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In coastal dunes, shrub encroachment disrupts natural disturbance, and reduces habitat heterogeneity and species composition. In this paper, we implemented a pilot scale trial aimed at restoring coastal dunes affected by the encroachment by the shrub Retama monosperma (hereinafter Retama) as well as strengthening the populations of Thymus carnosus (regionally cataloged as ‘Critically Endangered’). A total 3 ha of Retama shrub was clearcut in two sites with different Retama cover (54 and 72%). The effect of rabbits on vegetation recovery was assessed by placing exclosures both in treated and untreated plots in Spring, 2015. Plant composition, species richness and diversity were evaluated two years after treatments (with and without Retama clearing, and with and without rabbit exclusion). Retama clearing alone did not allow the recovery of plant composition typical of gray dunes two-years after treatments, but resulted in a biodiversity loss within the Retama understorey when rabbits were present. However, Retama clearing resulted in a significant vigor improvement of T. carnosus in the site with the highest density of Retama. Rabbit exclusion significantly increased species richness and Shannon-Wiener diversity index, and allowed the recovery of plant composition typical of gray dunes. The results suggest that shrub encroachment caused by Retama has a long-lasting negative impact on dune vegetation and that periodic clearing should be combined with rabbit exclusion at least during early restoration stages of dune vegetation. To recover the population of T. carnosus, Retama should be prevented from reaching high cover and periodic clearing without rabbit exclusion is suggested.

In coastal dunes, shrub encroachment disrupts natural disturbance, and reduces habitat heterogeneity and species composition. In this paper, we implemented a pilot scale trial aimed at restoring coastal dunes affected by the encroachment by the shrub Retama monosperma (hereinafter Retama) as well as strengthening the populations of Thymus carnosus (regionally cataloged as ‘Critically Endangered’). A total 3 ha of Retama shrub was clearcut in two sites with different Retama cover (54 and 72%). The effect of rabbits on vegetation recovery was assessed by placing exclosures both in treated and untreated plots in Spring, 2015. Plant composition, species richness and diversity were evaluated two years after treatments (with and without Retama clearing, and with and without rabbit exclusion). Retama clearing alone did not allow the recovery of plant composition typical of gray dunes two-years after treatments, but resulted in a biodiversity loss within the Retama understorey when rabbits were present. However, Retama clearing resulted in a significant vigor improvement of T. carnosus in the site with the highest density of Retama. Rabbit exclusion significantly increased species richness and Shannon-Wiener diversity index, and allowed the recovery of plant composition typical of gray dunes. The results suggest that shrub encroachment caused by Retama has a long-lasting negative impact on dune vegetation and that periodic clearing should be combined with rabbit exclusion at least during early restoration stages of dune vegetation. To recover the population of T. carnosus, Retama should be prevented from reaching high cover and periodic clearing without rabbit exclusion is suggested.

In coastal dunes, shrub encroachment disrupts natural disturbance, and reduces habitat heterogeneity and species composition. In this paper, we implemented a pilot scale trial aimed at restoring coastal dunes affected by the encroachment by the shrub Retama monosperma (hereinafter Retama) as well as strengthening the populations of Thymus carnosus (regionally cataloged as ‘Critically Endangered’). A total 3 ha of Retama shrub was clearcut in two sites with different Retama cover (54 and 72%). The effect of rabbits on vegetation recovery was assessed by placing exclosures both in treated and untreated plots in Spring, 2015. Plant composition, species richness and diversity were evaluated two years after treatments (with and without Retama clearing, and with and without rabbit exclusion). Retama clearing alone did not allow the recovery of plant composition typical of gray dunes two-years after treatments, but resulted in a biodiversity loss within the Retama understorey when rabbits were present. However, Retama clearing resulted in a significant vigor improvement of T. carnosus in the site with the highest density of Retama. Rabbit exclusion significantly increased species richness and Shannon-Wiener diversity index, and allowed the recovery of plant composition typical of gray dunes. The results suggest that shrub encroachment caused by Retama has a long-lasting negative impact on dune vegetation and that periodic clearing should be combined with rabbit exclusion at least during early restoration stages of dune vegetation. To recover the population of T. carnosus, Retama should be prevented from reaching high cover and periodic clearing without rabbit exclusion is suggested.

