PARENT SESSION
OOS 4: Organisms as Ecosystem Engineers: Conceptual Progress, Limits and Challenges.
Organized by: JP Wright and CG Jones
Monday, August 2, 8:00 AM to 11:30 AM, Meeting Room E 146.

Aquatic plants as chemical engineers in a large river.

Caraco, Nina^*,1, Cole, Jonathan¹, ¹ Institute of Ecosystem Studies, Millbrook, NY, USA

ABSTRACT- Aquatic plants (macrophytes) are well-known, important sources of organic matter in aquatic systems. Aquatic plants can also function as chemical engineers altering oxygen, nutrient, and trace gas dynamics both locally in plant beds and in the entire ecosystem. In the Hudson River a native aquatic plant species (Vallisneria americana) and an introduced species (Trapa natans) vary dramatically in how they alter the chemical environment. These two species have opposite impacts on dissolved oxygen (DO): Vallisneria adds DO to the system while Trapa consumes DO to the point of anoxia within large beds. The low DO in Trapa beds has cascading redox impacts on trace gas and nutrient dynamics that are not seen in Vallisneria beds. The spatio-temporal variation in the entire Hudson River Ecosystem may be impacted by the relative abundance and location of Trapa and Vallisneria beds within the river.

Key words: macrophyte, river, biogeochemistry, introductions