Search

En las últimas décadas, el desarrollo de nuevas técnicas de muestreo nos ha permitido recolectar con mayor facilidad novedosas muestras que enriquecen el conocimiento de los especímenes que estudiamos. En este sentido, las muestras audiovisuales, sobre todo las grabaciones de señales acústicas, se han convertido en parte esencial de la investigación herpetológica. El correcto almacenamiento de estos especímenes es clave para fortalecer la investigación científica. Sin embargo, la gran mayoría de repositorios audiovisuales de acceso público se encuentran en países del Norte Global, lo cual restringe la labor científica en países latinos. El uso de repositorios locales o regionales abre la posibilidad de almacenar la diversidad de muestras científicas generadas en la región, haciéndolas fácilmente accesibles a los investigadores regionales y a la divulgación de la ciencia local. Esta carta es un llamado urgente a la comunidad herpetológica en Latinoamérica para que se tomen tres acciones principales como comunidad para aumentar la accesibilidad, reproducibilidad y crecimiento de la investigación bioacústica de anfibios neotropicales: 1) los investigadores deben depositar las grabaciones usadas en investigaciones publicadas en repositorios acústicos nacionales o regionales, 2) las editoriales y revisores de documentos deben exigir a los autores los números de depósito de todos los archivos utilizados en cualquier investigación acústica y la correcta referenciación de las colecciones usadas para poder aceptar los manuscritos y, 3) las directivas de las instituciones regionales con repositorios deben garantizar el fortalecimiento y mantenimiento de los repositorios acústicos institucionales por parte de las directivas de instituciones regionales.

Anurans that breed in rivers and cascade streams need to deal with the influence of the low-frequency water flow noise that could interfere with their acoustic communication. To overcome that, some species display visual signals or emit high-pitched calls. However, there is a constraint related to body size [snout-vent length (SVL)] that limits the anurans' calling frequency range. Thus, to evaluate if water noise influences this allometric relationship, we analysed hylodid frogs’ SVL, dominant frequencies of advertisement call, and background noise to which individuals are submitted. Although Hylodes and Crossodactylus have differences in morphology and natural history, we found negative acoustic allometry in both genera. This allometry may be part of the explanation of the absence of advertisement calls in Megaelosia and Phantasmarana genera. Based on the large body lengths of Megaelosia and Phantasmarana species, if they could call, it would be low-pitched and acoustically masked by the stream noise. Besides, we found a positive relationship between Hylodes phyllodes advertisement call and background sound pressure level (SPL), thus, the analysed individuals, emitted louder calls when submitted to louder background SPLs. This study exemplifies the complexity of acoustic allometry in rheophilic species: we evidenced a strategy for intraspecific communication effectiveness in rivers and streams with broad water flow background noise; and how acoustic allometry coped with background noise could be implying in unexpected trait evolution, as lack of vocalization in anurans.

Advertisement call is the most common signal used by anurans for intraspecific communication. However, some species have lost the ability to emit these vocalizations and are denoted as mute. Alternatively, these species may communicate by visual, tactile and chemical signals. The lack of advertisement call could be explained by the high background noise of breeding microhabitats. A model group to study alternative communication tactics is the genus Megaelosia, which is composed by seven mute species that inhabit noisy streams, and for which no information on intraspecific communication is available. We monitored a population of M. apuana and described its visual signalling during aggressive interactions between males. This interaction included visual signalling, physical combat, and the retreat of the smaller individual. No audible sound was detected during the whole aggressive interaction, reinforcing the genus muteness. This is the first report of any communication behaviour for the genus Megaelosia.

We describe distress calls of Leptodactylusknudseni recorded in Colombia and Brazil. These calls share similar acoustic features with previous records from other species of L.pentadactylus group.

Anuran sound archives allow monitoring populations, studying animal communication, evolution, taxonomy, and natural history, besides evaluating historical events through the preservation of sound recordings. However, some of these materials are being lost because they are not deposited in archives. Thus, we investigated the percentage of herpetologists that do not deposit their recordings, their reason not to do so, and the number of recordings and financial funding lost. We observed that nearly 80% of herpetologists do not catalogue the sounds they collect, resulting in the loss of over six million dollars, only in Brazil, over the past decades. The main reasons for not cataloguing such records were lack of time, lack of expertise in cataloguing procedures, and the belief that it is not necessary. Over the past 18 years, the number of studies in which recordings were deposited increased; however, they never accounted for more than 50% of the total amount of studies. Leaving audiovisual files out of sound archives hinders public access, impairs scientific progress and increases the loss of information probability. Besides, as most of the bioacoustics studies are funded by taxpayer money (in Brazil), depositing recordings is also essential considering the proper allocation of public resources.

The spatial distribution of fauna associated to marine macroalgae has mostly been investigated considering a horizontal plane. However, the macroalgal substrates can present a three-dimensional structure. In this sense, investigating how the associated fauna varies throughout a vertical plane can contribute to understanding the distribution of these organisms. The brown macroalga Sargassumpresents a vertical stratification along its thallus and harbors an amphipod fauna with a variety of feeding habits. In this work, we tested if the amphipod assemblage varies along different portions of the Sargassum thallus. We collected whole Sargassum stenophyllum thalli, as well as isolated basal and distal portions, from a rocky shore located on the north coast of São Paulo, in southeastern Brazil. The composition of amphipod families varied according to the Sargassum portion and the families Corophiidae, Caprellidae and Hyalidae accounted for most of the differences. Moreover, the basal portion of Sargassum had a higher diversity of amphipod families than the distal one, which may be related to differences regarding habitat complexity (herein, measured as algal biomass) between these portions. Detritivores (such as Corophiidae) were more associated to the basal portion and herbivores to the distal portion (Hyalidae) or along the whole Sargassum thallus (Ampithoidae). The variation of amphipod assemblage along Sargassum thallus seems to result from the interaction between the fauna natural history and the differences in conditions and physical structure along the algal thallus. In this sense, the vertical stratification of Sargassum can add another source of variation to the spatial distribution of associated fauna.