Atrato River Basin Research Articles

Biomonitoring of Mercury and Lead Levels in the Blood of Children Living near a Tropical River Impacted by Artisanal and Small-Scale Gold Mining in Colombia.

(1) Background: Mercury and lead contamination resulting from various anthropogenic activities represents a global environmental problem and a considerable risk to the health of the human population. (2) Methods: The objective of this research was to evaluate the concentrations of mercury (Hg) and Lead (Pb) in the blood of the child population in the municipalities in the Atrato River basin using a direct Hg analyzer and graphite furnace atomic absorption spectrometry. (3) Results: In total, 171 children (5-14 years of age) were taken into account, and 18.71% (32) of the children had concentrations of Hg and Pb above the permissible values established by the WHO. In the municipality of UN, 19 children had blood Hg concentrations between 5.29 and 17.71 μg/L. In CA, two children had concentrations of 5.03 and 8.43 μg/L, separately. In the case of Pb, seven children showed concentrations between 3.60 and 4.83 μg/dL in the municipality of RQ, three in UN (3.59, 3.61, and 4.60 μg/dL), and one in Carmen de Atrato (5.47 μg/dL). (4) Conclusions: The levels of Hg and Pb in the blood of children living in the riparian areas of the Atrato River basin are related to gold mining activities in the basin and the consumption of contaminated fish.

Take me to the River: have riverine rights enhanced community participation in environmental governance within the Atrato River basin?

ABSTRACT This paper assesses the implementation of the Colombian Constitutional Court's 2016 Judgment T-622, which tackled human and environmental rights violations in the Atrato River basin due to extensive illegal mining, focusing on how it has enhanced community participation in environmental governance. The decision granted ‘biocultural’ rights to the river, its tributaries, and their human inhabitants. Findings indicate improved communication between riverine communities and Colombia's national government via the new Commission of River Guardians. However, significant gaps remain in integrating local communities into broader environmental governance seven years after the ruling, with current efforts mainly preparatory. Progress in executing the judgment, particularly in social benefits and reducing pollution, has been limited. This emphasises the urgency of addressing persistent chemical pollution in the river, as well as the equally persistent government neglect towards the river and its people. This paper argues for a restructuring of the legal framework for environmental governance in Colombia towards a participatory governance framework fitted for socioecological transitions, as the current structure hinders the full implementation of biocultural rights. Failing to implement the Atrato judicial decision risks deepening disillusionment with legal and political institutions among underserved riverine communities, posing a dual existential threat to ecosystems and democracy.

Ecological and human health risk from exposure to contaminated sediments in a tropical river impacted by gold mining in Colombia

Despite being one of the most important tropical biomes in the world, the Atrato River basin has experienced a critical ecological deterioration due to gold mining, posing a significant threat to wildlife and human health. In this study, we measured the concentrations of mercury (Hg) and arsenic (As) in sediments at various swamps within the basin. Classical indices were employed to assess the associated ecological and human health risks linked to exposure to these elements. The concentrations of Hg and As in the sediments ranged between 0.09 and 0.23 mg/kg and 0.59–2.68 mg/kg, respectively. The highest Hg values were found at upstream stations impacted by gold mining activities. For As, the highest levels were found near river mouth (except for station B), where agricultural practices are taken place. The contamination factor (CF) indicated that most of the sediments exhibited moderate contamination levels of Hg and As, depending on the specific sampling area. Conversely, the pollution load index (PLI) suggested a contamination level ranging from basic to moderate, with the exception of station B, which showed a progressive deterioration of the site. The geoaccumulation index (Igeo) indicated that the sediments were moderately contaminated with Hg, while showing signs of increasing contamination for As. According to the criteria for limiting effect concentrations (TEC), Hg concentrations exceeded the TEC at stations B and C, indicating a potential toxic risk to aquatic biota. A moderate potential ecological risk (PERI) was detected at downstream stations (D and E), and a high risk was detected at upstream stations (A, B and C). The hazard index (HI), used for non-carcinogenic risk assessment, suggested a risk of adverse effects on the population, particularly in children, with HI values exceeding 1. However, all lifetime cancer risk (TLCR) values fell within the acceptable range (1 × 10−6 to 1 × 10−4), indicating a negligible risk. Oral ingestion and inhalation were identified as the two primary routes of concern. This study serves as a valuable reference for risk assessment regarding exposures to environmental matrices that may not pose an immediate risk to human health.

