Structure and Function of Marine Ecosystems Steven Murawski Ph.D. Director, Office of Science & Technology National Marine Fisheries Service  Challenges of Integrating Ecosystem Knowledge  Definitions  Key Processes in Marine Ecosystems  Status of Ecosystem Science -1-

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Definitions An ecosystem is a geographically specified system of organisms (including humans), the environment, and the processes that control its dynamics. The environment is the biological, chemical, physical, and social conditions that surround organisms. When appropriate, the term environment should be qualified as biological, chemical, physical, and/or social. -3-

Spatial Scales & Boundaries -4-

Phytoplankton Zooplankton Forage Fish Piscivores Apex Predators Humans The Trophic Pyramid and Energy Flow 1000 units 100 units 10 units 1 unit 0.1 unit 0.01 unit If transfer efficiency is 10% -5-

Photosynthesis occurs primarily in waters less than 200 meters deep, which make up about 7% of the World’s Oceans below 200 m, nutrients accumulate and must be brought to the surface in order to support production - by upwelling & currents -6-

Scales and Observations -7-

Regional Climatology Affects Ecosystems -8-

Interactions Between Physical & Biological Components of Ecosystems -9-

Harvesting Affects Distributions & Abundances of Species Atlantic cod -10-

Known Unknown Unknowable Surface Production & Dynamics Status of Major Species Number of Species in the Oceans Structure of “pristine” ecosystems 3-D Structure of Selected Ocean Environments Evolutionary effects of human activities Synoptic Maps of the Sea Floor Food-web and particle size models Valuing Ecosystem Goods & Services Climate Variation effects on species & ecosystems Spatially-explicit models of predator-prey systems Status of all “important” species Mapping of Habitats Predictive models of many-species interactions Nutrient Enrichment & Toxics Reversibility of Human impacts