Daily activity rhythms, chronotypes, and risk-taking behavior in the signal crayfish

Consistent inter-individual differences in daily activity rhythms (i.e., chronotypes) can have ecological consequences in determining access to food resources and avoidance of predators. The most common measure to characterize chronotypes in animals as well as humans is the onset of activity (i.e., early or late chronotypes). However, daily activity rhythms may also differ in the relative amount of activity displayed at particular time periods. Moreover, chronotypes may also be linked to other consistent inter-individual differences in behavior (i.e., personality), such as the propensity to take risks. Here, we used the signal crayfish Pacifastacus leniusculus to test the presence of chronotypes and risk-taking personality traits and a potential behavioral syndrome between these traits. We first exposed crayfish to 5 days of light–darkness to measure daily activity rhythms and then we applied a visual predator-simulating stimulus in 2 different contexts (neutral and food). Our results showed consistent (i.e., across 5 days) inter-individual differences in the relative nocturnal activity displayed in the early and middle, but not in the late part of darkness hours. Moreover, while crayfish displayed inter-individual differences in risk-taking behavior, these were not found to be consistent across 2 contexts. Therefore, we were not able to formally test a behavioral syndrome between these 2 traits. In conclusion, our study provides the first evidence of chronotypes in the relative amount of activity displayed at particular time periods. This could be a valuable information for applied ecological aspects related to the signal crayfish, which is a major invasive species of freshwater ecosystems

Las iniciativas de conservación “bottom-up” en la pesca submarina recreativa sugieren el desarrollo de actitudes positivas hacia la conservación

We show that marine recreational spearfishers voluntarily organize bottom-up conservation actions. The main goals of these actions are to provide support to research in monitoring fish assemblages, tracking biological invasions or mitigating impacts on the environment, such as those stemming from pollution and littering. We show that such initiatives started more than 20 years ago and are now facilitated by social media networking. We argue that the emergence of bottom-up conservation actions in marine recreational spearfishers should be encouraged, supported and integrated into participatory management plans. This is important to mitigate the potential negative impacts of marine recreational spearfishing and to catalyse broader civil actions for conservation of marine ecosystems.Los pescadores submarinos recreativos organizan voluntariamente acciones “bottom-up” de conservación del medio ambiente. Los principales objetivos de estas acciones son apoyar a la investigación en el monitoreo de los ecosistemas marinos, detectar especies invasoras o mitigar los impactos sobre el medio ambiente, como los derivados de la contaminación y la basura. Tales iniciativas comenzaron hace más de 20 años y hoy en día podrían ser facilitadas por las redes sociales. El desarrollo de acciones de conservación “bottom-up” en los pescadores submarinos recreativos deben ser alentadas, apoyadas e integradas en los planes de manejo participativo. Esto es importante para mitigar los potenciales impactos negativos de la pesca submarina recreativa y para catalizar acciones civiles más amplias para la conservación de los ecosistemas marinos

Using ORB, BoW and SVM to identify and track tagged Norway lobster Nephrops norvegicus (L.)

Sustainable capture policies of many species strongly depend on the understanding of their social behaviour. Nevertheless, the analysis of emergent behaviour in marine species poses several challenges. Usually animals are captured and observed in tanks, and their behaviour is inferred from their dynamics and interactions. Therefore, researchers must deal with thousands of hours of video data. Without loss of generality, this paper proposes a computer vision approach to identify and track specific species, the Norway lobster, Nephrops norvegicus. We propose an identification scheme were animals are marked using black and white tags with a geometric shape in the center (holed triangle, filled triangle, holed circle and filled circle). Using a massive labelled dataset; we extract local features based on the ORB descriptor. These features are a posteriori clustered, and we construct a Bag of Visual Words feature vector per animal. This approximation yields us invariance to rotation and translation. A SVM classifier achieves generalization results above 99%. In a second contribution, we will make the code and training data publically available.Peer Reviewe

Video monitoring of Sparidae temporal rhythms: three-year study by OBSEA cabled observatory

