Scientific publications
- (2024). Open Protocols, the new standard for acoustic tracking: results from interoperability and performance tests in European waters. Animal Biotelemetry 12:40. doi: 10.1186/s40317-024-00396-9.
Abstract
Background: The lack of compatibility between acoustic telemetry equipment from different manufacturers has been a major obstacle to consolidating large collaborative tracking networks. Undisclosed encrypted signal coding protocols limit the use of acoustic telemetry to study animal movements over large spatial scales, reduce competition between manufacturers, and stifle innovation. The European Tracking Network, in collaboration with several acoustic telemetry manufacturers, has worked to develop new transparent protocols for acoustic tracking. The results are energy-efficient transmission protocols accessible to all researchers and manufacturers. Today, the Open Protocols (OP) are already available to manufacturers and developers, and the first transmitters and receivers to implement them are already in the water.
Results: The main objective of this study was to confirm the compatibility between devices from different manufacturers using OP, characterise the acoustic range of each transmitter–receiver manufacturer combination, compare the detection efficiency to the standard protocols used at present (R64K and encrypted protocols), and assess its robustness against spurious detections. An international collaborative effort was made to conduct acoustic range tests in four main aquatic habitats: a river, a coastal lagoon, a coastal habitat, and the open sea. Receivers and transmitters from different manufacturers were deployed at increasing distances from each other using the same experimental design at each location. The decay of detection probability with distance was modelled for each transmitter–receiver manufacturer combination by applying logistic regression using a Bayesian approach. Furthermore, to thoroughly assess performance differences in an applied research context, we conducted a direct field comparison between groups of smolts tagged with OP and R64K tags, tracking their migration to the sea.
Conclusions: Our results confirm full compatibility between the tested devices, with negligible differences in the measured acoustic ranges between OP manufacturers and when compared to encrypted protocols. The OP was also robust against spurious detections, and the field comparison between OP and R64K showed equal performance. We hope these novel insights will encourage international research groups to promote OP-based studies to ensure compatibility and maximise the benefits of acoustic telemetry networks. - (2024). Fully protected marine areas linked to reduced home ranges of fishes . Fish and Fisheries 25(6):985–996. doi: 10.1111/faf.12859.
Abstract
Home range size is a fundamental trait that can affect the probability of fish being harvested and, at the same time, may be affected by fishing. The relationship between home range size and fishing will impact the effectiveness of fully protected areas (FPAs), as it will influence the number of fish moving into fished areas, affecting both spillover and edge effects. One hypothesis is that individuals within FPAs will present reduced home range size relative to individuals in fished areas. This pattern can be driven by demographic selection (e.g. fishing of individuals with large home ranges leaving the FPAs), improved habitat requiring less foraging movements, or behavioural changes associated with reduced fishing threats. To test the relationship between home range size and protection, we compiled 1143 individual-level home range sizes based on acoustic tracking, covering 17 species from 11 FPAs in 7 countries, with information on distance from FPA borders. A dichotomic analysis (in/out of FPAs) did not support a significant change in the home range size between FPAs and fished areas. However, continuous analysis across the FPA borders demonstrated reduced home range size within the FPAs. We did not find an effect of FPA age or size on this pattern. While we cannot pinpoint the underlying mechanism for the pattern revealed, we suggest behavioural changes as the main driver for reduced home range within FPAs. This mechanism will lead to more resident populations within FPAs, reducing fishing mortality within FPAs yet limiting spillover benefits to adjacent fisheries. - (2024). The importance of locally sourced data in identifying population trends: Insights from Iberian vertebrates. Biological Conservation 298:110755. doi: 10.1016/j.biocon.2024.110755.
Abstract
Understanding species population trends is key for assessing their conservation status and proposing measures to ensure their future persistence amid recent biodiversity loss. However, studies are reporting contrasting biodiversity trends over time. These discrepancies can be partly attributed to biases in global datasets, which might not capture the representativeness of local processes. Here, we aimed to address this gap of knowledge by complementing data included in the Living Planet Database (LPD), one of the largest repositories of population time-series, with locally sourced data from the Iberian Peninsula. The study aim: (i) to assess the state of wildlife Iberian vertebrates using population time-series across taxonomic groups and (ii) to determine differences between locally sourced data and LPD (evaluating also the differences between data sources). To supplement LPD, we conducted a review, analysing over 6000 peer-reviewed manuscripts and grey literature documents. We obtained 999 population time-series for 294 vertebrate species compiled in an Iberian Vertebrate (IbeV) database, two times the number of populations as the LPD includes. Our results indicate contrasting population trends across taxonomic groups, with freshwater amphibians and bony fishes showing steep declines. Moreover, the LPD shows a positive trend and IbeV indicates no net change over time. Threatened species did not exhibit net changes in population trends, while non-threatened species showed positive trends. We showed that local databases can provide distinct population trends compared to global databases. This approach highlights the need to bridge the gap between global and local datasets, to support context-specific management and conservation programmes. - (2024). Measuring activity-rest rhythms under different acclimation periods in a marine fish using automatic deep learning-based video tracking. Chronobiology International 41(7):959–970. doi: 10.1080/07420528.2024.2371143.
Abstract
Most organisms synchronize to an approximately 24-hour (circadian) rhythm. This study introduces a novel deep learning-powered video tracking method to assess the stability, fragmentation, robustness and synchronization of activity rhythms in Xyrichtys novacula. Experimental X. novacula were distributed into three groups and monitored for synchronization to a 14/10 hours of light/dark to assess acclimation to laboratory conditions. Group GP7 acclimated for 1 week and was tested from days 7 to 14, GP14 acclimated for 14 days and was tested from days 14 to 21 and GP21 acclimated for 21 days and was tested from days 21 to 28. Telemetry data from individuals in the wild depicted their natural behavior. Wild fish displayed a robust and minimally fragmented rhythm, entrained to the natural photoperiod. Under laboratory conditions, differences in activity levels were observed between light and dark phases. However, no differences were observed in activity rhythm metrics among laboratory groups related to acclimation period. Notably, longer acclimation (GP14 and GP21) led to a larger proportion of individuals displaying rhythm synchronization with the imposed photoperiod. Our work introduces a novel approach for monitoring biological rhythms in laboratory conditions, employing a specifically engineered video tracking system based on deep learning, adaptable for other species. - (2024). When resilience is not enough: 2022 extreme marine heatwave threatens climatic refugia for a habitat-forming Mediterranean octocoral. Journal of Animal Ecology Early view:NA. doi: 10.1111/1365-2656.14112.