In coastal dunes, shrub encroachment disrupts natural disturbance, and reduces habitat heterogeneity and species composition. In this paper, we implemented a pilot scale trial aimed at restoring coastal dunes affected by the encroachment by the shrub Retama monosperma (hereinafter Retama) as well as strengthening the populations of Thymus carnosus (regionally cataloged as ‘Critically Endangered’). A total 3 ha of Retama shrub was clearcut in two sites with different Retama cover (54 and 72%). The effect of rabbits on vegetation recovery was assessed by placing exclosures both in treated and untreated plots in Spring, 2015. Plant composition, species richness and diversity were evaluated two years after treatments (with and without Retama clearing, and with and without rabbit exclusion). Retama clearing alone did not allow the recovery of plant composition typical of gray dunes two-years after treatments, but resulted in a biodiversity loss within the Retama understorey when rabbits were present. However, Retama clearing resulted in a significant vigor improvement of T. carnosus in the site with the highest density of Retama. Rabbit exclusion significantly increased species richness and Shannon-Wiener diversity index, and allowed the recovery of plant composition typical of gray dunes. The results suggest that shrub encroachment caused by Retama has a long-lasting negative impact on dune vegetation and that periodic clearing should be combined with rabbit exclusion at least during early restoration stages of dune vegetation. To recover the population of T. carnosus, Retama should be prevented from reaching high cover and periodic clearing without rabbit exclusion is suggested.

Pontederia cordata L. (Pontederiaceae) is an emerging aquatic plant native to the American continent that has been introduced to various continents through longdistance commerce as an ornamental plant. Individuals growing in the wild belonging to Pontederia L. genus where found in South Spain. The analysis of diagnostic characters of the collected specimens and their comparison to those represented in herbarium vouchers allowed us to distinguish them from its closest relative, P. sagittata C. Presl and to assign all the specimens found at the locality to P. cordata L. This is the southernmost European record of the species. It was clear that the origin of the introduction was the use as ornamental aquatic plant in the area. Its invasion risk was assessed for Europe, firstly, by analysing the suitability of European climate for the species, secondly, by assessing the potential impact. Results showed that from 92.5 to 92.9% of the meteorological stations analysed showed climate conditions that were compatible with the species' climatic requirements. The ecological characteristics of the species and the climatic features of the area analysed suggest a great risk of invasion that could lead to the species' spread in Europe. These findings suggest that P. cordata could threaten European wetlands.

Se informa del hallazgo de la planta acuática exótica invasora Eichhornia crassipes en la Dársena o canal Alfonso XIII, un brazo regulado del río Guadalquivir, en Sevilla (S. de la Península Ibérica). Se trata de la primera cita de esta especie para la provincia de Sevilla y se añade a diversas referencias ocasionales que existían en Andalucía., We present the finding of the invasive exotic aquatic plant Eichhornia crassipes in the Shipway or Alfonso XIII canal, a regulated tributary of the Guadalquivir river, Seville (S. Iberian Peninsula). This is the first record of this species for the province of Seville and it is added to several occasional references that previously had been reported for the Andalusian Region.

Se informa del hallazgo de la planta acuática exótica invasora Eichhornia crassipes en la Dársena o canal Alfonso XIII, un brazo regulado del río Guadalquivir, en Sevilla (S. de la Península Ibérica). Se trata de la primera cita de esta especie para la provincia de Sevilla y se añade a diversas referencias ocasionales que existían en Andalucía., We present the finding of the invasive exotic aquatic plant Eichhornia crassipes in the Shipway or Alfonso XIII canal, a regulated tributary of the Guadalquivir river, Seville (S. Iberian Peninsula). This is the first record of this species for the province of Seville and it is added to several occasional references that previously had been reported for the Andalusian Region.

Se informa del hallazgo de la planta acuática exótica invasora Eichhornia crassipes en la Dársena o canal Alfonso XIII, un brazo regulado del río Guadalquivir, en Sevilla (S. de la Península Ibérica). Se trata de la primera cita de esta especie para la provincia de Sevilla y se añade a diversas referencias ocasionales que existían en Andalucía., We present the finding of the invasive exotic aquatic plant Eichhornia crassipes in the Shipway or Alfonso XIII canal, a regulated tributary of the Guadalquivir river, Seville (S. Iberian Peninsula). This is the first record of this species for the province of Seville and it is added to several occasional references that previously had been reported for the Andalusian Region.

