Abstract

Two fundamental functions of ecosystems are nutrient cycling and trophic dynamics. Both have been well studied, but often they are not related to each other. A group of scientists in North Carolina conducted separate studies of nitrogen cycling relationships to loading and food web relationships to hypoxia in the Neuse River Estuary. We constructed and analyzed network models of nitrogen and carbon flow. Rapid and extensive nitrogen cycling promoted high primary production within the estuary. Hypoxia altered trophic dynamics with decreased capacity for benthic-pelagic coupling and short-circuiting of energy transfers. The two studies are compatible with a hypothesis that an active microbial loop dominates ecosystem-level dynamics within this eutrophic estuary.

Biographical Sketch

Dr. Christian's work has focused on coastal ecosystems, particularly salt marshes, estuaries and coastal lagoons along the Atlantic and Gulf coasts of the USA and in the Mediterranean. Most recently he has been involved in studies of low order and headwater streams within the coastal plain. In these ecosystems he has studied nutrient cycling, especially the nitrogen and carbon cycles, and energy flow. Much of his recent efforts have been devoted to network analysis as a mathematical tool for the comparisons among and within ecosystems

Light refreshments are served in the Interaction Area (4th floor of the Oceanography/Physics Building) at 4:00 p.m.

All seminars begin at 3:00 p.m. and are held in room 200 of the Oceanography/Physics building.