Stranding and mass mortality in humboldt penguins (Spheniscus humboldti), associated to HPAIV H5N1 outbreak in Chile.

The highly pathogenic Avian Influenza virus (HPAIV) H5N1 has caused a global outbreak affecting both wild and domestic animals, predominantly avian species. To date, cases of the HPAIV H5 Clade 2.3.4.4b in penguins have exclusively been reported in African Penguins. In Chile, the virus was confirmed in pelicans in December 2022 and subsequently spread across the country, affecting several species, including Humboldt penguins. This study aims to provide an overview of the incidents involving stranded and deceased Humboldt penguins and establish a connection between these events and HPAIV H5N1. Historical data about strandings between 2009 and 2023 was collected, and samples from suspected cases in 2023 were obtained to confirm the presence of HPAIV H5N1. Between January and August 2023, 2,788 cases of stranded and deceased penguins were recorded. Out of these, a total of 2,712 penguins deceased, evidencing a significative increase in mortality starting in early 2023 coinciding with the introduction and spreading of HPAIV H5N1 in the country. Thirty-seven events were categorized as mass mortality events, with the number of deceased penguins varying from 11 to 98. Most cases (97 %) were observed in the North of Chile. One hundred and eighty-one specimens were subjected to HPAIV diagnosis, four of which tested positive for HPAIV H5N1. Spatial analysis validates the correlation between mass mortality events and outbreaks of HPAIV in Chile. However, the limited rate of HPAIV H5N1 detection, which can be attributed to the type and quality of the samples, requiring further exploration.

Uneven demographic consequences of the 2022 disease outbreak for the sea urchin Diadema antillarum in Puerto Rico.

Pervasive epizootic events have had a significant impact on marine invertebrates throughout the Caribbean, leading to severe population declines and consequential ecological implications. One such event was the regional collapse of herbivory, partly caused by the Diadema antillarum mortality event in 1983-84, resulting in a trophic cascade and altering the structure of reef communities. Consequently, there was a notable decrease in coral recruitment and an increase in the coverage of macroalgae. Nearly four decades later, in early 2022, the Caribbean basin experienced another widespread mass mortality event, further reducing the populations of D. antillarum. To assess the effects of this recent mortality event on the current demographics of D. antillarum, we surveyed eight populations along the eastern, northeastern, northern, and northwestern coast of Puerto Rico from May to July 2022, estimating their population density, size distribution, and disease prevalence. Additionally, the study compared these population parameters with data from four sites previously surveyed in 2012 and 2017 to understand the impact of the recent mortality event. The survey conducted in 2022 showed varying population densities at the surveyed reefs. Some populations exhibited mean densities of nearly one individual per square meter, while others had extremely low or no living individuals per square meter. The four populations with the highest density showed no evidence of disease, whereas the four populations with the lowest D. antillarum densities exhibited moderate to high disease prevalence. However, when considering all sites, the estimated disease prevalence remained below 5%. Nevertheless, the comparison with data from 2012 and 2017 indicated that the recent mortality event had a negative impact on D. antillarum demographics at multiple sites, as the densities in 2022 were reduced by 60.19% compared to those from the previous years. However, it is still too early to determine the severity of this new mortality event compared to the 1983-84 mortality event. Therefore, it is imperative to continue monitoring these populations.

Taxonomic identity of Distapliastylifera (Tunicata, Ascidiacea), a new arrival to the eastern Pacific displaying invasive behavior in the Gulf of California, Mexico.

