Seabirds are often considered sentinel species of marine ecosystems, and their blood and eggs utilized to monitor local environmental contaminations. Most seabirds breeding in the Arctic are migratory and thus are exposed to geographically distinct sources of contamination throughout the year, including per- and polyfluoroalkyl substances (PFAS). Despite the abundance and high toxicity of PFAS, little is known about whether blood concentrations at breeding sites reliably reflect local contamination or exposure in distant wintering areas. We tested this by combining movement tracking data and PFAS analysis (nine compounds) from the blood of prelaying black-legged kittiwakes (Rissa tridactyla) nesting in Arctic Norway (Svalbard). PFAS burden before egg laying varied with the latitude of the wintering area and was negatively associated with time upon return of individuals at the Arctic nesting site. Kittiwakes (n = 64) wintering farther south carried lighter burdens of shorter-chain perfluoroalkyl carboxylates (PFCAs, C9-C12) and heavier burdens of longer chain PFCAs (C13-C14) and perfluorooctanesulfonic acid compared to those wintering farther north. Thus, blood concentrations prior to egg laying still reflected the uptake during the previous wintering stage, suggesting that migratory seabirds can act as biovectors of PFAS to Arctic nesting sites.

Anthropogenic noise is considered one important global pollutant. The impact of noise on marine invertebrates has been less assessed. The present study evaluated the chronic effect of the motorboat noise obtained from a lagoon\'s soundscape, the natural habitat of the key crab Neohelice granulata, on its whole embryonic development, considering morphological and physiological carryover effects on embryos and hatched larvae. Results demonstrated that embryonic development was shortened under noise exposure. The effects on advanced embryos, larvae and adult females were: increased heartbeats and non-viable eggs, and decreased fecundity. Biochemical responses showed lipid peroxidation in embryos while antioxidant enzymes were activated in larvae and adults, indicating a counteracting effect related to the life stage. The negative effects on fitness offspring may imply ecological consequences at the population level. Results are discussed in terms of the ecosystem engineer species studied and the habitat, a MAB UNESCO Reserve lagoon, suggesting the urgent need to develop mitigation plans.

BACKGROUND: Migratory birds generally have tightly scheduled annual cycles, in which delays can have carry-over effects on the timing of later events, ultimately impacting reproductive output. Whether temporal carry-over effects are more pronounced among migrations over larger distances, with tighter schedules, is a largely unexplored question.
METHODS: We tracked individual Arctic Skuas Stercorarius parasiticus, a long-distance migratory seabird, from eight breeding populations between Greenland and Siberia using light-level geolocators. We tested whether migration schedules among breeding populations differ as a function of their use of seven widely divergent wintering areas across the Atlantic Ocean, Mediterranean Sea and Indian Ocean.
RESULTS: Breeding at higher latitudes led not only to later reproduction and migration, but also faster spring migration and shorter time between return to the breeding area and clutch initiation. Wintering area was consistent within individuals among years; and more distant areas were associated with more time spent on migration and less time in the wintering areas. Skuas adjusted the period spent in the wintering area, regardless of migration distance, which buffered the variation in timing of autumn migration. Choice of wintering area had only minor effects on timing of return at the breeding area and timing of breeding and these effects were not consistent between breeding populations.
CONCLUSIONS: The lack of a consistent effect of wintering area on timing of return between breeding areas indicates that individuals synchronize their arrival with others in their population despite extensive individual differences in migration strategies.

