Category Archives: publications

Keesing lab: Blood meal effects on tick microbiome

Ticks are parasites that ingest blood from their hosts. During their blood meals, they can also ingest microbes, such as bacteria, from their host’s blood, which could influence the microbial community, or “microbiome”, of the tick itself. Using high-throughput sequencing, Felicia Keesing and her colleagues sampled the microbiomes of ticks that had fed on individuals of five different host species — raccoons, Virginia opossums, striped skunks, red squirrels, and gray squirrels. They found that ticks that had fed on different host species had significantly different microbiomes. This is important because some of the microbes that ticks can acquire during their blood meals are pathogens of humans, including the bacterium that causes Lyme disease.

Publication link:

Full citation:  Landesman, W. J., Mulder, K., Allan, B. F., Bashor, L. A., Keesing, F., LoGiudice, K., & Ostfeld, R. S. (2019). Potential effects of blood meal host on bacterial community composition in Ixodes scapularis nymphs. Ticks and tick-borne diseases.

Dueker lab: Fog in Urban Environments

The urban environment is complex and often highly contaminated. This paper from prof. Eli Dueker’s lab takes a close look at how this contamination influences bacteria in urban air.  The bacteria present in urban waterways were compared with the bacteria present in urban air, showing that there are many sources for atmospheric bacteria in an urban environment, including sewage contaminated waterways and polluted terrestrial areas. We also observed a ubiquitous distribution of sewage-associated bacteria, in water and air at several urban sites, highlighting the prevalence of of sewage contamination in crowded urban centers and underscoring the complexity of managing this form of pollution in water and air.  Surprisingly, we also found that, despite the absence of obvious ecological structures, the air harbored a much more diverse bacterial community than that found in urban waterways. This provides evidence for the possibility of an atmospheric “ecology” and is a step towards understanding the role of megacities in determining the quality of urban air.

Citation: Dueker, M. E., French, S., & O’Mullan, G. D. (2018). Comparison of Bacterial Diversity in Air and Water of a Major Urban Center. Frontiers in Microbiology9.


Keesing lab: livestock and wild animals can coexist

The savannas of East Africa are renowned for their abundant and diverse wildlife. But wildlife populations in this region are declining dramatically, in part because of conflicts with humans and their livestock. Felicia Keesing and her colleagues studied the ecological, economic, and social consequences that arise when livestock and wildlife co-occur versus when the two groups live separately. They found that when livestock, particularly cattle, are kept at moderate densities, they actually improve vegetation quality for wildlife, reduce the abundance of parasites, and provide economic and social benefits to people living in the area.

Keesing discussed the research, and its implications, with Scientific American.

Integrating livestock and wildlife

New paper from Felicia Keesing’s lab was published in Nature Sustainability. Globally, most wildlife live outside of protected areas, creating potential conflicts. Keesing et al. assess tradeoffs between management for wildlife and for livestock in an East African savanna (pictured), finding potential benefits from integrating the two.

Full citation and link: Keesing, F., Ostfeld, R. S., Okanga, S., Huckett, S., Bayles, B. R., Chaplin-Kramer, R., … & Warui, C. M. (2018). Consequences of integrating livestock and wildlife in an African savannaNature Sustainability1(10), 566.

Dueker lab: Biology of fog in Maine, and in Namib Desert

The lab of professor Eli Dueker published a new study on the microbial composition of fog in Maine and in the Namib Desert. Dr. Dueker and collaborators found that fog particles lift microorganisms off the surface of water, and deposit them inland, increasing the microbial diversity.

The study has made quite a splash in the press; look at these substantive and interesting reviews, one in The Atlantic, and this one on the Atlas Obscura website.

Professor Dueker was also invited for a radio interview at WAMC: you can listen to it here.

Full citation: Dueker, M. E. and S. Evans, R. Logan, and K. C. Weathers (2018). The biology of fog: results from coastal Maine and Namib Desert reveal common drivers of fog microbial composition. Science of the Total Environment 647: 1547-1556.

New paper from Perron lab: effects of arsenic on fish microbiome

We are our own zoos, harboring about 39 trillion bacteria symbionts, about as many as our cells. These bacteria, collectively called our microbiome, are indispensable for our health; they fight our infections, process our food, guide our behavior, and protect us from diseases. So, when our bacteria are disrupted so is our health.

