Spatial differences in the isotope values of widely distributed marine apex consumers may reflect geographical differences in the isotopic composition of basal resources (e.g., phytoplankton) fueling food webs (bottom-up effects) or spatial differences in the trophic ecology of the taxon of interest (top-down effects). We examined spatial variation in δ13C and δ15N values from 264 South American sea lions (SASL, Otaria flavescens) of different age classes (adults, subadults and juveniles), their putative prey consisting of pelagic and benthic coastal fishes, and particulate organic matter (POM) measured from locations situated across >2300 km of the Chilean coast (between 18°42\' and 39°17\' S). We used generalized least squares (GLS) models to compare the form of the relationship between δ13C and δ15N and latitude between the three functional groups. Our results show that SASL from northern, central, and southern areas were isotopically distinct, with individuals from the north having lower δ13C and higher δ15N values in comparison to individuals from the south. When the relationship for each functional group was modelled individually using GLS, results indicated that for each degree of increasing latitude δ15N decreased on average by 0.12‰ (POM), 0.15‰ (prey), and 0.14‰ (SASL), while δ13C increased by 0.06‰ (POM) and 0.05‰ in both prey and SASL. We suggest that the latitudinal differences observed in SASL δ13C and δ15N values reflect baseline isotopic variation rather than marked differences in trophic ecology of these widely distributed consumers.

The impacts and toxicological mechanisms of microplastics (MPs) or heavy metals on aquatic ecosystems have been the subject of extensive research and initial understanding. However, the combined toxicity of co-pollutants on organisms and cumulative toxic effects along the food chain are still underexplored. In this study, the ciliate protozoan Paramecium caudatum and zebrafish Danio rerio were used to represent the microbial loop and the higher trophic level, respectively, to illustrate the progressive exposure of MPs and cadmium (Cd2+). The findings indicate that MPs (ca. 1 ×105 items/L) containing with Cd2+ (below 0.1 µg/L) could permeate the bodies of zebrafish through trophic levels after primary ingestion by ciliates. This could cause adverse effects on zebrafish, including alterations in bioindicators (total sugar, triglycerides, lactate, and glycogen) associated with metabolism, delayed hepatic development, disruption of intestinal microbiota, DNA damage, inflammatory responses, and abnormal cellular apoptosis. In addition, the potential risks associated with the transfer of composite pollutants through the microbial loop into traditional food chain were examined, offering novel insights on the evaluation of the ecological risks associated with MPs. As observed, understanding the bioaccumulation and toxic effects of combined pollutants in zebrafish holds crucial implications for food safety and human health.

Here we describe the dietary patterns of the culpeo or Andean fox (Lycalopex culpaeus) on a biogeographical scale. We also analyse the influence of exotic lagomorphs on its diet and explore differences between culpeo subspecies. We selected 17 mutually comparable diet studies, which include 19 independent diet assessments. Then, we extracted and standardized the values of the different diet components from these studies and calculated the relative frequency of occurrence of the 10 main trophic groups that we found. Further, we calculated the Shannon-Wiener H\' trophic diversity index. The results showed that small mammals (41%), lagomorphs (21%), invertebrates (12.4%) and large herbivores (7.3%) were the most consumed groups. A factorial analysis of all trophic groups rendered four orthogonal factors that were used as response variables in relation to a set of environmental predictors. Altitude correlated with most factors (i.e. trophic groups). Exotic lagomorphs were consumed in lowlands, in higher latitudes and in regions showing high values of the human footprint index, enriching in those areas the culpeo\'s trophic spectrum. There were no differences in diet between the two main culpeo subspecies analysed, L.c. culpaeus and L.c. andinus. Finally, the best explanatory models (general linear model) of trophic diversity selected, using Akaike\'s information criterion, showed that the most diverse diets were those composed of large herbivores, edentates, carnivorous species, birds and herptiles (i.e. reptiles and frogs). Trophic diversity was low in rainy areas where big rodents dominated the diet. Neither latitude nor altitude seemed to have an effect on the trophic diversity of the culpeos, as they were not retained by the final models.

