Movement ecology of coastal fishes in a marine protected area: implications for management and conservation

[eng] Animal movement is a key biological process for the maintenance of ecosystem services, and a major concern for the conservation of biodiversity. The aim of movement ecology is to understand the causes and consequences of these movements, including the effect of internal and external factors and its ecological implications. This research field has rapidly grown in the last decades fostered by recent technological and analytical developments, and is making substantial contributions to conservation biology, such as allowing the incorporation of the spatial and temporal scales of movements into management policies to enhance their scope and efficiency. Marine protected areas (MPAs) are the most used tools to face the effects of anthropogenic impacts on marine ecosystems. They play a major role in restoring and conserving overfished fish populations, and also potentially enhancing fisheries yield in adjacent areas through the direct spillover of juvenile and adult individuals. However, in order to be effective and generate such benefits, MPAs must be designed according to the movement attributes of targeted species, but this information is still rarely available, specially in temperate regions. In the last decades, passive acoustic telemetry techniques have demonstrated to be a valuable tool to study the movements and behavior of fishes covering large spatial and temporal scales, but the acoustic nature of the signals and the large amounts of data that they provide entail a series of challenges for their analysis and interpretation. The main objective of this thesis is to characterize the movement ecology of coastal fishes in relation to MPAs. This constitutes a basic information on the biology of species, which is required to understand changes in populations and ecosystems driven by natural or human induced impacts, as well as to correctly evaluate the outcomes of management actions. Specifically, the movements of two species, the white seabream (Diplodus sargus) and the common dentex (Dentex dentex), were monitored using acoustic telemetry in the Medes Islands MPA (Catalonia, NW Mediterranean Sea). Both species play important ecological and economical roles, shaping the structure and functioning of biological communities through top-down controls, and being an important resource for local artisanal and recreational fisheries. Nevertheless, they present a contrasting biology (omnivorous vs. predator), and therefore, different conservation needs. Firstly, we characterized the general movement attributes of the two species, including their habitat requirements and space use and activity patterns, within zones with different protection levels of the MPA. Secondly, we studied the behavioral responses of the two species to environmental fluctuations, by adding environmental information (seawater temperature and wave height) to movement analysis. These behavioral responses provide essential information on the ecology of the species such as their resistance to perturbations. Thirdly, we characterized their movement behavior during the spawning season, describing, for the first time, the formation of spawning aggregations for both species. Finally, this thesis also has an important computational and numerical component. A special effort has been done to adapt and develop new methods to visualize and analyze acoustic telemetry data, specially to improve the space use estimations by incorporating the vertical dimension, in order to provide a more comprehensive view of complex movement patterns. By studying the movement ecology of these species, we provide general mechanistic insights to understand the effects of protection on coastal fish species, as well as to predict future changes in their populations derived from climate change. We specially highlight the importance of studying the movement ecology of diverse species in order to propose integrative and more efficient management actions.[spa] Las áreas marinas protegidas (AMPs), son las herramientas de gestión más utilizadas para contrarrestar los impactos antropogénicos sobre los ecosistemas marinos y juegan un papel fundamental en la protección y restauración de las poblaciones de peces afectadas por la sobrepesca. Sin embargo, para ser efectivas y generar los beneficios que se esperan de ellas, las AMPs deben ser diseñadas en concordancia con los atributos de los movimientos de las especies de peces que se pretenden proteger, pero esta información no suele estar disponible. El principal objetivo de esta tesis es caracterizar, mediante técnicas de telemetría acústica, la ecología del movimiento de especies de peces costeros en relación a AMPs, mediante el estudio del movimiento de dos especies: el sargo común (Diplodus sargus) y el dentón (Dentex dentex), en la reserva marina de las islas Medas (Catalunya, Mediterráneo NO). Específicamente, se han caracterizado los patrones de movimiento y actividad generales de las dos especies, la presencia de respuestas comportamentales a fluctuaciones ambientales (temperatura y oleaje), y su comportamiento reproductor. Además, se ha hecho un esfuerzo especial en adaptar y desarrollar nuevas técnicas de análisis y visualización para datos de telemetría acústica, con el objetivo de mejorar las estimaciones del uso del espacio, incorporando la dimensión vertical, y de proporcionar una visión más exhaustiva de los complejos patrones de movimiento. Toda esta información es de gran aplicabilidad para la gestión de estas y otras especies costeras, así como para entender los cambios en las poblaciones y en los ecosistemas derivados del cambio global