Toxic metal(loids) levels in the aquatic environment and nuclear alterations in fish in a tropical river impacted by gold mining

The Atrato River basin was protected by Colombian law due to anthropogenic impacts, mainly from illegal gold mining, which triggered a critical environmental health problem. In this study we quantified mercury (Hg), methylmercury (MeHg) and arsenic (As) concentrations in aquatic environmental matrices, and explored for the first-time nuclear degenerations in fish from the Atrato River. The median concentrations (μg/kg) for T-Hg, MeHg and As in fish were 195.0, 175.5, and 30.0; in sediments (μg/kg) 165.5, 13.8 and 3.1; and in water (ng/L), 154.7 for T-Hg and 2.1 for As. A 38% and 10% of the fish exceeded the WHO limit for the protection of populations at risk (200 μg Hg/kg) and for human consumption (500 μg Hg/kg); while As concentrations were below the international standard (1000 μg/kg) in all fish. The percentage of MeHg was 89.7% and the highest accumulation was observed in carnivorous fish (336.3 ± 245.6 μg/kg, p < 0.05) of high consumption, indicating risk to human health. In water, T-Hg concentrations exceeded the threshold effect value of 12 ng/L, whereas As concentrations were below the threshold of 10,000 ng/L, established by USEPA. On the contrary, 33% of the sediments exceeded the quality standard of 200 μg/kg for Hg. We found that Prochilodus magdalenae was the species with the highest susceptibility to nuclear alterations in its order, nuclear bud (CNB, 3.7 ± 5.4%), micronuclei (MN, 1.6 ± 2.5%) and binucleated cells (BC, 1.6 ± 2.3%). These results indicate that the species appears to be a good predictor of genotoxicity in the Atrato River. Fulton's condition factor (K) indicated that 31.7% of the fishes had poor growth condition, suggesting that the Atrato River basin needs to be monitored and restored in accordance with the agreements reached in the Minamata Convention on Mercury.

Health Risk Assessment for Human Exposure to Heavy Metals via Food Consumption in Inhabitants of Middle Basin of the Atrato River in the Colombian Pacific.

The Atrato river basin is one of the world's most biodiverse areas; however, it is highly impacted by mercury gold mining, which generates air, water, and soil pollution. (1) Background: The concentrations of persistent heavy metal pollutants, mercury (Hg), lead (Pb), cadmium (Cd), and arsenic (As) in the fish, fruits, and vegetables most consumed by the riverside inhabitants of the middle basin of the Atrato river represent a danger to public health; (2) Methods: A total of 154 samples of different fruits and vegetables and 440 samples of fish were analyzed by atomic absorption spectroscopy. A sample of 446 people were surveyed to evaluate food consumption and carcinogenic and non-carcinogenic risk; (4) Conclusions: High concentrations of As, Hg, Pb, and Cd were identified in fish, fruits-tubers, and vegetables-stems commonly consumed by inhabitants of the middle basin of the Atrato River, which exceeded the Codex limits and the limits established by the WHO/FAO, especially for carnivorous fish species. A high carcinogenic and non-carcinogenic risk was evidenced amongst inhabitants of the middle basin of the Atrato River due to the consumption of fish contaminated with high concentrations of As, MeHg, and THg. The risk due to the consumption of vegetables was very low.

