At Sea in the Eastern Tropical Pacific

Welcome to "At Sea in the Eastern Tropical Pacific"! This site has been established to follow the adventures and the research of 22 marine scientists at sea in the Eastern Tropical Pacific. This site is designed to host periodic messages posted directly from the scientific crew at sea, while allowing you to send questions regarding the cruise and its research. Send questions or comments to: etpcruise@yahoo.com. For older blog postings, select "older blogs" at the bottom of this page.

Wednesday, November 7, 2007

The Costa Rican Dome

We made it to our last long station - the Costa Rican Dome - located at 9°and 90°W. This station lies inside a highly productive upwelling system, receiving its name from the doming of the isobars (lines of constant pressure) that result from the upwelling of cold, nutrient water towards the surface. These nutrients support abundant phytoplankton growth (also known as primary productivity) which in turn supports higher-than-usual abundances of zooplankton and higher trophic levels, including dolphins and whales. So it was no surprise when our ship encountered a couple of whales just an hour before reaching the station last night, welcoming us to our last stop. We are all excited to reach our final station and to be in such a highly productive region. The flurry of activities began immediately last night with CTD casts, Tucker trawl and SIPPER deployment, continuing into the morning with the launching of the MOCNESS, and continued deployment of the CTD and SIPPER. So the race for sleep is on, but it is always exciting to reach a long station and resume research, especially in such a special place.

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Welcome Students!

This website is dedicated to the Eastern Tropical Pacific research project, which is being funded by the National Science Foundation (NSF) and involves 6 research labs from 5 U.S. oceanographic institutions. There are 22 scientists onboard made up of professors, graduate students, post-doctorates and laboratory technicians and 13 crew members on board. The cruise left out of Panama on October 18, 2007 and will travel north into international waters off the Pacific coast of Mexico before returning south to Panama on November 17, 2007. Along the way, the ship will stop at several research stations in the eastern tropical Pacific. Our 204 ft. research vessel, the R/V Seward Johnson is equipped with several research labs, an environmental chamber, one, two, and four-person staterooms each equipped with their own bathroom and shower, a full service kitchen, a meeting room with large television, a small weight room, laundry, and internet access. The aims of this research program are described on the right-hand portion of this page. Please send your questions to etpcruise@yahoo.com. This email is checked regularly, however due to research priorities and variable internet access, please allow one week for a response.

Eastern Tropical Pacific Research Program (continued)

The purpose of this research expedition is to investigate the vertical distribution and physiology of plants (phytoplankton), animals (zooplankton, fish, and squid), and microbes in relation to the low oxygen zone. We will sample both low productivity and high productivity sites, in order to better understand how marine organisms may adapt to decreasing oxygen levels in coming decades. Our combined projects also will provide information on how marine carbon and nitrogen cycles are modified in suboxic regions of the ocean.

References

IPCC. 2001. Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change. In, Houghton, J.P., Y. Ding, D.J. Griggs, M. Noguer, P.J. van der Liden, X. Dai, K. Maskell, and C.A. Johnson (eds). Cambridge University Press, pp 881.

Keeling, R.F. and H.E. Garcia. 2002. The change in oceanic O2 inventory associated with recent global warming. Proceedings of the National Academy of Sciences of the United States of America 99: 7,848-7,853.

Daly lab

We will use a high speed, digital, laser line scan camera (SIPPER; www.marine.usf.edu/sipper; http://figment.csee.edu/~kkramer/sipper) system to obtain fine-scale vertical distributions of zooplankton in relation to seawater temperature, salinity, oxygen, chlorophyll fluorescence, and particle density. We also will use an Acoustic Doppler Current Profiler (ADCP) to assess the timing and location of vertically migrating zooplankton and fish in and out of the low oxygen zone. Grazing and egestion rates of zooplankton will be determined for species that live in near-surface oxygenated waters and species that live or spend much of the day residing in the low oxygen zone. These experiments will provide information on how food web interactions vary between microbes, phytoplankton, and zooplankton at different depths and oxygen concentrations.

