Current Projects

Ecology and Evolution of Microbial Interactions in a Changing Ocean

Prochlorococcus is the most abundant photosynthetic organism on earth, but it has an Achilles heel- it can't get rid of the reactive oxygen products like hydrogen peroxide that are produced from photosynthesis. Prochlorococcus relies on 'helper' bacteria such as Alteromonas to clean up hydrogen peroxide.

 

However in an experiment in the lab we found that under ocean acidification predicted for 2100, Alteromonas decreased it's expression of a gene, catalase, that cleans up hydrogen peroxide. (Hennon et al. 2018)

These results led us to wonder if something similar would happen in a complex natural community.

Ambient CO2
Ambient CO2

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Elevated CO2
Elevated CO2

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Ambient CO2
Ambient CO2

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(Hennon et al. 2018 ISME Journal)

20191018_130443
Leaving Bermuda
20191019_141358
CTD deployment
On deck incubations
BIOS

We are studying how many potential 'helper' bacteria are in the natural community around Bermuda and whether they have similar responses to ocean acidification as Alteromonas in culture. We will also investigate whether there are wild pre-adapted Prochlorococcus strains that can handle predicted changes in dissolved carbon dioxide without experiencing  oxidative stress or whether there are other phytoplankton groups such as Synechococcus that are likely to increase in abundance.

This work is supported by the National Science Foundation (NSF) and made possible by collaboration with researchers at the Bermuda Institute of Ocean Sciences (BIOS) and the captain and crew of the R.V. Atlantic Explorer.

Diatoms on thin ice: sensitivity and resiliency to anthropogenic change in the Alaskan Arctic

Sea-ice algae are a key component of the base of the Arctic food web, especially in spring before adequate light can stimulate phytoplankton to bloom. Crude oil spills in the Arctic can be expected to cause lethal impacts to primary producers such as sea-ice algae and phytoplankton that are contacted by high concentrations of oil.

 

Less well constrained are the sublethal impacts of low concentrations of crude oil contamination on these primary producers and how sublethal impacts may be modulated by other variables such as declining snow cover and thinning ice due to climate change. In this project we aim to determine the concentration of Alaska North Slope crude oil that inhibits growth by 10% (IC10) and 50% (IC50) for a sea-ice diatoms isolated from Utqiaġvik, Alaska and how these toxicological parameters are impacted by changes in light that occur rapidly over the spring as snow and ice melt.

SEM images of sea ice algae from cultures and mixed samples. Scale bar = 5 um

This work is supported through the Alaska Coastal Marine Institute by the Bureau of Ocean Energy Management (Award Number: M20AC10007) with match funds from the State of Alaska