# Review on Cyanobacterial Studies in Portugal: Current Impacts and Research Needs
## 1 Introduction
### Toxic Cyanobacteria  
Although cyanobacterial studies began in Portugal in the 1930s the first identification of the first toxic cyanobacterium species in our waters was attributed to [PERSON] et al. [8] that with his surveillance and search for microcystins found that this was produced by the species _Microcytsis aeruginosa_ in several amounts and in a diverse range of freshwater systems of Portugal. In his survey 36 lakes, reservoirs and rivers were monitored. Then only _Microcytsis_ blooms were assessed and 60% of these were found to be toxic. The main species present in toxic blooms were _Microcytsis aeruginosa_ (72%) and _Anabaena flos-aquae_ (28%) [9]. The main hepatotoxins in Portuguese freshwaters include MCYST-LR, MCYST-LA, MCYST-YR and [D-Asp]MCYSTLR [8; 10]. Later [PERSON] et al. [11] found evidence of saxitoxins production in Montargil Reservoir (South Region) through the chemical analysis of an isolate of _Chrysosporum flos-aquae_. Studies persisted and in 2009 [PERSON] et al. [12] found anatoxin-a production in strains of _Chrysosporum_, _Dolichospermum_, _Microcytsis_ and _Oscillatoria_ with production values ranging from 0.06 ug/g to 24.62 ug/g of cyanobacterial dry weight [12]. In spite of this finding, the strains were only able to produce anatoxin-a under laboratory conditions failing so far its environmental detection through chemical methods. Cylindrospermopsins were found to occur in a lagoon located in the Center Region (Vela Lagoon) in amounts that reached 12 ug/L in the water [13]. In this study the cylindrospermopsin-producer identified belonged to _Chrysosporum_ sp. and this was only achieved after sequencing and blast web search of a positive amplicon that belonged to the _cyrC_ gene cluster since the isolation of the producing strain failed [13]. Since toxic cyanobacterium studies began in Portugal this was the first study to include molecular studies in the identification of a toxic cyanobacterium producer. More recently [PERSON] et al. [7] found evidence of cyanotoxins multiplication in Portugal since most of the previous studies were referred to the Center and South Regions of the country providing evidence that other cyanotoxins besides microcystins can be found in the colder North Region of Portugal. Other results from this study include that anatoxin-a and saxitoxins production were attributed to the _Chrysosporum_ sp. genus [7]. The invasive and toxic _Cylindrospermopsis rachorskii_ was found to occur for the first time in the colder North Region of Portugal without forming any blooms and with no cyanotoxicity being attributed so far [14]. Regarding bloom occurrence, the first intensive surveillance study that searched for all cyanotoxins in Portuguese freshwater systems belonged to [PERSON] et al. [14] where it was found that 50% of the ecosystems analyzed had blooms (Figure 1). Its composition was comprised of _Microcytsis_ alone or a mixture of _Microcytsis_ with _Chrysosphorum/Dolichospermum_. Though initial studies by [PERSON] described that _Microcytsis_ was the dominant bloom forming genus in Portugal recently in a year (2017) with two heat waves during the sampling season lead to the rise of other types of cyanobacterium species which may have contributed to the multiplication of cyanotoxicity recommending the deepening of monitoring campaigns as well as the integration of other cyanotoxins besides the legislated microcystins-LR (MCLR). In this study only North and Center water systems were sampled; nonetheless, previously in 2005 in Algarve (South Region) at Beliche reservoir, it was found a bloom of _Planktonrix rubescens_ that produced microcystins [15]. An extensive study on cyanobacterial blooms in the south regions of Alentejo and Algarve reservoirs highlighted the occurrence of blooms not only attributed to _M. aeruginosa_ but to other species belonging to the Nostocales order in Algarve reservoirs and _Microcytsis aeruginosa_ and _Anabaena circinals_ in reservoirs from Alentejo region as the predominant bloom-forming species [16].