Parmentier, E. | Search bioRxiv

bioRxiv2024

Visualization and quantification of coral reef soundscapes using CoralSoundExplorer software

Despite hosting some of the highest concentrations of biodiversity and providing invaluable goods and services in the oceans, coral reefs are under threat from global change and other local human impacts. Changes in living ecosystems often induce changes in their acoustic characteristics, but despite recent efforts in passive acoustic monitoring of coral reefs, rapid measurement and identification of changes in their soundscapes remains a challenge. Here we present the new open-source software CoralSoundExplorer (https://sound-scape-explorer.github.io/docs/CSE/), which is designed to study and monitor coral reef soundscapes. CoralSoundExplorer uses deep learning approaches and is designed to eliminate the need to extract conventional acoustic indices. To demonstrate CoralSoundExplorers functionalities, we use and analyze a set of recordings from three coral reef sites, each with different purposes (undisturbed site, tourist site and boat site) located on the island of Bora-Bora in French Polynesia. We explain the CoralSoundExplorer analysis workflow, from raw sounds to ecological results, detailing and justifying each processing step. We detail the software settings, the graphical representations used for visual exploration of soundscapes and their temporal dynamics, along with the analysis methods and metrics proposed. We demonstrate that CoralSoundExplorer is a powerful tool for identifying disturbances affecting coral reef soundscapes, combining visualizations of the spatio-temporal distribution of sound recordings with new quantification methods to characterize soundscapes at different temporal scales. Author summaryTodays scientists are faced with the challenge of analyzing large amounts of data, such as those generated by passive acoustic monitoring of ecosystems. We have built CoralSoundExplorer (https://sound-scape-explorer.github.io/docs/CSE/), an efficient tool for analyzing large datasets of sound recordings, which transforms coral reef soundscape recordings into visual representations in 2D or 3D spaces. By spreading them across easy-to-explore acoustic spaces, CoralSoundExplorer enables the observer to quickly grasp the characteristics of soundscapes, their differences and similarities, and their organization on different temporal scales. These acoustic spaces and their temporal dynamics can be quantified, for example to account for the speed at which soundscapes change over time. In this study, we take the example of reef soundscapes from the island of Bora-Bora to illustrate the features and possibilities offered by CoralSoundExplorer. CoralSoundExplorer is open source and easy to use, even for non-specialists, thanks to an interface that requires no coding skills. We provide detailed instructions for installing and using CoralSoundExplorer to help users get started easily. CoralSoundExplorer needs to be installed on a computer to perform the analyses and calculations based on sound recordings. There is also an online interface (https://sound-scape-explorer.github.io/coral-sound-explorer/) enabling users to visualize data that have already been processed by CoralSoundExplorer.

ecology↗

bioRxiv2021

The initial response of females towards congeneric males matches the propensity to hybridize in Ophthalmotilapia.

AO_SCPLOWBSTRACTC_SCPLOWCichlid radiations often harbour closely related species with overlapping niches and distribution ranges. Such species sometimes hybridise in nature, which raises the question how can they coexist. This also holds for the Tanganyika mouthbrooders Ophthalmotilapia ventralis and O. nasuta. Earlier studies found indications of asymmetrical hybridisation with females of O. ventralis accepting males of O. nasuta, but not the other way around. We hypothesised that this was due to differences in the capacity for species recognition. Given the higher propensity of O. ventralis females towards hybridisation, we expect a reduced ability for species recognition in O. ventralis females, compared to O. nasuta females. We staged two experiments, one focusing on 22 female O. nasuta and one on 21 female O. ventralis. These fish were placed in one half of a tank and briefly exposed to a conspecific or a heterospecific male, a conspecific female, or nothing (control). Female response was evaluated by scoring six tracking parameters and by noting the occurrence of ten discrete behaviours before and during the encounter. Females always responded to the presence of another fish by approaching it. Remarkably, for both O. nasuta and O. ventralis, we did not find a different response between encounters with conspecific males and females. However, in agreement with our hypothesis, O. nasuta females behaved differently towards conspecific or heterospecific males, whereas O. ventralis females did not. When presented with a heterospecific male, O. nasuta females performed a lower number of ram behaviours. Additionally, they never displayed the flee behaviour, a component of the species mating repertoire that was seen in all but one of the presentations with a conspecific male. Our findings show that differences in species recognition at first encounter predict to a large degree the outcome of the mating process, even in the absence of mating behaviour.

animal behavior and cognition↗