Conservation threats and future prospects for the freshwater fishes of Ecuador: A hotspot of Neotropical fish diversity

Assessing scientific knowledge on Ecuadorian bony fishes from a scientometric perspective

Bony fishes play a pivotal role in Ecuador's social, economic, and ecological aspects. However, the current state of scientific knowledge on this group remains poorly understood. This study aims to assess the scientific output related to Ecuadorian bony fishes, identifying both well-researched and understudied areas. A scientometric analysis was conducted using the Scopus database, evaluating 265 peer-reviewed publications on marine and freshwater bony fishes. The results revealed that 55.5% of studies focused on marine environments, 41.9% on freshwater ecosystems, and 2.6% on mixed environments. The earliest study was published more than 130 years ago, with a marked increase in research output since 2018. Geographic and regional disparities in research efforts were evident, with the Galapagos Islands hosting the highest number of studies at the provincial level and the coastal region leading in regional publications. Additionally, there has been a notable increase in the participation of women in research over time; however, it remains significantly below parity. English was the dominant language in these publications. On average, the delay between data collection and publication was 8.43 years, which may lead to outdated or ineffective management decisions. This underscores the importance of continually updating data to ensure the accuracy of conservation status assessments. Both marine and freshwater species that were endemic have been less studied compared to non-endemic species. Most of the studied species were categorized as "least concern," although a significant proportion of species classified as "data deficient" have started to be investigated by Ecuadorian researchers. The categories "endangered" and "near threatened" were the least studied, highlighting the urgent need for conservation initiatives targeting these vulnerable taxa. Biases in the number of studies among families, species, and geographic distribution indicate the need to expand research efforts to underrepresented taxa and regions. This analysis underscores the necessity of diversifying methodologies and broadening the research focus to more comprehensively address the challenges associated with the conservation and management of bony fishes in Ecuador.

Exceptional concentration of fish diversity in Yasuní National Park, Ecuador (Napo River Basin)

Background

Despite limited access and rather deficient sampling in many lowland areas of eastern Ecuador, scientists have been able to demonstrate that this specific region of Amazonia houses extraordinarily high concentrations of species within several taxa - terrestrial and aquatic, plant and animal, vertebrate and invertebrate.

New information

In this work, we developed an updated list of the ichthyofauna of the Yasuní National Park (YNP), based on an extensive literature review and databases of the most representative ichthyological collections from Ecuador. Our results yielded 458 species of freshwater fishes distributed in 47 families and 13 orders. This number exceeded previous fish lists from YNP and accounts for a considerable proportion of species inhabiting the Napo River Basin as well as the entire Amazon River Basin.The higher-than-previously-reported species diversity within this protected area, the services these species provide to humans and the absence of invasive species underscore the need for greater efforts and investment in protecting and managing western Amazonian lands and waters.

Fungal Diversity in an Undisturbed Andean Páramo Soil in Quimsacocha (Ecuador)

The Andean Páramo is an environment known for its high biodiversity; however, due to its remote location and difficult access, it is still relatively poorly studied. The aim of this work was to explore the fungal biodiversity of Ecuadorian Páramo soils in the undisturbed natural reserve of Quimsacocha through ITS metabarconding with an MiSeq platform. This analysis revealed the presence of 370 fungal Amplicon Sequence Variants (ASVs), mainly composed by Ascomycota, Mortierellomycota and Basidiomycota. The biodiversity had a great variability among the 19 samples, but the soil humidity proved to be a significant driver of diversity in the relatively dry environment of Páramo. Some of most abundant fungal genera have important relationships with plant roots. This work represents the first glimpse into the complex biodiversity of soil fungi in this understudied area, and further studies will be needed to better understand the fungal biodiversity in this region, together with the development of necessary measures of environmental protection.

Mercury in aquatic ecosystems of two indigenous communities in the Piedmont Ecuadorian Amazon: evidence from fish, water, and sediments

Mercury is a highly toxic element present in water, soil, air, and biota. Anthropogenic activities, such as burning fossil fuels, mining, and deforestation, contribute to the presence and mobilization of mercury between environmental compartments. Although current research on mercury pathways has advanced our understanding of the risks associated with human exposure, limited information exists for remote areas with high diversity of fauna, flora, and indigenous communities. This study aims to deepen our understanding of the presence of total mercury in water, sediments, and fish, within aquatic ecosystems of two indigenous territories: Gomataon (Waorani Nationality) and Sinangoé (Ai´Cofán Nationality) in the Ecuadorian Amazon. Our findings indicate that, for most fish (91.5%), sediment (100%) and water (95.3%) samples, mercury levels fall under international limits. For fish, no significant differences in mercury levels were detected between the two communities. However, eight species exceeded recommended global limits, and one surpassed the threshold according to Ecuadorian legislation. Piscivore and omnivore fish exhibited the highest concentrations of total mercury among trophic guilds. Only one water sample from each community's territory exceeded these limits. Total mercury in sediments exhibited greater concentrations in Gomataon than Sinangoé. Greater levels of mercury in sediments were associated with the occurrence of total organic carbon. Considering that members of the communities consume the analyzed fish, an interdisciplinary approach, including isotopic analysis, methylmercury sampling in humans, and mercury monitoring over time, is imperative for a detailed risk assessment of mercury exposure in Amazonian communities.

