No abstract

Knowledge on genetic structure is key to understand species connectivity patterns and to define the spatiotemporal scales over which conservation management plans should be designed and implemented. The distribution of genetic diversity (within and among populations) greatly influences species ability to cope and adapt to environmental changes, ultimately determining their long-term resilience to ecological disturbances. Yet, the drivers shaping connectivity and structure in marine fish populations remain elusive, as are the effects of fishing activities on genetic subdivision. To investigate these questions, we conducted a meta-analysis and compiled genetic differentiation data (FST/ΦST estimates) for more than 170 fish species from over 200 published studies globally distributed. We modeled the effects of multiple life-history traits, distance metrics, and methodological factors on observed population differentiation indices and specifically tested whether any signal arising from different exposure to fishing exploitation could be detected. Although the myriad of variables shaping genetic structure makes it challenging to isolate the influence of single drivers, results showed a significant correlation between commercial importance and genetic structure, with widespread lower population differentiation in commercially exploited species. Moreover, models indicate that variables commonly used as proxy for connectivity, such as larval pelagic duration, might be insufficient, and suggest that deep-sea species may disperse further. Overall, these results contribute to the growing body of knowledge on marine genetic connectivity and suggest a potential effect of commercial fisheries on the homogenization of genetic diversity, highlighting the need for additional research focused on dispersal ecology to ensure long-term sustainability of exploited marine species.

This work introduces a new lightweight, small, and modular data logger that can be used to record a vast array of environmental and physiological parameters in the field or in the laboratory, together with the corresponding software. The device, named NanoLogger, is based on the open-source platform Arduino, featuring a custom-made circuit board with easily serviceable connectors, a real-time clock and a MicroSD memory card. The assemblage of the entire system does not require extensive electronics knowledge and can be done spending under $150 in parts, contrasting with most commercially available scientific loggers, which are at least one or two orders of magnitude more expensive. To demonstrate the system's capabilities and limitations, we connected the NanoLogger with (i) a triple-axis accelerometer to log the effect of wave action on Fucus spiralis, (ii) a thermocouple to register the body temperature of intertidal gastropods (Patella depressa and P. vulgata) during a low tide, and (iii) an infrared sensor to record the heartbeat of a mussel (Mytilus galloprovincialis) in the laboratory. NanoLogger's relative low price and versatility can contribute to build networks of environmental loggers to monitor multiple environmental parameters across large geographical scales.

The CETUS project is a cetacean monitoring program that takes advantage of cargo ships to undertake survey routes between Continental Portugal, Macaronesian archipelagos and West Africa. From 2012 to 2017, over 50 volunteers participated in the program, actively surveying more than 124.000 km, mostly beyond national jurisdictions in the high seas, for which little or no previous data existed. In total, the collection comprises 3058 georeferenced transect lines and 8913 positions, which are associated with 2833 cetacean sightings, 362 occurrences of other pelagic megafauna, 5260 estimates of marine traffic and 8887 weather observations. This dataset may provide new insights into the distribution of marine mammals in the Eastern North Atlantic and was published following the OBIS-ENV-DATA format (with the most recent biodiversity data standards at the time of writing). Consequently, it may serve as a model for similar visual line transect data collections yet to be published.

The protection provided by marine reserves directly depends on the short and long-term movement patterns of local organisms. Although there has been an increase in research assessing the behavioural patterns of fishes in reef-based habitats, there is still a paucity of studies addressing the benefits of marine protected areas (MPAs) for soft-sediment species. Here, we investigated both diel and seasonal shifts in spatial behaviour of the Senegalese sole, Solea senegalensis, within a recently-established marine reserve using long-term passive acoustic telemetry. Results showed variable levels of site attachment, with nearly half of the fish (n = 8) disappearing from the monitored area within 30 days, and the remaining (n = 9) being detected for periods up to 293 days and spending 95% of their time within an average area of 0.88 ± 0.46 km. Although detection frequency was higher during daytime periods, the larger home range areas and greater movement observed during nighttime periods are consistent with a nocturnal activity regime, which might increase the vulnerability of S. senegalensis to illegal fishing. Additionally, patterns observed during the spawning season suggest the existence of shifts in habitat use linked with reproductive activity, opening the door to further research on soles' fine-scale interaction dynamics. Overall, this study provides novel insights into the ecology of a flatfish species and suggests that small no-take areas encompassing suitable soft-sediment habitats can offer adequate protection to at least part of the Senegalese sole population.