Coco, S. ... et al.-- 7th International Workshop on Marine Technology – Martech Workshop 2016, 26-28 October 2016, Barcelona.-- 2 pages, 1 figure,1 tableThe abundance and composition of fish assemblages varies at different temporal scales as a product of diel and annual rhythms. In this study, we used a video-wired observatory (OBSEA, www.obsea.es) to monitor annual rhythms in a coastal fish assemblage with a 3-year data set (2012-2014). The photographs were acquired at 30 min frequency. Five species of the family Sparidae were studied (i.e. Dentex dentex, Diplodus sargus, Diplodus vulgaris, Diplodus annularis and Diplodus puntazzo) together with water temperature and daylength. The results of the annual rhythmicity analysis indicated that most of the peaks of abundance occured in the autumn months. Results suggest differentially temporal use of the reproductive or trophic nichePeer Reviewe

Using ORB, BoW and SVM to identify and track tagged Norway lobster Nephrops norvegicus (L.)

7th International Workshop on Marine Technology – Martech Workshop 2016, 26-28 October 2016, Barcelona.-- 3 pages, 4 figures, 1 tableSustainable capture policies of many species strongly depend on the understanding of their social behaviour. Nevertheless, the analysis of emergent behaviour in marine species poses several challenges. Usually animals are captured and observed in tanks, and their behaviour is inferred from their dynamics and interactions. Therefore, researchers must deal with thousands of hours of video data. Without loss of generality, this paper proposes a computer vision approach to identify and track specific species, the Norway lobster, Nephrops norvegicus. We propose an identification scheme were animals are marked using black and white tags with a geometric shape in the center (holed triangle, filled triangle, holed circle and filled circle). Using a massive labelled dataset; we extract local features based on the ORB descriptor. These features are a posteriori clustered, and we construct a Bag of Visual Words feature vector per animal. This approximation yields us invariance to rotation and translation. A SVM classifier achieves generalization results above 99%. In a second contribution, we will make the code and training data publically availablePeer Reviewe

Analyzing publicly available videos about recreational fishing reveals key ecological and social insights : A case study about groupers in the Mediterranean Sea

iEcology and conservation culturomics are two emerging research approaches that rely on digital data for studying ecological patterns and human-nature interactions. We applied data mining of videos published on YouTube related to recreational fishing of four species of groupers (family: Epinephelidae) in Italy between 2011 and 2017 to learnwhether digital user-supplied data help uncover key spatio-temporal ecological patterns characteristic of the studied species. Our results support an ontogenetic deepening of the dusky grouper (Epinephelusmarginatus) as revealed by a positive relationship between body mass and depth of captures declared in spearfishing videos. In addition, the data support a northward expansion of the white grouper (Epinephelus aeneus) because the average latitude associated to the catch was found to be positively correlatedwith the years when the videos were uploaded on YouTube. Furthermore, the georeferenced data about the white grouper filled a knowledge gap in a well-established international occurrence records dataset. The approach presented here could help mitigating data deficiencies and inform about harvesting patterns shown by recreational anglers and spearfishers. Our work illustrates the value of digital data associated with recreational fishing for advancing fish and fisheries research. The approach can be broadened to larger spatial and temporal scales, and to different species, contributing to a better understanding ofmacroecological patterns, assessment and conservation of exploited species, and monitoring of recreational fisheries. (C) 2020 Elsevier B.V. All rights reserved.Peer reviewe

Fighting over burrows : the emergence of dominance hierarchies in the Norway lobster (Nephrops norvegicus)

Animals fight over resources such as mating partners, territory, food or shelter and repeated contests lead to stable social hierarchies in different phyla. The group dynamics of hierarchy formation are not characterized in the Norway lobsters (Nephrops norvegicus). Lobsters spend most of the day in burrows and forage outside of them according to a diel (i.e. 24-h based) activity rhythm. Here, we use a linear and generalized mixed model approach to analyse, in 7 groups of 4 male lobsters, the formation of dominance hierarchies and rank related changes in burrowing behaviour. We show that hierarchies emerge within 1 to 3 days and increase in steepness over a period of 5 days, while rank changes and number of fights gradually decrease over a 5 day period. The rank position determined by open area fights predicts the outcome of fights over burrows, the time spent in burrows, and the locomotor activity levels. Dominant lobsters are more likely to evict subordinate lobsters from their burrows and more successful in defending their own burrows. They spend more time in burrows and display lower levels of locomotor activity outside the burrow. Lobsters do not change their diel activity rhythms as a result of a change in rank, and all tested individuals showed higher activity at night and dusk compared to dawn and day. We discuss how behavioural changes in burrowing behaviour could lead to rank related benefits such a reduced exposure to predators and energy savings

