**1. Introduction**

158 Studies on Water Management Issues

Mihaiescu, T.; Mihaiescu, R.; Muntean, E.; Muntean, N. (2010). Study Regarding

Odagiu, A. (2010). Municipality of Cluj-Napoca – The Quality of Wastewaters. Note 1.

Oroian, I.Gh., Petrescu–Mag, M.R. (2011). *Environmental Law and Legislation*, Bioflux, ISBN

Papaioannou, A., Athina Mavridou, C. Hadjichristodoulou, P. Papastergiou, Olga Papp,

Shirodkar, P. V., Mesquita, A., Pradhan, U. K., Verlekar, X. N., Buba, M. T., & Vethamony, P.

Sojka, M., Siepak, M., Ziola, A., Frankowski, M., Murat-Blazejewska, S., Siepak, J. (2008).

Wake, H. (2005). Oil refineries: a review of their ecological impacts on the aquatic

Environmental Report of the National Romanian Agency of Environmental Protection by the year 2005, http://www.anpm.ro/Mediu/rapoarte [in Romanian] Environmental Report of the National Romanian Agency of Environmental Protection by the year 2006, http://www.anpm.ro/Mediu/rapoarte [in Romanian] Environmental Report of the National Romanian Agency of Environmental Protection by the year 2007, http://www.anpm.ro/Mediu/rapoarte [in Romanian] Environmental Report of the National Romanian Agency of Environmental Protection by the year 2008, http://www.anpm.ro/Mediu/rapoarte [in Romanian] Environmental Report of the National Romanian Agency of Environmental Protection by the year 2009, http://www.anpm.ro/Mediu/rapoarte [in Romanian]

ISSN: 1844-6698 (print version), ISSN: 2066-1363 (electronic version) Odagiu, A.; Oroian, I.; Mihăiescu T.; Şotropa A.; Petrescu–Mag,I.V.; Burduhos P.; Balint, C.

1844-6698 (print version), ISSN: 2066-1363 (electronic version)

978-606-8191-04-1, Cluj-Napoca, Romania [in Romanian]

ISSN: 2066-1363 (electronic version)

2009) pp. 245 – 257, ISSN: 0013-9351

ISSN: 1573-2959 (electronic version)

140, ISSN: 0272-7714

version)

Hydrochemical Classification of the main Lakes from Fizeş Watershed (Romania), *ProEnvironment* Vol. 3 No. 5 (June 2010) pp. 72 - 87, ISSN: 1844-6698 (print version),

Monitoring Disolved Oxygen, *ProEnvironment* Vol. 3 No. 5 (June 2010) pp. 78 - 83,

(2010). Municipality of Cluj-Napoca – The Quality of Wastewaters. Note 2. Monitoring Turbidity, *ProEnvironment* Vol. 3 No. 5 (June 2010) pp. 84 - 88, ISSN:

Eleni Dovriki, I. Rigas (2010). Application of multivariate statistical methods for groundwater physicochemical and biological quality assessment in the context of public health. *Environmental Monitoring & Assessment*, Vol. 170 No. 1 - 4 (November 2010) pp. 87 – 97, ISSN: 0167-6369 (print version), ISSN: 1573-2959 (electronic

(2009). Factors controlling physicochemical characteristics in the coastal waters off Mangalore - A multivariate approach. *Environmental Research*, Vol. 109 No. 2 (July

Application of multivariate statistical techniques to evaluation of water quality in the Mala Welna River (Western Poland). *Environmental Monitoring & Assessment*, Vol. 147 No. 1-3 (December 2008) pp. 159 – 170, ISSN: 0167-6369 (print version),

environment. *Estuarine, Costal and Shelf Science* Vol. 62 No. 4 (March 2005) pp. 131 –

Strong water demand for irrigation, energy and drinking water production is responsible for an increasingly regulation of freshwater flow patterns and watersheds. In this context, the construction of dams allows water storage but seriously restricts freshwater flow downstream. Due to scarcity of freshwater resources, reservoir water management often promotes high hydraulic residence. This may cause strong impacts on biological components of aquatic ecosystems, influencing the development of cyanobacteria blooms and aggravating their harmful impacts.

Aquatic cyanobacteria, a group of relatively slow growing photosynthetic organisms, are stimulated by high water residence times as well as increased temperatures and low N : P ratios, conditions that usually limit the growth of other competing phytoplankton groups (Carmichael et al., 1996; Chorus & Bartram, 1999; Kawara et al., 1998; Kononen et al., 1998; Paerl, 2008). Cyanobacteria blooms have been repeatedly associated with eutrophication processes (Berg et al., 1987; Carmichael et al., 1988; Codd, 2000; Chorus, 2005; Druvietis, 1997; Pinckney et al., 1998), but they might also dominate under oligotrophic conditions (Galvão et al., 2008; Havens et al., 2003; Mez et al., 1997; Sivonen & Jones, 1999).