Abstract
1. Climate change is impacting ecosystems worldwide, and the Mediterranean Sea is no exception. Extreme climatic events, such as marine heat waves (MHWs), are increasing in frequency, extent and intensity during the last decades, which has been associated with an increase in mass mortality events for multiple species.
2. Coralligenous assemblages, where the octocoral Paramuricea clavata lives, are strongly affected by MHWs. The Medes Islands Marine Reserve (NW Mediterranean) was considered a climate refugia for P. clavata, as their populations were showing some resilience to these changing conditions.
3. In this study, we assessed the impacts of the MHWs that occurred between 2016 and 2022 in seven shallow populations of the octocoral P. clavata from a Mediterranean Marine Protected Area.
4. The years that the mortality rates increased significantly were associated with the ones with strong MHWs, 2022 being the one with higher mortalities. In 2022, with 50 MHW days, the proportion of total affected colonies was almost 70%, with a proportion of the injured surface of almost 40%, reaching levels never attained in our study site since the monitoring was started.
5. We also found spatial variability between the monitored populations. Whereas few of them showed low levels of mortality, others lost around 75% of their biomass
6. The significant impacts documented here raise concerns about the future of shallow P. clavata populations across the Mediterranean, suggesting that the resilience of this species may not be maintained to sustain these populations face the ongoing warming trends. - (2024). Marine protected areas promote stability of reef fish communities under climate warming. Nature Communications 15:1822. doi: 10.1038/s41467-024-44976-y.
Abstract
Protection from direct human impacts can safeguard marine life, yet ocean warming crosses marine protected area boundaries. Here, we test whether protection offers resilience to marine heatwaves from local to network scales. We examine 71,269 timeseries of population abundances for 2269 reef fish species surveyed in 357 protected versus 747 open sites worldwide. We quantify the stability of reef fish abundance from populations to metacommunities, considering responses of species and functional diversity including thermal affinity of different trophic groups. Overall, protection mitigates adverse effects of marine heatwaves on fish abundance, community stability, asynchronous fluctuations and functional richness. We find that local stability is positively related to distance from centers of high human density only in protected areas. We provide evidence that networks of protected areas have persistent reef fish communities in warming oceans by maintaining large populations and promoting stability at different levels of biological organization. - (2024). Circadian-related behavioural types in free-living marine fish revealed by high-throughput telemetry. Animal Behaviour 210:255–274. doi: 10.1016/j.anbehav.2023.12.019.
Abstract
Like terrestrial animals, wild fish exhibit individual differences in daily activity patterns, known as chronotypes. However, monitoring free-living fish has posed challenges in studying chronotypes and their plasticity in response to the environment. To address this issue, we utilized high-throughput telemetry to measure daily activity in a large group of free-living pearly razorfish, Xyrichtys novacula, while also monitoring fine-scale environmental variables. Using hidden Markov models for behavioural segmentation, we quantified four circadian-related traits (awakening time, rest onset, activity duration relative to the daytime and rest midpoint relative to middle of the night) during two biological contexts (prespawning and spawning). We then used linear mixed-effects models to decompose the variation of these traits into individual, ecological (contextual environment) and population components. Our findings revealed the presence of chronotypes in both sexes, with greater between-individual variation in behaviour during spawning. Males exhibited longer activity duration due to an earlier awakening time than females, and temperature, waves and light significantly influenced daily activity behaviours. However, there was considerable individual variation in response to environmental changes, indicating the emergence of behavioural reaction norms (i.e. plasticity), with females showing greater plasticity in rest onset and relative rest midpoint. Our study also identified significant correlations among traits, suggesting that the activity duration continuum defines the pearly razorfish chronotype. Overall, our work represents the most comprehensive description of individual and ecological contextual variation in chronotypes within a wild marine fish population. It underscores the importance of environmental fluctuations in shaping the expression of internal clocks. - (2024). Electronic tagging and tracking aquatic animals to understand a world increasingly shaped by a changing climate and extreme weather events. Canadian Journal of Fisheries and Aquatic Sciences 81(3):326–339. doi: 10.1139/cjfas-2023-0145.
Abstract
Despite great promise for understanding the impacts and extent of climate change and extreme weather events on aquatic animals, their species, and ecological communities, it is surprising that electronic tagging and tracking tools, like biotelemetry and biologging, have not been extensively used to understand climate change or develop and evaluate potential interventions that may help adapt to its impacts. In this review, we provide an overview of methodologies and study designs that leverage available electronic tracking tools to investigate aspects of climate change and extreme weather events in aquatic ecosystems. Key interventions to protect aquatic life from the impacts of climate change, including habitat restoration, protected areas, conservation translocations, mitigations against interactive effects of climate change, and simulation of future scenarios, can all be greatly facilitated by using electronic tagging and tracking. We anticipate that adopting animal tracking to identify phenotypes, species, or ecosystems that are vulnerable or resilient to climate change will help in applying management interventions such as fisheries management, habitat restoration, invasive species control, or enhancement measures that prevent extinction and strengthen the resilience of communities against the most damaging effects of climate change. Given the scalability and increasing accessibility of animal tracking tools for researchers, tracking individual organisms will hopefully also facilitate research into effective solutions and interventions against the most extreme and acute impacts on species, populations, and ecosystems. - (2024). Movements and spatial distribution of an endangered fish (Sciaena umbra) within a Marine Protected Area. Scientific Reports 14:3103. doi: 10.1038/s41598-023-50194-1.
