An array system comprising a microarray slide configured to detect simultaneously a plurality of organisms in a sample, wherein the microarray slide comprises nucleic acid probes having fragments of 18S or 28S RNA sequence unique to each organism or taxonomical group thereof, wherein the plurality of organisms comprise toxic algae organisms and wherein some of the nucleic acid probes are specific for the detection of the species of each organism to be detected and other nucleic acid probes are specific for detection of at least one higher-level taxon to which each of the organism to be detected belongs, wherein the microarray slide comprises: a. At least one probe selected from the group consisting of positive and negative controls, having a sequence selected from SEQ ID NO: 1 to SEQ ID NO: 4, SEQ ID NO:7 and SEQ ID NO: 8; b. at least both of the probes capable of selectively detecting at least one of eukaryotic organisms, having sequences respectively given in SEQ ID NO:9 to SEQ ID NO: 10; c. at least all of the probes capable of selectively detecting the taxonomical phylum of the organism, having sequences respectively given in SEQ ID NO: 1 1 to SEQ ID NO: 13; d. at least all of the probes capable of selectively detecting the taxonomical class of the organism, having sequences respectively given in SEQ ID NO: 14 to SEQ ID NO: 16; e. at least all of the probes capable of selectively detecting a taxonomical clade of the organism at a taxonomical level intermediate between class and genus, having sequences respectively given in SEQ ID NO: 17 to SEQ ID NO: 41; f. at least all of the probes capable of selectively detecting the taxonomical genus of the organism, having sequences respectively given in SEQ ID NO: 42 to SEQ ID NO: 69; g. at least all of the probes capable of selectively detecting the taxonomical species of the organism, having sequences respectively given in SEQ ID NO: 70 to SEQ ID NO: 252 and h. at least all of the probes capable of selectively detecting the taxonomical strain of the organism where both toxic and non-toxic strains of the same species exist, having sequences respectively given in SEQ ID NO: 70 to SEQ ID NO: 252. a. At least one probe selected from the group consisting of positive and negative controls, having a sequence selected from SEQ ID NO: 1 to SEQ ID NO: 4, SEQ ID NO:7 and SEQ ID NO: 8; b. at least both of the probes capable of selectively detecting at least one of eukaryotic organisms, having sequences respectively given in SEQ ID NO:9 to SEQ ID NO: 10; c. at least all of the probes capable of selectively detecting the taxonomical phylum of the organism, having sequences respectively given in SEQ ID NO: 1 1 to SEQ ID NO: 13; d. at least all of the probes capable of selectively detecting the taxonomical class of the organism, having sequences respectively given in SEQ ID NO: 14 to SEQ ID NO: 16; e. at least all of the probes capable of selectively detecting a taxonomical clade of the organism at a taxonomical level intermediate between class and genus, having sequences respectively given in SEQ ID NO: 17 to SEQ ID NO: 41; f. at least all of the probes capable of selectively detecting the taxonomical genus of the organism, having sequences respectively given in SEQ ID NO: 42 to SEQ ID NO: 69; g. at least all of the probes capable of selectively detecting the taxonomical species of the organism, having sequences respectively given in SEQ ID NO: 70 to SEQ ID NO: 252 and h. at least all of the probes capable of selectively detecting the taxonomical strain of the organism where both toxic and non-toxic strains of the same species exist, having sequences respectively given in SEQ ID NO: 70 to SEQ ID NO: 252.