Tracking fish abundance by underwater image recognition

Marine cabled video-observatories allow the non-destructive sampling of species at frequencies and durations that have never been attained before. Nevertheless, the lack of appropriate methods to automatically process video imagery limits this technology for the purposes of ecosystem monitoring. Automation is a prerequisite to deal with the huge quantities of video footage captured by cameras, which can then transform these devices into true autonomous sensors. In this study, we have developed a novel methodology that is based on genetic programming for content-based image analysis. Our aim was to capture the temporal dynamics of fish abundance. We processed more than 20,000 images that were acquired in a challenging real-world coastal scenario at the OBSEA-EMSO testing-site. The images were collected at 30-min. frequency, continuously for two years, over day and night. The highly variable environmental conditions allowed us to test the effectiveness of our approach under changing light radiation, water turbidity, background confusion, and bio-fouling growth on the camera housing. The automated recognition results were highly correlated with the manual counts and they were highly reliable when used to track fish variations at different hourly, daily, and monthly time scales. In addition, our methodology could be easily transferred to other cabled video-observatories.Peer ReviewedPostprint (published version

Video monitoring of Sparidae temporal rhythms: three-year study by OBSEA cabled observatory

The abundance and composition of fish assemblages varies at different temporal scales as a product of diel and annual rhythms. In this study, we used a video-wired observatory (OBSEA, www.obsea.es) to monitor annual rhythms in a coastal fish assemblage with a 3-year data set (2012-2014). The photographs were acquired at 30 min frequency. Five species of the family Sparidae were studied (i.e. Dentex dentex, Diplodus sargus, Diplodus vulgaris, Diplodus annularis and Diplodus puntazzo) together with water temperature and daylength. The results of the annual rhythmicity analysis indicated that most of the peaks of abundance occured in the autumn months. Results suggest differentially temporal use of the reproductive or trophic niche.Peer ReviewedPostprint (published version

Recreational angling and spearfishing on social media : insights on harvesting patterns, social engagement and sentiments related to the distributional range shift of a marine invasive species

Fisheries are among the human activities that are most strongly affected by ongoing climate-related changes in the presence and abundance of fish species across the globe. The ecological and social repercussions of such changes for recreational fisheries are however still poorly understood. Here, we compare selected ecological and social dimensions of both recreational angling and spearfishing targeting the bluefish (Pomatomus saltatrix) in Italy. The bluefish has undergone a northward expansion in the region over the last 20-30 years, during which it reached new areas and increased in abundance. Using digital videos and their associated data published by both recreational anglers and spearfishers on YouTube we characterized ecological and social dimensions using a culturomics approach. Specifically, we focused on harvesting patterns, social engagement and sentiments related to the bluefish. Our study revealed four major results: (1) similar harvesting patterns (i.e., declared mass and seasonal upload patterns) related to videos by both recreational anglers and spearfishers; (2) higher social engagement (i.e., number of views and likes) for videos by recreational anglers than spearfishers; (3) differences in themes of discussion, with anglers being mainly interested in fishing strategy and gears and spearfishers being more interested in fishing actions shown on the videos; (4) positive and negative sentiments of both recreational anglers and spearfishers towards the invasiveness and aggressiveness of the species. The latter represents an interesting trade-off associated with recreational fishing of the bluefish: it is perceived as an invasive species, but it is also a valued target fish because its voracity contributes to the quality of the recreational fishing experience. Our study showcases the value of exploring social media and associated data to better understand the ecological and human dimensions of marine recreational fisheries in relation to distributional range shifts of species associated with climate change.Peer reviewe