The recent research article, written by Bard graduate Dylan Dahan ’15 and professor Gabriel Perron, in collaboration with professors Brooke Jude and Felicia Keesing, used zebrafish as a model to investigate how arsenic poisoning affects fish microbiomes. The researchers found that microbiomes were readily affected, with striking consequences such as loss of bacterial community members and potential increases in antibiotic resistance.

Arsenic poising in contaminated drinking water affects over 60 million people in Bangladesh and West Bengal. This research will inform how contaminated water may be altering peoples microbiomes and thus supports the case for cleaning contaminated water.

Full citation: Dahan, D., Jude, B. A., Lamendella, R., Keesing, F., & Perron, G. G. (2018). Exposure to arsenic alters the microbiome of larval zebrafishFrontiers in microbiology9.

On the photo: Dylan Dahan (class of 2015) presenting his data.

Nine genome announcements from Brooke Jude’s lab

This winter the lab of professor Brooke Jude published nine draft genomes of bacteria endemic to the Hudson Valley watershed. This work is a result of several senior projects performed in the Biology program, and three graduated biology students (Alexandra Bettina, Georgia Doing, and Kelsey O’Brien) are now first authors on three publications!

Bettina, A. M., Doing, G., O’Brien, K., Perron, G. G., & Jude, B. A. (2018). Draft Genome Sequences of Phenotypically Distinct Janthinobacterium sp. Isolates Cultured from the Hudson Valley Watershed. Genome announcements6(3), e01426-17.

Doing, G., Perron, G. G., & Jude, B. A. (2018). Draft Genome Sequence of a Violacein-Producing Iodobacter sp. from the Hudson Valley Watershed. Genome announcements6(1), e01428-17.

O’Brien, K., Perron, G. G., & Jude, B. A. (2018). Draft Genome Sequence of a Red-Pigmented Janthinobacterium sp. Native to the Hudson Valley Watershed. Genome announcements6(1), e01429-17.

New paper: Onshore Wind Speed and Microbial Aerosols at Urban Waterfronts

In this new paper, Bard professor Elias Dueker and collaborators study microbes that fly in the air, after small droplets of water get lifted from the ocean surface by the coastal wind. They found that depending on the wind speed, different amounts of microbes were picked up, and they were transported different distances into the city. They also described which types of microbes are more likely to get airborne, compared to those found below the water surface.

Citation: Dueker, M. E., O’Mullan, G. D., Martínez, J. M., Juhl, A. R., & Weathers, K. C. (2017). Onshore Wind Speed Modulates Microbial Aerosols along an Urban WaterfrontAtmosphere8(11), 215.

New paper: Susceptibility to ecological traps is sensitive to spatial isolation

Animals caught in ‘ecological traps’ prefer the worst available habitats. This happens when environmental change makes habitats look superficially attractive when they are actually dangerous. Ecological traps are increasingly common, but it remains unclear how susceptible animals are to them. Aquatic flies, for example, can be highly attracted to asphalt because it reflects polarized light the same way that natural water bodies do.

In this study, Bard professor Bruce Robertson and his students exposed seven ecologically similar species of aquatic flies to different levels of polarized light, including abnormally strong polarized light associated with man-made habitats that are dangerous to them. They found that, in every species tested, animals actually preferred levels of polarized light typical of asphalt where their eggs perish, over levels typical of natural ponds. We also found that the degree of their preference depended on whether the cue was closer or more distant from a natural river.

Citation: Robertson, B. A., Keddy-Hector, I. A., Shrestha, S. D., Silverberg, L. Y., Woolner, C. E., Hetterich, I., & Horváth, G. (2018). Susceptibility to ecological traps is similar among closely related taxa but sensitive to spatial isolationAnimal Behaviour135, 77-84.

New paper: integrating wildlife and livestock in central Kenya

In this paper, Felicia Keesing and her collaborators explore the potential for positive interactions between livestock and wildlife in African savannas. Historically, the prevailing view has been that savanna landscapes should be managed for either livestock or wildlife, but not both. Keesing and her colleagues suggest that under some conditions, both groups — and the humans who share their habitat — could benefit ecologically and economically by sharing land.

Citation: Allan BF, Tallis H, Chaplin‐Kramer R, Huckett S, Kowal VA, Musengezi J, Okanga S, Ostfeld RS, Schieltz J, Warui CM, Wood SA, Keesing F. Can integrating wildlife and livestock enhance ecosystem services in central Kenya?. Frontiers in Ecology and the Environment. 2017 Aug 1;15(6):328-35. Full text at Research Gate.