Ivan A. Hinojosa

Acoustic recording can be a very interesting way of monitoring cetaceans for conservation purposes. However, some sympatric species produce very similar sounds and are thus difficult to study specifically. In this work, we are interested in characterizing the narrow band high frequency (NBHF) clicks emitted by several species of odontocetes, among which all porpoises and some species of dolphins. The traditional acoustic parameters (durations, frequencies, bandwidths) of NBHF clicks show several drawbacks, such as redundancy, lack of precise definition, and poor robustness to noise. In this study, we propose a new method of characterizing NBHF clicks by fitting a Gabor wavelet to the signal and thus extracting two specific metrics, the Gabor frequency and the Gabor duration. We first assess the theoretical usefulness of this mathematical model, and then test it against traditional measurements in numerical examples with varying levels of noise. Our method is then applied to two empirical datasets recorded in South America, a place were many sympatric species are found to emit NBHF clicks. Two large sets of signals are thus analyzed and compared : one of clicks of Peale’s dolphins (Cephalorhynchus australis) from Chaihuin bay, Chile, and the other of clicks of Franciscana dolphins (Pontoporia blainvillei) from San Clemente del Tuyu, Argentina. Our metrics allow a good characterization of each species’ clicks with quick and efficient computation, with good reproducibility across different recording devices, and a clear separation of the two species. We suggest it could be applied to more datasets from different species, and possibly be used to classify NBHF of sympatric species.

Our research aims to examine the level of biodiversity knowledge among urban residents who engage in recreational activities in different natural areas of the Province of Concepción, Chile. This territory is part of a biodiversity hotspot and has undergone significant transformations, either due to large-scale productive activities or urban expansion. To assess this type of knowledge, we used species identification as a proxy and administered an in-person questionnaire across all communes of the province (n = 232 adults). The questionnaire included illustrations of 14 species characteristic of different ecosystems in the area, and sociodemographic information was also collected from participants. Responses were analyzed using a scoring matrix, hypothesis testing, and regression analyses. The results indicate that species with food-related value were more frequently identified by older participants and less by younger individuals, whereas threatened species such as marine otter Lontra felina were poorly identified (36%) by participants aged 50 years or older. Participants without nature-related occupations (82% of the sample) identified, on average, 50% of the species, whereas those with nature-related occupations identified 71%. An intergenerational divergence in species knowledge and significant occupational differences may potentially reduce the social support needed to protect ecosystems while action is still possible.

This study provides the first characterization of the acoustic signals emitted by Lahille’s bottlenose dolphins (Tursiops gephyreus) in Argentine waters, establishing a baseline for the species’ southern distribution limit. Passive acoustic monitoring was conducted in the inner channels of the Bahía Blanca Estuary using a broadband hydrophone and F-POD detectors. We documented a diverse acoustic repertoire consisting of echolocation clicks, whistles, bray-calls, and chirps. Acoustic presence was predominantly diurnal and showed a marked synchronization with the tidal cycle, with peak activity occurring during the ebbing tide. Whistles had a mean center frequency of 8.1 kHz, showing spectral overlap with other regional populations in the Southwestern Atlantic. Echolocation clicks were broadband, with peak frequencies ranging from 18 to 127 kHz and a mode around 40 kHz. These results suggest that dolphin movement in the estuary’s internal channels is structured by hydrodynamics, likely reflecting foraging opportunities associated with tidal flow. Given the endangered status of this species, these data establish a technical framework for non-invasive monitoring and habitat-use assessments in complex estuarine environments.