A colonial ascidian of the genus Distaplia caused a mass mortality of the pen shell Atrinamaura (Sowerby, 1835) during June 2016 in the southwest of the Gulf of California (Mexico), with a significant socio-economic cost. Tentatively identified in previous works as Distapliacf.stylifera, a precise taxonomic determination was still lacking. In the present work, based on a detailed morphological study, it is confirmed that this aggressive species is Distapliastylifera (Kowalevsky, 1874). Originally described from the Red Sea, the species currently has a wide circumtropical distribution (with the exception of the Eastern Pacific to date) and is reported as introduced in parts of its range. The present account thus represents an important range extension of this species. However, when revising the original description and later observations, the reported variability of several characters makes it likely that the binomen is in fact a complex of species, as is common in other ascidians with wide distributions. A complete morphological and genetic study including populations from the entire range of distribution would be necessary to settle the status of D.stylifera. Taxonomic uncertainties hinder a correct interpretation of biogeographical patterns and inference on the origin of the studied population. Nevertheless, the known introduction potential of the species, coupled with an explosive growth in an anthropized environment, and the lack of any previous reports in the Eastern Pacific, strongly suggest that the investigated population represents yet another instance of ascidian introduction. From the point of view of management, its invasive behavior is cause for great concern and warrants mitigation measures.

Enterogyrus spp. (Monogenea: Ancyrocephalinae) and Aeromonas jandaei co-infection associated with high mortality following transport stress in cultured Nile tilapia.

Monogenean infection of the internal organs is extremely rare when compared to external infections. This study describes mass mortality of Nile tilapia (Oreochromis niloticus L.) originating from co-infection with Enterogyrus spp. and Aeromonas jandaei following transport stress. The first fish deaths occurred on day 1 post-transport, while cumulative mortality reached approximately 90% by day 10 post-stocking. An atypical amount of pale (whitish) faeces floating on the surface of the water as well as typical clinical signs of motile Aeromonas septicemia, were reported. Adult monogeneans and countless eggs of monogeneans were found in the stomachs and the intestines of both moribund and dead fish, respectively. Two strains of A. jandaei were isolated from the kidneys. Scanning electron microscope microphotographs of the stomach revealed the presence of numerous monogeneans penetrating deep into the gastric tissue, and diffuse lesions filled with bacilliform bacteria. Histopathological examination showed multifocal eosinophilic infiltrate, gastric gland and epithelial necrosis with sloughed necrotic debris in the lumen. This is the first report of co-infection by Enterogyrus spp. and A. jandaei in Nile tilapia and the first report of Enterogyrus coronatus, Enterogyrus foratus, and Enterogyrus malbergi parasitizing tilapia in Brazil. These findings indicate that synergic co-infection by Monogenean stomach parasites (E. coronatus, E. foratus, and E. malbergi) and A. jandaei may induce high mortalities in tilapia following transport stress.

Disease-driven mass mortality event leads to widespread extirpation and variable recovery potential of a marine predator across the eastern Pacific.

The prevalence of disease-driven mass mortality events is increasing, but our understanding of spatial variation in their magnitude, timing and triggers are often poorly resolved. Here, we use a novel range-wide dataset comprised 48 810 surveys to quantify how sea star wasting disease affected Pycnopodia helianthoides, the sunflower sea star, across its range from Baja California, Mexico to the Aleutian Islands, USA. We found that the outbreak occurred more rapidly, killed a greater percentage of the population and left fewer survivors in the southern half of the species's range. Pycnopodia now appears to be functionally extinct (greater than 99.2% declines) from Baja California, Mexico to Cape Flattery, Washington, USA and exhibited severe declines (greater than 87.8%) from the Salish Sea to the Gulf of Alaska. The importance of temperature in predicting Pycnopodia distribution rose more than fourfold after the outbreak, suggesting latitudinal variation in outbreak severity may stem from an interaction between disease severity and warmer waters. We found no evidence of population recovery in the years since the outbreak. Natural recovery in the southern half of the range is unlikely over the short term. Thus, assisted recovery will probably be required to restore the functional role of this predator on ecologically relevant time scales.

