2016-2017 USAP Field Season
Southern Ocean diatoms and climate change: quantifying the relative roles of diversity and plasticity in evolution
Dr. Tatiana A Rynearson
University of Rhode Island
Supporting Stations: RV/IB Nathaniel B. Palmer
The objective of this project is to characterize the physiological and genetic diversity of Southern Ocean diatoms along a transect from Punta Arenas, Chile to McMurdo Station. These characterizations will quantify the capacity of this type of phytoplankton to adapt to environmental change. The transect crosses five oceanographically distinct regions that vary in their carbonate chemistry and temperature and are thus likely to contain populations that differ in their plastic responses to environmental change. The evolutionary response of cold-adapted, biogeochemically important phytoplankton is essentially unknown and represents a knowledge gap that hampers the ability to predict future changes at the base of the marine food web. This work expands the understanding of evolutionary potential of diatoms by examining the interplay of plasticity and diversity in determining how natural selection acts on these populations.
Field Season Overview
Team members will sail on the RVIB Nathaniel B. Palmer (NBP) on a transit cruise (NBP17-01) to sample water along a transect from Punta Arenas, Chile to McMurdo Station. The transect will run through five regions: the Drake Passage, the Palmer Long-Term Ecological Research (PAL-LTER) grid, the Amundsen Sea, the Ross Sea Gyre, and the Ross Sea Continental Shelf. A conductivity, temperature, depth (CTD) sensor and rosette package will be used to collect diatoms and analyze the surface water column. They will conduct CTD casts to a maximum depth of 200 meters and will collect samples at two depths, including the surface (five meters) and at the subsurface chlorophyll maximum (estimated at no deeper than approximately 60 meters). Ideally, the team will conduct five to seven casts per region, with a greater frequency in the Drake Passage region. The team will also use a bucket to capture any particularly important phytoplankton samples on the ocean surface. Water sample analyses will include phytoplankton, chlorophyll a, and nutrients (nitrogen, phosphorus, silica). Analysis of the nutrient samples will occur at the home institution. On arrival at McMurdo, the science team will offload their samples and cargo on to station. They will store live cultures in a light and temperature (0-4°C) controlled incubator at Crary Lab in a ready-to-ship state. Crary Lab staff will assist with preparing their samples to return to the home institution.
Deploying Team Members