APROVECHAMIENTO TRADICIONAL DE AVES SILVESTRES POR COMUNIDADES AFRODESCENDIENTES DE LA CUENCA BAJA DEL RÍO ATRATO, COLOMBI

&lt;p&gt;&lt;strong&gt;Background. &lt;/strong&gt;The Afro-descendant communities inhabiting the lower portion of the Atrato River basin in Colombia maintain a close relationship with their environment's biological diversity and ecosystem. Although the wild birds in the basin have been studied for their richness and ecological value, there are no ethnobiological accounts, even though this resource has been traditionally used in these communities’ feeding. Even though most of such communities consist of fishers, farmer families, and wood merchants, they have a solid vocation for occasional hunting since the performance of their regular activities requires that they carry tools such as a shotgun for hunting the wild birds and mammals they come across in passing through the jungle or near a swamp. &lt;strong&gt;Objective.&lt;/strong&gt; Know the traditional use of meat and wild bird by-products by two Afro-descendant communities in the lower basin of the Atrato River in northwestern Colombia. &lt;strong&gt;Methodology.&lt;/strong&gt; Interviews were conducted with 21 key informants (local experts) as well as 173 household surveys. Mann-Whitney end Kruskal Wallis tests were performed to determine statistically significant differences using the &lt;em&gt;R Software&lt;/em&gt; 4.1.2 and &lt;em&gt;RStudio&lt;/em&gt; 1.4.1103 programs. &lt;strong&gt;Results. &lt;/strong&gt;Wild bird diversity in the tropical rainforest provides a wide range of meat products for food security of the Afro-descendant communities that inhabit the lower portion of the Atrato River basin in Colombia. This assortment consists of at least 20 species, Galliformes foremost. Meat and viscera are generally consumed through preparations such as sancocho, stewed meat, fried meat, smoked meat, roasted meat, ground meat, or shredded meat, and no disease or discomfort for human health have thus far been associated with its consumption. Wild birds are consumed in all the households that were surveyed, and the most important for these communities are &lt;em&gt;Cairina moschata sylvestris&lt;/em&gt; (mountain duck), &lt;em&gt;Penelope ortoni&lt;/em&gt; (dusky-legged guan), &lt;em&gt;Dendrocygna autumnalis&lt;/em&gt; (black-bellied whistling duck), &lt;em&gt;Chauna chavaria&lt;/em&gt; (northern screamer), &lt;em&gt;Colinus cristatus&lt;/em&gt; (crested bobwhite), &lt;em&gt;Phalacrocorax brasilianus&lt;/em&gt; (crow duck) and &lt;em&gt;Ortalis cinereiceps&lt;/em&gt; (little ground tyrant). Comparisons between the two communities showed that this resource becomes more critical the more isolated the territory. &lt;strong&gt;Implications.&lt;/strong&gt; This study is an input to understand the importance of wild biological diversity for family feeding in human communities in tropical zones. &lt;strong&gt;Conclusions.&lt;/strong&gt; The seven species indicated above constitute the basis for prioritizing wild birds for bioprospecting purposes in planning food and nutritional security for these communities, which also requires that the parties involved in biodiversity conservation pay particular attention to certain species being used for food.&lt;/p&gt;

A human health risk assessment of methylmercury, arsenic and metals in a tropical river basin impacted by gold mining in the Colombian Pacific region