Condición del arrecife coralino de Playa Blanca, Punta Gorda, uno de los arrecifes más extensos de la costa Pacífica de Costa Rica / Condition of the Playa Blanca coral reef, Punta Gorda, one of the most extensive reefs on the Pacific of Costa Rica

Introducción: Los arrecifes coralinos son afectados negativamente por diferentes causas antropogénicas y ambientales en el Golfo de Papagayo. Objetivo: En esta investigación, la condición del arrecife coralino de Playa Blanca fue evaluado. Métodos: Entre agosto de 2010 y setiembre de 2011 el porcentaje de coral vivo por especie y del alga Caulerpa sertularoides fue determinado; el crecimiento anual de P. damicornis y P. elegans fue medido y relacionado con variables ambientales. Resultados: Se encontraron 14 especies de corales, dos de ellas, F. curvata y L. papyracea, únicamente como esqueletos. La zona con la mayor cobertura fue en la zona media de la playa. La especie con mayor CCV en todos los ámbitos de profundidad fue P. damicornis, seguido de P. elegans. La CCV descendió de 29 % en septiembre 2010 a 1 % en octubre 2010. La mortalidad masiva fue causada por una Floración Algal Nociva (FAN). La tasa de crecimiento de P. damicornis (26.0 ± 8.9 mm año-1) y de P. elegans (27.9 ± 4.5 mm año-1), no mostraron diferencias significativas entre profundidades ni por ubicación en el arrecife. Conclusiones: El exuberante arrecife de coral de Playa Blanca experimentó una regresión repentina de la CCV similar a las descritas por Glynn et al. (1983). Esto sugiere que ocurren ciclos de mortalidad y recuperación natural de los arrecifes de coral, aunque las presiones antropogénicas reducen la capacidad de resiliencia de estos. El ordenamiento espacial, tanto en tierra como en el mar, es vital para un adecuado desarrollo humano, en el que se incorpore en el análisis el aumento de la capacidad de recuperación de los ecosistemas coralinos.

Introduction: Coral reefs are negatively affected by different anthropogenic and environmental causes in the Gulf of Papagayo, Costa Rican Pacific coast. Objective: The health status of the Playa Blanca coral reef was evaluated. Methods: Between August 2010 and September 2011, the percentage of live coral cover (LCC) per species and of the macroalgae Caulerpa sertularoides was determined in four sectors and at three depths of the coral reef; the annual growth of Pocillopora damicornis and P. elegans was measured and related to temperature, nutrients, wind, sun irradiation and rain. Results: 14 species of corals were found, two of them, Fungia curvata and Leptoseris papyracea, only as skeletons. The area with the highest LCC was offshore in the middle zone of Playa Blanca. The species with the highest coverage in all depth ranges was P. damicornis, followed by P. elegans. The LCC decreased from 29% in September 2010 to 1% in October 2010 due to a mass coral mortality caused by harmful algal blooms. The growth rate of P. damicornis (26.0 ± 8.9 mm year-1) and P. elegans (27.9 ± 4.5 mm year-1) did not show significant differences between depths or location in the reef. Conclusions: The exuberant Playa Blanca coral reef experienced a sudden drop in LCC similar to those described by Glynn et al. (1983). This suggests that cycles of mortality and natural recovery of coral reefs occur, although anthropogenic pressures reduce the resilience capacity of the reefs. Spatial planning, both on land and in the sea, is vital for adequate human development, in which the increase in the resilience of coral ecosystems is incorporated into the analysis.

Lack of recovery of the long-spined sea urchin Diadema antillarum Philippi in Puerto Rico 33 years after the Caribbean-wide mass mortality.

Caribbean populations of the long-spined black sea urchin Diadema antillarum Philippi were decimated by a disease-induced mass mortality in the early 1980's. The present study provides an updated status of the D. antillarum recovery and population characteristics in La Parguera Natural Reserve, Puerto Rico. The last detailed study to assess population recovery in 2001, indicated a slow, and modest recovery, albeit densities remained far below pre-mass mortality levels. Population densities were assessed along three depth intervals in six reef localities and one depth in three lagoonal sea-grass mounds using ten 20 m2 (10 × 2 m) belt-transects at each depth interval. Most of these were previously surveyed in 2001. All individuals encountered along the belt transects were sized in situ with calipers and rulers to characterize the size (age) structure of each population and get insight into the urchin's population dynamics and differences across localities in the area. Habitat complexity (rugosity) was assessed in all depth intervals. No significant differences in population densities between reef zones (inner shelf and mid-shelf) were observed, but significantly higher densities were found on shallow habitats (<5 m depth; 2.56 ± 1.6 ind/m2) compared to intermediate (7-12 m; 0.47 ± 0.8 ind/m2) and deep (>12 m; 0.04 ± 0.08 ind/m2) reef habitats in almost all sites surveyed. Habitat complexity had the greatest effect on population densities at all levels (site, zone and depth) with more rugose environments containing significantly higher densities and wider size structures. Comparison between survey years revealed that D. antillarum populations have not increased since 2001, and urchins seem to prefer shallower, more complex and productive areas of the reef. Populations were dominated by medium to large (5-9 cm in test diameter) individuals and size-frequency distributions indicated that smaller juveniles were virtually absent compared to 2001, which could reflect a recruitment-limited population and explain in part, the lack of increase in population densities. The limited temporal scale of this study, high horizontal movement of individuals along the complex, shallower reef and inshore habitats could also explain the general decline in mean densities. Other extrinsic factors affecting reproductive output and/or succesful recruitment and survival of juveniles likely contribute to the high variablility in population densities observed over time.

