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

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.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