The Atrato River basin is one of the most biodiverse areas worldwide, and paradoxically, it is one of the sites in Colombia with the highest environmental impact from gold mining. This study assessed the distribution of Hg, As, Pb, and Cd in 47 fish species (n = 1372) and the accumulative human health risk in inhabitants (n = 2325) from 13 municipalities located along the Atrato River basin. The results revealed that Hg and As in fish present a high potential human health risk based on their mean concentrations. Estimated daily intake (EDI) calculations showed that humans could present detrimental health effects, while that target hazard quotient (THQ) above 1 showed that the exposed population might experience noncarcinogenic health risks, mainly from the accumulative effects of Hg (80.4%) and As (18.2%). The species that would most affect the health of the inhabitants are carnivorous H. malabaricus, A. pardalis, P. schultzi, R. quelen, and C. kraussii, which are among the fourteen most consumed in the region. These species had values of estimated weekly intake (EWI) above the provisional tolerable weekly intake thresholds for MeHg (PTWI of 1.6 and 3.2 μg/kg bw/week for adults and children, respectively) in 7 of the 13 localities evaluated. According to the surveys, the calculated weekly allowable fish amount (MFW) showed that carnivorous fish may generate adverse effects on the consumers because the allowed MeHg is about 2 times higher than the upper reference limit. Other results indicate a significant carcinogenic health risk, mainly from As, in 8 of the 13 localities evaluated. Due to the high rates of unsatisfied basic needs and the monetary poverty in the region, the possibility that inhabitants can replace fish as the principal source of protein is low. Therefore, a food guidance is required to avoid risks, obtain nutritional benefits, and sustain fish populations.

Contribution to a reference library of DNA barcodes of Colombian freshwater fishes.

BackgroundThe Barcode of Life initiative was originally motivated by the large number of species, taxonomic difficulties and the limited number of expert taxonomists. Colombia has 1,610 freshwater fish species and comprises the second largest diversity of this group in the world. As genetic information continues to be limited, we constructed a reference collection of DNA sequences of Colombian freshwater fishes deposited in the Ichthyology Collection of the University of Antioquia (CIUA), thus joining the multiple efforts that have been made in the country to contribute to the knowledge of genetic diversity in order to strengthen the inventories of biological collections and facilitate the solution of taxonomic issues in the future.New informationThis study contributes to the knowledge on the DNA barcodes and occurrence records of 96 species of Colombian freshwater fishes. Fifty-seven of the species represented in this dataset were already available in the Barcode Of Life Data System (BOLD System), while 39 correspond to new species to the BOLD System. Forty-nine specimens were collected in the Atrato River Basin and 708 in the Magdalena-Cauca asin during the period 2010-2020. Two species (Loricariichthysbrunneus (Hancock, 1828) and Poeciliasphenops Valenciennes, 1846) are considered exotic to the Atrato, Cauca and Magdalena Basins and four species (Oncorhynchusmykiss (Walbaum, 1792), Oreochromisniloticus (Linnaeus, 1758), Parachromisfriedrichsthalii (Heckel, 1840) and Xiphophorushelleri Heckel, 1848) are exotic to the Colombian hydrogeographic regions. All specimens are deposited in CIUA and have their DNA barcodes made publicly available in the BOLD online database. The geographical distribution dataset can be freely accessed through the Global Biodiversity Information Facility (GBIF).

Mercury species in fish from a tropical river highly impacted by gold mining at the Colombian Pacific region

This study was carried out in the Atrato River basin, a tropical ecosystem in northwestern Colombia, highly impacted by gold mining. The aim of this study was to show how these activities have deteriorated the quality of fish species, and how their intensity has influenced the distribution of mercury (Hg) pollution in the Atrato River basin. Results showed that total mercury (THg, n = 842) ranged between 32 ± 53 μg kg−1 (Cyphocharax magdalenae) and 678.5 ± 345 μg kg−1 (Agneiosus pardalis); 38% of the samples exceeded the WHO limit for the protection of populations at risk, and 15% surpassed the WHO maximum limit of THg in fish for human consumption. A significant positive correlation (p < 0.001) was found between THg with total fish length and trophic level, indicating bioaccumulation and biomagnification of mercury in fish, respectively. Using the non-migratory and carnivorous fish species Hoplias malabaricus and Caquetaia kraussii, Hg contamination was found distributed from high mining activity zones (Rio Quito, Medio Atrato, and Murindó & Vigía del Fuerte - upstream zones) to low activity areas (Rio Sucio & Carmen del Darién, and Ciénaga de Ungía & Tumaradó - downstream zones). In the first-ever performed methylmercury (MeHg) measurements in 520 fish muscle samples analyzed from the Atrato River basin, a high MeHg/THg ratio (91% of the THg) in species such as A. pardalis and H. malabaricus were recorded. Results indicated that the environment and the fish species in the Atrato River basin had been greatly affected by gold mining activities practiced on the river and its tributaries. Therefore, environmental authorities must take protection measures for the inhabitants of the area as well as for the environment.