The Juan Fernández Archipelago (JFA) is a unique ecosystem due to its diversity and high endemism. In recent years, there has been an increase in the populations of the endemic sea urchin Centrostephanus sylviae, generating negative impacts on the ecological and socio-economic systems of the Archipelago. Here, we describe the establishment of C. sylviae and the consequences of its overabundance on the subtidal communities, specifically around Robinson Crusoe and Santa Clara islands. Also, we describe the variation in SST (°C) around both islands during the last 40 years. The increase in abundance of C. sylviae and its community-level impacts (i.e. sessile benthic, macroinvertebrates, and fishes) were documented by visual surveys using scuba diving at various sites during January 2014 (12 sites), March 2017 (12 sites), March 2020 (4 sites), and January 2024 (7 sites). Over this period, the increase of C. sylviae abundance (∼400%) was associated with a significant decrease in sessile biotic benthic cover and an increase in the percentage of barren grounds (40%–84%). Additionally, there was a significant decrease in the abundance of the sea star Patiriella calcarata (100%) and the sea cucumber Mertensiothuria platei (70%). In terms of fish, a decrease in the abundance of the endemic wrasse Malapterus reticulatus (95%), and an increase of the chilean sweeper Scorpis chilensis (40%) were observed. Both species evidenced a decrease in biomass (90% and 84%, respectively). In general, the abundance of C. sylviae could be attributed to the synergistic effects of both top-down and bottom-up processes, including the low presence of predators (Astrotole platei and Jasus frontalis), by the increase in nutrient concentrations, and by the influence of climate change. These results could serve as a baseline for exploring ongoing community changes in subtidal environments.

Gorgonians (like corals) are important habitat-forming organisms that support a diversity of macrofauna. This study explored structural attributes of gorgonian gardens formed by rose gorgonians (Leptogorgia sp. nov.) and associated macrofaunal assemblages in Caleta Pichicuy (Central Chile). Hierarchical sampling was conducted at 20 m depth (maximum colony abundances) in order to assess spatial variability in abundance and colony attributes at two spatial scales (among sites and rocky walls). The abundance and composition of the associated vagile and sessile macrofauna were also examined using univariant (Taxa richness and Shannon index (H’e)) and multivariant approaches and were compared with adjacent bare rocky habitats. Our results showed a high abundance of gorgonians (ca. 28.9–36.5 colonies m⁻²) compared to other gorgonian gardens in the world. For structural attributes, our results showed smaller colonies with thicker holdfasts in more exposed sites, suggesting the influence of hydrodynamic forces on the colony morphology. Taxa richness and H’e of vagile fauna showed threefold and twofold, respectively, higher values in gorgonian gardens compared to bare walls, but no differences were observed for sessile fauna. In addition, PCoA and PERMANOVA evidenced a distinctive assemblages’ composition between habitats for both vagile and sessile fauna. Correlation analyzes and dbRDA showed, however, little association between structural attributes and associated faunal assemblages (R ² = 0.06, and ca. 3–9.4% of the total variation explained, respectively). Our results constitute the first assessment of structural habitat complexity and accompanying fauna in these gorgonian gardens and establish the baseline for understanding possible future changes associated to human activities.

Most biodiversity studies of octocorals have focused on tropical shallow waters, particularly from Mexico to Peru, and more recently in Chile. The first description of a Chilean octocorals dates back to the H.M.S Challenger expedition in 1873–1876. Since then, only few descriptions of new soft coral species from this region have been published. In addition, the taxonomic status of most gorgonians reported from the temperate Pacific coast of South America is dubious due to the loss of the original type material for most taxa. Here, we use morphological characters and nuclear and mitochondrial markers to reevaluate the taxonomy of the Chilean gorgonians Phycogorgia fucata and Leptogorgia chilensis, and describe a new species named Leptogorgia pichicuyensis sp.n. We present the first description of their latitudinal distribution patterns. Our results support the monophyly of the Chilean gorgoniids investigated, and the provisional placement of P. fucata with other species of the genus Leptogorgia in the absence of further specimens of Phycogorgia in GenBank. Our distribution analyses reveal a clear biogeographic break congruent with the Central Chile and Araucanian marine ecoregions. Overall, our study provides the first integrative taxonomic study of Southern Eastern Pacific cold-water gorgonians suggesting a higher number of species than expected for this underexplored region.