Abstract
The brown meagre (Sciaena umbra) is an endangered species, which requires specific protection measures to ensure its conservation. These measures need to be informed by high-quality scientific knowledge on their space use patterns. Here, we used acoustic telemetry to assess its seasonal movement patterns and habitat use within a marine protected area (MPA). Our results suggested that S. umbra is a highly sedentary species (home range < 1.0 km2) and, therefore, the MPA is extensive enough to protect the local population. Their population was discretely distributed in two main areas within the MPA, which was likely a result of habitat segregation and density-dependent movements. The temporal variability of their movements further uncovered when and where spawning occurs (mainly, but probably not only, in the fully protected area in June) and indicated that spillover of this species is limited but still possible. Overall, we highlight the importance of MPAs in the recovery of S. umbra, we advocate the need to perpetuate the current national fishing bans and extend it to other countries in the Mediterranean region, and we emphasize that considering the fine-scale movements of S. umbra in future management actions is key to achieving a successful recovery of their populations. - (2023). Chronotypes-personality behavioural syndromes in wild marine fish. Scientific Reports 13:20281. doi: 10.1038/s41598-023-45579-1.
Abstract
Chronotypes, the individual differences in daily activity timing, have profound associations with numerous physiological processes. Despite this, the covariance between chronotypes and other aspects of an individual's behaviour has been infrequently explored in non-human animals. This study delves into individual's variation across four axes of personality in a controlled environment, utilising the pearly razorfish, a model species for fish chronotype studies. We identified behavioural types across the aggressiveness continuum and established behavioural syndromes amongst exploration, activity, and boldness, irrespective of body size and condition. Subsequent to this, the experimental subjects were reintroduced to their natural habitat and individually tracked using high-resolution technology to ascertain their chronotypes. Our results revealed that whilst the exploration-activity-boldness syndrome bore no correlation with chronotypes, a significant association was observed between aggressiveness and chronotype. Hence, individuals with later awakening times and rest onsets were more aggressive than their counterparts with earlier awakening times and rest onsets. This study provides pioneering evidence linking fish chronotypes with other behavioural traits, such as aggressiveness, suggesting that behavioural variation could be potentially linked to the individuals' variation in internal clocks and the environmental variables influencing their expression. - (2023). Positioning aquatic animals with acoustic transmitters. Methods in Ecology and Evolution 14(10):2514–2530. doi: 10.1111/2041-210X.14191.
Abstract
1. Geolocating aquatic animals with acoustic tags has been ongoing for decades, relying on the detection of acoustic signals at multiple receivers with known positions to calculate a 2D or 3D position, and ultimately recreate the path of an aquatic animal from detections at fixed stations.
2. This method of underwater geolocation is evolving with new software and hardware options available to help investigators design studies and calculate positions using solvers based predominantly on time-difference-of-arrival and time-of-arrival.
3. We provide an overview of the considerations necessary to implement positioning in aquatic acoustic telemetry studies, including how to design arrays of receivers, test performance, synchronize receiver clocks and calculate positions from the detection data. We additionally present some common positioning algorithms, including both the free open-source solvers and the ‘black-box’ methods provided by some manufacturers for calculating positions.
4. This paper is the first to provide a comprehensive overview of methods and considerations for designing and implementing better positioning studies that will support users, and encourage further knowledge advances in aquatic systems. - (2023). Disparate behavioral types in wild and reared juveniles of gilthead seabream. Scientific Reports 13:11226. doi: 10.1038/s41598-023-37554-7.
Abstract
Fish differ consistently in behavior within the same species and population, reflecting distinct behavioral types (BTs). Comparing the behavior of wild and reared individuals provides an excellent opportunity to delve into the ecological and evolutionary consequences of BTs. In this work, we evaluated the behavioral variation of wild and reared juvenile gilthead seabreams, Sparus aurata, a highly relevant species for aquaculture and fisheries. We quantified behavioral variation along the five major axes of fish behavioral traits (exploration-avoidance, aggressiveness, sociability, shyness-boldness, and activity) using standardized behavioral tests and a deep learning tracking algorithm for behavioral annotation. Results revealed significant repeatability in all five behavior traits, suggesting high consistency of individual behavioral variation across the different axes in this species. We found reared fish to be more aggressive, social and active compared to their wild conspecifics. Reared individuals also presented less variance in their aggressiveness, lacking very aggressive and very tame individuals. Phenotypic correlation decomposition between behavioral types revealed two different behavioral syndromes: exploration-sociability and exploration-activity. Our work establishes the first baseline of repeatability scores in wild and reared gilthead seabreams, providing novel insight into the behavior of this important commercial species with implications for fisheries and aquaculture. - (2023). Intense scuba diving does not alter activity patterns of predatory reef fish: evidence from a protected tourism hotspot. Journal of Environmental Management 344:118491. doi: 10.1016/j.jenvman.2023.118491.
Abstract
The rise of nature-based tourism has provided a new avenue for disturbing animal behaviour, especially in protected areas. One of the most important tourism sectors in aquatic environments is scuba diving, an activity considered sustainable given its non-extractive nature and capability of bringing relevant socio-economic benefits to local communities. However, knowledge about its impact on the activity patterns of aquatic animals is still scarce. Here, we used biotelemetry techniques to assess the importance of scuba diving in modulating the activity patterns of the dusky grouper (Epinephelus marginatus, Lowe, 1834), a marine predatory fish of high interest for fishing and tourism. We implemented Hidden Markov Models (HMMs) on high-resolution acceleration data using a temporal and spatial control while controlling for a set of environmental variables (i.e. photoperiod, time-of-day, moon phase, temperature, wave height, and intensity and direction of marine currents) within a multiple-use marine protected area, and diving tourism hot-spot, of the western Mediterranean Sea. Our results underlined the more decisive influence of environmental-related stressors on the activity patterns of the dusky grouper compared to the impact of scuba diving. A high heterogeneity existed in the response against most of the stressors, including the presence of scuba divers. Overall, the activity of dusky grouper was higher at night than at day, showing a positive relationship with wave height, water temperature, and current intensity and a negative one with the moon phase. Remarkably, our findings, based on novel biotelemetry tools, differed substantially from the common wisdom accepted for this species. In conclusion, there is no clear evidence of scuba divers influence on the general activity patterns of the dusky grouper. Beyond their relevance from an ecological perspective, these results provide useful insights for the sustainable management of coastal resources, suggesting that scuba diving, when properly carried out, can represent an important sector to foster for the blue growth of coastal communities. - (2023). Activity–Rest Circadian Rhythm of the Pearly Razorfish in Its Natural Habitat, before and during Its Mating. Biology 12(6):810. doi: 10.3390/biology12060810.