We present the finding of the invasive exotic aquatic plant Eichhornia crassipes in the Shipway or Alfonso XIII canal, a regulated tributary of the Guadalquivir river, Seville (S. Iberian Peninsula). This is the first record of this species for the province of Seville and it is added to several occasional references that previously had been reported for the Andalusian Region., Se informa del hallazgo de la planta acuática exótica invasora Eichhornia crassipes en la Dársena o canal Alfonso XIII, un brazo regulado del río Guadalquivir, en Sevilla (S. de la Península Ibérica). Se trata de la primera cita de esta especie para la provincia de Sevilla y se añade a diversas referencias ocasionales que existían en Andalucía.

Very few mass stranding events of invertebrates have been reported. In this paper, we report a mass stranding of multiple benthic organisms occurred at Punta Umbría beach (S Spain) after the passage of storm Emma (28 February to 5 March 2018). The most abundant organisms were identified, and exceptional meteorological and oceanographic events were analyzed, as a basis to understand the causes of stranding. The morphodynamic changes affecting the beach profile during the storm were inferred using a cross shore depth-integrated and time averaged numerical model (CSHORE). Among the stranded species, decapods (Upogebia spp., Atelecyclus undecimdentatus), sipunculids (Sipunculus nudus), starfish (Astropecten sp.), and sessile tunicates were dominant. Storm Emma involved extreme significant wave heights of up to 7.27 m, low pressures, strong SW winds, precipitations and spring tides that modified the seabed elevation to depth as deep as −10 m. Simulations suggest that benthic organisms living at a water depth between −10 to −0.3 m were buried under a layer of sediment of up to ca. 10 cm deposited during the storm. This burial preceded the transport of intertidal and subtidal benthic organisms to the dry beach, causing their stranding. Impacts on the quality of habitat, biodiversity and the productivity of coastal ecosystems are discussed.

Very few mass stranding events of invertebrates have been reported. In this paper, we report a mass stranding of multiple benthic organisms occurred at Punta Umbría beach (S Spain) after the passage of storm Emma (28 February to 5 March 2018). The most abundant organisms were identified, and exceptional meteorological and oceanographic events were analyzed, as a basis to understand the causes of stranding. The morphodynamic changes affecting the beach profile during the storm were inferred using a cross shore depth-integrated and time averaged numerical model (CSHORE). Among the stranded species, decapods (Upogebia spp., Atelecyclus undecimdentatus), sipunculids (Sipunculus nudus), starfish (Astropecten sp.), and sessile tunicates were dominant. Storm Emma involved extreme significant wave heights of up to 7.27 m, low pressures, strong SW winds, precipitations and spring tides that modified the seabed elevation to depth as deep as −10 m. Simulations suggest that benthic organisms living at a water depth between −10 to −0.3 m were buried under a layer of sediment of up to ca. 10 cm deposited during the storm. This burial preceded the transport of intertidal and subtidal benthic organisms to the dry beach, causing their stranding. Impacts on the quality of habitat, biodiversity and the productivity of coastal ecosystems are discussed.

[Background] Few women have been included in darunavir/cobicistat clinical development studies, and hardly any of them were antiretroviral experienced or treated with anything other than triple-based therapies., [Objectives] Our aim was to increase our knowledge about women living with HIV undergoing darunavir/cobicistat-based regimens., [Methods] A multicentre (21 hospitals), retrospective study including a centrally selected random sample of HIV-1 patients starting a darunavir/cobicistat-based regimen from June 2014 to March 2017 was planned. Baseline characteristics, 24 and 48 week viral load response (<50 copies/mL), CD4+ lymphocyte count increase, time to change darunavir/cobicistat and adverse event occurrence were all compared by sex. The study was approved by each of the 21 ethics committees, and patients signed informed consent., [Results] Out of 761 participants, 193 were women. Similar characteristics were found for both sexes, except that the women had a longer duration of HIV infection (P = 0.001), and were less frequently pre-treated with darunavir/cobicistat in their previous regimen (P = 0.02). The main reason for using a darunavir/cobicistat-based regimen was simplification, without differences by sex, while monotherapy seems to be more frequently prescribed in women than in men (P = 0.067). The main outcomes, HIV viral load response, CD4+ lymphocyte count increase at 24 or 48 weeks, occurrence of adverse events, main reasons for changing and time to the modify darunavir/cobicistat regimen, did not show differences between the sexes., [Conclusions] No sex disparities were found in the main study outcomes. These results support the use of a darunavir/cobicistat-based regimen in long-term pre-treated women. Clinical Trial.gov No. NCT03042390.