Streamflow Variability in Colombian Pacific Basins and Their Teleconnections with Climate Indices

Oceanic-atmospheric phenomena of different time scales concurrently might affect the streamflow in several basins around the world. The Atrato River Basin (ARB) and Patía River Basin (PRB) of the Colombian Pacific region are examples of such basins. Nevertheless, the relations between the streamflows in the ARB and PRB and the oceanic-atmospheric factors have not been examined considering different temporal scales. Hence, this article studies the relations of the climate indices and the variability of the streamflows in the ARB and PRB at interannual and decadal timescales. To this, the streamflow variability modes were obtained from the principal component analysis (PCA); furthermore, their linear dependence with indices of the El Niño/Southern Oscillation (ENSO), precipitation (PRP), the Choco low-level jet (CJ), and other indices were quantified through (a) Pearson and Kendall’s tau correlations, and (b) wavelet transform. The PCA presented a single significant mode for each basin, with an explained variance of around 80%. The correlation analyses between the PC1s of the ARB and PRB, and the climate indices showed significant positive (negative) high correlations with PRP, CJ, and Southern Oscillation Index (SOI) (ENSO indices). The wavelet coherence analysis showed significant coherencies between ENSO and ARB: at interannual (2–7 years) and decadal scale (8–14), preferably with the sea surface temperature (SST) in the east and west Tropical Pacific Ocean (TPO). For PRB with the SST in the central and western regions of the TPO in the interannual (4–8 years) and decadal (8–14 years) scales, the decreases (increases) in streamflow precede the El Niño (La Niña) events. These results indicate multiscale relations between the basins’ streamflow and climate phenomena not documented in previous works, relevant to forecast the extreme flow events in the Colombian Pacific rivers and for planning and implementing strategies for the sustainable use of water resources in the basins studied.

Streamflow Intensification Driven by the Atlantic Multidecadal Oscillation (AMO) in the Atrato River Basin, Northwestern Colombia

The impact of the Atlantic Multidecadal Oscillation (AMO) on the variations in the streamflow in the Atrato River Basin (ARB) during the 1965–2016 period was analyzed here by considering the cold (1965–1994) and warm (1995–2015) phases of this oscillation. The mean streamflow increased after 1994 (AMO phase change). This increase is related to the strengthening of the zonal gradients of the sea surface temperature (SST) and sea level pressure (SLP) between the tropical central Pacific and the tropical Atlantic after 1994 (warm AMO phase). These gradients contributed to strengthen the Walker cell related upward movement over northern and northwestern South America, in particular during November-December (ND). Consistently, the frequency (R20 mm) and intensity (SDII) of extreme daily rainfall events increased during the 1995–2015 period. Our results show a connection between the AMO and the increase in the streamflow in the ARB during the last five decades. These results contribute to the studies of resilience and climate adaptation in the region.

Hydrological responses in equatorial watersheds indicated by Principal Components Analysis (PCA) – study case in Atrato River Basin (Colombia)

ABSTRACT The Atrato river basin is located in the Pacific fringe of Colombia, region with one of the highest precipitation rates in the world. The main purpose of this study is to determine the dominant processes in the hydrological responses along 17 sub-basins within the basin using principal component analysis. Watersheds located at the headwater presented a fast or medium response to the precipitation events, while higher flow homogeneity was observed in watersheds located at the lower portions of the basin. Three principal components were responsible for explaining 85.18% of the total variance. The component PC1 revealed the largest contributions for low flow behavior, being associated to precipitation, characteristic discharge values, compactness index, soil coverage and soil coarse textures. The component PC2 was assigned to the geological variables, fine and average texture soil and the average basin slope. Finally, the component PC3 has shown to be related to high flow patterns (maximum characteristic discharge values Q5 and Q1), igneous rocks and length of the basin. Highest specific discharge was associated to alluvial deposits and forest cover, whereas the slope was considered determinant for the run-off generation.

