NEOTROPICAL FRESHWATER FISHES: A dataset of occurrence and abundance of freshwater fishes in the Neotropics.

The Neotropical region hosts 4225 freshwater fish species, ranking first among the world's most diverse regions for freshwater fishes. Our NEOTROPICAL FRESHWATER FISHES data set is the first to produce a large-scale Neotropical freshwater fish inventory, covering the entire Neotropical region from Mexico and the Caribbean in the north to the southern limits in Argentina, Paraguay, Chile, and Uruguay. We compiled 185,787 distribution records, with unique georeferenced coordinates, for the 4225 species, represented by occurrence and abundance data. The number of species for the most numerous orders are as follows: Characiformes (1289), Siluriformes (1384), Cichliformes (354), Cyprinodontiformes (245), and Gymnotiformes (135). The most recorded species was the characid Astyanax fasciatus (4696 records). We registered 116,802 distribution records for native species, compared to 1802 distribution records for nonnative species. The main aim of the NEOTROPICAL FRESHWATER FISHES data set was to make these occurrence and abundance data accessible for international researchers to develop ecological and macroecological studies, from local to regional scales, with focal fish species, families, or orders. We anticipate that the NEOTROPICAL FRESHWATER FISHES data set will be valuable for studies on a wide range of ecological processes, such as trophic cascades, fishery pressure, the effects of habitat loss and fragmentation, and the impacts of species invasion and climate change. There are no copyright restrictions on the data, and please cite this data paper when using the data in publications.

Molecular testing and analysis of disease spreading during the emergence of COVID-19 in Macaé, the Brazilian National Capital of Oil.

The Brazilian strategy to overcome the spread of COVID-19 has been particularly criticized due to the lack of a national coordinating effort and an appropriate testing program. Here, a successful approach to control the spread of COVID-19 transmission is described by the engagement of public (university and governance) and private sectors (hospitals and oil companies) in Macaé, state of Rio de Janeiro, Brazil, a city known as the National Oil Capital. In 2020 between the 17th and 38th epidemiological week, over two percent of the 206,728 citizens were subjected to symptom analysis and RT-qPCR testing by the Federal University of Rio de Janeiro, with positive individuals being notified up to 48 h after swab collection. Geocodification and spatial cluster analysis were used to limit COVID-19 spreading in Macaé. Within the first semester after the outbreak of COVID-19 in Brazil, Macaé recorded 1.8% of fatalities associated with COVID-19 up to the 38th epidemiological week, which was at least five times lower than the state capital (10.6%). Overall, considering the successful experience of this joint effort of private and public engagement in Macaé, our data suggest that the development of a similar strategy countrywise could have contributed to a better control of the COVID-19 spread in Brazil. Quarantine decree by the local administration, comprehensive molecular testing coupled to scientific analysis of COVID-19 spreading, prevented the catastrophic consequences of the pandemic as seen in other populous cities within the state of Rio de Janeiro and elsewhere in Brazil.

Predation risk and abiotic habitat parameters affect personality traits in extremophile populations of a neotropical fish (Poecilia vivipara).

Understanding whether and how ambient ecological conditions affect the distribution of personality types within and among populations lies at the heart of research on animal personality. Several studies have focussed on only one agent of divergent selection (or driver of plastic changes in behavior), considering either predation risk or a single abiotic ecological factor. Here, we investigated how an array of abiotic and biotic environmental factors simultaneously shape population differences in boldness, activity in an open-field test, and sociability/shoaling in the livebearing fish Poecilia vivipara from six ecologically different lagoons in southeastern Brazil. We evaluated the relative contributions of variation in predation risk, water transparency/visibility, salinity (ranging from oligo- to hypersaline), and dissolved oxygen. We also investigated the role played by environmental factors for the emergence, strength, and direction of behavioral correlations. Water transparency explained most of the behavioral variation, whereby fish from lagoons with low water transparency were significantly shyer, less active, and shoaled less than fish living under clear water conditions. When we tested additional wild-caught fish from the same lagoons after acclimating them to homogeneous laboratory conditions, population differences were largely absent, pointing toward behavioral plasticity as a mechanism underlying the observed behavioral differences. Furthermore, we found correlations between personality traits (behavioral syndromes) to vary substantially in strength and direction among populations, with no obvious associations with ecological factors (including predation risk). Altogether, our results suggest that various habitat parameters simultaneously shape the distribution of personality types, with abiotic factors playing a vital (as yet underestimated) role. Furthermore, while predation is often thought to lead to the emergence of behavioral syndromes, our data do not support this assumption.

