Examining the potential impacts of a coastal renourishment project on the presence and abundance of Escherichia coli.

Erosion poses a significant threat to oceanic beaches worldwide. To combat this threat, management agencies often utilize renourishment, which supplements eroded beaches with offsite sand. This process can alter the physical characteristics of the beach and can influence the presence and abundance of microbial communities. In this study, we examined how an oceanic beach renourishment project may have impacted the presence and abundance of Escherichia coli (E. coli), a common bacteria species, and sand grain size, a sediment characteristic that can influence bacterial persistence. Using an observational field approach, we quantified the presence and abundance of E. coli in sand (from sub-tidal, intertidal, and dune zones on the beach) and water samples at study sites in both renourished and non-renourished sections of Folly Beach, South Carolina, USA in 2014 and 2015. In addition, we also measured how renourishment may have impacted sand grain size by quantifying the relative frequency of grain sizes (from sub-tidal, intertidal, and dune zones on the beach) at both renourished and non-renourished sites. Using this approach, we found that E. coli was present in sand samples in all zones of the beach and at each of our study sites in both years of sampling but never in water samples. Additionally, we found that in comparison to non-renourished sections, renourished sites had significantly higher abundances of E. coli and coarser sand grains in the intertidal zone, which is where renourished sand is typically placed. However, these differences were only present in 2014 and were not detected when we resampled the study sites in 2015. Collectively, our findings show that E. coli can be commonly found in this sandy beach microbial community. In addition, our results suggest that renourishment has the potential to alter both the physical structure of the beach and the microbial community but that these impacts may be short-lived.

From Then to now: Diversity, Equity, and Inclusion in the Association of Southeastern Biologists.

The Association of Southeastern Biologists was founded in 1937 with the goal of increasing the contact and collaboration between scientists in the southeastern United States (US). With the exception of two years during World War II and one year during the COVID-19 pandemic, the Association has met annually to promote research and education in the biological sciences by providing a student-friendly networking environment. In recent years, the Association has placed an increased focus on diversity, equity, and inclusion among elected and appointed leaders, among participants in the annual meeting, and in the development of funding and other opportunities for students. This work prompted us to review the history of our Association, including periods of racial segregation and inequity, and focus on our current efforts to promote access and inclusion by students and scientists from myriad underrepresented groups. In so doing, the past provides us with the opportunity to cast a vision for the future of the Association. In this paper, we seek to share the journey of the Association of Southeastern Biologists in this regard so that we may be transparent, exposing the missteps and amplifying the successes of our organization. We envision this work as a first step toward creating a more open and inclusive scientific community for the future.

Sourcing Antibiotic-Resistant Escherichia coli in Aquatic Ecosystems: A Combined Laboratory and Field Module.

The emergence of antibiotic-resistant bacteria represents a growing threat in aquatic ecosystems. In this combined field and laboratory activity, students will determine whether Escherichia coli, an indicator bacteria species commonly found in aquatic ecosystems, shows signs of resistance to common antibiotics. In addition, students will use molecular biology techniques to identify whether Escherichia coli cells sourced from different hosts (i.e., phylogroups) show different patterns of antibiotic resistance. This activity will help students to gain experience in environmental microbiology, environmental science, molecular biology, and public health. This module is also designed to provide instructors with flexibility to pick and choose activities that best meet the needs of their class or research program.

Borane catalysed cyclopropenation of arylacetylenes.

Triarylboranes have gained substantial attention as catalysts for C-C bond forming reactions due to their remarkable catalytic activities. Herein, we report B(C6F5)3 catalysed cyclopropenation of a wide variety of arylacetylenes using donor-acceptor diazoesters. A mild reaction protocol has been developed for the synthesis of functionalised cyclopropenes (33 examples) in good to excellent yields.

Variation in the presence and abundance of anthropogenic microfibers in the Cumberland River in Nashville, TN, USA.

Anthropogenic microfibers (thread-like pieces of litter < 5 mm in size) including microplastic fibers have been suggested to pose a growing threat to urban rivers across the world. However, in most urban rivers, we have a limited understanding of how anthropogenic microfibers vary in presence and abundance over time. In this study, we examined how the presence and abundance of anthropogenic microfibers varied in the Cumberland River in Nashville, TN, a growing city with more than one million residents. To measure anthropogenic microfibers, we collected grab samples of surface water weekly from three locations along the Cumberland River in Nashville, TN (one upstream of the city, one in downtown, and one downstream of the city), over a 7-week period in summer of 2018 (n = 151 total samples). We found that anthropogenic microfibers were present at all study sites over time (mean of all samples = 27.9 microfibers/L) and that the mean abundance of anthropogenic microfibers significantly increased in the city and downstream of the city relative to our upstream collection site. In addition, we found that anthropogenic microfiber abundance was significantly variable over time (sample values ranged from 0 to 195 pieces/L) and that multiple factors including the presence of wastewater treatment plants may be contributing to the abundance and distribution of anthropogenic microfibers in this urban river.

The threat of disease increases as species move toward extinction.

At local scales, infectious disease is a common driver of population declines, but globally it is an infrequent contributor to species extinction and endangerment. For species at risk of extinction from disease important questions remain unanswered, including when does disease become a threat to species and does it co-occur, predictably, with other threats? Using newly compiled data from the International Union for Conservation of Nature (IUCN) Red List, we examined the relative role and co-occurrence of threats associated with amphibians, birds, and mammals at 6 levels of extinction risk (i.e., Red List status categories: least concern, near threatened, vulnerable, endangered, critically endangered, and extinct in the wild/extinct). We tested the null hypothesis that the proportion of species threatened by disease is the same in all 6 Red List status categories. Our approach revealed a new method for determining when disease most frequently threatens species at risk of extinction. The proportion of species threatened by disease varied significantly between IUCN status categories and linearly increased for amphibians, birds, and all species combined as these taxa move from move from least concern to critically endangered. Disease was infrequently the single contributing threat. However, when a species was negatively affected by a major threat other than disease (e.g., invasive species, land-use change) that species was more likely to be simultaneously threatened by disease than species that had no other threats. Potential drivers of these trends include ecological factors, clustering of phylogenetically related species in Red List status categories, discovery bias among species at greater risk of extinction, and availability of data. We echo earlier calls for baseline data on the presence of parasites and pathogens in species when they show the first signs of extinction risk and arguably before. La Amenaza de Enfermedades Incrementa a Medida que las Especies se Aproximan a la Extinción.

Coexistence between native and exotic species is facilitated by asymmetries in competitive ability and susceptibility to herbivores.

Differences between native and exotic species in competitive ability and susceptibility to herbivores are hypothesized to facilitate coexistence. However, little fieldwork has been conducted to determine whether these differences are present in invaded communities. Here, we experimentally examined whether asymmetries exist between native and exotic plants in a community invaded for over 200 years and whether removing competitors or herbivores influences coexistence. We found that natives and exotics exhibit pronounced asymmetries, as exotics are competitively superior to natives, but are more significantly impacted by herbivores. We also found that herbivore removal mediated the outcome of competitive interactions and altered patterns of dominance across our field sites. Collectively, these findings suggest that asymmetric biotic interactions between native and exotic plants can help to facilitate coexistence in invaded communities.