Despite the increasing number of invasive species, protocols devoted to assess the feasibility (i.e., probability of success or failure) of management actions in the field are scarce, yet success depends on a broad scope of issues beyond the biology of species and the ecosystem to be managed. In this paper we make a retrospective analysis of 90 actions and management proposals developed in Andalusia (southern Spain) in 2004 to 2018. Actions included 59 terrestrial and aquatic taxa. We identified items that in case of deficiency were responsible for either the rejection of action proposals (n = 44) or failure of implemented actions for which the goal was not achieved (n = 22). The most frequent deficiencies included the absence of funding during the necessary time to achieve the goals, the risk of reinvasion and an insufficient removal rate to achieve the specific objective. Based on the deficiencies found, we built a comprehensive, broadscope compliance checklist to assist decision-makers to identify deficiencies before action. In addition, implemented actions for which the goal was achieved (n = 24) were used for validating the checklist. The checklist contains 40 items related to IAS features, administrative features, methodology effectiveness, efficiency and impacts of the action, and invaded ecosystem features. The checklist is valid across all taxa and habitats. The use of this checklist will help reduce the degree of arbitrariness and subjectivity of actions aimed at managing IAS, and a more efficient use of resources.

The subtropical ocean gyres are recognized as great marine accummulation zones of floating plastic debris; however, the possibility of plastic accumulation at polar latitudes has been overlooked because of the lack of nearby pollution sources. In the present study, the Arctic Ocean was extensively sampled for floating plastic debris from the Tara Oceans circumpolar expedition. Although plastic debris was scarce or absent in most of the Arctic waters, it reached high concentrations (hundreds of thousands of pieces per square kilometer) in the northernmost and easternmost areas of the Greenland and Barents seas. The fragmentation and typology of the plastic suggested an abundant presence of aged debris that originated from distant sources. This hypothesis was corroborated by the relatively high ratios of marine surface plastic to local pollution sources. Surface circulation models and field data showed that the poleward branch of the Thermohaline Circulation transfers floating debris from the North Atlantic to the Greenland and Barents seas, which would be a dead end for this plastic conveyor belt. Given the limited surface transport of the plastic that accumulated here and the mechanisms acting for the downward transport, the seafloor beneath this Arctic sector is hypothesized as an important sink of plastic debris.

Human-driven landscape changes may promote plant invasions by increasing propagule pressure and providing favourable conditions for non-native species to establish and spread. The increase in invasion levels might not be immediate but rather exhibit a time-lag (i.e. invasion debt). Moreover, the relationship between invasion and landscape history (i.e. changes in landscape composition) might be extremely complex as it might also include extinction debts of invasive species currently in regression. In order to understand the effect of landscape history on plant invasion, we studied the invasion level in coastal plant communities affected by intense human-driven landscape alteration in the last 50 years. We identified all non-native plant species within 809 grid cells (250 × 250 m) along ~500 km of the Spanish SW coast. We tested the association of (1) non-native richness conditional on the overall presence of non-natives (at least one species), and (2) the occurrence of the most frequent non-native species, with the percentage of human land-cover categories in 1956, 1991 and 2007 using a multimodel inference approach. We used these models to project future invasion patterns in the region. We found non-native richness to be more associated with land-cover variables in 1956 than in 2007, suggesting the existence of an invasion debt, but not for the overall presence of non-natives. For most frequent species, the effects of past landscape alteration depended on the introduction pathway and the region of origin. Species used in agriculture were more related to past cropland area, while most of the species used in gardening or forestry showed higher affinity for recently altered areas. These results highlight the relevance of the species’ introduction history and landscape history in assessing future long-term invasion trends.

The deficiency in the distributional data of invertebrate taxa is one of the major impediments acting on the bias towards the low awareness of its conservation status. The present study sets a basic framework to understand the large branchiopods distribution in the Iberian Peninsula and Balearic Islands. Since the extensive surveys performed in the late 1980s, no more studies existed updating the information for the whole studied area. The present study fills the gap, gathering together all available information on large branchiopods distribution since 1995, and analysing the effect of human population density and several landscape characteristics on their distribution, taking into consideration different spatial scales (100 m, 1 km and 10 km). In overall, 28 large branchiopod taxa (17 anostracans, 7 notostracans and 4 spinicaudatans) are known to occur in the area. Approximately 30% of the sites hosted multiple species, with a maximum of 6 species. Significant positive co-occurring species pairs were found clustered together, forming 4 different associations of large branchiopod species. In general, species clustered in the same group showed similar responses to analysed landscape characteristics, usually showing a better fit at higher spatial scales.