Cyanobacteria blooms management became an emergent priority as a result of worldwide surveys of aquatic ecosystems affected by massive cyanobacteria blooms and their serious health and ecosystem risks (Blaha et al., 2009). Indeed, cyanobacteria are able to produce a wide range of secondary metabolites which are toxic to humans and wildlife, generally referred as cyanotoxins. From a toxicological perspective, cyanotoxins are classified as

<sup>\*</sup> Margarida P. Reis1, Rita B. Domingues1, Sandra M. Caetano1, Sandra Mesquita1, Ana B. Barbosa1, Cristina Costa1, Carlos Vilchez3 and Margarida Ribau Teixeira2

*<sup>1</sup>Center for Marine and Environmental Research (CIMA), Universidade do Algarve, Gambelas Campus, Faro, Portugal* 

*<sup>2</sup>Center for Environmental and Sustainability Research (CENSE), Universidade do Algarve, Gambelas Campus,* 

*Faro, Portugal 3International Center for Environmental Research (CIECEM), University of Huelva, Huelva, Spain* 

Ecological Tools for the Management of Cyanobacteria

Blooms in the Guadiana River Watershed, Southwest Iberia 161

Fig. 1. Guadiana River water basin and location of study sites: Guadiana estuary and

The main goal of this work is to evaluate recent water management strategies adopted for the Guadiana watershed, comparing different criteria used to classify ecological status and potential. The study is based on long-term ecological data series, and addresses two distinct case studies: (i) the Guadiana estuary (1997-2009); and (ii) adjacent Beliche and Odeleite

The Guadiana estuary is a mesotidal system (tidal amplitude: 1.3–3.5 m), with a length of 70 km, a maximum width of ca. 550 m, an average depth of 6.5 m, and an average water residence time of 12 days (Domingues & Galvão, 2007; Vasconcelos et al., 2007). The upstream saltwater intrusion is usually located close to Alcoutim (ca. 38 km from river mouth), whereas tidal influence extends to Mértola (ca. 70 km from river mouth; see Fig. 1). The lower estuary ranges from partially stratified to well-mixed, whereas the upper estuary is generally well-mixed (Cravo et al., 2006; Morais et al., 2009; Oliveira et al., 2006; Rocha et al. 2002). A series of dams has severely restricted its freshwater flow (ca. 75 %), and the recent construction of the large Alqueva dam (ca. 150 km upstream from river mouth) increased flow regulation up to 81% of the total catchment area (55 000 km2) starting in 2003 (Galvão et al., 2008). Since human activity in the Guadiana watershed is mostly agriculture and the main anthropic pressure is associated to dams, the Guadiana is considered one of

adjacent freshwater reservoirs (Alqueva, Odeleite and Beliche)

freshwater reservoirs (2003-2010).

**2. Guadiana estuary study** 

**2.1 Study area, sampling strategy and methods** 

hepatotoxins, neurotoxins, cytotoxins, and dermatotoxins (Wiegand & Pflugmacher, 2005). According to their chemical structure, these toxic compounds are peptides, heterocyclic (alkaloids) or lipidic compounds (Sivonen & Jones, 1999). Effects of toxins on humans can be triggered mainly by direct skin contact or consumption of contaminated water. Furthermore other potential routes of exposure have been documented including aerosol inhalation, contaminated food ingestion and dialysis (Chorus & Bartram, 1999; Dunn, 1996; Jochimsen et al., 1998; Pouria et al., 1998). Additional problems related to cyanobacteria bloom episodes in raw water sources used for drinking water production include noxious effects such as bad taste and odour, due to the presence of geosmin and 2-methylisoborneol (Jähnichen et al., 2011). Cyanobacteria may also produce a wide range of currently unknown toxins with great toxicological significance (Blaha et al., 2009). Thus, cyanobacteria blooms constitute a key concern for drinking water production, and are also relevant for establishing water quality management policies (e.g., Water Frame Directive, WFD; Directive 2000/60/CE of 23 October 2000).

Phytoplankton is recognized as an essential biological element in monitoring programs used to define the ecological quality and health of aquatic environments. In the scope of the WFD, phytoplankton is used to classify trophic state of aquatic ecosystems (Domaizon et al., 2003), as well as to determine the effectiveness of management, restoration programs and environmental legislation (Brierley, et al., 2007). Phytoplankton biomass and composition, along with trophic state indices (TSI) and physical-chemical variables, are essential to establish freshwater ecological status (Carlson, 1977; Reynolds et al., 2002).

