1999 Projects

Current Projects

	Benthic processes
	Midwater research
	Upper ocean biogeochemistry
	New research platforms
	ROV improvements
	Mooring improvements
	New in-situ Instruments
	Information management and archiving
	Education and outreach
	1998 Projects
	1997 Projects

1999 Projects: Benthic processes

Benthic biology and ecology

Project lead/manager: James Barry
Project team: John Ashen, Kurt Buck, Shana Goffredi, Scott Grandsen, Chris Lovera, Doug Nelson, Tim Pennington, James Smith, and Patrick Whaling

Some benthic communities of organisms are dependent on the downward transport of organic matter from the surface waters. Others are chemosynthetic, deriving their energy from hydrogen sulfide and methane flowing through pores in the seafloor sediments. MBARI’s research on the ecology of these communities has evolved from reconnaissance sampling and mapping to in-situ experiments on rates of metabolism using benthic respiration chambers. The overall goal is to quantify the role of benthic communities in carbon cycling and the balance of energy in the deep ocean. These studies are closely tied to in-situ sampling and analyses of pore-fluid chemistry and its evolution over time and space.

The objective of this project is to increase our understanding of processes that control the structure (species distribution and abundance) and function (demographic rates, species interactions, and community productivity) of deep-sea faunal communities. The research will focus on changes in community composition and metabolism along environmental gradients in food input, and oxygen and sulfide concentrations. Studies will continue on chemosynthetic communities inhabiting sulfide-rich cold-seep habitats on the continental margin of the Pacific Ocean that also occur along a gradient in oxygen levels. Also, we will further develop studies initiated in 1998 to quantify rates of energy consumption by benthic species across a range of organic carbon flux to the deep-sea. This research will serve to identify links between food input to deep-sea habitats and the structure and function of underlying seafloor communities.

These studies represent the first stage of a long-term research theme concerning coupling between the physics and biology of the upper ocean and their impact on the patterns and function of seafloor communities. Our investigations will initially focus on benthic and near-benthic processes, and will interface with upper water-column studies in subsequent years. One focus of these pelagic-benthic coupling studies will be on the relative importance of organic detritus derived from pelagic phytoplankton production versus nearshore macrophytic debris within and around Monterey Canyon. This research on energetics will be coupled to limited studies of the population biology of selected species, thereby linking energetic constraints with the demography of key benthic species.

The principal elements of chemosynthetic community studies will include:

• Measurements of environmental conditions such as sulfide and pH levels in relation to faunal patterns
  
• Measurements of sulfate reduction and methane oxidation in seep sediments to quantify sulfide production and improve our understanding of microbial mediation of chemical processes in seep sediments
  
• Physiological investigations on seep biota, including endosymbiont-host relationships and gas exchange processes and sulfide physiology of various species of vesicomyid (cold-seep) clams
  
• Taxonomic resolution of vacuolate bacteria (Beggiatoa and Thioploca) inhabiting seep habitats.

Research on pelagic-benthic coupling will include:

• Studies of the structure of benthic communities in areas of high and low organic input in Monterey Canyon
  
• In-situ measurements of oxygen consumption rates for the sediment community and selected megafaunal species
  
• Measurements of microbial productivity in the sediment community
  
• Measurements of grazing rates within the infaunal community
  
• Population biology studies on dense brachiopod communities
  
• Measurements of oxygen consumption by the sediment community in the Challenger Deep of the Marianas Trench
  
• Identification and tracking of benthic food-webs using lipid biomarkers.

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Last updated: 07 October 2004