By: Lauren McCarthy, Science Communications intern
Today is the last day on the job for Bigelow’s 2016 summer interns! It has been a busy 10 weeks full of lab work, literature reviews, writing, and coding. For our 16 REU students, today was a chance to orally present their research projects. Students presented on a wide range of topics, including marine viruses, benthic invertebrates, oil spill weathering, coccolithophores, bioturbating worms, and the American lobster.
The first REU presenter was Sydney Tiemann (Colby College), and she discussed her research with the marine protozoan parasite Perkinsus. This species is closely related to the Malaria-causing parasite Plasmodium falciparum. Perkinsus is also known to cause disease in mollusks. A proposed mediation technique involves creating an extract of the Chaga mushroom, which has been known for its antibacterial, antifungal, and antioxidant-rich properties. Sydney found that although the growth of P. marinus was inhibited within the first 12 hours of the testing period, it displayed an increase in growth after this 12 hour period. For future studies, different treatment extracts are being tested with Plasmodium falciparum.
Catherine Carlisle’s (University of Virginia) research involved a bacteria-produced polyketide metabolite called Bryostatin. This compound is important due to its potential use as a tumor suppressor for cancer treatment and a memory enhancer for Alzheimer’s patients. Catherine collected and identified six species of benthic marine invertebrates from Bigelow’s dock and the nearby Ocean Point. She performed this analysis through DNA sequencing, PCE, and diversity analysis of each species’ bacterial community. Ultimately, Catherine found that there were significant differences in diversity amongst her invertebrate samples, and that invertebrates are a rich source of microbial diversity.
Tatiana Barreto Vélez (University of Puerto Rico – Río Piedras) presented her research on harmful algal blooms (HABs), specifically the toxic dinoflagellate Alexandrium fundyense. This organism originates from the Bay of Fundy and blooms in the Gulf of Maine yearly. Climate change is predicted to cause an increase in river-sourced humic material, in addition to the intensification of hydrological cycle, increased temperatures, and a change in nutrient availability. Tatiana found that dissolved humic substances (DHS) from terrestrial sources will ultimately decrease the amount of dissolved organic phosphorus (DOP) available for use by Alexandrium fundyense.
Abby Onos (Smith College) is interested in the classification of coccolithophores as mixotrophs. Her experiment utilized Biolog EcoPlatesᵀᴹ to test if certain organic compounds were oxidized in coccolithophore growth media under dark conditions. Abby found that different coccolithophores species will oxidize different combinations of the 31 organic compounds, and that there was evidence of mixotrophy within coccolithophores. It is possible that mixotrophy is evolutionarily advantageous for coccolithophores.
Nate Matteson (University of New Mexico) discussed how viruses will be influenced by ocean acidification and warming. Through six mesocosm experiments, Nate tested how the abundance of several types of viruses changed as temperatures and carbon dioxide concentrations increased. He found that most viruses decreased in abundance as these two parameters increased. The mesocosm that replicated current ocean conditions did not experience this change. However, viral production increased after 6 days of increased temperature and carbon dioxide, suggesting that viruses may be able to adapt to changing ocean conditions, as can the virus’s host.
Darcy Gonzalez (University of Texas – Rio Grande Valley) studied the effects of a changing ocean on American lobster larvae. The lobster industry is of economic and cultural importance to the state of Maine, and warming waters and ocean acidification have been projected to negatively impact lobsters’ size and survival rates. Darcy used IPCC predicted pCO2 and temperatures levels in her experiment. Interestingly, she found that lobsters were not significantly affected by increased water temperatures or acidity. This is encouraging because it suggests that lobsters in southern New England regions may display resilience to warmer and more acidic ocean waters.
Yannik Büchi (Colby College) became an expert on Nereis (Hediste) diversicolor, a polychaete worm, this summer. These worms are important bioturbating organisms that have diverse feeding behaviors. Most worms are detritivores, carnivores, or filter feeders. This species allows researchers to monitor sediment and water quality and displays astounding resilience to environmental changes in temperature, sulfide concentrations, and salinity. Previous studies have suggested that the high metabolic activity within the worms’ guts makes them more resistant to these environmental changes. Yannik found that N. diversicolor has sulfur-cycling bacteria in its gut.