The need for translating complex biological information into Multimetric Indicators of Ecological Condition, required by water managers, has led to the development and testing of multiple ecological indices. According to the Evaluation Guidelines adopted by the United States, (Jackson et al., 2000), selected ecological indicators used for ecological classification should: (1) be easily obtained through standardized well-documented methods; (2) provide relevant information in terms of specific management concerns; (3) allow for temporal and spatial variability, without losing discriminant capacity, and (4) maintain reliability. Despite the great effort put into sampling and analytical methods standardization, we consider that indices recently adopted to evaluate ecological status of surface waters are still far from complying with all these criteria.

The Guadiana River watershed (Fig. 1) is the fourth largest river basin in the Iberian Peninsula (67480 km2), and is located in a semi-arid region with a Mediterranean climate. Annual precipitation averages ca. 500 mm, and the hydrographic regime is torrential, with concentrated rainy periods and a prolonged dry season, usually from May to September. The Mediterranean climate irregularity is also expressed in strong interannual variability, with intense rainy years alternating with years of extended droughts (Daveau, 1987). Managing water availability under such demanding conditions lead to the construction of hundreds of dams, from which almost 90 have a volume capacity over 1 hm3. Reservoir water management strategies are strongly limited by increasing water demands for irrigation and drinking water production, causing severe restriction of freshwater flow. Recent construction of the large Alqueva dam further increased flow regulation.

hepatotoxins, neurotoxins, cytotoxins, and dermatotoxins (Wiegand & Pflugmacher, 2005). According to their chemical structure, these toxic compounds are peptides, heterocyclic (alkaloids) or lipidic compounds (Sivonen & Jones, 1999). Effects of toxins on humans can be triggered mainly by direct skin contact or consumption of contaminated water. Furthermore other potential routes of exposure have been documented including aerosol inhalation, contaminated food ingestion and dialysis (Chorus & Bartram, 1999; Dunn, 1996; Jochimsen et al., 1998; Pouria et al., 1998). Additional problems related to cyanobacteria bloom episodes in raw water sources used for drinking water production include noxious effects such as bad taste and odour, due to the presence of geosmin and 2-methylisoborneol (Jähnichen et al., 2011). Cyanobacteria may also produce a wide range of currently unknown toxins with great toxicological significance (Blaha et al., 2009). Thus, cyanobacteria blooms constitute a key concern for drinking water production, and are also relevant for establishing water quality management policies (e.g., Water Frame Directive, WFD;

Phytoplankton is recognized as an essential biological element in monitoring programs used to define the ecological quality and health of aquatic environments. In the scope of the WFD, phytoplankton is used to classify trophic state of aquatic ecosystems (Domaizon et al., 2003), as well as to determine the effectiveness of management, restoration programs and environmental legislation (Brierley, et al., 2007). Phytoplankton biomass and composition, along with trophic state indices (TSI) and physical-chemical variables, are essential to establish freshwater ecological status (Carlson, 1977; Reynolds et

The need for translating complex biological information into Multimetric Indicators of Ecological Condition, required by water managers, has led to the development and testing of multiple ecological indices. According to the Evaluation Guidelines adopted by the United States, (Jackson et al., 2000), selected ecological indicators used for ecological classification should: (1) be easily obtained through standardized well-documented methods; (2) provide relevant information in terms of specific management concerns; (3) allow for temporal and spatial variability, without losing discriminant capacity, and (4) maintain reliability. Despite the great effort put into sampling and analytical methods standardization, we consider that indices recently adopted to evaluate ecological status of

The Guadiana River watershed (Fig. 1) is the fourth largest river basin in the Iberian Peninsula (67480 km2), and is located in a semi-arid region with a Mediterranean climate. Annual precipitation averages ca. 500 mm, and the hydrographic regime is torrential, with concentrated rainy periods and a prolonged dry season, usually from May to September. The Mediterranean climate irregularity is also expressed in strong interannual variability, with intense rainy years alternating with years of extended droughts (Daveau, 1987). Managing water availability under such demanding conditions lead to the construction of hundreds of dams, from which almost 90 have a volume capacity over 1 hm3. Reservoir water management strategies are strongly limited by increasing water demands for irrigation and drinking water production, causing severe restriction of freshwater flow. Recent construction of the large Alqueva dam further increased flow

surface waters are still far from complying with all these criteria.

Directive 2000/60/CE of 23 October 2000).

al., 2002).

regulation.

Fig. 1. Guadiana River water basin and location of study sites: Guadiana estuary and adjacent freshwater reservoirs (Alqueva, Odeleite and Beliche)

The main goal of this work is to evaluate recent water management strategies adopted for the Guadiana watershed, comparing different criteria used to classify ecological status and potential. The study is based on long-term ecological data series, and addresses two distinct case studies: (i) the Guadiana estuary (1997-2009); and (ii) adjacent Beliche and Odeleite freshwater reservoirs (2003-2010).