Stable isotope records of sei whale baleens from Chilean Patagonia as archives for feeding and migration behavior.

Carbon (δ13C) and nitrogen (δ15N) stable isotope variations in baleen plates of sei whales (Balaenoptera borealis) stranded after a mass mortality event in Chilean Patagonia were investigated to assess potential dietary and migratory patterns. Carbon and nitrogen isotope ratios of seven baleens from six individuals were analyzed. The δ13C values ranged from - 19.1 to - 15.9‰ and the δ15N values from 8.7 to 15.4‰. Variations of up to 2.9‰ for δ13C and 5.3‰ for δ15N were observed within one baleen. Carbon and nitrogen isotope records of each baleen were significantly correlated and showed recurring oscillations confirmed by wavelet analyses. Oscillations slightly differed in periodicity indicating variable baleen growth rates between 10.0 and 16.5 cm/year. Food sources of the whales are discussed in terms of available isotope data for potential prey taxa and potential migratory behavior on the basis of latitudinal isotope gradients of particulate organic matter. Cyclicity could be explained by regular migrations of the sei whales from subtropical calving areas to high-latitude foraging grounds. δ15N records of baleens differed between individuals eventually pointing to diverse feeding and migratory preferences among sei whale individuals.

Paralytic Shellfish Toxins in Surf Clams Mesodesma donacium during a Large Bloom of Alexandrium catenella Dinoflagellates Associated to an Intense Shellfish Mass Mortality.

In late February 2016, a harmful algal bloom (HAB) of Alexandrium catenella was detected in southern Chiloé, leading to the banning of shellfish harvesting in an extended geographical area (~500 km). On April 24, 2016, this bloom produced a massive beaching (an accumulation on the beach surface of dead or impaired organisms which were drifted ashore) of surf clams Mesodesma donacium in Cucao Bay, Chiloé. To determine the effect of paralytic shellfish poisoning (PSP) toxins in M. donacium, samples were taken from Cucao during the third massive beaching detected on May 3, 2016. Whole tissue toxicity evidence a high interindividual variability with values which ranged from 1008 to 8763 µg STX eq 100 g-1 and with a toxin profile dominated by GTX3, GTX1, GTX2, GTX4, and neoSTX. Individuals were dissected into digestive gland (DG), foot (FT), adductor muscle (MU), and other body fractions (OBF), and histopathological and toxin analyses were carried out on the obtained fractions. Some pathological conditions were observed in gill and digestive gland of 40⁻50% of the individuals that correspond to hemocyte aggregation and haemocytic infiltration, respectively. The most toxic tissue was DG (2221 µg STX eq 100 g-1), followed by OBF (710 µg STX eq 100 g-1), FT (297 µg STX eq 100 g-1), and MU (314 µg STX eq 100 g-1). The observed surf clam mortality seems to have been mainly due to the desiccation caused by the incapability of the clams to burrow. Considering the available information of the monitoring program and taking into account that this episode was the first detected along the open coast of the Pacific Ocean in southern Chiloé, it is very likely that the M. donacium population from Cucao Bay has not had a recurrent exposition to A. catenella and, consequently, that it has not been subjected to high selective pressure for PSP resistance. However, more research is needed to determine the effects of PSP toxins on behavioral and physiological responses, nerve sensitivity, and genetic/molecular basis for the resistance or sensitivity of M. donacium.

