Oceanography Seminar

Kathleen Ruttenburg
Assistant Professor
Department of Oceanography
University of Hawai'i at Manoa

“Phosphorous Biochemistry in Aquatic Systems”

ABSTRACT:
Phosphorus (P) is an essential, potentially bio-limiting nutrient in aquatic systems. As such, it is critically important to understand the processes that control its delivery to and its bioavailability within aquatic systems. Upon entry into a body of water, a variety of physical and biogeochemical processes dictate the immediate as well as the long-term bioavailability of P, as well as the conditions under which it is permanently sequestered in bottom sediments and enters the long-term geological sedimentary reservoir. P bioavailability, particularly in relationship to other essential nutrients, exerts strong control on biological productivity and ecosystem structure, beginning with the community composition of primary producers at the base of aquatic food webs.

My research has emphasized tracking biogeochemical transformations of P that occur during delivery of P to aquatic systems, and during early diagenesis of near-surface sediments.

A second area of focus has involved enquiry into the nutritional status of primary producers with respect to phosphorus bioavailability. In the first instance, I have utilized selective sequential extraction methods to separately quantify reactive versus refractory forms of particulate P during riverine transport, water column cycling, and burial with sediments. To address questions of P-stress and P-limitation within aquatic systems, I have employed bulk and cell-specific enzymatic assays that permit assessment of nutritional status of the phytoplankton, in tandem with quantifying presence and bioavailability of dissolved organic P (DOP).

The cycles of carbon and phosphorus are linked through photosynthetic biomass production. As a bio-limiting nutrient, P has the potential to exert profound control on the global cycle of carbon, on both modern and geological time scales, and thus climate change through the nutrient-CO2 connection.

In this talk, I will present highlights from a number of my on-going research projects.

Ticket Information
Free

Event Sponsor
Department of Oceanography, Manoa Campus

More Information
Ocean, 808-956-7633, ocean@soest.hawaii.edu, http://www.soest.hawaii.edu/oceanography

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