Abstract
Recent technological advances in marine biotelemetry have demonstrated that marine fish species perform activity–rest rhythms that have relevant ecological and evolutionary consequences. The main objective of the present report is to study the circadian rhythm of activity–rest of the pearly razorfish, Xyrichtys novacula in its own habitat, before and during the reproduction season using a novel biotelemetry system. This fish species is a small-bodied marine species that inhabits most shallow soft habitats of temperate areas and has a high interest for commercial and recreational fisheries. The activity of free-living fish was monitored by means of high-resolution acoustic tracking of the motor activity of the fish in one-minute intervals. The obtained data allowed the definition of the circadian rhythm of activity–rest in terms of classical non-parametric values: interdaily stability (IS), intradaily variability (IV), relative amplitude (RA), average activity during the most-active period of consecutive 10 h (M10), and average activity during the least-active period of consecutive 5 h (L5). We observed a well-marked rhythm, with little fragmentation and good synchrony with the environmental cycle of light–darkness, regardless of sex and the period studied. However, the rhythm was found to be slightly more desynchronized and fragmented during reproduction because of variations in the photoperiod. In addition, we found that the activity of the males was much higher than that of the females (p < 0.001), probably due to the peculiar behavior of the males in defending the harems they lead. Finally, the time at which activity began in males was slightly earlier than it was in females (p < 0.001), presumably due to the same fact, as differences in activity or for the individual heterogeneity of this species in the time of awakening are considered to be an independent axis of the fish’s personality. Our work is novel, as it is one of the first studies of activity–rest rhythm using classical circadian-related descriptors in free-living marine fish using locomotory data facilitated by novel technological approaches. - (2023). Food determines ephemerous and non-stable gut microbiome communities in juvenile wild and farmed Mediterranean fish. Science of the Total Environment 889:164080. doi: 10.1016/j.scitotenv.2023.164080.
Abstract
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. - (2023). ATfiltR: A solution for managing and filtering detections from passive acoustic telemetry data. MethodsX 10:102222. doi: 10.1016/j.mex.2023.102222.
Abstract
Acoustic telemetry is a popular and cost-efficient method for tracking the movements of animals in the aquatic ecosystem. But data acquired via acoustic telemetry often contains spurious detections that must be identified and excluded by researchers to ensure valid results. Such data management is difficult as the amount of data collected often surpasses the capabilities of simple spreadsheet applications. ATfiltR is an open-source package programmed in R that allows users to integrate all telemetry data collected into a single file, to conditionally attribute animal data and location data to detections and to filter spurious detections based on customizable rules. Such tool will likely be useful to new researchers in acoustic telemetry and enhance results reproducibility.
– ATfiltR compiles telemetry files and identifies and stores all data that was collected outside of your study period (e.g. when your receivers were on land for servicing) elsewhere.
– As spurious detections are unlikely to appear sequentially in the data, ATfiltR finds all detections that occurred only once (per receiver or in the whole array) within a user-designated time period and stores them elsewhere.
– ATfiltR identifies detections that are impossible given the animals’ swimming speeds and the receivers detection range and stores them elsewhere. - (2023). Marine protected areas in a changing ocean: Adaptive management can mitigate the synergistic effects of local and climate change impacts. Biological Conservation 282:110048. doi: 10.1016/j.biocon.2023.110048.
Abstract
During the last two decades, several Marine Heatwaves (MHWs) have affected coralligenous assemblages in the Mediterranean Sea, causing catastrophic mass mortalities of several habitat-forming species such as gorgonians, corals, and sponges. Even though Marine Protected Areas (MPAs) are contributing to effectively protect marine ecosystems, the impacts associated to extreme climatic events within MPAs are jeopardizing their protective role. Therefore, minimizing local stressors within MPAs is crucial to minimize interactive effects with global, more difficult to manage, stressors. To address this, we assessed to what extent the regulation of diving frequentation can support more effective protection to climate change, focusing on the case study of the Medes Islands, which has recently suffered the impacts of different global stressors and is one of the most visited MPAs in the Mediterranean Sea. We combined 6 years of demographic data of the red gorgonian Paramuricea clavata with population modelling tools, to explore the long-term viability of this species to different managing schemes and mass mortality events scenarios. Overall, our results show that climate-adaptive management of the recreational diving activity under climate change can enhance the long-term viability of this key Mediterranean habitat-forming octocoral, which is otherwise predicted to go locally extinct at shallow depths (<25 m) within the next 20 years. This study provides one of the few attempts to quantify to what extent an adaptive management scheme may help delay climate change impacts in a Marine Protected Area. - (2023). Body size scaling of space use in coastal pike (Esox lucius) in brackish lagoons of the southern Baltic Sea. Fisheries Research 260:106560. doi: 10.1016/j.fishres.2022.106560.
