Oceanography and Atmospheric Sciences and Meteorology Commons^™

Microplankton Dynamics In The River-Dominated Mississippi Bight, Adam D. Boyette

Dissertations

The Mississippi Bight (MSB) is a river-dominated continental margin influenced by multiple large river systems, including the Mississippi River, Alabama and Tombigbee rivers via Mobile Bay, and numerous smaller rivers, creeks, and bayous. This is part of a biologically-rich ecosystem that supports the second largest fishery industry by volume in the United States. Despite our understanding of the linkages between primary production with higher trophic levels, there remains limited studies quantifying these trophic interactions in this system. Microplankton (µm) community dynamics and trophic connectivity between primary producers and heterotrophic protists represent a critical nexus influencing overall biological productivity in this …

Alexandrium In The Arctic: Are Harmful Algae Spreading As The Arctic Warms?, Sveinn Einarsson, Kate Lowry, Robert Pickart, Karin Ashjian, P. Dreux Chappell

College of Sciences Posters

Alexandrium tamerense is a well-studied dinoflagellate known for its ability to produce the neurotoxin that causes paralytic shellfish poisoning. Until 1970 Alexandrium tamerense was only found in Europe, North America, and Japan but has been increasingly found all over the globe. Alexandrium is characteristically found in temperate and subtropical regions and as the Arctic warms, there is considerable concern that it may be expanding into the Arctic. We found Alexandrium tamerense during a research expedition to the Alaskan Beaufort Sea shelf to study upwelling. Upwelling events are known to support seasonal blooms of phytoplankton, which are important primary producers at …

Developing A Method To Track Marine Snow Aggregation Through Individual Collisions Using Stereoscopic Imaging, Riley Henning

Theses

The aggregation of individual phytoplankton into marine snow allows particles to sink more quickly, thus resulting in the transport of particulate organic carbon from surface waters to the deep ocean. Aggregate formation has previously been measured in experiments indirectly by quantifying how particle size or particle concentration changes over time. Here, I present my thesis in which I applied high-resolution imaging to quantify aggregate formation using two different methodologies.

We conducted experiments to investigate aggregate formation using stereoscopic imaging, tracking individual particles directly in a 3D volume. Phytoplankton cultures were rolled in cylindrical tanks and imaged by two cameras illuminated …

Taxonomic And Nutrient Controls On Phytoplankton Iron Quotas In The Ocean, Benjamin S. Twining, Olga Antipova, P. Dreux Chappell, Natalie R. Cohen, Jeremy E. Jacquot, Elizabeth L. Mann, Adrian Marchetti, Daniel C. Ohnemus, Sara Rauschenberg, Alessandro Tagliabue

OES Faculty Publications

Phytoplankton iron contents (i.e., quotas) directly link biogeochemical cycles of iron and carbon and drive patterns of nutrient limitation, recycling, and export. Ocean biogeochemical models typically assume that iron quotas are either static or controlled by dissolved iron availability. We measured iron quotas in phytoplankton communities across nutrient gradients in the Pacific Ocean and found that quotas diverged significantly in taxon‐specific ways from laboratory‐derived predictions. Iron quotas varied 40‐fold across nutrient gradients, and nitrogen‐limitation allowed diatoms to accumulate fivefold more iron than co‐occurring flagellates even under low iron availability. Modeling indicates such “luxury” uptake is common in large regions of …

Synoptic Mesoscale To Basin Scale Variability In Biological Productivity And Chlorophyll In The Kuroshio Extension Region, Sophie Clayton, Hilary I. Palevsky, Luanne Thompson, Paul D. Quay

OES Faculty Publications

The Kuroshio current separates from the Japanese coast to become the eastward flowing Kuroshio Extension (KE) characterized by a strong latitudinal density front, high levels of mesoscale (eddy) energy, and high chlorophyll a (Chl). While satellite measurements of Chl show evidence of the impact of mesoscale eddies on the standing stock of phytoplankton, there have been very limited synoptic, spatially resolved in situ estimates of productivity in this region. Here, we present underway measurements of oxygen/argon supersaturation (ΔO2/Ar), a tracer of net biological productivity, for the KE made in spring, summer, and early autumn. We find large seasonal differences in …