Nutrient Addition Differentially Affects Ecological Processes of Avicennia germinans in Nitrogen versus Phosphorus Limited Mangrove Ecosystems

• Published in: Ecosystems (New York) Vol. 10; no. 3; pp. 347 - 359
• Main Authors: Feller, Ilka C., Lovelock, Catherine E., McKee, Karen L.
• Format: Journal Article
• Language: English
• Published: New York, NY Springer Science+Business Media 01.04.2007; Springer; Springer Nature B.V
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Avicennia germinans; Biological and medical sciences; Biomass; Brackish; Brackish water ecosystems; Coastal ecosystems; Ecosystem structure; Ecosystem studies; Eutrophication; Freshwater ecosystems; Fundamental and applied biological sciences. Psychology; General aspects; Herbivores; Herbivory; Keys; Lagoons; Leaf area; Leaves; Mangrove forests; Mangroves; Marine ecosystems; Marine environment; Nitrogen; Nutrient deficiency; Nutrient loading; Nutrients; Phosphorus; Plant nutrition; Plants; Rainforests; Synecology; Central America; Belize; America; ASW, USA, Florida, Indian River Lagoon; ASW, Belize, Stann Creek Dist., Twin Cays; ASW, Belize; Avicennia germinans; Fertilization; Herbivorous; Growth; Loss; Resorption; Phosphorus; loss of yield; Ecology; Belize; Biomass; Nitrogen; Indian River Lagoon; Medium enrichment; nutrient resorption; Mangrove; Ecosystem; herbivory; Nutrient; Yield; nutrient over-enrichment; fertilization experiment; biomass allocation
• ISSN: 1432-9840; 1435-0629
• DOI: 10.1007/s10021-007-9025-z

Nutrient over-enrichment is a major threat to marine environments, but system-specific attributes of coastal ecosystems may result in differences in their sensitivity and susceptibility to eutrophication. We used fertilization experiments in nitrogen (N)- and phosphorus (P)-limited mangrove forests to test the hypothesis that alleviating different kinds of nutrient limitation may have different effects on ecosystem structure and function in natural systems. We compared a broad range of ecological processes to determine if these systems have different thresholds where shifts might occur in nutrient limitation. Growth responses indicated N limitation in Avicennia germinans (black mangrove) forests in the Indian River Lagoon (IRL), Florida, and P limitation at Twin Cays, Belize. When nutrient deficiency was relieved, A. germinans grew out of its stunted form by increasing wood relative to leaf biomass and shoot length relative to lateral growth. At the P-limited site, P enrichment (+P) increased specific leaf area, N resorption, and P uptake, but had no effect on P resorption. At the N-limited site, +N increased both N and P resorption, but did not alter biomass allocation. Herbivory was greater at the P-limited site and was unaffected by +P, whereas +N led to increased herbivory at the N-limited site. The responses to nutrient enrichment depended on the ecological process and limiting nutrient and suggested that N- versus P-limited mangroves do have different thresholds. +P had a greater effect on more ecological processes at Twin Cays than did +N at the IRL, which indicated that the P-limited site was more sensitive to nutrient loading. Because of this sensitivity, eutrophication is more likely to cause a shift in nutrient limitation at P-limited Twin Cays than N-limited IRL.