Dípteros acuáticos del departamento del Chocó, Colombia

Se presenta un reporte preliminar sobre la riqueza y distribución de los dípteros acuáticos en el departamento del Chocó, a partir de 490 especímenes (larvas y pupas) de la Colección Limnológica del Chocó (CLCH-Insec, Universidad Tecnológica del Chocó), que corresponden a 18 municipios (entre 5 y 3202 m s.n.m.), 46 corrientes hídricas de diferente orden y 14 ecosistemas lénticos de las cuencas de los ríos Atrato, San Juan y Baudó. Se reportan 12 familias y 30 géneros, de los cuales 4 familias y 16 géneros, son registrados por primera vez para el Chocó. Chironomidae es la familia más abundante y más ampliamente distribuida, mientras que Dixidae y Sciomyzidae son las familias de menor abundancia y distribución. La mayor riqueza taxonómica la registran las familias Culicidae y Ceratopogonidae, con cinco géneros cada una. Las macrófitas son el sustrato con mayor riqueza específica. El mayor registro taxonómico se encuentra en la cuenca del río Atrato, con 11 familias y 24 géneros. Estos resultados permiten evidenciar la enorme diversidad de los dípteros acuáticos en el departamento del Chocó y la necesidad de adelantar nuevas investigaciones que amplíen su conocimiento taxonómico y ecológico en la región.

Analysis of Floodplain Dynamics in the Atrato River Colombia Using SAR Interferometry

Floodplain water flows have large volumetric flowrates and high complexity in space and time that are difficult to understand using water level gauges. We here analyze the spatial and temporal fluctuations of surface water flows in the floodplain of the Atrato River, Colombia, in order to evaluate their hydrological connectivity. The basin is one of the rainiest areas of the world with wetland ecosystems threatened by the expansion of agriculture and mining activities. We used 16 Differential Interferometric Synthetic Aperture Radars (DInSAR) phase observations from the ALOS-PALSAR L-band instrument acquired between 2008–2010 to characterize the flow of surface water. We were able to observe water level change in vegetated wetland areas and identify flooding patterns. In the lower basin, flow patterns are conditioned by fluctuations in the levels of the main river channel, whereas in the middle basin, topography and superficial channels strongly influence the flow and connectivity. We found that the variations in water level in a station on the main channel 87 km upstream explained more than 56% of the variations in water level in the floodplain. This result shows that, despite current expansion of agriculture and mining activities, there remain significant hydrological connectivity between wetlands and the Atrato River. This study demonstrates the use of DInSAR for a spatially comprehensive monitoring of the Atrato River basin hydrology. For the first time, we identified the spatiotemporal patterns of surface water flow of the region. We recommend these observations serve as a baseline to monitor the potential impact of ongoing human activities on surface water flows across the Atrato River basin.

Aspectos reproductivos y pesqueros de Prochilodus magdalenae Steindachner, 1879 (Characiformes: Prochilodontidae) en la ciénaga de Marriaga, río Atrato, Colombia