Sambrotto lab

Our component of the research cruise focuses on the nutrients for plankton growth, particularly nitrogen. Like land plants, ocean phytoplankton require nitrogen to photosynthesize and grow. Nitrogen is often in short supply in surface waters. Therefore we will measure two critical aspects related to maintaining ocean productivity: the rate at which nitrogen is taken up by phytoplankton in surface waters as well as the rates at which nitrogen is removed from the ocean’s biological system by denitrification in the Oxygen Minimum Zone (OMZ). These two processes may be closely linked in regions with an OMZ. The result of this interaction can have far reaching impacts on large scale marine food webs by altering the amount of nitrogen available for phytoplankton growth.

Seibel lab

We’re interested in the physiological attributes of animals that allow them to spend time where oxygen is scarce. Some permanent OMZ residents survive by being effective at extracting oxygen from the seawater. They have large gills and blood that binds oxygen effectively despite low environmental oxygen concentrations. Species that spend only a portion of their day in the OMZ may survive by shutting down metabolically expensive processes and so require less oxygen. Still others utilize anaerobic metabolic pathways similar to the pathway that produces lactic acid in humans during intense exercise. OMZ’s are also associated with high levels of carbon dioxide that may impair oxygen transport in the blood and calcification in organisms that produce a shell, such as pteropods (open ocean snails called sea angels). Regions with strong oxygen minimum zones act as natural experiments that allow us to view how organisms world-wide may respond to elevated oceanic CO2 and reduced oxygen that result from human emissions.

Taylor lab

Our project will determine the abundance, distribution, and growth rates of marine bacteria (prokaryotes) in relation to the OMZ. The depths where oxygen concentrations rapidly decrease and increase (i.e., the edges of the midwater OMZ) are likely to be regions of elevated microbial activity based on previous findings in other ocean regions. Prokaryote community composition will be investigated using molecular methods, such as Fluorescence In Situ Hybridization (FISH) and Terminal Restriction Fragment Length Polymorphism (TRFLP), a phylogenetic fingerprinting technique.

Wakeham lab

Stuart Wakeham and I, Heidi Albrecht, are looking at the biogeochemistry of the ETP. Stuart Wakeham is one of the Principle Investigators, PIs, on this research vessel. He works at Skidaway Institute of Oceanography in Savannah Georgia. He has worked there close to 30 years and this is his 22nd cruise. I am a PhD candidate at Pennsylvania State University. My advisor, Kate Freeman, has collaborated with Stuart since the early 90’s.
Our goal is to relate the microbial community in the low oxygen zone with organic biomarkers that the microbes produce. Biomarkers are organic compounds that have unique molecular structures that can be attributed to their source organisms, thereby providing a means of inferring the origins of organic matter in the ocean and in oceanic sediments. This in turn allows us to reconstruct past oceanic environments from the sediment record. We will collect particulate matter samples using large volume in-situ filtration systems and then measure the biomarkers back in our home laboratory. Microbial distributions will be measured by collecting samples and using molecular microbial techniques (e.g., fluorescence in-situ hybridization and polymerize chain reaction) to quantify and identify the major microbial groups.

Wishner lab

Karen Wishner, a Professor of Oceanography at the University of Rhode Island, and her group are studying the zooplankton (small animals) in the Oxygen Minimum Zone. We use a large multiple-sampling plankton net called a MOCNESS to collect these animals at various depths from 1000 m deep to the sea surface. We are looking at how the strong oxygen gradients of the Oxygen Minimum Zone affect their distributions. Many animals are excluded from the lowest oxygen water. The upper and lower “edges” of the Oxygen Minimum Zone are often areas of high abundances. Zooplankton species show vertical zonation across the Oxygen Minimum Zone, with different species being most abundant at different depths and oxygen concentrations. We are also looking at food webs of the zooplankton to see what they are eating.