Use of acoustic telemetry techniques to understand the individual variability in movement ecology of juvenile lemon sharks, Negaprion brevirostris, in natural conditions, around Bimini Islands, Bahamas: a comparison study with preliminary personality traits observed in mesocosms

Dissertação de Mestrado, Biologia Marinha, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2016Unevenness within a population is challenging to explain. It appears hazardous to interpret inter-individual dissimilarities in behavior, mainly due to a lack of information about the underlying mechanisms responsible for such expression. The key component of this study was the focus on the relationship between an intrinsic decision-making mechanism and the expression of individual movements. The uniqueness of this research laid in the study of how personality in juvenile lemon sharks, Negaprion brevirostris (Poey, 1868), may influence their natural behavior, providing a correlative analysis between personality and movement ecology. Twelve individuals were preliminarily exposed to a novel open field test to quantify a personality trait. Afterwards, the sharks were fitted with acoustic transmitters and monitored inside their nursery area, using an array of fifteen acoustic receivers, over an eight-month period. Movement patterns were assessed using active tracking. Home range and core area were measured using Minimum Convex Polygon (MCP) and Kernel Utilization Density (KUD). Although the two analyses produced different outputs, both revealed high individual differences in term of location and size. The results suggested an extensive use of the mangrove by the juveniles. The home range varied from 568.52m2 to 1296.01 m2 whilst using MCP approach, and ranged from 770.10 m2 to 1474.51 m2 based on the kernel-bivariate analysis. Similarly, core area estimates ranged from 85.88 m2 to 323.67 m2 (KUD). The estimation of the distance from the nearest shore captured a similar pattern and ranged from 38.16 m to 155.38 m. These inter-individual differences persisted even after effects of body size, sex or monitoring features were removed. However, multiple correlations revealed a strong relationship between personality traits and the spatial metrics (home range, Rs = 0.71; core area, Rs = 0.84; distance from the shore, Rs = 0.69). The results uncovered the likelihood of an influence of personality on the movement ecology of juvenile lemon sharks. Identifying mechanisms driving the expression of movement patterns provided crucial insight into decision-making processes at an individual level. Such observation should encourage further investigations to consider individual-based analyses for conservation purposes and advocate for the integration of behavioral ecology and movement ecology into a common framework to enhance the understanding of evolutionary and ecological processes.É difícil explicar a ausência de uniformidade em populações. Pode ser arriscado interpretar diferenças comportamentais entre indivíduos, principalmente devido à falta de informação sobre os mecanismos subjacentes responsáveis pela expressão destes comportamentos. O principal foco deste estudo foi a relação entre o mecanismo intrínseco de tomada de decisão e a expressão dos movimentos individuais. A originalidade deste trabalho baseia-se no estudo de como a personalidade na tubarões jovens, Negaprion brevirostris (Poey, 1868), pode influenciar o seu comportamento natural, criando uma análise de correlação entre a personalidade e a ecologia do movimento. Doze indivíduos foram previamente expostos a um teste novo para quantificar traços de personalidade. Seguidamente, os tubarões foram equipados com transmissores acústicos e monitorados dentro de sua área de maternidade, usando um conjunto de quinze receptores acústicos, ao longo de um período de oito meses. Os padrões de movimento foram avaliados através de um seguimento activo. A extensão da área habitada e a área central foram medidas usando Minimum Convex Polygon (MCP) e Kernel Utilization Density (KUD). Embora as duas análises tenham tido resultados diferentes, ambas revelaram grandes diferenças individuais em termos de localização e tamanho. Os resultados sugerem um uso intensivo de mangais pelos juvenis. Utilizando a abordagem MCP, a extensão da área habitada variou entre 568.52m2 e 1 296.01 m2. Utilizando a análise bivariada de kernel, a variação foi entre 770.10 m2 e 1 474.51 m2. Da mesma forma, as estimativas da área central variaram entre 85.88 m2 e 323.67 m2 (KUD). A estimativa da distância à costa mais próxima evidenciou um padrão semelhante, com uma variação de 38.16 a 155.38 m. Estas diferenças inter-individuais persistiram mesmo depois de removidos os efeitos do tamanho, sexo e características de monitorização. No entanto, várias correlações revelaram uma relação forte entre traços de personalidade e as métricas espaciais (área habitada, Rs = 0.71; área central, Rs = 0.84; distância à costa, Rs = 0.69). Os resultados revelaram a possibilidade da personalidade influenciar a ecologia do movimento de tubarões-limão jovens. A identificação de mecanismos que impulsionam a expressão de padrões de movimento forneceu percepção crucial sobre os processos de tomada de decisão a nível individual. Estas observações devem servir de incentivo a novas investigações, para que considerem análises individuais para fins de conservação, e insistir na integração da ecologia comportamental e ecologia do movimento num plano de trabalhos comum, com o fim de melhorar a compreensão dos processos evolutivos e ecológicos

‘Solo datasets’: unexpected behavioural patterns uncovered by acoustic monitoring of single individuals

A holistic understanding of the life-history strategies of marine populations is often hindered by complex population dynamics, exacerbated by an intricate movement ecology across their life history (Nathan et al. 2008; Parsons et al. 2008; Jeltsch et al. 2013). Movement patterns and spatial ecology can vary spatially and temporally for different reasons, mainly related to the organism’s life history and environmental variability (Abecasis et al. 2009, 2013; Afonso et al. 2009). Changes in spatial use and movement can occur daily when visiting feeding grounds or avoiding predators, or seasonally, when sexually mature individuals migrate to spawning/breeding grounds (Kozakiewicz 1995; Sundström et al. 2001). However, observed shifts in spatial use and movement patterns, as a result of behavioural plasticity, may also vary greatly from one individual to another of the same species and/or population (Afonso et al. 2009). Further, ontogeny can also play an important role and explain a possible change in individual spatial variation. Noticeable differences in the behaviour and movements of mature and immature individuals have been documented in various marine organisms (Lowe et al. 1996; Lecchini and Galzin 2005). Permanent habitat shifts have been associated with ontogenesis in pigeye sharks (Carcharhinus amboinensis), moving from inshore to offshore areas after reaching maturity (Knip et al. 2011).This research was partially funded by the EU LIFE-BIOMARES Project (LIFE06 NAT/P/000192).info:eu-repo/semantics/publishedVersio

Preliminary insights into the spatial ecology and movement patterns of a regionally critically endangered skate (Rostroraja alba) associated with a marine protected area

The implementation of spatial protection measures is currently a priority in batoid species' conservation strategies, but their spatial ecology remains largely unknown. We provide some preliminary insights into the movement patterns of the white skate (Rostroraja alba), a batoid classified as Critically Endangered in European waters. Three individuals (two females: one mature, one immatureand one immature male) were monitored with acoustic telemetry in a marine protected area (Portugal). The mature female remained present in the study area throughout the whole monitoring period (20 months). Residency analyses revealed this specimen spent more than 70% of the time within this coastal marine park. The immature female and the immature male were only detected during three and four months, respectively. Whether the uncovered movement patterns are common within the population remains unclear, but the present study provides useful information to better plan future research on the movement ecology of a rather unstudied species.Fundacao para a Ciencia e a TecnologiaPortuguese Foundation for Science and Technology [CCMAR/Multi/04326/2013]LIFE-BIOMARES project [LIFE06 NAT/P/000192]Project Buffer ERA-Net BiodivERsA [ANR-12-EBID-0006]CCMAR - Centre of Marine Sciences [CCMAR/BI/0004/2018