Diadema antillarum on St. Croix, USVI: Current Status and Interactions with Herbivorous Fishes.

The 1983-84 mass mortality of the long-spined sea urchin, Diadema antillarum, intensified the loss of herbivory that was a major factor in the degradation of coral reefs in the wider Caribbean. As determined from recent surveys, densities of D. antillarum populations at back reef locations on St. Croix, US Virgin Islands, are higher than densities immediately following the die-off - but still about an order of magnitude below pre-die-off densities and patchy in both time and space. Comparisons to similar surveys during the past twelve years and to earlier historical records indicate that recovery on St. Croix continues at the very slow rate that typified the first decade after the mass mortality. Populations of herbivorous fishes on St. Croix surged following the D. antillarum die-off but have experienced heavy fishing pressure ever since then. Reciprocal densities of D. antillarum versus roaming grazers (parrotfishes and surgeonfishes) on survey transects and stationary point counts indicate that negative interaction between these two groups is present despite the reductions to their populations during the last 35 years.

Octocoral densities and mortalities in Gorgona Island, Colombia, Tropical Eastern Pacific / Densidades y mortalidades de octocorales en Isla Gorgona, Colombia, Pacífico Oriental Tropical

Owing to the decrease of reef organisms in general, it has become essential to study populations that are prone to marine diseases, with the purpose of developing accurate survivorship predictions and in turn alarm on triggers and drivers of disease outbreaks. In this study, we quantified the octocorals of Gorgona island, Tropical Eastern Pacific (Colombia), during 2007 and 2009 documenting a mass mortality occurred during 2008. We recorded 16 octocoral species with densities that ranged between 2 and 30 colonies m-2. Most abundant octocorals were Leptogorgia alba and Pacifigorgia spp. (Gorgoniidae: Octocorallia). During 2009 we noticed a mass mortality involving Pacifigorgia irene, P. adamsi, P. rubicunda and P. eximia, with a reduction of 70% of the colonies between 12 and 20 m in water depth. Around 5% of seafans during 2007 had an epizootic disease similar to aspergillosis, which seems the cause of the mass octocoral mortality. This disease outbreak observed in Gorgona island, and other nearby areas of the Colombian Pacific during 2007-2010, corresponded to extended periods of anomalous elevated seawater surface temperatures and thermal anomalies during the upwelling season of 2008. Constant monitoring of seawater temperatures and octocoral populations are urgently needed in this area to understand the nature of this new disease outbreak. Rev. Biol. Trop. 62 (Suppl. 1): 209-219. Epub 2014 February 01.

Debido a la disminución de los organismos de los arrecifes en general, es fundamental conocer las poblaciones de organismos propensos a enfermedades marinas, con el propósito de desarrollar predicciones precisas de supervivencia y a su vez dar la alarma sobre los motivos y las causas de los brotes de las enfermedades. En este estudio, hemos cuantificado los octocorales de la Isla Gorgona, Pacífico Oriental Tropical (Colombia), durante 2007 y 2009, y documentamos una mortalidad masiva que se produjo durante el año 2008. Se registraron 16 especies de octocorales con densidades que oscilan entre 2 y 30 colonias m-2. Los octocorales más abundantes fueron Leptogorgia alba y Pacifigorgia spp. (Gorgoniidae: Octocorallia). Durante el año 2009 nos dimos cuenta de una mortalidad masiva que afectaba a Pacifigorgia irene, P. adamsi, P. rubicunda y P. eximia, con una reducción del 70% de las colonias entre 12 y 20 m de profundidad. Alrededor del 5% de los abanicos de mar durante el año 2007 tenían una epizootia similar a la aspergilosis, que parece ser la causa de la mortalidad masiva de octocorales. Este brote de la enfermedad observada en la Isla Gorgona, y otras zonas cercanas del Pacífico colombiano durante el período 2007-2010, corresponden a períodos prolongados de altas temperaturas superficiales del mar y de anomalías térmicas durante la temporada de surgencia durante 2008. Se necesita con urgencia un monitoreo constante de las temperaturas marinas y de las poblaciones de octocorales en esta área para comprender la naturaleza de este nuevo brote de enfermedad marina.