Magnetic fields are widely used for neuromodulation in clinical settings. The intended effect of magnetic stimulation is that neural activity resumes its pre-stimulation state right after stimulation. Many theoretical and experimental works have focused on the cellular and molecular basis of the acute neural response to magnetic field. However, effects of magnetic stimulation can still last after the termination of the magnetic stimulation (named \"carry-over effects\"), which could generate profound effects to the outcome of the stimulation. However, the cellular and molecular mechanisms of carry-over effects are largely unknown, which renders the neural modulation practice using magnetic stimulation unpredictable. Here, we investigated carry-over effects at the cellular level, using the combination of micro-magnetic stimulation (µMS), electrophysiology, and computation modeling. We found that high frequency magnetic stimulation could lead to immediate neural inhibition in ganglion neurons from Aplysia californica, as well as persistent, carry-over inhibition after withdrawing the magnetic stimulus. Carry-over effects were found in the neurons that fired action potentials under a variety of conditions. The carry-over effects were also observed in the neurons when the magnetic field was applied across the ganglion sheath. The state of the neuron, specifically synaptic input and membrane potential fluctuation, plays a significant role in generating the carry-over effects after magnetic stimulation. To elucidate the cellular mechanisms of such carry-over effects under magnetic stimulation, we simulated a single neuron under magnetic stimulation with multi-compartment modeling. The model successfully replicated the carry-over effects in the neuron, and revealed that the carry-over effect was due to the dysfunction of the ion channel dynamics that were responsible for the initiation and sustaining of membrane excitability. A virtual voltage-clamp experiment revealed a compromised Na conductance and enhanced K conductance post magnetic stimulation, rendering the neurons incapable of generating action potentials and, therefore, leading to the carry over effects. Finally, both simulation and experimental results demonstrated that the carry-over effects could be controlled by disturbing the membrane potential during the post-stimulus inhibition period. Delineating the cellular and ion channel mechanisms underlying carry-over effects could provide insights to the clinical outcomes in brain stimulation using TMS and other modalities. This research incentivizes the development of novel neural engineering or pharmacological approaches to better control the carry-over effects for optimized clinical outcomes.

Early-life experiences can drive subsequent variation in social behaviours, but how differences among individuals emerge remains unknown. We combined experimental manipulations with GPS-tracking to investigate the pathways through which developmental conditions affect social network position during the early dispersal of wild red kites (Milvus milvus). Across 211 juveniles from 140 broods, last-hatched chicks-the least competitive-had the fewest number of peer encounters after fledging. However, when food supplemented, they had more encounters than all others. Using 4425 bird-days of GPS data, we revealed that this was driven by differential responses to competition, with less competitive individuals naturally spreading out into marginal areas, and clustering in central foraging areas when food supplemented. Our results suggest that early-life adversities can cause significant natal legacies on individual behaviour beyond independence, with potentially far-reaching consequences on the social and spatial structure of animal populations.

Winter is an energetically challenging period for many animals in temperate regions because of the relatively harsh environmental conditions and reduction in food availability during this season. Moreover, stressors experienced by individuals in the fall can affect their subsequent foraging strategy and energy stores after exposure has ended, referred to as carryover effects. We used exogenous cortisol manipulation of wild juvenile brown trout (Salmo trutta) in the fall to simulate a physiological stress response and then investigated short-term (2 weeks) and long-term (4 months) effects on condition metrics (hepatosomatic index and water muscle content), diet (stomach contents and stable isotopes), and morphology during growth in freshwater. We revealed some short-term impacts, likely due to handling stress, and long-term (seasonal) changes in diet, likely reflecting prey availability. Unfortunately, we had very few recaptures of cortisol-treated fish at long-term sampling, limiting detailed analysis about cortisol effects at that time point. Nonetheless, the fish that were sampled showed elevated stable isotopes, suggestive of a cortisol effect long after exposure. This is one of few studies to investigate whether cortisol influences foraging and morphology during juvenile growth, thus extending the knowledge of proximate mechanisms influencing ecologically-relevant phenotypes.