Abstract
The northern pike (Esox lucius) has been intensively studied in terms of behaviour due to its relevance to fisheries and its importance for structuring fish communities in freshwater ecosystems. However, little is known about the behaviour of coastal pike living in brackish lagoons. Freshwater ecosystems, particularly lakes and small rivers, are usually finite in space, which can limit the expression of space use as a function of body size and other traits. Better understanding the spatial behaviour shown by coastal pike in extended brackish lagoons and its relationship to body size, sex, season and vulnerability to fishing is an important step to further our knowledge on brackish pike populations and can inform management. Here, we present two years of acoustic telemetry data acquired on a large sample of coastal pike (n = 210) with an extended size range (480 to 1.210 mm total length) inhabiting six interconnected coastal lagoons bordered by the islands of Fischland-Darß-Zingst, Hiddensee, Rügen and Usedom in the Baltic Sea (area ca. 1.200 km2). Overall, the space used by coastal pike (50 % and 95 % utilization distribution, UD) scaled positively with body size, with larger fish using significantly more space after controlling for co-variates, but this effect was mainly observed at the between lagoon level. Within a given lagoon, body size scaling of space use was only observed for the 50 % UD of males. We also found the ratio of 50 % UD on 95 % UD to scale negatively with size, meaning that larger-sized pike used areas out of their core ranges more intensively regardless of sex. Space use also differed between seasons, with activity spaces being elevated in spring likely due to spawning migrations and increased reproduction-related activity. Study design was an important co-variate for our space use proxies, as we collected proportionally more data on pike that used less space, but fish recaptured by fisheries did not differ in space use from those that were not recaptured. All space use proxies were found to be repeatable, suggesting an influence of pike personalities on their individual spatial behaviour. This study provides an updated understanding of spatial behaviour in Brackish water-adapted pike and its ties to body size, highlighting how body size in interaction with biotic and abiotic factors drives space use patterns. - (2022). Toward a decade of ocean science for sustainable development through acoustic animal tracking. Global Change Biology 28(19):5630–5653. doi: 10.1111/gcb.16343.
Abstract
The ocean is a key component of the Earth's dynamics, providing a great variety of ecosystem services to humans. Yet, human activities are globally changing its structure and major components, including marine biodiversity. In this context, the United Nations has proclaimed a Decade of Ocean Science for Sustainable Development to tackle the scientific challenges necessary for a sustainable use of the ocean by means of the Sustainable Development Goal 14 (SDG14). Here, we review how Acoustic animal Tracking, a widely distributed methodology of tracking marine biodiversity with electronic devices, can provide a roadmap for implementing the major Actions to achieve the SDG14. We show that acoustic tracking can be used to reduce and monitor the effects of marine pollution including noise, light, and plastic pollution. Acoustic tracking can be effectively used to monitor the responses of marine biodiversity to human-made infrastructures and habitat restoration, as well as to determine the effects of hypoxia, ocean warming, and acidification. Acoustic tracking has been historically used to inform fisheries management, the design of marine protected areas, and the detection of essential habitats, rendering this technique particularly attractive to achieve the sustainable fishing and spatial protection target goals of the SDG14. Finally, acoustic tracking can contribute to end illegal, unreported, and unregulated fishing by providing tools to monitor marine biodiversity against poachers and promote the development of Small Islands Developing States and developing countries. To fully benefit from acoustic tracking supporting the SDG14 Targets, trans-boundary collaborative efforts through tracking networks are required to promote ocean information sharing and ocean literacy. We therefore propose acoustic tracking and tracking networks as relevant contributors to tackle the scientific challenges that are necessary for a sustainable use of the ocean promoted by the United Nations. - (2022). Marine heatwaves drive recurrent mass mortalities in the Mediterranean Sea. Global Change Biology 28(19):5708–5725. doi: 10.1111/gcb.16301.
Abstract
Climate change is causing an increase in the frequency and intensity of marine heatwaves (MHWs) and mass mortality events (MMEs) of marine organisms are one of their main ecological impacts. Here, we show that during the 2015–2019 period, the Mediterranean Sea has experienced exceptional thermal conditions resulting in the onset of five consecutive years of widespread MMEs across the basin. These MMEs affected thousands of kilometers of coastline from the surface to 45 m, across a range of marine habitats and taxa (50 taxa across 8 phyla). Significant relationships were found between the incidence of MMEs and the heat exposure associated with MHWs observed both at the surface and across depths. Our findings reveal that the Mediterranean Sea is experiencing an acceleration of the ecological impacts of MHWs which poses an unprecedented threat to its ecosystems' health and functioning. Overall, we show that increasing the resolution of empirical observation is critical to enhancing our ability to more effectively understand and manage the consequences of climate change. - (2022). Measuring inter-individual differences in behavioural types of gilthead seabreams in the laboratory using deep learning. PeerJ 10:e13396. doi: 10.7717/peerj.13396.
Abstract
Deep learning allows us to automatize the acquisition of large amounts of behavioural animal data with applications for fisheries and aquaculture. In this work, we have trained an image-based deep learning algorithm, the Faster R-CNN (Faster region-based convolutional neural network), to automatically detect and track the gilthead seabream, Sparus aurata, to search for individual differences in behaviour. We collected videos using a novel Raspberry Pi high throughput recording system attached to individual experimental behavioural arenas. From the continuous recording during behavioural assays, we acquired and labelled a total of 14,000 images and used them, along with data augmentation techniques, to train the network. Then, we evaluated the performance of our network at different training levels, increasing the number of images and applying data augmentation. For every validation step, we processed more than 52,000 images, with and without the presence of the gilthead seabream, in normal and altered (i.e., after the introduction of a non-familiar object to test for explorative behaviour) behavioural arenas. The final and best version of the neural network, trained with all the images and with data augmentation, reached an accuracy of 92,79% ± 6.78% [89.24–96.34] of correct classification and 10.25 ± 61.59 pixels [6.59-13.91] of fish positioning error. Our recording system based on a Raspberry Pi and a trained convolutional neural network provides a valuable non-invasive tool to automatically track fish movements in experimental arenas and, using the trajectories obtained during behavioural tests, to assay behavioural types. - (2022). Global trends in aquatic animal tracking with acoustic telemetry. Trends in Ecology & Evolution 37(1):79–94. doi: 10.1016/j.tree.2021.09.001.
Abstract
Acoustic telemetry (AT) is a rapidly evolving technique used to track the movements of aquatic animals. As the capacity of AT research expands it is important to optimize its relevance to management while still pursuing key ecological questions. A global review of AT literature revealed region-specific research priorities underscoring the breadth of how AT is applied, but collectively demonstrated a lack of management-driven objectives, particularly relating to fisheries, climate change, and protection of species. In addition to the need for more research with direct pertinence to management, AT research should prioritize ongoing efforts to create collaborative opportunities, establish long-term and ecosystem-based monitoring, and utilize technological advancements to bolster aquatic policy and ecological understanding worldwide. - (2021). Seasonal influence on the bathymetric distribution of an endangered fish within a marine protected area. Scientific Reports 11:13342. doi: 10.1038/s41598-021-92633-x.