The first records of Ipomoea imperati (Vahl) Griseb (Convolvulaceae) in the province of Cádiz are documented. This rhizomatous and creeping species is native to North America. I. imperati was found as incipient naturalized populations (between 300-750 m2) on beaches from Barbate and Algeciras municipalities. In both cases, I. imperati colonizes shifting (yellow) dunes with different levels of development. The origin of the introduction is uncertain. The risk assessment resulted in a high risk of invasion of habitats of Community interest, Se documentan los primeros registros de Ipomoea imperati (Vahl) Griseb. (Convolvulaceae) en la provincia de Cádiz. Esta especie rizomatosa y rastrera es nativa de Norteamérica y se ha encontrado formando poblaciones naturalizadas incipientes (entre 300 - 750 m 2 ) en playas de los municipios de Barbate y Algeciras. Ipomoea imperati coloniza en ambos casos dunas móviles con diferente grado de desarrollo. El origen de la introducción es incierto. La evaluación del riesgo sugiere un riesgo alto de invasión, pudiendo extenderse la invasión sobre hábitats de interés comunitario

Legislation on biological invasions has been evolving in recent decades. The use of lists of harmful alien organisms (LHAO) is becoming a widespread policy practice in many countries. LHAO aims to prevent the introduction of undesirable organisms at the pre-border level, regulate their use within the country and deter their spread. However, a systematic review and comparison of the current legislations is lacking. It remains unknown whether there are gaps or weaknesses that may compromise and effective strategy against biological invasions. In this study, a total of 77 LHAO from Australia, Japan, New Zealand, Spain, South Africa, Switzerland, the United Kingdom and the United States of America were evaluated and compared in terms of the taxonomic criteria of inclusion, the impacts of concern and the activities regulated. The number of LHAO has increased exponentially since 1924. Countries widely varied in the number of lists. Within a country, LHAO are scattered across different regulations that consider different impacts and regulate activities from introduction to management. The number of taxa ranged between 0.15 and 55.4 taxa km-2 in the USA and New Zealand, respectively. These lists totaled 21,029 records of 18,149 different taxa, showing a prevalence of taxa listed as species (rather than genera of higher ranks). Primary attention is paid to the kingdoms Animalia and Plantae. Taxa affecting livelihood/uses were more prevalent than those related to biodiversity and human health impacts. The most common regulations concern trade and tenure followed by use. This study reveals the need for more comprehensive (intersectoral) regulations on invasive alien species within countries as well as the development of homogeneous regulations adapted to the globalized world.

There is a rising concern regarding the accumulation of floating plastic debris in the open ocean. However, the magnitude and the fate of this pollution are still open questions. Using data from the Malaspina 2010 circumnavigation, regional surveys, and previously published reports, we show a worldwide distribution of plastic on the surface of the open ocean, mostly accumulating in the convergence zones of each of the five subtropical gyres with comparable density. However, the global load of plastic on the open ocean surface was estimated to be on the order of tens of thousands of tons, far less than expected. Our observations of the size distribution of floating plastic debris point at important size-selective sinks removing millimeter-sized fragments of floating plastic on a large scale. This sink may involve a combination of fast nano-fragmentation of the microplastic into particles of microns or smaller, their transference to the ocean interior by food webs and ballasting processes, and processes yet to be discovered. Resolving the fate of the missing plastic debris is of fundamental importance to determine the nature and significance of the impacts of plastic pollution in the ocean.

determinados usos del suelo pueden actuar como fuente de propágulos de plantas exóticas o propiciar condiciones favorables para su establecimiento, derivando en procesos de invasión con grandes impactos en la biodiversidad. Nuestro objetivo ha sido entender los efectos de la antropización del paisaje litoral desde 1956 a 2007 en la riqueza de plantas exóticas. Identificamos todas las especies vegetales exóticas a lo largo de transectos recorriendo 381 Km de la costa del Sudoeste español. Estudiamos la asociación de la riqueza de exóticas con el clima, cubiertas de suelo en 1956, 1991 y 2007, intensidad de antropización entre 1956 y 2007 y área protegida. Encontramos una asociación positiva entre la riqueza de exóticas y el área antropizada. En cambio, la intensidad de antropización o área protegida no presentaron asociación. La asociación fue mayor considerando el paisaje de 1956, reflejando un posible crédito de invasión.