Although coastal ecosystems are naturally submitted to temporal variations of salinity, salinization has been increasing over time threatening coastal biodiversity. Species that exploit such habitats can thus be exposed to brackish water at different life stages. However, the impacts of variations of salinity on wildlife remain poorly understood. This is particularly true for coastal amphibians, due to the strong dependency of early life stages (embryos and larvae) on aquatic environments. In order to investigate the effect of salinity during egg laying and embryonic and larval development of coastal amphibians, we used a full-factorial design to expose reproductive adults, eggs, and larvae of coastal spined toads (Bufo spinosus) to fresh (0 g.l-1) or brackish water (4 g.l-1). At egg laying, we evaluated parental investment in reproduction. During embryonic and larval development, we assessed effects on survival, development, and growth. We highlighted strong effects of environmental salinity on reproduction (reduced egg laying time, marginally reduced egg size, and reduced investment in reproduction). Responses to salinity were highly dependent on the developmental stages of exposure (stronger effects when individuals were exposed during embryonic development). These effects carried over when exposure occurred at egg laying or during embryonic development, highlighting the importance of the environmental conditions during early life on ontogenetic trajectories. We also highlighted partial compensation when individuals were transferred back to freshwater. Whether the magnitude of these responses can allow coastal biodiversity to overcome the observed detrimental effects of salinization remain to be assessed.

Recent evidence suggests that the adult phenotype is influenced by temperatures experienced in early life. However, our understanding of the extent to which the embryonic environment can modulate thermal tolerance later in life is limited, owing to the paucity of studies with appropriate experimental designs to test for this form of developmental plasticity. We investigated whether the thermal environment experienced during embryonic development affects thermal limits in later life. Embryos of the estuarine amphipod Gammarus chevreuxi were incubated until hatching to 15 °C, 20 °C and 25 °C, then reared under a common temperature. Using thermal ramping assays, we determined upper thermal limits in juveniles, four weeks post-hatch. Individuals exposed to higher temperatures during embryonic development displayed greater thermal tolerance as juveniles (acclimation response ratio ≈ 0.10-0.25 for upper lethal temperature). However, we suggest that the degree of developmental plasticity observed is limited, and will provide little benefit under future climate change scenarios.

Climate change is expected to dramatically alter autumnal and winter conditions in many temperate regions. However, limited data is available to accurately predict how these changes will impact species\' overwinter survival and post-winter fitness. Here, we determine how a longer, warmer fall period and winter heatwaves affect overwintering fitness and post-winter performance of the invasive mosquito vector, Aedes albopictus. We found that a longer, warmer fall period representative of early entry into diapause did not affect overwinter survival but did lead to reduced post-winter performance for multiple traits. Specifically, larvae that experienced longer, warmer fall conditions as diapause embryos exhibited reduced post-diapause larval starvation tolerance, increased post-diapause larval mortality, and longer post-diapause larval development compared to individuals from the short-fall treatments. These negative post-diapause fitness effects likely resulted from the greater energetic demands and/or damage incurred during the warmer, longer fall period. In contrast, exposure to winter heatwaves increased overwinter survival, possibly by allowing diapausing embryos to escape or repair cold injury. Finally, fall treatment and winter heatwaves had an interactive effect on male development time, while neither treatment impacted pupal mass in either sex. Overall, our results highlight that experiments that fail to measure post-diapause fitness are likely to substantially under-estimate the impacts of climate change on post-winter performance. Additionally, our results emphasize that it is crucial to consider the potentially conflicting effects of different aspects of climate change on a species\' overall overwintering success.

Recent advances in wearable motion sensors, mobile devices, the Internet of Things, and telecommunications have created new potential for telerehabilitation. Recognizing that there is no systematic review of smartphone- or tablet-based balance and gait telerehabilitation technology for long-term use (i.e., four weeks or more), this systematic review summarizes the effects of smartphone- or tablet-based rehabilitation technology on balance and gait exercise and training in balance and gait disorders. The review examined studies written in English published from 2013 to 2023 in Web of Science, Pubmed, Scopus, and Google Scholar. Of the 806 studies identified, 14 were selected, and the National Institutes of Health Quality Assessment Tool for Observational Cohort and Cross-sectional Studies was applied to evaluate methodological quality. The systematic review concluded that all 14 studies found balance and gait performance improvement after four weeks or more of balance and gait telerehabilitation. Ten of the 14 studies found that carry-over effects (improved functional movements, muscle strength, motor capacity, cognition, and reduced fear of falling and anxiety levels) were maintained for weeks to months. The results of the systematic review have positive technical and clinical implications for the next-generation design of rehabilitation technology in balance and gait training and exercise programs.