Prochilodus magdalenae ha sido históricamente una de las fuentes de alimento de mayor importancia para la población a nivel nacional. Esta especie endémica de Colombia ha proporcionado más del 50 % del volumen de capturas en las principales cuencas trasandinas del país. El aislamiento de la población de P. magdalenae en la cuenca del Atrato hace necesario que se establezcan medidas de conservación ajustadas a sus características biológicas y reproductivas. En el presente estudio se registró información biométrica de las capturas de P. magdalenae provenientes de la pesca artesanal en la ciénaga de Marriaga (cuenca baja del río Atrato) desde abril de 2014 a marzo de 2015. Se registraron 574 individuos de los cuales 427 eran hembras y 147, machos. La distribución de las tallas para las hembras estuvo entre 200 y 470 mm de longitud estándar (LE) y para los machos entre 210 y 415 mm. El análisis de la longitud y el peso evidenció un crecimiento isométrico (b=2,9577) y una gran correlación entre las dos variables (r2=0,8119) para las hembras, en tanto que para los machos el crecimiento fue alométrico negativo (b=1,8793) con una correlación baja (r2=0,5628). La talla media de madurez (TMM) para la población total fue de 365 mm (LE). La época de mayor actividad reproductiva se estimó entre octubre y mayo. La distribución de las tallas y la talla media de madurez (TMM), así como las épocas de desove, difirieron de las registradas en las zonas baja y media del Atrato, así como en las otras cuencas trasandinas. © 2019. Acad. Colomb. Cienc. Ex. Fis. Nat.

Preliminary inventory of the generic richness and distribution of the aquatic coleopters of the Chocó department, Colombia

A preliminary record on the richness and distribution of aquatic Coleoptera in the Department of Choco is presented. The report is made from 1824 specimens (larvae and adults) found in the Limnological Collection of Choco «CLCH-In- sec» of the Technological University of Choco, collected in 20 municipalities at altitudes between 5m and 3202m, in 40 water streams of different order and 17 lentic ecosystems of the Atrato, San Juan and Baudo river basins. This collection includes 16 families (4 Adephaga and 12 Polyphaga) and 40 genera . Four families and 20 genera are register for Choco for the first time. The family Psephenidae is the most abundant and most widely distributed, while Hydraenidae is of lowest abundance and distribution. The highest taxono- mic richness is register for elmids with 12 genera . Rocks are the substrate with greatest abundance and specific richness. The largest taxonomic record occurs in the Atrato river basin with 16 families and 33 genera. These results show the enormous diversity of aquatic and semi - aquatic beetles in the department of Choco and the need to carry out new research to increase their taxonomic and ecological knowledge in the region

Revision of the Astyanax orthodus species-group (Teleostei: Characidae) with descriptions of three new species

The Astyanax orthodus species-group includes nine species: Astyanax boliviensis sp. nov., A. bopiensis nom. nov., A. embera sp. nov., A. gandhiae sp. nov., A. moorii comb. nov., A. orthodus, A. superbus, A. villwocki and A. yariguies comb. nov. The group is diagnosed by the presence of a series of pinnate-shaped marks (chevrons) located along the lateral midline, which extends from the humeral region to the caudal peduncle. Astyanax bopiensis nom. nov. is proposed as a substitute name for Astyanacinus multidens, which, along with Astyanax yariguies comb. nov., we reassign to Astyanax.We also propose the synonymy of Astyanacinus with Astyanax. The members of the A. orthodus species-group are distributed in northwestern South America, occurring in the Patia River drainage (A. embera sp. nov.) of the Pacific coast of Colombia, the Atrato River Basin (A. orthodus), the Magdalena River Basin (A. yariguies comb. nov.) of Caribbean Colombia, streams of the southern flank of the Andes of the Orinoco Basin in Venezuela (A. superbus), in the upper Amazon River Basin of Colombia, Ecuador and Peru (A. villwocki, A. gandhiae sp. nov.), from the upper Paraguay River (A. moorii comb. nov.), the Madidi and Mamore Rivers, Bolivia (A. boliviensis sp. nov. and A. bopiensis nom. nov.). All species currently included in Astyanacinus are reassigned to the Astyanax orthodus species-group.

