Submitted to: Journal of Freshwater Ecology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/22/2002
Publication Date: 6/1/2003
Citation: Spencer, D.F., Ksander, G.G. 2003. Nutrient limitation of Zannichellia palustris and Elodea canadensis growing in sediments from Fall River, California. Journal of Freshwater Ecology. 18:207-213. Interpretive Summary: Aquatic weeds clog irrigation systems, crowd out desirable native vegetation, and make waterways unsuitable for boating, fishing, and swimming. Abundance of horned pondweed in Fall River in northern California decreased following entry of large quantities of sandy sediment into the river. To understand how sediment accumulation regulates aquatic plant growth we used Fall River aquatic plants as a model system. We grew plants in two types of river sediments in greenhouse experiments to test the hypothesis that sandy sediments provided insufficient nutrients compared to silty sediments. Horned pondweed and common waterweed increased in dry weight more when nitrogen or a combination of nitrogen and phosphorus were added to sandy sediments. Plants grown in silty sediments did display similar responses. Experimental results indicated that nitrogen may be a limiting nutrient for plant growth in some sediment types. These results support a hypothesis in the scientific literature about nitrogen's role in limiting the growth of rooted aquatic plants. This demonstrates that accumulation of sandy sediments may lead to reduced plant growth through effects on nutrient availability.
Technical Abstract: Predicting aquatic plant growth based on sediment nutrients is problematic. Two experiments with sandy or silty sediments from Fall River, California were performed to identify the limiting nutrient for two abundant species of submersed plants in the river. Growth of Zannichellia palustris L. or Elodea canadensis Rich. was significantly enhanced by the addition of N or a combination of N and P to sandy sediments but not those that were silty. Root:shoot ratios declined for plants growing with added nutrients. Plant tissue N concentrations increased as well. Tissue N:P ratios indicated that N rather than P limited growth. Results support the literature hypothesis that sediment N availability may limit growth and distribution of submersed rooted aquatic plants.