Threatened fish spawning area revealed by specific metabarcoding identification of eggs and larvae in the Beni River, upper Amazon

Identifying fish spawning areas is of great ecological and conservation importance as fishes are suffering increasing threats levels from anthropogenic activities. However, to date very few studies have done so in the Amazon basin. In the Beni River located in the upper Madeira basin, fishers reported that a particular ecotone near Rurrenabaque city was a fish reproduction area. To test the importance of this zone as a spawning site, we conducted an ichthyoplankton survey during the month when reproduction is most likely to occur. The specific identification of larvae and eggs was made with a metabarcoding analysis. With this approach 13 different fish species of high importance for regional and local fisheries were identified, including the long-distance migratory gilded catfish (Brachyplatystoma rousseauxii), considered as endangered in the upper Madeira. Combining the development time of morula-gastrula egg stages with the integrated current velocity of the river, we identified a spawning area that ranges between the last gravel beaches close to Altamarani community and the San Miguel del Bala community on top of Suse strait, the last foothill of the Andes. This spawning area further extends upstream in the Madidi and Pilon Lajas protected areas and Tacana and Tsimane indigenous communities, when considering eggs in final embryo stage. This portion of the Beni River, at the Andean foothills, is heavily impacted by anthropogenic activities, ranging from unmanaged fisheries to contamination coming from the extraction of fluvial aggregates, upstream gold mining, deforestation associated with a sugar cane mill, an existing downstream dam, and projected upstream dam projects. Some urgent solutions for the conservation of this already impacted area are proposed. Confirming fish spawning zones, although difficult, is crucial to inform the definition of priority areas for conservation and management measures, in particular when these sites host endangered species

Delimiting species by reproductive isolation : the genetic structure of epigean and hypogean Trichomycterus spp. (Teleostei, Siluriformes) in the restricted area of Torotoro (Upper Amazon, Bolivia)

Genetic variability of Trichomycterus from the region of Torotoro (Bolivia, Upper Amazon), distributed in the same watershed where the habitat is structured by waterfalls, canyons and a cave, was studied by allozyme (twelve putative loci) and RFLP-mtDNA (DLoop and cytochrome b) analyses. Alloenzymatic variation studied by Correspondence Analysis and Maximum Likelihood Analysis revealed a four-group structure, which was largely congruent with the distribution of the 14 mtDNA haplotypes. Two of these four clusters (I and II) were differentiated by two diagnostic loci (IDH and G3PDH), two semi-diagnostic loci (PGM and 6PGDH) and consequently a very high F-st value (estimator theta = 0.77). Therefore, clusters I and II are reproductively isolated. The distribution limit of these two (sibling) species does not correspond to those of the morphological species of Trichomycterus identified in this region: the epigean T. cf. barbouri and the hypogean T. chaberti. However, hypogean fish exhibited two mtDNA haplotypes, a private one and another shared with the epigean Trichomycterus from upstream reaches

The Silent Threat of Non-native Fish in the Amazon: ANNF Database and Review

Non-native fish (NNF) can threaten megadiverse aquatic ecosystems throughout the planet, but limited information is available for the Amazon Region. In this study we review NNF data in the Amazonian macroregion using spatiotemporal records on the occurrence and the richness of NNF from a collaborative network of 35 regional experts, establishing the Amazon NNF database (ANNF). The NNF species richness was analyzed by river basin and by country, as well as the policies for each geopolitical division for the Amazon. The analysis included six countries (Brazil, Peru, Bolivia, Ecuador, Venezuela, and Colombia), together comprising more than 80% of the Amazon Region. A total of 1314 NNF occurrence records were gathered. The first record of NNF in this region was in 1939 and there has been a marked increase in the last 20 years (2000–2020), during which 75% of the records were observed. The highest number of localities with NNF occurrence records was observed for Colombia, followed by Brazil and Bolivia. The NNF records include 9 orders, 17 families and 41 species. Most of the NNF species are also used in aquaculture (12 species) and in the aquarium trade (12 species). The most frequent NNF detected were Arapaima gigas, Poecilia reticulata and Oreochromis niloticus. The current data highlight that there are few documented cases on NNF in the Amazon, their negative impacts and management strategies adopted. The occurrence of NNF in the Amazon Region represents a threat to native biodiversity that has been increasing “silently” due to the difficulties of large-scale sampling and low number of NNF species reported when compared to other South American regions. The adoption of effective management measures by decision-makers is urgently needed and their enforcement needed to change this alarming trend and help protect the Amazon’s native fish diversity.

Rayas de agua dulce (Potamotrygonidae) de Suramérica. Parte II. Colombia, Brasil, Perú, Bolivia, Paraguay, Uruguay y Argentina

El libro es la continuación de una iniciativa de hace ya unos años (2012), donde varios países del área de distribución de la familia, decidieron unirse al ver como este recurso estaba disminuyendo o bien, era prácticamente desconocido. Este grupo tiene un gran impacto principalmente por su importancia como recurso pesquero ornamental, aunque también se usa como alimento, en la pesca deportiva y tiene incidencia en la salud pública. Para poder mitigar la posible sobreexplotación, surgió la necesidad de regular el comercio e intentar convertir la pesca ornamental de rayas en una actividad sostenible. Por ello, desde 2012 el IAvH junto a varios países propusieron la inclusión de varias especies al Apéndice III de Cites. Una de las limitantes de esta propuesta y por la cual no prosperó en su inicio, fue la falta de información sobre las especies.Bogotá, D. C