Micronutrient Limitation in the Oceans

Microbe infested biogenic debris collected in drifting sediment traps

Principal Investigators: Gordon Taylor and Sergio Sañudo-Wilhelmy

Funded by NSF

Student Supported: Caterina Panzeca (Ph.D.)

Project Description: Recent information suggests that both macro- and micronutrients that limit plankton production can be released from suspended and sinking particles in the water column owing to microbial activity. Furthermore, trends reviewed in Karl (2002) suggest that plankton in large oceanic regions may be vitamin B₁₂-limited. Based on earlier independent research, we (Sañudo-Wilhelmy & Taylor) just initiated a study of environmental and microbiological factors that govern vitamins B₁ and B₁₂ production and consumption. Findings to date suggest that in the ocean B-vitamins: (i) are produced almost exclusively by bacteria, (ii) have short residence times in oxic water, (iii) appear to be exported from anoxic systems (e.g., sediments, anoxic basins, interior of biogenic seston, animals' guts) and (iv) are required for growth of most phytoplankton as extracellular micronutrients. Using newly-developed state-of-the-art techniques (ICP-MS and HPLC), Sañudo-Wilhelmy’s lab measures ambient B-vitamin levels and concentrations and speciation of cobalt because Co is the coordination atom in vitamin B₁₂. Taylor's lab is examining how B-vitamins stimulate phytoplankton growth and alter species composition as well as the ecophysiology of B-vitamin-producing bacteria.

Gordon Taylor deploying drifting sediment traps in the Drake Passage

Caterina Panzeca at work in the lab