Estructura de la comunidad de esponjas (Porifera) en tres arrecifes del Parque Nacional Morrocoy, Venezuela y su relación con algunas variables ambientales / Community structure of sponges (Porifera) in three reefs at Morrocoy National Park, Venezuela and its correspondence with some environmental variables

Sponges have an important ecological role in coral reef ecosystems. However, when compared to other benthic Phyla, it has been little researched. This research was focused in the variability of the community structure of sponges in three locations at Morrocoy National Park (Cayo Sombrero, Playa Mero and Punta Brava) exposed to different environmental conditions (transparency and currents intensity) and affected in different degree of severity by a mass mortality event in 1996. A total of 15 transects (10m long and 1m wide) were evaluated in three strata (between 3 and 15m depth) in each site, where all the individuals were counted by species. Relative abundance by species, diversity and evenness were calculated. Locations showed differences respect turbidity, wave and current intensity. 27 species were found in Morrocoy; Cayo Sombrero (23), Playa Mero (18) and Punta Brava (15). Agelas sceptrum, Amphimedon erina and Niphates erecta were the most common in first location; Niphates erecta and Dysidea etheria in Playa Mero and Dysidea etheria, Niphates erecta and Amphimedon erina in Punta Brava. The species composition showed statistical differences between all three locations; Cayo Sombrero resulted the most diverse and even, followed by Playa Mero and Punta Brava. According to Sorensen Similarity Index results, Cayo Sombrero and Playa Mero were more similar, while Punta Brava resulted the most different. The variability in environmental conditions and the differential mass mortality effects of 1996 in all three reefs, were probably the main causes of the differences between their sponge communities. Nevertheless, we cannot conclude about the weight of these factors.

El presente estudio pone en evidencia la variación en la estructura de la comunidad de esponjas en tres localidades del Parque Nacional Morrocoy (Cayo Sombrero, Playa Mero y Punta Brava) con distintas condiciones ambientales y afectadas diferencialmente por una mortalidad masiva ocurrida en 1996. En un total de 15 transectos de 10m de largo y 1m de ancho en cuatro estratos comprendidos entre 3 y 15m de profundidad en cada localidad; se contabilizaron los individuos por especie para calcular la abundancia relativa, diversidad y equidad. Se analizaron las variables ambientales por localidad y se aprecian diferencias entre ellas con respecto a la corriente, turbidez, y exposición al oleaje. Fueron totalizadas 27 especies; Cayo Sombrero (23), Playa Mero (18) y Punta Brava (15), en la primera localidad domina: Agelas sceptrum, Amphimedon erina y Niphates erecta, en Playa Mero: Niphates erecta y Dysidea etherea y en Punta Brava: Dysidea etherea, Niphates erecta y Amphimedon erina. La composición de especies mostró diferencias estadísticamente significativas entre localidades. La mayor diversidad y equidad correspondió a Cayo Sombrero; donde las condiciones fueron más favorables para el crecimiento de estos organismos, seguido de Playa Mero y Punta Brava, guardando las dos primeras mayor similitud entre sí, según Índice de Sorensen.

Cianobacterial bloom and animal mass mortality in a reservoir from Central Argentina / Florescimento de cianobactérias e mortalidade em massa de animais em um reservatório da Argentina Central

