INTERPLAY BETWEEN ENERGY LIMITATION AND NUTRITIONAL DEFICIENCY: EMPIRICAL DATA AND FOOD WEB MODELS

By U. Gaedke, Silke Hochstädter, D. Straile. 2002

97 citations recorded by the source corpus.

Food quality may play an important role in consumer population dynamics. The frequently large differences in elemental and biochemical composition observed be- tween autotrophs and their grazers suggest that food quality may be of particular importance for herbivores. Under nutrient-depleted conditions the carbon-to-nutrient ratios of auto- trophs can increase to such an extent that consumers become nutrient rather than energy limited. Estimating the importance of this effect in situ in pelagic food webs is complicated by the omnivory of many consumers and by rapid nutrient recycling. Isolated predator- prey studies inadequately represent this interaction; instead, an ecosystem perspective is required. We used seven years of data from large, deep Lake Constance to develop seasonally resolved flux models of the pelagic food web and analyzed the balance between energy and nutrient constraints. The carbon (C) and phosphorus (P) flows were simultaneously quantified and balanced. C represented food quantity/energy. P was taken as a surrogate of food quality, because algal C:P ratios exceeded the threshold above which P limitation of herbivores is predicted by stoichiometric theory throughout summer and autumn. Primary production exceeded bacterial C production by a factor of 3, but autotrophs and bacteria took up approximately equal amounts of P during summer and autumn. As a consequence, the C and P supplies of suspension-feeding zooplankton were decoupled: Consumer C demands were largely met by phytoplankton whereas P was mostly obtained from bacteria and their protist predators. The degree of consumer P deficiency varied according to supplementation of their algal diet with P-enriched bacteria or bacterivores. This favored the occurrence of omnivores, i.e., organisms that minimized P deficiencies at the cost of enhanced energy limitation. In contrast with previous perceptions, P reminer- alization during P-depleted summer conditions was dominated by bacterivorous flagellates, carnivorous crustaceans, and fish, which fed on prey with an elemental composition similar to their own, whereas herbivores contributed only 30% of P cycling despite their large biomass and C production. Our results suggested a co-limitation of predominantly herbiv- orous consumers by C and P and a mutual dependence of the two types of deficiency at the individual and system level. This pattern is not specific to pelagic systems but appears to be applicable across ecosystem types.

Subfields: Ecology, Environmental Chemistry, Oceanography

View Paper: https://www.semanticscholar.org/paper/c3a76cac928a73f1132bb33c4175edf4deac8694

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In Ecology

1. James J. Elser
2. D. Hessen
3. Jotaro Urabe
4. R. Sterner
5. Robert Stelzer
6. S. Moe
7. Takehito Yoshida
8. M. Forman

In Environmental Chemistry

1. James J. Elser
2. D. Hessen
3. R. Sterner
4. Jotaro Urabe
5. Robert Stelzer
6. T. Daufresne
7. J. Lennon
8. S. Hall

In Oceanography

1. James J. Elser
2. D. Hessen
3. Jotaro Urabe
4. R. Sterner
5. S. Hall
6. M. Spohn

Citations in the corpus

• Source and supply of terrestrial organic matter affects aquatic microbial metabolism (2005, background): “Comparative studies have revealed that BP is positively correlated with net primary productivity (NPP) across fresh- and saltwater ecosystems (Cole et al. 1988), but is usually 70 to 90% less than NPP (Ducklow et al. 2002, Gaedke et al. 2002).”
• Ecological stoichiometry: An elementary approach using basic principles (2013, background): “By and large, however, carnivores should be less likely than herbivores or detritivores to face N or P deficiency (Gaedke et al. 2002).”
• Theory of materials and energy flow analysis in ecology and economics (2005, unknown): “Ghosh, who proposed the supplydriven model in 1958, is almost completely unknown in ecological literature. But although the two disciplines are thus relatively isolated from each other, exactly the same problem formulation as that used by Ghosh (1958)appears from the very beginning of its introducti”
• Recent advances in ecological stoichiometry: insights for population and community ecology (2005, background): “(Daphnia ) that recycles at a high N:P ratio (Grover 2002) and thus promotes P limitation and extinction of the resource species with less efficient P uptake. Recent stoichiometric studies of species interactions can be viewed as resource-ratio theory applied to higher trophic levels. With a stoichi”