Trachemys medemin. sp. from northwestern Colombia turns the biogeography of South American slider turtles upside down

South America was invaded by slider turtles (Trachemys spp.) twice, with one immigration wave estimated to have reached South America 8.6–7.1 million years ago (mya) and a second wave, 2.5–2.2 mya. The two widely disjunct South American subspecies of Trachemys dorbigni (northeastern and southern Brazil, Rio de la Plata region of Argentina and Uruguay) are derived from the first dispersal pulse, while the two South American subspecies of Trachemys venusta (Colombia, Venezuela) originated from the second immigration event. We describe a new species of slider turtle from the lower Atrato river basin of Antioquia and Choco departments, northwestern Colombia. This new species, the Atrato slider (Trachemys medemi n. sp.), is the first representative of the older immigration wave inhabiting northern South America. Using phylogenetic analyses of 3,242 bp of mitochondrial and 3,396 bp of nuclear DNA, we show that T. medemi is more closely related to T. dorbigni than to the geographically neighboring subspecies of Trachemys grayi and T. venusta from Central America and northern South America. The two subspecies of T. dorbigni are separated from the Atrato slider by the Andes and the Amazon Basin, and occur approximately 4,600 km and 3,700 km distant from T. medemi. According to molecular clock calculations, T. medemi diverged from the last common ancestor of the two subspecies of T. dorbigni during the Pliocene (4.1–2.8 mya), with T. dorbigni diversifying later (2.3–1.9 mya) in eastern South America beyond the Amazon basin. The divergence of the T. dorbigni subspecies overlaps with the estimated arrival of T. venusta in South America (2.5–2.2 mya). This time is characterized by massive climatic and environmental fluctuations with intermittent dispersal corridors in South America. According to their distribution, it seems likely that the ancestors of the extant subspecies of T. dorbigni dispersed along the eastern corridor, leaving a relict population northwest of the Andes with T. medemi. The distribution range of T. medemi is surrounded by taxa derived from the second southern range expansion of slider turtles, so that it can be concluded that T. venusta circumvented the habitats occupied by the ancestors of the Atrato slider when entering South America.

Comportamiento fenológico de Euterpe oleracea (Arecaceae) en bosques inundables del Chocó biogeográfico

Euterpe oleracea Mart. (Arecaceae) is a clustered palm tree occurring in seasonally flooded areas of the Atrato river basin, where it forms homogeneous forests. This palm has economic importance because of the production of palm hearts and numerous products derived from its fruits. The reproductive phenology of Euterpe oleracea was studied in 2 forest types: mixed murrapal, where other species occur, and pure murrapal, almost totally dominated by this palm tree. Phenological observations were made in 2 periods: from October 1999 to December 2001 in both forest types, and from October 2006 to May 2009 in the mixed murrapal only. The reproductive phenology showed an annual pattern in both ecosystems; however, the timing of flowering and fruiting in each forest type was different. A significant correlation was found between rainfall and reproductive structures (fruits) in the pure murrapal, suggesting an effect of flooding on timing of flowering and fruiting. Contrarily, no significant correlation was found in the mixed murrapal, probably because flooding during rainy season was less severe in this topographic position, and therefore, water did not cover the palm pneumatophores.

Taxonomic review of Colombian Parodon (Characiformes: Parodontidae), with descriptions of three new species

We review species of Parodon Valenciennes, 1850 from the Magdalena, Cauca, Orinoco, Amazonas, Atrato and Caribbean-Guajira River basins of Colombia using meristic and morphological characters. We recognize eight valid species, five previously described: P. apolinari Myers, from the Orinoco River basin; P. buckleyi Boulenger and P. pongoensis (Allen) from the upper Amazon; P. caliensis Boulenger, from the upper Cauca River drainage; and P. suborbitalis Valenciennes, from Lake Maracaibo basin. Three new species are described: P. alfonsoi, from the lower Magdalena River drainage; P. magdalenensis, from the middle Magdalena and upper Cauca River drainages; and P. atratoensis, from the Atrato River basin. We redescribe Parodon suborbitalis using type specimens and topotypes, and designate lectotypes. A taxonomic key is included for identification of the species, as well as geographic distribution maps.