High-Throughput Tracking of Social Networks in Marine Fish Populations

Despite their potential to generate high-quality positioning data, the use of high-resolution acoustic telemetry systems (HRATS) has been neglected in coastal marine areas due to the limitations that these environments pose to the transmission of acoustic signals. In this work, we applied a HRATS and social network analysis (SNA) to study the social interactions of the pearly razorfish (Xyrichtys novacula), a small coastal wrasse, in a Mediterranean marine reserve. Our analysis was based on proximity measures estimated from high-resolution trajectories from 232 individuals tracked during 55 days within a marine protected area. Associations were defined as the proportion of 5-min intervals in which two individuals were observed within 1 m from each other, and social networks were generated for the overall tracking period and for each particular day. The obtained network parameters were contrasted against 1,000 null association models obtained by randomly redistributing individual trajectories within the study area. The obtained networks showed a harem-like social structure, with agonistic behavior between males and larger association indices between individuals of different sex. Occasionally, sporadic associations of large groups of females were observed conducting excursions along the study area. By providing a comprehensive view of the organizational structure of the pearly razorfish, our study demonstrates the potential of HRATS to efficiently produce high-throughput tracking data from large numbers of individuals and of proper null social model formulation to reconstruct the social networks in wild-living marine fish populations. The combination of HRATS and SNA represents a powerful tool to study key ecological processes regarding the social interactions of individuals, including social dynamics, collective movements, and the response to environmental perturbations.Peer Reviewe

Effective dispersal and density-dependence in mesophotic macroalgal forests: Insights from the Mediterranean species Cystoseira zosteroides

Dispersal and recruitment are fundamental processes for population recovery following disturbances in sessile species. While both processes are well understood for many terrestrial species, they still remain poorly resolved for some macroalgal species. Here we experimentally investigated the effective dispersal and recruit survival of a mesophotic Mediterranean fucoid, Cystoseira zosteroides. In three isolated populations, four sets of settlement collectors were placed at increasing distances (from 0 to 10 m) and different orientations (North, South, East and West). We observed that effective dispersal was restricted to populations' vicinity, with an average of 6.43 m and not further than 13.33 m, following a Weibull distribution. During their first year of life, survival was up to 50%, but it was lower underneath the adult canopy, suggesting a negative density-dependence. To put our results in a broader context we compared the effective dispersal of other fucoid and kelp species reported in the literature, which confirmed the low dispersal ability of brown algae, in particular for fucoids, with an effective dispersal of few meters. Given the importance of recruitment for the persistence and recovery of populations after disturbances, these results underline the vulnerability of C. zosteroides and other fucoid species to escalating threats

Acquisition et renseignement de l’indicateur espèces thermophobes: État des populations de la gorgone blanche Eunicella singularis dans le Parc national de Port-Cros dans le cadre de OBi_1. (2016). Rapport final. Contrat Parc national de Port-Cros & Universitat de Barcelona

Étude réalisée par l’Universitat de Barcelona, dans le cadre d’un Partenariat Scientifique avec le Parc National de Port-Cros. Contrat n°: 16-010 - 83400 P

Indicateurs espèces thermophobes: État des populations de la gorgone blanche Eunicella singularis dans le Parc national de Port-Cros.