Total mercury and fatty acids content in selected fish marketed in Quito - Ecuador. A benefit-risk assessment

Total mercury and fatty acids contents were determined in muscles of croaker, snapper, dolphinfish, blue marlin, and shark, from different markets in the Metropolitan District of Quito, Ecuador. Fifty-five samples were collected and analyzed for total mercury using cold vapor atomic fluorescence spectrometry, and the fatty acids were analyzed using gas chromatography equipped with a flame ionization detector. The lowest total mercury levels were found in snapper [0.041 µg·g^-1 wet weight (ww)] while blue marlin showed the highest (5.883 µg·g^-1 ww). EPA + DHA ranged from 1.0 mg·g^-1 in snapper to 2.4 mg·g^-1 in shark. A high omega-3/omega-6 ratio was found for all fish types; however, the HQ_EFA for the benefit-risk ratio was above 1, suggesting an evident risk to human health. Based on our results, consumption of croaker and dolphinfish is recommended up to one serving per week, considering the importance of EFAs intake and avoiding fish with elevated MeHg content. Therefore, Ecuadorian authorities could enhance public standards for seafood safety and develop consumer advice for pregnant women and young children to determine good fish choices or those to avoid.

Diversidad, abundancia y dominancia de las especies ícticas en el río Churute, Ecuador

En esta investigación se evaluó la diversidad de especies nativas e introducidas en el río Churute, el cual atraviesa la Reserva Ecológica Manglares Churute, en Ecuador, utilizando para ello un enfoque empírico-inductivo, con diseño no experimental de corte transversal-explicativo. Las capturas se realizaron con atarraya, arte de pesca tradicional en época de sequía, a lo largo del río Churute. Se muestrearon 25 sitios, considerando 33 lances como esfuerzo de pesca por cada sitio, y los peces capturados fueron clasificados taxonómicamente, contados y pesados para estimar los índices ecológicos de riqueza, abundancia, diversidad y dominancia en el área de estudio. Se identificaron 20 especies ícticas (19 nativas y 1 introducida) distribuidas en 18 géneros de 13 familias y 5 órdenes; las familias con mayor número de especies fue CICHLIDAE con cuatro especies, BRYCONIDAE, CHARACIDAE, ELEOTRIDAE y HEPTAPTERIDAE con dos especies cada una. De las especies identificadas, siete calificaron como importantes, sobresaliendo la tilapia, pez introducido con un Índice de Importancia Relativa (IRI) de 40.075,58, dominando en los sitios de muestreo en un 61,13 %. Se concluye que la tilapia es una especie dominante, con tasas de reproducción superiores al de las especies nativas presentes en el río Churute, por lo que su presencia constituye una seria amenaza a la biodiversidad de este ecosistema.

Divergence times of the Rhoadsia clade (Characiformes: Characidae)

Abstract The family Characidae is the most diverse group of fishes in the Neotropics with challenging systematics. The three genera Carlana, Parastremma, and Rhoadsia, formerly considered the subfamily Rhoadsiinae, are now included in the subfamily Stethaprioninae. Previous phylogenetic analyses did not include all genera of Rhoadsiinae, specifically Parastremma. Here, we estimated the phylogenetic relationships and divergence times of the genera of Rhoadsiinae (the Rhoadsia clade) relative to the most representative genera of the Characidae. We used six molecular markers from the mitochondrial and nuclear genome to estimate the phylogeny and divergence times. We confirmed the monophyly of the Rhoadsia clade. Furthermore, we estimated that the Central American genus Carlana and the western Colombian genus Parastremma diverged approximately 13 Mya (95% HPD 8.36–18.11), consistent with the early-closure estimates of the Isthmus of Panama (~15 Mya). The genus Rhoadsia, endemic to Western Ecuador and Northern Peru, was estimated to originate at around 20 Mya (95% HPD 14.35–25.43), consistent with the Andean uplift (~20 Mya).