Abstract
The spatio-temporal variability of fish distribution is important to better manage and protect the populations of endangered species. In this sense, the vertical movements of a vulnerable and protected species, Sciaena umbra, were assessed in a marine protected area (the Réserve Naturelle Marine de Cerbère-Banyuls, south of France) to study the variability of their bathymetric distribution at different time scales. Twenty adults were marked with acoustic transmitters and acoustically monitored over 2.5 years. This revealed that some individuals remained at shallow waters (< 8 m) all year round, while others presented vertical segregation at deeper waters during the cold months (mean depth of 22.5 ± 0.04 m) and all aggregated in shallow waters during the warm months. The brown meagre was more active during the night, except in June and July when peaks of activity were observed at dusk. These patterns are likely associated with foraging and reproductive behavior during the cold and warm periods, respectively, and likely regulated by water temperature and the depth of the thermocline. Here, we provide valuable information on when and where in the water column critical periods of S. umbra life cycle are expected to occur, which should be considered in management and protection plans. - (2021). High-Throughput Tracking of Social Networks in Marine Fish Populations. Frontiers in Marine Science 8:688010. doi: 10.3389/fmars.2021.688010.
Abstract
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. - (2021). Aggressiveness-related behavioural types in the pearly razorfish. PeerJ 9:e10731. doi: 10.7717/peerj.10731.
Abstract
Behavioural types (i.e., personalities or temperament) are defined as among individual differences in behavioural traits that are consistent over time and ecological contexts. Behavioural types are widespread in nature and play a relevant role in many ecological and evolutionary processes. In this work, we studied for the first time the consistency of individual aggressiveness in the pearly razorfish, Xyrichtys novacula, using a mirror test: a classic method to define aggressive behavioural types. The experiments were carried out in semi-natural behavioural arenas and monitored through a novel Raspberry Pi-based recording system. The experimental set up allowed us to obtain repeated measures of individual aggressivity scores during four consecutive days. The decomposition of the phenotypic variance revealed a significant repeatability score (R) of 0.57 [0.44–0.60], suggesting high predictability of individual behavioural variation and the existence of different behavioural types. Aggressive behavioural types emerged irrespective of body size, sex and the internal condition of the individual. Razorfishes are a ubiquitous group of fish species that occupy sedimentary habitats in most shallow waters of temperate and tropical seas. These species are known for forming strong social structures and playing a relevant role in ecosystem functioning. Therefore, our work provides novel insight into an individual behavioural component that may play a role in poorly known ecological and evolutionary processes occurring in this species. - (2021). Performance of a novel system for high-resolution tracking of marine fish societies. Animal Biotelemetry 9:1. doi: 10.1186/s40317-020-00224-w.
Abstract
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. - (2020). Acoustic Telemetry: A Tool to Monitor Fish Swimming Behavior in Sea-Cage Aquaculture. Frontiers in Marine Science 7:645. doi: 10.3389/fmars.2020.00645.
Abstract
Acoustic telemetry techniques are very useful tools to monitor in detail the swimming behavior and spatial use of fish in artificial rearing environments at individual and group levels. We evaluated the feasibility of using passive acoustic telemetry to monitor fish welfare in sea-cage aquaculture at an industrial scale, characterizing for the first time the diel swimming and distribution patterns of gilthead seabream (Sparus aurata) at fine-scale. Ten fish were implanted with acoustic tags equipped with pressure and acceleration sensors, and monitored in a commercial-size sea-cage for a period of 1 month. Overall, fish exhibited clear differences in day vs. night patterns both on swimming activity and vertical distribution throughout the experiment. Space use increased at night after the implementation of structural environmental enrichment in the sea-cage. Acoustic telemetry may represent an advancement to monitor fish farming procedures and conditions, helping to promote fish welfare and product quality. - (2020). Long-term monitoring of temperate macroalgal assemblages inside and outside a No take marine reserve. Marine Environmental Research 153:104826. doi: 10.1016/j.marenvres.2019.104826.
Abstract
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 non-protected 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. - (2020). Unravelling the population dynamics of the Mediterranean bryozoan Pentapora fascialis to assess its role as an indicator of recreational diving for adaptive management of marine protected areas. Ecological Indicators 109:105781. doi: 10.1016/j.ecolind.2019.105781.
Abstract
Marine Protected Areas (MPAs) have been recognized as effective management and conservation tools to protect marine coastal ecosystems. However, due to an increasing interest in marine ecosystems, recreational activities such as scuba diving are rapidly growing in these areas, highlighting the need to implement adaptive management strategies based on continuous monitoring and evaluation of protected areas. To date, several studies have quantified the impact of diving using benthic species as indicators, such as bryozoans, but usually ignoring their population dynamics. Here, we studied the population dynamics of the abundant and common bryozoan Pentapora fascialis on a Mediterranean MPA with high levels of diving activity. Specifically, we monitored eight different localities with two different levels of diving frequentation (non-frequented versus frequented) from October 2015 to October 2018, accounting for the demographic parameters before and after the summer. Our results showed the impact of diving on the density, recruitment, survival, and size of colonies, reaching higher values on non-frequented localities. In addition, we detected two peaks of recruitment during July 2016 and July 2018, suggesting that bryozoan recruitment events are stochastic, with a high inter-annual variation. Contrastingly, regardless of the diver frequentation level, we found higher growth rates during the colder months and higher necrosis rates after the summer in all the studied localities. Besides the aforementioned differences, the densities observed in this study were much higher compared to previous studies performed in the same area during the 1990s. Taken together, these results suggested rapid population dynamics of P. fascialis, with fast growth rates and a high capacity to recover from perturbations. Despite the quantified effects of diving on our studied species, their abundance in frequented sites remained very low over the whole study period, compromising the use of P. fascialis as an optimal indicator of diving impact for adaptive management of temperate benthic populations. Overall, our results highlight the importance of continuous monitoring programs to unravel the population dynamics of indicator species to effectively manage marine populations and evaluate the impact of human activities on marine protected areas. - (2019). Comparison of diver operated stereo-video and visual census to assess targeted fish species in Mediterranean marine protected areas. Journal of Experimental Marine Biology and Ecology 520:151205. doi: 10.1016/j.jembe.2019.151205.