Micro/nano-plastics (MPs/NPs) represent an emerging contaminant, posing a significant threat to oceanic halobios. While the adverse effects of joint pollutants on marine organisms are well-documented, the potential biological impacts on the food chain transmission resulting from combinations of MPs/NPs and heavy metals (HMs) remain largely unexplored. This study exposed the microbial loop to combined contaminants (MPs/NPs + HMs) for 48h, bacteria and contaminants are washed away before feeding to the traditional food chain, employing microscopic observation, biochemical detection, and transcriptome analysis to elucidate the toxicological mechanisms of the top predator. The findings revealed that MPs/NPs combined with Cd2+ could traverse both the microbial loop and classical food chain. Acute exposure significantly affected the carbon biomass of the top predator Tigriopus japonicus (75.8% lower). Elevated antioxidant enzyme activity led to lipid peroxidation, manifesting in increased malondialdehyde levels. Transcriptome sequencing showed substantial differential gene expression levels in T. japonicus under various treatments. The upregulation of genes associated with apoptosis and inflammatory responses, highlighting the impact of co-exposure on oxidative damage and necroptosis within cells. Notably, NPs-Cd exhibited stronger toxicity than MPs-Cd. NPs-Cd led to a greater decrease in the biomass of top predators, accompanied by lower activities of GSH, SOD, CAT, and GSH-PX, resulting in increased production of lipid peroxidation product MDA and higher oxidative stress levels. This investigation provides novel insights into the potential threats of MPs/NPs combined with Cd2+ on the microbial loop across traditional food chain, contributing to a more comprehensive assessment of the ecological risks associated with micro/nano-plastics and heavy metals.

Raptors are threatened by anthropogenic land modifications, but targeted quantitative assessment of these impacts is lacking. We conducted the first global quantitative evaluation of the impacts of human-modified land on raptors. We used eBird data from 2001 to 2020 on 425 raptor species and occupancy models to assess the impacts of human-modified land on raptor distribution. The mean spatiotemporal correlations of human settlement, cropland, and pasture with raptor occupancy probability were -0.048 (SE 0.031), -0.134 (0.032), and -0.145 (0.032), respectively. The mean sensitivity of raptor occupancy probability to settlement, cropland, and pasture was -5.760 (2.266), -3.128 (1.540), and -2.402 (1.551), respectively. The occupancy probability of raptors with a large body mass was more negatively correlated with cropland (phylogenetic generalized least squares regressions: slope = -0.052 [SE 0.022], t = -2.335, df = 1, 407, p = 0.020, λ = 0.006) and more positively correlated with pasture (slope = 0.047 [0.022], t = 2.118, df = 1, 407, p = 0.035, λ = 0.013). The occupancy probability of raptors with a more extensive range size was more positively correlated with cropland (slope = 0.002 [0.004], t = 0.399, df = 1, 407, p < 0.001, λ = 0.000). Raptors that prefer open habitats were more positively correlated with cropland (analysis of variance: F = 3.424, df = 2, p = 0.034, λ = 0.000) and pasture (F = 6.577, df = 2, p = 0.002, λ = 0.000). In Africa and South America, where raptor species are most abundant, raptor occupancy probability decreased over 20 years, most likely due to habitat fragmentation associated with human land modification. Although raptors with different ecological characteristics had different responses to human land modification, the impacts of settlement, cropland, and pasture on mean raptor occupancy probability were negative, regardless of space and time.
Evaluación cuantitativa del impacto global de la modificación humana del uso de suelo sobre las rapaces Resumen Las rapaces se encuentran amenazadas por las modificaciones de suelo antropogénicas, pero la evaluación cuantitativa focalizada de estos impactos es muy escasa. Realizamos la primera evaluación cuantitativa mundial del impacto del suelo modificado por humanos sobre las rapaces. Usamos datos de eBird desde 2001 hasta 2020 sobre 425 especies rapaces y modelos de ocupación para evaluar el impacto del suelo modificado por humanos sobre la distribución de estas especies. La correlación espaciotemporal media de los asentamientos humanos, las tierras de cultivo y las pasturas con probabilidad de ocupación por rapaces fueron ‐0,048 (SE 0,031), ‐0,134 (0,032) y ‐0,145 (0,032), respectivamente. La sensibilidad media de la probabilidad de ocupación de las rapaces a los asentamientos, las tierras de cultivo y las pasturas fue de ‐5,760 (2,266), ‐3,128 (1,540) y ‐2,402 (1,551), respectivamente. La probabilidad de ocupación de las rapaces con gran masa corporal tuvo una correlación más negativa con las tierras de cultivo (regresiones filogenéticas por mínimos cuadrados generalizados: pendiente =‐0. 052 [SE 0,022], t = ‐2,335, gl = 1, 407, p = 0,020, λ = 0,006) y una correlación más positiva con los pastos (pendiente = 0,047 [0,022], t = 2,118, gl = 1, 407, p = 0,035, λ = 0,013). La probabilidad de ocupación de las rapaces con un área de distribución más extensa tuvo una correlación más positiva con las tierras de cultivo (pendiente = 0,002 [0,004], t = 0,399, gl = 1, 407, p < 0,001, λ = 0,000). Las rapaces que prefieren hábitats abiertos tuvieron una correlación más positiva con las tierras de cultivo (análisis de la varianza: F = 3,424, gl = 2, p = 0,034, λ = 0,000) y los pastos (F = 6,577, df = 2, p = 0,002, λ = 0,000). En África y América del Sur, en donde son más abundantes las especies rapaces, la probabilidad de ocupación de las rapaces disminuyó a lo largo de 20 años, probablemente debido a la fragmentación de hábitat asociada con la modificación del suelo por humanos. Aunque las rapaces con características ecológicas diferentes tienen diferentes respuestas a estas modificaciones, el impacto de los asentamientos, las tierras de cultivo y las pasturas fue negativo para la probabilidad de ocupación media de las rapaces, sin importar el espacio ni el tiempo.
猛禽受到土地改造的威胁, 但目前缺乏针对这些影响的定量评估。我们进行了首次全球范围内的土地改造对猛禽影响的定量评估。我们使用占域模型, 基于2001年至2020年的eBird数据, 评估了土地改造对425种猛禽分布的影响。人类定居点、耕地和牧场与猛禽占域率的平均时空相关性分别为‐0.048 (SE 0.031), ‐0.134(0.032) 和 ‐0.145(0.032)。猛禽占域率对定居点、耕地和牧场的平均敏感性分别为‐5.760 (2.266), ‐3.128 (1.540)和‐2.402 (1.551)。体重较大猛禽的占域率更多地与耕地呈负相关(系统发育广义最小二乘回归:斜率 = ‐0.052 [SE 0.022], t = ‐2.335, df = 1, 407, p = 0.020, λ = 0.006), 更多地与牧场呈正相关(斜率 = 0.047 [0.022], t = 2.118, df = 1,407, p = 0.035, λ = 0.013)。分布范围较广猛禽的占域率更多地与耕地呈正相关 (斜率 = 0.002 [0.004], t = 0.399,df = 1,407,p < 0.001, λ = 0.000)。偏好开阔栖息地的猛禽的占域率更多地与耕地(方差分析:F = 3.424, df = 2,p = 0.034, λ = 0.000) 和牧场 (F = 6.577, df = 2, p = 0.002, λ = 0.000) 呈正相关。在猛禽物种丰富度最高的非洲和南美洲, 猛禽占域率在20年间呈下降趋势, 最可能的原因是人类土地改造导致的栖息地破碎化。尽管具有不同生态学特征的猛禽对人类土地改造的响应不同, 但无论在空间和时间上, 定居点、耕地和牧场对猛禽的平均占域率都有负面的影响。.