Vernal pools are preferred breeding habitats for numerous amphibian species. The analysis of prey composition during the amphibian larval stages is necessary to understand diet composition and food choice in aquatic communities. We studied the diet of larvae of Pleurodeles waltl when exogenous feeding begins and throughout the flooding period in an episodic Mediterranean pond. The stomach contents were analyzed and the diet was compared to the availability of prey in the pond. The diet analysis revealed an ample diversity of prey, the most abundant being cyclopoid and calanoid copepods and podocopid ostracods. Changes in the composition of the diet corresponded principally to the variations in the availability of different prey as a consequence of the succession of the zooplankton community throughout the flooding period. However, certain taxa such as large anostracans, small anomopods, and turbellarias were not consumed although they were available and abundant. In contrast, prey scarcely represented in the pond such as coleopteran, dipteran, and hemipteran larvae were efficiently captured, suggesting their accessibility to newt larvae. The proportion of prey found in stomachs with respect to their abundance in the pond increased with larval size, coinciding with a reduction in number and bio-volume of available prey. The results suggest that newt larvae are opportunistic feeders and that breeding success of newts may be highly dependent on early egg-laying to match the abundant food supply found at early flooding stages of vernal pools. © 2012 by the American Society of Ichthyologists and Herpetologists.

We investigated the phylogeography of the main lineages in the tadpole shrimp Triops mauritanicus Ghigi in the south-western Iberian Peninsula, using mito- chondrial 12S and 16S rDNA sequences. Our results indicate that a fourth, hitherto unknown main phylogenetic lineage occurs in Iberia, so that in total, the species is divided into six distinct clades, comprising T. m. mauritanicus, T. m. simplex Ghigi, and four as yet unnamed lineages that appear to be endemic to Iberia. Percentages of sequence divergence among the main clades in T. mauritanicus reach the range reported for recognized species in other notostracan lineages. A thorough morphological investigation also revealed that the differentiation among these lineages is higher than previously thought, and that populations of three of the main clades within T. mauritanicus can be reliably separated from each other and from the remaining lineages based on the morphology of adult males. The remaining clades also show a significant level of morphological differentiation, but include a certain proportion of populations for which the additional application of molecular methods is needed for a reliable determination. The geographic distribu- tions of 12S haplotypes are indicative of frequent dispersal events and gene flow among populations belonging to the same main lineage, but give no evidence of recent migration events among different main lineages, suggesting that there is no gene flow among the latter. Our data thus suggest that the six main lineages within T. mauritanicus represent distinct species. We therefore describe the Iberian lineages as T. baeticus Korn n. sp., T. emeritensis Korn & Pérez-Bote n. sp., T. gadensis Korn & García-de-Lomas n. sp., and T. vicentinus Korn, Machado, Cristo & Cancela da Fonseca n. sp., and reinstate T. simplex Ghigi to full species status. Our data confirm the general, previously recognized pattern of a lower dispersal probability in gonochoric Triops taxa. However, we found e

Biogenic production of sulfide in wastewater treatment plants involves odors, toxicity and corrosion problems. The production of sulfide is a consequence of bacterial activity, mainly sulfate-reducing bacteria (SRB). To prevent this production, the efficiency of nitrate addition to wastewater was tested at plant-scale by dosing concentrated calcium nitrate (Nutriox™) in the works inlet. Nutriox™ dosing resulted in a sharp decrease of sulfide, both in the air and in the bulk water, reaching maximum decreases of 98.7% and 94.7%, respectively. Quantitative molecular microbiology techniques indicated that the involved mechanism is the development of the nitrate-reducing, sulfide-oxidizing bacterium Thiomicrospira denitrificans instead of the direct inhibition of the SRB community. Denitrification rate in primary sedimentation tanks was enhanced by nitrate, being this almost completely consumed. No significant increase of inorganic nitrogen was found in the discharged effluent, thus reducing potential environmental hazards to receiving waters. This study demonstrates the effectiveness of nitrate addition in controlling sulfide generation at plant-scale, provides the mechanism and supports the environmental adequacy of this strategy.