Nutrient limitation of phytoplankton production in Alaskan Arctic foothill lakes

• Published in: Hydrobiologia Vol. 455; no. 1-3; pp. 189 - 201
• Main Authors: LEVINE, M. A, WHALEN, S. C
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer 01.07.2001; Springer Nature B.V
• Subjects: Algae; Animal and plant ecology; Animal, plant and microbial ecology; Anthropogenic factors; Arctic; Bioassays; Biological and medical sciences; Climate change; Fresh water ecosystems; Freshwater; Fundamental and applied biological sciences. Psychology; Lakes; Nutrient availability; Nutrient loading; Nutrient status; Phytoplankton; Plankton; Primary production; Streams; Synecology; USA, Alaska; Water temperature; Watersheds; Alaska; United States; North America; America; Freshwater environment; Medium enrichment; Primary productivity; Pond; Limitation; Lakes; Nutrient; Phosphorus; Phytoplankton; Nitrogen; Experimental study
• ISSN: 0018-8158; 1573-5117
• DOI: 10.1023/A:1011954221491

We used 54 enrichment bioassays to assess nutrient limitation (N, P) of ^sup 14^C uptake by natural phytoplankton assemblages in 39 lakes and ponds in the Arctic Foothills region of Alaska. Our purpose was to categorize phytoplankton nutrient status in this under-represented region of North America and to improve our ability to predict the response of primary production to anticipated anthropogenically mediated increases in nutrient loading. Experiments were performed across several watersheds and included assays on terminal lakes and lakes occupying various positions in chains (lakes in series within a watershed and connected by streams). In total, 89% (48 of 54) of the bioassays showed significant stimulation of ^sup 14^C primary production by some form of nutrient addition relative to unamended controls. A significant response was observed following enrichment with N and P, N alone and P alone in 83, 35 and 22% of the bioassays, respectively. In experiments where N and P proved stimulatory, the influence of N alone was significantly greater than the influence of P alone. Overall, the data point to a greater importance for N than P in regulating phytoplankton production in this region. The degree of response to N and P enrichment declined as the summer progressed and showed no relationship to irradiance or water temperature, suggesting secondary limitation by some micronutrient such as iron as the summer advanced. Phytoplankton nutrient status was often consistent across lakes within a watershed, suggesting that watershed characteristics influence nutrient availability. Lakes in this region will clearly show increased phytoplankton production in response to anthropogenic activities and anticipated changes in climate that will increase nutrient loading.[PUBLICATION ABSTRACT]