Freshwater megafauna, such as sturgeons, giant catfishes, river dolphins, hippopotami, crocodylians, large turtles, and giant salamanders, have experienced severe population declines and range contractions worldwide. Although there is an increasing number of studies investigating the causes of megafauna losses in fresh waters, little attention has been paid to synthesising the impacts of megafauna on the abiotic environment and other organisms in freshwater ecosystems, and hence the consequences of losing these species. This limited understanding may impede the development of policies and actions for their conservation and restoration. In this review, we synthesise how megafauna shape ecological processes in freshwater ecosystems and discuss their potential for enhancing ecosystem restoration. Through activities such as movement, burrowing, and dam and nest building, megafauna have a profound influence on the extent of water bodies, flow dynamics, and the physical structure of shorelines and substrata, increasing habitat heterogeneity. They enhance nutrient cycling within fresh waters, and cross-ecosystem flows of material, through foraging and reproduction activities. Freshwater megafauna are highly connected to other freshwater organisms via direct consumption of species at different trophic levels, indirect trophic cascades, and through their influence on habitat structure. The literature documenting the ecological impacts of freshwater megafauna is not evenly distributed among species, regions, and types of ecological impacts, with a lack of quantitative evidence for large fish, crocodylians, and turtles in the Global South and their impacts on nutrient flows and food-web structure. In addition, population decline, range contraction, and the loss of large individuals have reduced the extent and magnitude of megafaunal impacts in freshwater ecosystems, rendering a posteriori evaluation more difficult. We propose that reinstating freshwater megafauna populations holds the potential for restoring key ecological processes such as disturbances, trophic cascades, and species dispersal, which will, in turn, promote overall biodiversity and enhance nature\'s contributions to people. Challenges for restoration actions include the shifting baseline syndrome, potential human-megafauna competition for habitats and resources, damage to property, and risk to human life. The current lack of historical baselines for natural distributions and population sizes of freshwater megafauna, their life history, trophic interactions with other freshwater species, and interactions with humans necessitates further investigation. Addressing these knowledge gaps will improve our understanding of the ecological roles of freshwater megafauna and support their full potential for facilitating the development of effective conservation and restoration strategies to achieve the coexistence of humans and megafauna.