Étude réalisée par l’Universitat de Barcelona, dans le cadre d’un Partenariat Scientifique avec le Parc National de Port-Cros Contrat n° : 13-030 - 83400 PCLes gorgones sont des composantes courantes des communautés coralligènes et elles jouent un rôle très important dans certains écosystèmes méditerranéens de fond dur car il s’agit d’espèces ingénieures qui modèlent l’habitat. Cependant, ces espèces sont parmi les plus menacées par le réchauffement climatique, mais des informations sur leur démographie et leur distribution, aspect crucial pour la conservation et la gestion durable, sont encore rares. Par conséquent, nous avons caractérisé les populations de Eunicella singularis dans le Parc national de Port-Cros tout en examinant leur distribution spatiale et en profondeur, ainsi que la structure de tailles de ces populations et l’affectation des perturbations. Cette espèce est présente principalement dans la partie sud des îles, sur des sites exposés à des courants et à une profondeur allant de 9,5 à 38 m, mais montrant une grande variabilité dans les limites de distribution supérieures et inférieures entre les sites. Les valeurs de la densité, la taille et la mortalité des populations étudiées ont été très semblables aux études précédentes menées dans d'autres endroits de la Méditerranée. La plupart des populations étudiées ont été dominées par des colonies de taille moyenne, ont montré une faible proportion de colonies fortement endommagées, et les colonies les plus blessées avaient des épibiontes, suggérant que la plupart d'entre elles n'ont pas été exposées à de fortes perturbations récentes. Dans un seul site, Le Petit Sarranier, les populations de E. singularis montrent un pourcentage élevé de la surface endommagée, principalement sans épibiose, ainsi que des colonies mortes et une forte dominance de petites colonies. Ça semble indiquer que cette population, celle de moindre profondeur parmi les populations examinées, est exposée à des perturbations naturelles. Nos résultats montrent que les populations les moins profondes (moins de 15 m) présentent des signaux de mortalité récente avec une forte proportion de blessures par rapport aux populations les plus profondes. Ainsi, il semble que la température de l’eau, avec une formation d'une thermocline saisonnière, pourrait être le principal facteur qui affecte les populations peu profondes de E. singularis dans le Parc national de Port-Cros, bien que d'autres facteurs que la température pourraient avoir un rôle important dans le façonnement des tendances observées. Cette étude a fourni une base pour de futures études sur cette espèce dans le Parc, ce qui sera essentiel pour améliorer notre compréhension de la dynamique de cette espèce sur des échelles de temps plus grandes et de leurs tendances futures dans le cadre du scénario global de changement environnemental

Performance of a novel system for high-resolution tracking of marine fish societies

Recent advances in tracking systems have revolutionized our ability to study animal movement in the wild. In aquatic environments, high-resolution acoustic telemetry systems make it technically possible to simultaneously monitor large amounts of individuals at unprecedented spatial and temporal resolutions, providing a unique opportunity to study the behaviour and social interactions using a reality mining approach. Despite the potential, high-resolution telemetry systems have had very limited use in coastal marine areas due to the limitations that these environments pose to the transmission of acoustic signals. This study aims at designing and testing a high-resolution acoustic telemetry system to monitor, for the first time, a natural fish population in an open marine area. First, we conducted preliminary range tests and a computer simulation study to identify the optimal design of the telemetry system. Then, we performed a series of stationary and moving tests to characterize the performance of the system in terms of positioning efficiency and precision. Finally, we obtained a dataset corresponding to the movements of 170 concurrently tagged individuals to demonstrate the overall functioning of the system with a real study case of the behaviour of a small-bodied coastal species. Our results show that high-resolution acoustic telemetry systems efficiently generate positional data in marine systems, providing a precision of few meters, a temporal resolution of few seconds, and the possibility of tracking hundreds of individuals simultaneously. Data post-processing using a trajectory filter and movement models proved to be key to achieve a sub-meter positioning precision. The main limitation detected for our system was the restricted detection range, which was negatively affected by the stratification of the water column. Our work demonstrates that high-resolution acoustic telemetry systems are an effective method to monitor the movements of free-ranging individuals at the population level in coastal sites. By providing highly precise positioning estimates of large amounts of individuals, these systems represent a powerful tool to study key ecological processes regarding the social interactions of individuals, including social dynamics, collective movements, or responses to environmental perturbations, and to extend the studies to poorly studied small-sized species or life-stages.The telemetry system was financed by the German Federal Ministry of Education and Research (grant no. #033W024A). EA was supported by a Margalida Comas postdoctoral grant from the Government of the Balearic Islands and the European Social Fund (Grant No. PD/023/2018). JA was supported by a Ramon y Cajal Grant (Grant No. RYC2018-024488-I) and received funding from the CLOCKS R&D Project (Grant No. PID2019-104940GA-I00) and the intramural research project JSATS (Grant No. PIE 202030E002) funded by the Spanish Ministry of Science and Innovation and the Spanish National Research Council. GFB was supported by a Ph.D. fellowship (FPI-INIA 2015–0013-CPD2015-0084) from the National Institute for Agricultural and Food Research and Technology.Peer reviewe

Ordinary and Extraordinary Movement Behaviour of Small Resident Fish within a Mediterranean Marine Protected Area

