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CARBON AND NITROGEN ALLOCATION MODEL FOR THE SUB-TROPICAL SEAGRASS THALASSIA TESTUDINUM AND THE TEMPERATE SEAGRASS ZOSTER MARINA
Eldridge, P M. AND J E. Kaldy. CARBON AND NITROGEN ALLOCATION MODEL FOR THE SUB-TROPICAL SEAGRASS THALASSIA TESTUDINUM AND THE TEMPERATE SEAGRASS ZOSTER MARINA. Presented at Estuarine Research Federation meeting, Seattle, WA, September 14-18, 2003.
Our understanding of seagrass physiology is based on crude estimates of production and biomass. To better understand the complex physiological relationships between the plants and the environment we developed a model of carbon and nitrogen allocation in the sub-tropical seagrass Thalassia testudinum from Laguna Madre, Texas and the temperate seagrass Zostera marina from Yaquina Bay, Oregon. The optimization model is composed of linear equations and inequality constraints, which describe material flows between the seagrass tissues (i.e., leaf, rhizomes and roots) and the environment (e.g., water column and sediments). Results for the T. testudinum model showed that carbon fixed in the leaves (i.e., primary production) was partitioned equally between growth of leaf and non-photosynthetic tissues, with the greatest proportion of non-photosynthetic material going to the root and rhizome tissue. The below ground growth/storage rate was about 30% lower than above ground growth even though there was 5 times more below ground tissue than leaf tissue. Continued loss of leaf detritus in the autumn and winter, when gross primary production is low, would account for the yearly cycles in leaf biomass. Improved seagrass models of this type are needed to help set protective criteria.
Record Details:Record Type: DOCUMENT (PRESENTATION/ABSTRACT)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL HEALTH AND ENVIRONMENTAL EFFECTS RESEARCH LABORATORY
WESTERN ECOLOGY DIVISION
PACIFIC COASTAL ECOLOGY BRANCH