Diel vertical migration (DVM) structures pelagic food webs by bringing mesopelagic organisms into surface waters at night. Whether this recurrent prey pulse can also support transfers across the marine-terrestrial boundary has received less attention. Here, we combine empirical measurements of the energetic characteristics of two abundant Gulf of California myctophids, Benthosema panamense and Triphoturus mexicanus, with station-level biomass-density data from a published regional survey to characterize the potential energy represented by the vertically migrating prey field. Monthly mean biomass densities were calculated across eight stations, including zero catches, and the two monthly means corresponding to each season were then averaged. We integrate these survey-derived estimates with published dietary, molecular, and movement evidence for the fishing bat Myotis vivesi to evaluate how DVM may enable a recurrent pathway of marine-to-terrestrial biomass transport. Estimated prey-field energy density varied among species and seasons from 0.07 to 5.81 MJ per 1000 m3, primarily reflecting variation in biomass density while energetic density remained high across the analyzed samples. These values describe the energetic potential of a regional prey field rather than prey capture by bats or realized terrestrial deposition. Nevertheless, recurrent consumption of myctophids by M. vivesi, together with its return to coastal and island roosts, supports a biological pathway through which a fraction of mesopelagic-derived biomass can cross the marine-terrestrial boundary. This framework identifies DVM as the process that makes an energy-rich mesopelagic resource temporarily accessible to a terrestrial consumer while defining the measurements required to quantify the magnitude of transfer.
Macroinvertebrates are key components of freshwater food webs in both natural and human-made waterbodies, yet the trophic structure of many macroinvertebrate assemblages remains poorly described. With new analytical approaches, macroinvertebrate trophic assessment via stable isotopes may be accomplished with relatively few samples. This study quantified trophic niche breadth, niche overlap, and seasonal influences on niche for macroinvertebrates at a littoral site in Grand Lake, a reservoir in northeast Oklahoma (USA). We analyzed stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) for nine macroinvertebrate taxa collected over three seasons. From there, niche breadth and overlap were determined based on Bayesian standardized elliptical area, elliptical overlap, and various traditional metrics (e.g. total area, mean values, range). Through the Bayesian approaches, we were able to quantify uncertainty around breadth and overlap that would not be present in standard statistical approaches. Our results showed that trophic niche breadth varied substantially among taxa, with several taxa typically considered generalists occupying unexpectedly narrow niche spaces. With this, macroinvertebrates exhibited substantial niche overlaps, consistent with resource sharing amongst taxa. Isotopic signatures showed limited seasonal variation, which may represent a relatively homogenized resource base throughout the year. Together, these results describe isotopic relationships within the sampled assemblage and illustrate the application of Bayesian niche analyses to sparse consumer isotope data. Improved understanding of trophic structure in human-made waterbodies is needed to inform aquatic management, and more robust statistical approaches may provide valuable information even when data are sparse.
Mediterranean-type ecosystems (MTEs) are among the most biodiverse and climate-vulnerable ecosystems globally. Rising temperatures, combined with more frequent and intense droughts, have driven widespread forest decline across all five MTE regions, accounting for 48% of globally documented forest mortality events. Among these, Central Chile has experienced the most severe climatic anomalies, including a persistent megadrought since 2010, two hyperdroughts in 2019 and 2021 with precipitation deficits exceeding 75%, and recurrent spring and summer heatwaves. These unprecedented conditions position Central Chile as a potential worst-case scenario for the future of MTEs worldwide. This review synthesises current knowledge on climate-induced forest decline in Central Chile, summarising recent research conducted across multiple spatial and ecological scales. Emerging evidence reveals a regional forest decline characterised by reduced productivity, radial growth declines, impaired seedling establishment, and widespread canopy browning. While these responses are comparable to those observed in other MTEs, the ecological implications of hyperdroughts and regional warming for forest resilience remain poorly understood. Despite growing research efforts, critical knowledge gaps persist regarding forest mortality rates, regeneration dynamics, and the physiological mechanisms underlying tree survival and mortality. We identify key research priorities, including the need for quantified mortality data, mechanistic understanding of decline processes, assessment of post-disturbance ecological dynamics, and integrative approaches that link plot-based observations with remote sensing and modelling. Addressing these gaps is essential to evaluate changes in productivity, species composition, and the long-term trajectory of Chilean MTEs, while contributing to a broader predictive understanding of forest resilience in Mediterranean-type ecosystems globally.
Climate change, distinct from short-term temperature fluctuations, encompasses long-term shifts in environmental conditions and poses a major threat to biodiversity-particularly for habitat-specialist species such as Drosera intermedia and Drosera rotundifolia. These carnivorous plants rely on the unique conditions of peat bogs, including high and stable soil moisture, low pH, and nutrient-poor substrates. This ex situ study investigated the effect of cold stratification duration and temperature interruption (simulating winter heat waves) on seed germination. Seeds were exposed to - 10 degrees C for 5 to 25 days, with or without a 5-day warming period at 1 degrees C. Control seeds (no stratification) exhibited low germination rates (10-26%), while interrupted stratification increased germination to as much as 60%, suggesting a potential adaptive response to increasingly variable winter temperatures. Significant differences were also found between populations, possibly reflecting local environmental factors such as soil moisture. These results indicate that winter warming events may alter both the timing and success of seed germination, with implications for population persistence. Understanding such mechanisms is essential for the effective conservation and restoration of peatland ecosystems under climate change.