Piedras Moras reservoir (32° 10'27" S and 64° 16' 29" W; 832 ha), integrates a series of artificial lakes belonging to the Rio Tercero basin (Córdoba, Argentina). During March 2009 an algal bloom occurred, coinciding with several animal species mortality, mainly wild birds. The goal of this work was to establish the trophic status of the reservoir in relation to that mortality. Variables were evaluated in situ (temperature and water transparency) and samples were taken in order to identify algal species, Chl-a concentration (spectrophotometry) and toxins - total microcystines- (inmuno-enzymatic assay, ELISA). Histopathology studies were made on Fulica sp. A strong heterogenity in water transparency was observed, and "patches" of Potamogeton berteroanus distributed all along the lake, with Secchi disk minimal and medium values of 0.15 and 0.94 m. Chl-a concentration oscillated from 35.7 to 320.9 mg.m-3. Predominant phytoplankton species were Anabaena spiroides and Microcystis aeruginosa (Cyanophyceae). Water temperature was 27.8 °C (±0.88). Maximal value of total microcystine concentration was 0.23 μg.L-1. Chl-a concentration at the moment when mass mortality occurred (2.022 mg.m-3), and histopathological observations, strongly suggest that the animals' death was due to cianotoxins.

O reservatório de Piedras Moras (32° 10'27" S e 64° 16' 29" W; 832 ha) faz parte de uma série de lagos artificiais que estão localizados na bacia do rio Tercero (Córdoba, Argentina). Durante março de 2009, ocorreu um florescimento maciço de cianobactérias que resultou na morte de muitas espécies de animais, especialmente aves aquáticas silvestres. O objetivo deste trabalho foi o de estabelecer o estado trófico do reservatório em função desta mortalidade. As variáveis foram avaliadas in situ (temperatura e transparência da água). Foram coletadas amostras para analisar as espécies de algas encontradas nos florescimentos. Foram determinados chl-a (espectrofotometria) e toxinas (microcistinas totais - ensaio imunoenzimático ELISA). Estudos histopalógicos foram realizados em Fulica sp. Uma grande heterogeneidade em transparência de água foi observada e agrupamentos de Potamogeton berteroanus estavam distribuídos em todo o reservatório com valores mínimos e médios do disco de Secchi de 0,15 a 0,54 m. Concentrações de chl-a oscilaram de 35,7 a 320,9 mg.m-3. As espécies fitoplanctônicas dominantes identificadas foram Anabaena spiroides e Microcystis aeruginosa (Cyanophyceae). A temperatura da água foi de 27,8 °C (±0.88). O valor máximo de concentração de microcistinas foi de 0,23 µg.L-1. A concentração de chl-a, quando ocorreu a mortalidade em massa (2,022 mg.m-3), e as lesões histopatológicas indicam que a mortalidade de animais foi devida a cianotoxinas.

Cianobacterial bloom and animal mass mortality in a reservoir from Central Argentina

Piedras Moras reservoir (32° 10'27" S and 64° 16' 29" W; 832 ha), integrates a series of artificial lakes belonging to the Rio Tercero basin (Córdoba, Argentina). During March 2009 an algal bloom occurred, coinciding with several animal species mortality, mainly wild birds. The goal of this work was to establish the trophic status of the reservoir in relation to that mortality. Variables were evaluated in situ (temperature and water transparency) and samples were taken in order to identify algal species, Chl-a concentration (spectrophotometry) and toxins - total microcystines- (inmuno-enzymatic assay, ELISA). Histopathology studies were made on Fulica sp. A strong heterogenity in water transparency was observed, and "patches" of Potamogeton berteroanus distributed all along the lake, with Secchi disk minimal and medium values of 0.15 and 0.94 m. Chl-a concentration oscillated from 35.7 to 320.9 mg.m-3. Predominant phytoplankton species were Anabaena spiroides and Microcystis aeruginosa (Cyanophyceae). Water temperature was 27.8 °C (±0.88). Maximal value of total microcystine concentration was 0.23 g.L-1. Chl-a concentration at the moment when mass mortality occurred (2.022 mg.m-3), and histopathological observations, strongly suggest that the animals' death was due to cianotoxins.