Megan Harder’s (Carleton College) research also focused on bioturbating worms, but provided a different perspective. Burrowing worms enable the oxygenation of sediments at depth, causing idealized conditions within the burrows for iron-oxidizing bacteria to live. Megan’s results suggested the iron oxidation within worm burrows was biologically facilitated, and that natural variability is present within heterogeneous microbial communities.
Renee Torrie (McGill University) used her computational skills to model trace metal data provided by the GEOTRACES program. She used power curves to model remineralization and investigated the processes behind trace metal cycling in the ocean. Renee ultimately found that phosphorus, cadmium, and nickel are modelled well across the whole water column. She also successfully modelled cobalt, copper, and zinc at shallower depths. These models allow for spatial comparisons between elements in different ocean basins.
Andrew Hirzel (University of Miami) spent his summer studying the relationship between phytoplankton biomass and cell biovolume. This topic is especially important because phytoplankton sequester large amounts of carbon dioxide. Using four different algorithms, Andrew was able to determine the effectiveness of each algorithm in determining the volume of a cell using 2D FlowCAM images in combination with 3D images from a confocal microscope. Each algorithm had a different level of effectiveness for different cell types.
Johanna Holman (Husson University) worked in collaboration with Bigelow’s Single Cell Genomics Center to analyze partial genomes from the Woesearchaeota phylum. Johanna’s research confirmed the presence of Woesearchaeota in marine pelagic waters and hydrothermal vents, and that Woesearchaeota may comprise several phylum instead of one. Potential future research questions will explore if Woesearchaeota will degrade organic matter or act as pathogens to bacteria.
Cynthia Michaud (University of Rhode Island) studied both the inorganic and organic forms of phosphorus and the role they play in phytoplankton growth. In general, phytoplankton prefer inorganic phosphorus as a source of nutrients, but may be forced to use organic phosphorus when the inorganic form is deficient. Cindy found that phytoplankton, specifically Emiliania huxleyi, were able to sustain their growth with organic phosphorus.
Halle Sauer (Humboldt State University) researched the ability of Saccharina latissima, or sugar kelp, to mediate the effects of rising ocean temperature and acidity in the water column. Halle measured photosynthetic yield, photosynthetic quotient, primary production rate, and inorganic carbon uptake rate. All four parameters were reduced under warmer, more acidic conditions. Climate change will likely negatively affect sugar kelp’s ability to absorb carbon dioxide and will reduce its economic harvest value.
Emma Posega Rappeleye (Carleton College) studied the distribution of jellyfish in the Gulf of Maine through citizen science reports. This type of surveying will help to better assess the locations, times, and sizes of jellyfish blooms under changing ocean conditions. Emma also used satellite measurements to create jellyfish distribution forecasts. She found that higher sea surface temperatures and greater amounts of photosynthetically active radiation may cause an increase in jellyfish. Smaller time frames yielded the most accurate models. Effective forecasting of these jellyfish blooms will reduce the amount of negative interactions between jellyfish and machines, boats, and humans.
Briar Bragdon (University of New England) focused on virus-infected (cyanophage present) Synechococcus for his research. He found that when infected with a virus, Synechococcus displays a photosynthetic efficiency that was equal or greater than that of the uninfected control group. Briar’s results suggest that certain types of viruses that occur in cyanobacteria can enhance light energy acquisition in a wide range of hosts.
Amanda Herzog (Wheaton College) described her research regarding the weathering of oils through a study of the 2010 Deepwater Horizon oil spill in the Gulf of Mexico. It is widely acknowledged that the chemical composition of oil changes as it is released from the ground, but Amanda wanted to explore more about how the toxicity of oil changes over time. She found that toxic aromatic compounds were mostly lost in weathered oil patty samples. Weathered oils were shown to have no toxic effect on Vibrio fischeri bacteria and caused lower mortality rates in copepods than crude or slick oil. Overall, weathered oil no longer displays substantial toxicity in the regions affected by the Deepwater Horizon spill.
All information for this post was obtained from intern oral presentations and written abstracts. Thanks to all the REU students for an informative symposium!