Abstract
Underwater visual census (UVC) is currently the primary tool used to survey shallow water fish assemblages in the Mediterranean Sea. However, the rapid development of digital technologies, such as underwater video cameras and photogrammetric techniques, are providing new sampling opportunities in marine ecosystems. In this study we compare two non-destructive sampling methods, UVC and diver operated stereo-video systems (stereo-DOVs), to characterize assemblages of targeted fish species. Surveys were undertaken in three zones with different levels of protection from fishing (MR, marine reserve; PP, partially protected reserve; NP, non-protected area) in the Montgrí, Medes Islands and Baix Ter Natural Park (NW Mediterranean Sea). There were no statistically significant differences between stereo-DOVs and UVC surveys in terms of species richness, relative abundance and biomass of targeted fish species across the three protection levels. Both methodologies found statistically significant differences between areas closed to fishing (MR) and areas where fishing is regulated (PP) or allowed (NP), whereby higher fish biomass, density, species richness and larger sizes were found in MR surveys. Length estimates of fish were comparable between methods albeit with some species-specific differences in the size-distribution, and a tendency for UVC to overestimate the size of larger fishes. Our results suggest that stereo-DOVs provide an equivalent and complementary technique to UVC to survey assemblages of targeted fish species. In addition to structural data (e.g., biomass, abundance, and length) recorded by UVC, stereo-DOVs provide a permanent visual record of a fish community and enable additional factors such as fish behaviour, precise distance and length, and benthic composition to be quantified. Stereo-DOVs may, therefore, facilitate the continuity and expansion of long-term monitoring programs of fish assemblages in the Mediterranean Sea. - (2019). Modelling the three-dimensional space use of aquatic animals combining topography and Eulerian telemetry data. Methods in Ecology and Evolution 10(9):1551–1557. doi: 10.1111/2041-210X.13232.
Abstract
1. Passive acoustic telemetry provides the opportunity to monitor and contextualize the movements of diverse aquatic animals. Despite depth being an essential dimension along which many processes are organized, the Eulerian structure of the acoustic telemetry data (movements perceived from fixed locations) and the consequences of sound propagation in water hinders the incorporation of the vertical dimension into animal’s space use analyses.
2. Here, we propose a new data-driven quantitative method to estimate 3D space use from telemetry networks. The methodology is based on simulating large numbers of stochastic synthetic paths, accommodating the detection probability around receivers and the depth information from transmitters and integrating the local topography.
3. The methodological protocol is explained in detail and tested with acoustic telemetry data from the common dentex Dentex dentex in a Mediterranean marine protected area. We present 3D space use estimations for the tagged individuals and compare them with other 3D and 2D estimations derived with existing probabilistic methods.
4. 3D space use estimations that incorporate topography provided a more comprehensive view of the movement ecology of tracked individuals, with relevant pieces being missed by 2D representations. Our method generated realistic representations of the actual spatial co-occurrence of individuals, including the spatio-temporal identification of relevant aggregation areas. - (2019). No-take marine reserves control the recovery of sea urchin populations after mass mortality events. Marine Environmental Research 145:147–154. doi: 10.1016/j.marenvres.2019.02.013.
Abstract
Understanding how no-take zones (NTZs) shape the population dynamics of key herbivores is crucial for the conservation and management of temperate benthic communities. Here, we examine the recovery patterns of sea urchin populations following a high-intensity storm under contrasting protection regimes in the NW Mediterranean Sea. We found significant differences in the recovery trends of Paracentrotus lividus abundance and biomass in the five years following the storm. The P. lividus populations outside the NTZ recovered faster than the populations inside the NTZ, revealing that predation was the main factor controlling the sea urchin populations inside the NTZ during the study period. Arbacia lixula reached the highest abundance and biomass values ever observed outside the NTZ in 2016. Our findings reveal that predation can control the establishment of new sea urchin populations and emphasize top-down control in NTZs, confirming the important role of fully protected areas in the structure of benthic communities. - (2018). Lateral Transport of N-Rich Dissolved Organic Matter Strengthens Phosphorus Deficiency in Western Subtropical North Atlantic. Global Biogeochemical Cycles 32(9):1350–1366. doi: 10.1029/2017gb005868.
Abstract
The ability of the subtropical North Atlantic to sustain export production despite the lack of available nutrients is fascinating. Subtropical gyres are expected to expand under a global warming scenario, so it is important to understand the mechanisms supplying the required nutrients. Current issues for the region concern the nutrient and metabolic balance, the origin of excess nitrogen and phosphorus shortage, and the maintenance of nitrogen fixation. We report data on the allocation of nitrogen and phosphorus in dissolved and suspended pools, the isotopic δ15N of suspended nitrogen, and the lability of dissolved organic phosphorus (DOP) along a section crossing the eastern seasonally stratified North Atlantic and the western subtropical North Atlantic (NASW). We find extreme P-deficiency in the NASW, with the highest dissolved inorganic N:P ratios located within the upperthermocline isopycnals (σϴ = 26.3–26.8). Our data indicate an important role of the midlatitude northeast seasonally stratified North Atlantic bringing dissolved organic matter (DOM) to the thermocline of the North Atlantic. The mineralization of N-rich DOM contributes to the N excess (P deficit) of the upperthermocline of NASW. We find lower concentrations of more reactive DOP in the western than in the eastern part of the transect, indicating an active role of DOP in the nutrition of microbial communities. Our results support recent hypotheses concerning the environmental controls of marine nitrogen fixation identifying the key role of DOP utilization. - (2018). Effective dispersal and density-dependence in mesophotic macroalgal forests: Insights from the Mediterranean species Cystoseira zosteroides. PLoS ONE 13(1):e0191346. doi: 10.1371/journal.pone.0191346.
