Association between anthropization and rodent reservoirs of zoonotic pathogens in Northwestern Mexico

The world is facing a major pulse of ecological and social changes that may favor the risk of zoonotic outbreaks. Such risk facilitation may occur through the modification of the host's community diversity and structure, leading to an increase in pathogen reservoirs and the contact rate between these reservoirs and humans. Here, we examined whether anthropization alters the relative abundance and richness of zoonotic reservoir and non-reservoir rodents in three Socio-Ecological Systems. We hypothesized that anthropization increases the relative abundance and richness of rodent reservoirs while decreasing non-reservoir species. We first developed an Anthropization index based on 15 quantitative socio-ecological variables classified into five groups: 1) Vegetation type, 2) Urbanization degree, 3) Water quality, 4) Potential contaminant sources, and 5) Others. We then monitored rodent communities in three regions of Northwestern Mexico (Baja California, Chihuahua, and Sonora). A total of 683 rodents of 14 genera and 27 species were captured, nine of which have been identified as reservoirs of zoonotic pathogens (359 individuals, 53%). In all regions, we found that as anthropization increased, the relative abundance of reservoir rodents increased; in contrast, the relative abundance of non-reservoir rodents decreased. In Sonora, reservoir richness increased with increasing anthropization, while in Baja California and Chihuahua non-reservoir richness decreased as anthropization increased. We also found a significant positive relationship between the anthropization degree and the abundance of house mice (Mus musculus) and deer mice (Peromyscus maniculatus), the most abundant reservoir species in the study. These findings support the hypothesis that reservoir species of zoonotic pathogens increase their abundance in disturbed environments, which may increase the risk of pathogen exposure to humans, while anthropization creates an environmental filtering that promotes the local extinction of non-reservoir species.

Major shifts in biogeographic regions of freshwater fishes as evidence of the Anthropocene epoch

Animals and plants worldwide are structured in global biogeographic regions, which were shaped by major geologic forces during Earth history. Recently, humans have changed the course of events by multiplying global pathways of introduction for nonindigenous species and propagating local species extirpations. Here, we report on how introductions and extirpations have changed the distributions of freshwater fishes worldwide and how it affected their natural biogeographic regions. We found major shifts in natural regions, with the emergence of an intercontinental region arising from the fusion of multiple faunas, which we named Pan-Anthropocenian Global North and East Asia (PAGNEA). The PAGNEA region is evocative of the Pangea supercontinent, as flows of introductions show that dispersal has become possible again across multiple continents, suggesting that human activities have superseded natural geological forces. Our results constitute evidence on the expected modification of biostratigraphic boundaries based on freshwater fish, which are abundant in the fossil record, thereby supporting the concept of the Anthropocene epoch.

Spatiotemporal impacts of the Anthropocene on small mammal communities, and the role of small biological preserves in maintaining biodiversity

The multi-faceted impacts of the Anthropocene are increasingly modifying natural ecosystems and threatening biodiversity. Can small protected spaces conserve small mammal diversity across spatial and temporal scales of human impact? We identified small mammal remains from modern raptor pellets and Holocene archeological sites along a human modification gradient in the San Francisco Bay Area, CA and evaluated alpha and beta diversity across sites and time periods. We found that Shannon diversity, standardized species richness, and evenness decrease across modern sites based on level of human modification, with no corresponding change between Holocene sites. Additionally, the alpha diversity of modern sites with moderate and high levels of human modification was significantly lower than the diversity of modern sites with low levels of human modification as well as all Holocene sites. On the other hand, the small mammal communities from Jasper Ridge Biological Preserve, a small protected area, retain Holocene levels of alpha diversity. Jasper Ridge has also changed less over time in terms of overall community composition (beta diversity) than more modified sites. Despite this, Holocene and Anthropocene communities are distinct regardless of study area. Our results suggest that small mammal communities today are fundamentally different from even a few centuries ago, but that even relatively small protected spaces can partially conserve native faunal communities, highlighting their important role in urban conservation.

Microplastics as novel sedimentary particles in coastal wetlands: A review

Coastal wetlands are often neglected in marine debris studies. Interactions of plastics with natural particles are also largely understudied across all ecosystems but are becoming the focus of an emerging field on plastic cycling. Some studies have investigated short-term interactions, and some models predict short turnover times at the sediment surface on open shorelines. However, buried plastics may be retained longer in wetlands where accretion is often high, and some studies suggest their use as historical markers. The ubiquity, persistence, and behavior of plastic particles within wetlands warrants their consideration as novel sedimentary particles. Viewing plastics in this context will allow land managers to better predict how these vulnerable systems respond to increasing inputs of plastic pollution. This review evaluates debris distributions in coastal wetland sediments, heteroaggregation, plastic degradation within sediments, and persistence of plastic in the sedimentary record to highlight knowledge gaps and opportunities in this rapidly developing field.

A Meaningful Anthropocene?: Golden Spikes, Transitions, Boundary Objects, and Anthropogenic Seascapes

As the number of academic manuscripts explicitly referencing the Anthropocene increases, a theme that seems to tie them all together is the general lack of continuity on how we should define the Anthropocene. In an attempt to formalize the concept, the Anthropocene Working Group (AWG) is working to identify, in the stratigraphic record, a Global Stratigraphic Section and Point (GSSP) or golden spike for a mid-twentieth century Anthropocene starting point. Rather than clarifying our understanding of the Anthropocene, we argue that the AWG’s effort to provide an authoritative definition undermines the original intent of the concept, as a call-to-arms for future sustainable management of local, regional, and global environments, and weakens the concept’s capacity to fundamentally reconfigure the established boundaries between the social and natural sciences. To sustain the creative and productive power of the Anthropocene concept, we argue that it is best understood as a “boundary object,” where it can be adaptable enough to incorporate multiple viewpoints, but robust enough to be meaningful within different disciplines. Here, we provide two examples from our work on the deep history of anthropogenic seascapes, which demonstrate the power of the Anthropocene to stimulate new thinking about the entanglement of humans and non-humans, and for building interdisciplinary solutions to modern environmental issues.

El “antropoceno” al desnudo

El “Antropoceno”, definido como una nueva época geológica caracterizada por la huella humana global sobre el Sistema Tierra, se ha convertido en un término muy usado en una gran variedad de disciplinas. Sin embargo, todavía hay una serie de ideas equivocadas sobre el origen y la validez científica de este término. Un error muy común es pensar que el término y el concepto de “Antropoceno” se originaron a principios de este siglo, pero la verdad es que este concepto ya estaba plenamente desarrollado hace más de 140 años. Otra equivocación frecuente es considerar que el “Antropoceno” ya es un término geológico formal, cuando la realidad es que el proceso de su formalización como una nueva época de la Escala del Tiempo Geológico ni siquiera ha empezado. Otro aspecto muy poco tratado es la importancia del futuro cultural y evolutivo de nuestra especie en la eventual definición de una nueva época geológica como el “Antropoceno”. En este ensayo se discuten estos aspectos para una audiencia no especializada. Las posibles consecuencias de la presión humana incontrolada sobre el Sistema Tierra y la necesidad de reconsiderar nuestra relación con el planeta no se discuten aquí. El ensayo está centrado, únicamente, en la utilización de este argumento para proponer que hemos entrado en una nueva época de la Escala del Tiempo Geológico.