Second-generation Anticoagulant Rodenticides (ARs) can be critical for carnivores, due to their widespread use and impacts. However, although many studies explored the impacts of ARs on small and mesocarnivores, none assessed the extent to which they could contaminate large carnivores in anthropized landscapes. We filled this gap by exploring spatiotemporal trends in grey wolf (Canis lupus) exposure to ARs in central and northern Italy, by subjecting a large sample of dead wolves (n = 186) to the LC-MS/MS method. Most wolves (n = 115/186, 61.8 %) tested positive for ARs (1 compound, n = 36; 2 compounds, n = 47; 3 compounds, n = 16; 4 or more compounds, n = 16). Bromadiolone, brodifacoum and difenacoum, were the most common compounds, with brodifacoum and bromadiolone being the ARs that co-occurred the most (n = 61). Both the probability of testing positive for multiple ARs and the concentration of brodifacoum, and bromadiolone in the liver, systematically increased in wolves that were found at more anthropized sites. Moreover, wolves became more likely to test positive for ARs through time, particularly after 2020. Our results underline that rodent control, based on ARs, increases the risks of unintentional poisoning of non-target wildlife. However, this risk does not only involve small and mesocarnivores, but also large carnivores at the top of the food chain, such as wolves. Therefore, rodent control is adding one further conservation threat to endangered large carnivores in anthropized landscapes of Europe, whose severity could increase over time and be far higher than previously thought. Large-scale monitoring schemes for ARs in European large carnivores should be devised as soon as possible.

The absence of functional top predators has been proposed as a mechanism acting to shape fish assemblages in temperate marine ecosystems, with cascading effects on lower trophic levels. We explore this scenario by comparing the trophic and functional status of fish assemblages in Norwegian marine national parks, open to fishing, to a nearby coastal seascape that harbors a system of marine protected areas (MPAs) including a no-take zone. Demersal fish assemblages were sampled using fyke nets over three consecutive seasons. Atlantic cod (Gadus morhua) is potentially a dominant top predator in this ecosystem, and historically, this and other gadids have been targeted by the full range of former and present fisheries. In the present study, we find that average body size of the Atlantic cod was significantly larger in the zoned seascape compared to the unprotected areas (mean ± SD: 36.6 cm ± 14.38 vs. 23.4 ± 7.50; p < .001) and that the unprotected seascape was characterized by a higher abundance of mesopredator fish species. These observations are consistent with the hypothesis that the protection of top predators within MPAs aids to control the mesopredator populations and provides empirical support to the notion that the present state of many coastal fish assemblages is driven by mesopredator release linked to functional depletion of large top predators.

Exposure of wildlife to anticoagulant rodenticides (ARs) has been extensively documented for species directly or indirectly linked to pest rodents via the terrestrial food web. Recently, the scientific focus extended to a former blind spot, namely AR emissions to the aquatic environment, and provided clear evidence of AR residues in freshwater fish. As second-generation ARs are likely to be transferred along the aquatic food chain, a total of 122 Eurasian otter (Lutra lutra) individuals found dead in Germany between 2005 and 2021 were investigated to shed more light on resultant environmental risks. Target analytes comprised one pharmaceutical and eight biocidal anticoagulants, as well as one suspected bait impurity. Notably, all target compounds were detected in the analyzed livers of otters, a primarily piscivorous top predator and indicator species for the aquatic environment, strictly protected by conservation laws. In regions with pronounced rodent control measures, otters were frequently exposed to biocidal ARs. The elevated AR levels measured in multiple otters, compared to freshwater fish, hinted at biomagnification of second-generation ARs within the aquatic food web. The results indicated that risk mitigation measures implemented in Germany within the biocidal product authorization may not be sufficient to protect aquatic non-target wildlife from AR exposure, challenging the effectiveness of current regulatory measures.

Anthropogenic noise is ubiquitous globally. However, we know little about how the impacts of noise alter fundamental ecosystem properties, such as resource consumption by invertebrate consumers. Using experimental noise manipulation and faecal DNA metabarcoding, we assessed how the direct and cross-trophic indirect effects of noise altered the dietary richness and specializations of omnivorous grasshoppers in a grassland ecosystem. We found that the experimental noise treatment expanded grasshoppers\' dietary richness and resulted in dietary generalizations in both noise-exposed and adjacent relatively quieter areas. Unexpectedly, however, these dietary changes were primarily explained by the direct effect of noise not only in the noise-exposed areas but also in the adjacent quieter areas and were relaxed by indirect effects of noise such as reduced birds and predation risk and increased grasshoppers. Our work suggests that noise pollution can be key in explaining the variation of invertebrate consumers\' diets across a gradient of noise-exposed environments.