O reservatório de Piedras Moras (32° 10'27" S e 64° 16' 29" W; 832 ha) faz parte de uma série de lagos artificiais que estão localizados na bacia do rio Tercero (Córdoba, Argentina). Durante março de 2009, ocorreu um florescimento maciço de cianobactérias que resultou na morte de muitas espécies de animais, especialmente aves aquáticas silvestres. O objetivo deste trabalho foi o de estabelecer o estado trófico do reservatório em função desta mortalidade. As variáveis foram avaliadas in situ (temperatura e transparência da água). Foram coletadas amostras para analisar as espécies de algas encontradas nos florescimentos. Foram determinados chl-a (espectrofotometria) e toxinas (microcistinas totais - ensaio imunoenzimático ELISA). Estudos histopalógicos foram realizados em Fulica sp. Uma grande heterogeneidade em transparência de água foi observada e agrupamentos de Potamogeton berteroanus estavam distribuídos em todo o reservatório com valores mínimos e médios do disco de Secchi de 0,15 a 0,54 m. Concentrações de chl-a oscilaram de 35,7 a 320,9 mg.m-3. As espécies fitoplanctônicas dominantes identificadas foram Anabaena spiroides e Microcystis aeruginosa (Cyanophyceae). A temperatura da água foi de 27,8 °C (±0.88). O valor máximo de concentração de microcistinas foi de 0,23 µg.L-1. A concentração de chl-a, quando ocorreu a mortalidade em massa (2,022 mg.m-3), e as lesões histopatológicas indicam que a mortalidade de animais foi devida a cianotoxinas.

Cianobacterial bloom and animal mass mortality in a reservoir from Central Argentina

Piedras Moras reservoir (32° 10'27" S and 64° 16' 29" W; 832 ha), integrates a series of artificial lakes belonging to the Rio Tercero basin (Córdoba, Argentina). During March 2009 an algal bloom occurred, coinciding with several animal species mortality, mainly wild birds. The goal of this work was to establish the trophic status of the reservoir in relation to that mortality. Variables were evaluated in situ (temperature and water transparency) and samples were taken in order to identify algal species, Chl-a concentration (spectrophotometry) and toxins - total microcystines- (inmuno-enzymatic assay, ELISA). Histopathology studies were made on Fulica sp. A strong heterogenity in water transparency was observed, and "patches" of Potamogeton berteroanus distributed all along the lake, with Secchi disk minimal and medium values of 0.15 and 0.94 m. Chl-a concentration oscillated from 35.7 to 320.9 mg.m-3. Predominant phytoplankton species were Anabaena spiroides and Microcystis aeruginosa (Cyanophyceae). Water temperature was 27.8 °C (±0.88). Maximal value of total microcystine concentration was 0.23 g.L-1. Chl-a concentration at the moment when mass mortality occurred (2.022 mg.m-3), and histopathological observations, strongly suggest that the animals' death was due to cianotoxins.

O reservatório de Piedras Moras (32° 10'27" S e 64° 16' 29" W; 832 ha) faz parte de uma série de lagos artificiais que estão localizados na bacia do rio Tercero (Córdoba, Argentina). Durante março de 2009, ocorreu um florescimento maciço de cianobactérias que resultou na morte de muitas espécies de animais, especialmente aves aquáticas silvestres. O objetivo deste trabalho foi o de estabelecer o estado trófico do reservatório em função desta mortalidade. As variáveis foram avaliadas in situ (temperatura e transparência da água). Foram coletadas amostras para analisar as espécies de algas encontradas nos florescimentos. Foram determinados chl-a (espectrofotometria) e toxinas (microcistinas totais - ensaio imunoenzimático ELISA). Estudos histopalógicos foram realizados em Fulica sp. Uma grande heterogeneidade em transparência de água foi observada e agrupamentos de Potamogeton berteroanus estavam distribuídos em todo o reservatório com valores mínimos e médios do disco de Secchi de 0,15 a 0,54 m. Concentrações de chl-a oscilaram de 35,7 a 320,9 mg.m-3. As espécies fitoplanctônicas dominantes identificadas foram Anabaena spiroides e Microcystis aeruginosa (Cyanophyceae). A temperatura da água foi de 27,8 °C (±0.88). O valor máximo de concentração de microcistinas foi de 0,23 µg.L-1. A concentração de chl-a, quando ocorreu a mortalidade em massa (2,022 mg.m-3), e as lesões histopatológicas indicam que a mortalidade de animais foi devida a cianotoxinas.