rapid tools for the identification of toxic algae and their toxins so that they can comply with ECC directive 91/1491/CEE that can be converted to cell numbers and reduce the need for the mouse bioassay.