It is important to account for the movement behaviour of fishes when designing effective marine protected areas (MPAs). Fish movements occur across different spatial and temporal scales and understanding the variety of movements is essential to make correct management decisions. This study describes in detail the movement patterns of an economically and commercially important species, Diplodus sargus, within a well-enforced Mediterranean MPA. We monitored horizontal and vertical movements of 41 adult individuals using passive acoustic telemetry for up to one year. We applied novel analysis and visualization techniques to get a comprehensive view of a wide range of movements. D. sargus individuals were highly territorial, moving within small home ranges ( 50 m), where they aggregated to spawn. This study advances our understanding about the functioning of an established MPA and provides important insights into the biology and management of a small sedentary species, suggesting the relevance of rare but important fish behaviours

Long-term monitoring of temperate macroalgal assemblages inside and outside a No take marine reserve

Macroalgal communities have an essential role in the shallow benthic habitats of temperate seas, where changes in their composition can resonate through entire coastal ecosystems. As all major ecosystems on Earth, algal beds have already been affected by multiple disturbances. Passive conservation tools, such as marine protected areas or No-take zones, have the potential to reduce some of the anthropogenic impacts by limiting human activity. However, without a good knowledge of the natural community dynamics, it is not easy to discern between changes fruit of the intrinsic variability of biological communities and the ones caused by human-related stressors. In this study, we evaluated the natural variability of macroalgal communities' composition inside and outside a Mediterranean No-Take marine reserve during 15 years. We described their temporal dynamics considering their main drivers and we tested the effect of protection in seaweed beds. We did not find differences either in the composition of the macroalgal assemblages or the total algal cover between protected and nonprotected locations over the fifteen years of study. Nevertheless, we observed a positive effect of the protection increasing the cover of some specific species, such as the canopy-forming Treptacantha elegans. Our results highlight the importance of obtaining long-term data in ecological studies to better understand the natural variability of marine communities. Accordingly, a robust understanding of the community dynamics would help us to avoid misinterpretations between 'impacted' or 'in-recovery' communities when recovery times are longer than the study periods

Estudi de la dinàmica de la població de l'espècie de briozou Pentapora fascialis de la Reserva Marina de les Illes Medes. Informe tècnic per al Parc Natural del Montgrí, les Illes Medes i el Baix Ter.

Estudi realitzat per la Universitat de Barcelona per encàrrec del Parc Natural del Montgrí, les Illes Medes i el Baix TerAquesta memòria presenta els resultats del grup de treball del Departament d’Ecologia de la UB respecte a l’estudi de les comunitats de briozous de la Reserva Marina de les Illes Medes amb l’objectiu d’estudiar i caracteritzar la dinàmica del briozou Pentapora fascialis i establir les bases per a utilitzar aquesta espècie com a indicadora de l’efecte dels submarinistes sobre les comunitats bentòniques

Food determines ephemerous and non-stable gut microbiome communities in juvenile wild and farmed Mediterranean fish

Novel insights were provided by contrasting the composition of wild and farmed fish gut microbiomes because the latter had essentially different environmental conditions from those in the wild. This was reflected in the gut microbiome of the wild Sparus aurata and Xyrichtys novacula studied here, which showed highly diverse microbial community structures, dominated by Proteobacteria, mostly related to an aerobic or microaerophilic metabolism, but with some common shared major species, such as Ralstonia sp. On the other hand, farmed non-fasted S. aurata individuals had a microbial structure that mirrored the microbial composition of their food source, which was most likely anaerobic, since several members of the genus Lactobacillus, probably revived from the feed and enriched in the gut, dominated the communities. The most striking observation was that after a short fasting period (86 h), farmed gilthead seabream almost lost their whole gut microbiome, and the resident community associated with the mucosa had a very much reduced diversity that was highly dominated by a single potentially aerobic species Micrococcus sp., closely related to M. flavus. The results pointed to the fact that, at least for the juvenile S. aurata studied, most of the microbes in the gut were transient and highly dependent on the feed source, and that only after fasting for at least 2 days could the resident microbiome in the intestinal mucosa be determined. Since an important role of this transient microbiome in relation to fish metabolism could not be discarded, the methodological approach needs to be well designed in order not to bias the results. The results have important implications for fish gut studies that could explain the diversity and occasional contradictory results published in relation to the stability of marine fish gut microbiomes, and might provide important information for feed formulation in the aquaculture industry.info:eu-repo/semantics/publishedVersio