Abstract
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. - (2017). Thermal stratification drives movement of a coastal apex predator. Scientific Reports 7:526. doi: 10.1038/s41598-017-00576-z.
Abstract
A characterization of the thermal ecology of fishes is needed to better understand changes in ecosystems and species distributions arising from global warming. The movement of wild animals during changing environmental conditions provides essential information to help predict the future thermal response of large marine predators. We used acoustic telemetry to monitor the vertical movement activity of the common dentex (Dentex dentex), a Mediterranean coastal predator, in relation to the oscillations of the seasonal thermocline during two summer periods in the Medes Islands marine reserve (NW Mediterranean Sea). During the summer stratification period, the common dentex presented a clear preference for the warm suprathermoclinal layer, and adjusted their vertical movements following the depth changes of the thermocline. The same preference was also observed during the night, when fish were less active. Due to this behaviour, we hypothesize that inter-annual thermal oscillations and the predicted lengthening of summer conditions will have a significant positive impact on the metabolic efficiency, activity levels, and population dynamics of this species, particularly in its northern limit of distribution. These changes in the dynamics of an ecosystem’s keystone predator might cascade down to lower trophic levels, potentially re-defining the coastal fish communities of the future. - (2017). Bridging disciplines with training in remote sensing for animal movement: an attendee perspective. Remote Sensing in Ecology and Conservation 3(1):30–37. doi: 10.1002/rse2.22.
Abstract
Remote sensing and animal movement datasets are increasingly used to answer key questions in ecology and conservation. Collecting and accessing this data is becoming ever cheaper and easier, but limited analytical expertise limits its wider use. Working at the interface between these two disciplines is challenging as there are no standard techniques for handling the complex spatial data, so specific and in-depth training is required. Higher education programs rarely cover remote sensing for animal movement, so external courses play a major role in training newcomers and creating a more unified global community. We conducted an online survey to investigate the views of previous attendees of four training courses that involve remote sensing and animal location data. These courses provided subject-specific knowledge, practical and coding skills, networking, collaboration opportunities, insightful discussions and transferable research skills. Our survey highlighted the importance of real-world examples, practical sessions, time for participants to work with their own data, preparatory material and open source software. Despite the value of interdisciplinary training in remote sensing and animal movement, it reaches few ecology and conservation practitioners outside of academia. We advocate more funding for underrepresented participants to attend existing course and the development of new courses. - (2016). Ordinary and Extraordinary Movement Behaviour of Small Resident Fish within a Mediterranean Marine Protected Area. PLoS ONE 11(7):e0159813. doi: 10.1371/journal.pone.0159813.
Abstract
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 (< 1 km2), inside which they displayed repetitive diel activity patterns. Extraordinary movements beyond the ordinary home range were observed under two specific conditions. First, during stormy events D. sargus presented a sheltering behaviour, moving to more protected places to avoid the disturbance. Second, during the spawning season they made excursions to deep areas (> 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. - (2015). Persistent natural acidification drives major distribution shifts in marine benthic ecosystems. Proceedings of the Royal Society B 282(1818):20150587. doi: 10.1098/rspb.2015.0587.
Abstract
Ocean acidification is receiving increasing attention because of its potential to affect marine ecosystems. Rare CO2 vents offer a unique opportunity to investigate the response of benthic ecosystems to acidification. However, the benthic habitats investigated so far are mainly found at very shallow water (less than or equal to 5 m depth) and therefore are not representative of the broad range of continental shelf habitats. Here, we show that a decrease from pH 8.1 to 7.9 observed in a CO2 vent system at 40 m depth leads to a dramatic shift in highly diverse and structurally complex habitats. Forests of the kelp Laminaria rodriguezii usually found at larger depths (greater than 65 m) replace the otherwise dominant habitats (i.e. coralligenous outcrops and rhodolith beds), which are mainly characterized by calcifying organisms. Only the aragonite-calcifying algae are able to survive in acidified waters, while high-magnesium-calcite organisms are almost completely absent. Although a long-term survey of the venting area would be necessary to fully understand the effects of the variability of pH and other carbonate parameters over the structure and functioning of the investigated mesophotic habitats, our results suggest that in addition of significant changes at species level, moderate ocean acidification may entail major shifts in the distribution and dominance of key benthic ecosystems at regional scale, which could have broad ecological and socio-economic implications. - (2015). Recruitment patterns in the Mediterranean deep‑water alga Cystoseira zosteroides. Marine Biology 162:1165–1174. doi: 10.1007/s00227-015-2658-0.
Abstract
Although recruitment is considered an essential process regulating populations of many marine species, there is still a lack of knowledge about the ultimate factors that influence it. This is especially true for seaweeds, where population dynamics studies are also lacking. The main objective of this study was to investigate the main mechanisms driving the recruitment patterns of an emblematic deep-water alga in the NW Mediterranean, Cystoseira zosteroides, and its influence on their population dynamics. Five C. zosteroides populations were monitored annually at different sites along the coast of Spain by using permanent transects over 3–4 years. Some of these populations suffered mass mortality events from natural or anthropogenic disturbances, allowing us to study the influence of such events. Our findings agreed with the expected results for a long-lived species. Under low frequency of disturbances, C. zosteroides populations displayed few fluctuations over time given the longevity of the adults, and they were poorly influenced by the dynamics of early life stages because of negative density-dependent control of conspecifics. Moreover, disturbances had a great influence on population dynamics because the removal of adults decreased the effects of density-dependent processes and enhanced the recruitment. Nonetheless, a high mortality was found for early life stages (~50 % year–1), contrasting with the high survival of adults (~90 % year–1). This study confirmed the slow population dynamics of these deep assemblages, demonstrated the influence of density in the C. zosteroides population dynamics and highlighted their vulnerability to the increase in natural and human-induced disturbances.