Effects of productivity, consumers, competitors, and El Nino events on food chain patterns in a rocky intertidal community

Journal Article · Wed Nov 06 04:00:00 EST 1996 · Proceedings of the National Academy of Sciences of the United States of America

DOI:https://doi.org/10.1073/pnas.93.24.13855· OSTI ID:468356

Wootton, J T; Pfister, C A ^[1]; Paine, R T ^[2]

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1. Univ. of Chicago, IL (United States)
2. Univ. of Washington, Seattle, WA (United States); and others

We experimentally manipulated nutrient input to a rocky intertidal community, using nutrient-diffusing flowerpots, to determine (i) whether nutrients limited intertidal productivity, (ii) how a large-scale oceanographic disturbance (an El Nino event) affected patterns of nutrient limitation, (iii) the relative impacts of molluscan grazers and nutrient limitation, and (iv) if responses to experimental nutrient addition among trophic levels were more consistent with prey-dependent or ratio-dependent food chain models. Nutrients measurably increased the abundance of micrograzers (amphipods and chironomid larvae), but not algal biomass, during the summer of an El Nino years and during the autumn of an El Nino year. Adding nutrients did not affect food chain stability as assessed by temporal variation in algal biomass and micrograzer abundance. Large molluscan grazers caused large reductions in micrograzers and smaller reductions in algae, indicating consistent consumer effects. The results demonstrate that in this intertidal community, nutrient limitation can occur under conditions of nutrient stress, that top-down grazing effects are typically stronger than bottom-up nutrient effects, and that prey-dependent models are more appropriate than ratio-dependent models. 40 refs., 1 fig., 1 tab.

• OSTI ID: 468356
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Journal Issue: 24 Vol. 93; ISSN PNASA6; ISSN 0027-8424
• Country of Publication: United States
• Language: English

Related Subjects

56 BIOLOGY AND MEDICINE
APPLIED STUDIES
BIOLOGICAL EFFECTS
COASTAL WATERS
ECOSYSTEMS
POPULATION DYNAMICS
PRODUCTIVITY
SOUTHERN OSCILLATION
SPECIES DIVERSITY
VARIATIONS