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. 2017 Oct 18;9(10):327.
doi: 10.3390/toxins9100327.

Risk Levels of Toxic Cyanobacteria in Portuguese Recreational Freshwaters

Carina Menezes  1 , Catarina Churro  2 , Elsa Dias  3
Affiliations

Risk Levels of Toxic Cyanobacteria in Portuguese Recreational Freshwaters

Carina Menezes et al. Toxins (Basel). .

Abstract

Portuguese freshwater reservoirs are important socio-economic resources, namely for recreational use. National legislation concerning bathing waters does not include mandatory levels or guidelines for cyanobacteria and cyanotoxins. This is an issue of concern since cyanotoxin-based evidence is insufficient to change the law, and the collection of scientific evidence has been hampered by the lack of regulatory levels for cyanotoxins in bathing waters. In this work, we evaluate the profile of cyanobacteria and microcystins (MC) in eight freshwater reservoirs from the center of Portugal, used for bathing/recreation, in order to determine the risk levels concerning toxic cyanobacteria occurrence. Three of the reservoirs did not pose a risk of MC contamination. However, two reservoirs presented a high risk in 7% of the samples according to the World Health Organization (WHO) guidelines for MC in bathing waters (above 20 µg/L). In the remaining three reservoirs, the risk concerning microcystins occurrence was low. However, they exhibited recurrent blooms and persistent contamination with MC up to 4 µg/L. Thus, the risk of exposure to MC and potential acute and/or chronic health outcomes should not be disregarded in these reservoirs. These results contribute to characterize the cyanobacterial blooms profile and to map the risk of toxic cyanobacteria and microcystins occurrence in Portuguese inland waters.

Keywords: cyanobacteria; cyanotoxins; guidelines; microcystins; recreational freshwaters; risk levels.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Cyanobacteria densities and microcystin concentrations over the monitoring periods for reservoirs A1, A2, A3, A4, A5, A6, A7 and A8. The arrows indicate the main cyanobacterial genera in the selected time points. Legend: Aph—Aphanizomenon spp.; Dol—Dolichospermum spp.; Mic—Microcystis spp.; Osc—Oscillatoria spp.; Plank—Planktothrix spp.; OT—Other taxa.
Figure 2
Figure 2
Risk levels of the eight freshwater reservoirs based on cyanobacterial cell density (a) and on microcystin concentration (b).
Figure 3
Figure 3
Geographic locations of the reservoirs studied in Portugal.
See this image and copyright information in PMC

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