A macroscopic classification of the embryonic development of the one-sided livebearer Jenynsia multidentata (Teleostei: Anablepidae)

This study proposes eight stages according to the main discernible changes recorded throughout the embryonic development of Jenynsia multidentata. The development of morphological embryo structures, pigmentation, and changes in tissues connecting mother and embryo were included in the stage characterization. From the fertilized egg (Stage 1), an embryo reaches the intermediary stages when presenting yolk syncytial layer (Stage 2), initial pigmentation of the outer layers of the retina and dorsal region of the head (Stage 3), and the sprouting of the caudal (Stage 4), dorsal and anal fins (Stage 5). During the later stages, the ovarian folds enter the gills, and the body pigmentation becomes more intense (Stage 6), the body becomes elongated (Stage 7), and there is a greater intensity in body pigmentation and increased muscle mass (Stage 8). The dry weight of the batches varied between 0.6 ± 0.3 mg (Stage 3) to 54.6 ± 19.7 mg (Stage 8), but the dry weight of the maternal-embryonic connecting tissues remained almost constant. After controlling the effect of those reproductive tissues, the gain in dry weight of the batches throughout development increased exponentially from Stage 6, reflecting the increase in size and weight of the embryos due to matrotrophy.(AU)

Este estudio propone una clasificación constituida por ocho etapas, establecidas con base en los principales cambios macroscópicos registrados a lo largo del desarrollo embrionario de Jenynsia multidentata. El desarrollo de estructuras embrionarias, los patrones de pigmentación y los cambios en los tejidos de conexión entre la madre y el embrión fueron incluidos en la caracterización de cada etapa. Inicia con el huevo fertilizado (Etapa 1), siguiendo con etapas intermedias del embrión en las cuales es visible la capa sincitial del vitelo (Etapa 2), la pigmentación inicial de las capas externas de la retina y el dorso de la cabeza (Etapa 3), y la aparición de las aletas caudal (Etapa 4), dorsal y anal (Etapa 5). En las etapas posteriores, los pliegues del tejido ovárico se introducen por las branquias y se intensifica la pigmentación corporal (Etapa 6), el cuerpo se extiende (Etapa 7) y hay un marcado aumento en la pigmentación corporal y masa muscular (Etapa 8). El peso seco de los lotes varió entre 0,6 ± 0,3 mg (Etapa 3) y 54,6 ± 19,7 mg (Etapa 8); sin embargo, el peso seco del tejido que conecta a la madre con el embrión se mantuvo prácticamente constante. Después de controlar el efecto del peso seco de estos tejidos, la ganancia de peso seco de los lotes de embriones a lo largo del desarrollo aumentó de forma exponencial a partir de la Etapa 6, evidenciándose en el aumento en tamaño y peso de los embriones debido a la matrotrofia.(AU)

Effects of the interannual variations in the flood pulse mediated by hypoxia tolerance: the case of the fish assemblages in the upper Parana River floodplain

The effects of the duration of the floods on abiotic variables and attributes of species tolerant and intolerant to hypoxia (STH and SIH respectively) were evaluated in rivers and lakes of the upper Paraná River. Fish were sampled once a year, in six sampling stations, during the high water period from 2000 to 2003. There were overall reductions in dissolved oxygen levels and increases in transparency of water in lakes in years of moderate floods. The duration of floods influenced species differentially based on their tolerance to hypoxia: in moderate floods, richness of STH increased and numerical abundance and biomass of SIH reduced significantly. Opposite relationships were detected between dissolved oxygen and the attributes of STH and SIH. Dissolved oxygen was the best predictor of variability of STH and SIH in years of moderate floods, whereas water transparency predicted significant amounts of STH in years of short floods. Being positively affected by dissolved oxygen reductions, STH seem to take advantages in persisting in seasonally harsh lentic habitats. The incorporation of abiotic data as well the differential tolerance of species to hypoxia would improve further investigations of the effects of interannual variations in the flood pulse on tropical fish assemblages.

Os efeitos da duração da cheia sobre algumas variáveis abióticas e atributos das assembleias de peixes (espécies tolerantes e intolerantes à hipóxia, STH e SIH, respectivamente) foram avaliados em rios e lagoas do alto rio Paraná. Os peixes foram amostrados uma vez ao ano, em seis localidades, durante o período de águas altas entre 2000 e 2003. Houve reduções generalizadas nos níveis de oxigênio dissolvido e aumentos na transparência da água em lagos em anos de cheias moderadas. A duração das cheias influenciou as espécies diferencialmente em função de sua tolerância à hipóxia: em anos de cheias moderadas, a riqueza das STH aumentou e a abundância numérica e de biomassa das SIH reduziram significativamente. Relações opostas foram detectadas entre o oxigênio dissolvido e os atributos das STH e SIH. O oxigênio dissolvido foi o melhor preditor da variabilidade de STH e SIH em anos de cheias moderadas, enquanto a transparência da água explicou uma significativa proporção das STH em anos de cheias curtas. Por serem positivamente afetadas pelas reduções no oxigênio dissolvido, as STH parecem ter vantagens em persistir em ambientes lênticos sazonalmente inóspitos. A incorporação de dados abióticos bem como da tolerância diferencial das espécies à hipóxia deve aprimorar as investigações dos efeitos das variações interanuais no pulso de inundação nas assembleias de peixes tropicais.