Trophic Structure and Carbon Flow Dynamics in the Pelagic Community of a Large Lake

Gaedke, Ursula; Straile, Dietmar; Pahl‐Wostl, Claudia

doi:10.1007/978-1-4615-7007-3_6

Cited by 29 publications

(21 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As predicted by stoichiometric theory, the extent of herbivore P depletion depended on their grazing of P-enriched organisms. As a consequence Protozoa improved the food quality of algae and bacteria for larger consumers not only by repacking them into larger food particles (Gaedke et al 1996) but also by providing a more suitable chemical composition. Unexpectedly, herbivores were unambiguously ruled out as the dominant P remineralizers during summer and autumn, independent of the exact specification of their P-retention ability and their direct growth reduction by P limitation.…”

Section: Discussionmentioning

confidence: 99%

Interplay between Energy Limitation and Nutritional Deficiency: Empirical Data and Food Web Models

Gaedke

Hochstädter

Straile

2002

Ecological Monographs

Self Cite

View full text Add to dashboard Cite

Abstract. Food quality may play an important role in consumer population dynamics. The frequently large differences in elemental and biochemical composition observed between 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 autotrophs 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 predatorprey 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 remineralization 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 herbivorous 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.

show abstract

Section: Discussionmentioning

confidence: 99%

Interplay between Energy Limitation and Nutritional Deficiency: Empirical Data and Food Web Models

Gaedke

Hochstädter

Straile

2002

Ecological Monographs

Self Cite

View full text Add to dashboard Cite

show abstract

“…Pahl-Wostl(1993) posited that the distribution of body mass and resulting trophic positions 'can be interpreted as a fingerprint for a food web's internal dynamic structure', and can therefore be conveniently used for cross-system comparisons. Gaedke et al (1996) empirically determined that a correlation did exist between body size and trophic position within a pelagic foodweb, and that diagrams of such relationships provide a good summary of the trophic structure and function of these communities. However, Gaedke et al's (1996) estimates of potential trophic position, determined from the weighted average lengths of presumed feeding pathways, will not be as accurate as realized trophic positions measured through 615N analysis (Kling et al 1992, Vander Zanden & Rasmussen 1996, Hansson et al 1997).…”

mentioning

confidence: 99%

Mapping trophic continua of benthic foodwebs:body size-δ15N relationships

France¹,

Chandler²,

Peters³

1998

Mar. Ecol. Prog. Ser.

View full text Add to dashboard Cite

ABSTRACT. The stable nitrogen isotopic composition (6:'N) of benthic foodwebs was analyzed to determine trophic relationships among 23 taxa composited from 4 proximal oligotrophic lakes and 35 taxa composited from 2 proximal seagrass meadows. Because omnivory was prevalent, animals in both foodwebs existed along continua of trophic positions rather than in discrete trophic levels. These trophic continua were in turn related to organism body size in support of Elton's early suppositions about foodweb structuring. These foodweb delineations developed due to feedlng hierarchies being determined by size-related predation, resulting in 'upper triangular' foodweb matrices as posited by Cohen's cascade model. Expressing aquatic foodweb structure in relatlon to the ataxonomic cont~nuous variables of organismal trophic position (6"N) and body size has the advantage of providing a convenient common currency for comparative purposes that dispenses with the artificiality and impossibility of constraining omnivorous animals into rigidly defined trophic levels.KEY WORDS: Benthic foodwebs Body size 6I5N Trophic continua 'A little cons~deration will show that size 1s the main reason underlying the existence of food chains, and that it explains many of the phenomena connected with the food cycle. ' (Elton 1927)

show abstract

“…Because the biomass of hdf (a competitor of cope for nanop and mircop) was small in 1990, direct grazing of cope on nanop and microp in 1990 was relatively greater than in the other years (Appendix 1). Trophic level of bac was assumed to be 2 (after Gaedke et al 1996). Lines connecting functional groups show suggested main predator-prey relationships.…”

Section: Resultsmentioning

confidence: 99%

Size-dependent carbon flow in the epipelagic food web of the Western Equatorial Pacific

Ichinokawa¹,

Takahashi²

2006

Mar. Ecol. Prog. Ser.

View full text Add to dashboard Cite

The present study examines the complexity of plankton food-web structure related to size diversity in lower trophic levels of the Equatorial Pacific and its possible effects on community stability and food availability of mesozooplankton. Food-web interactions and carbon flows in the plankton community were estimated from size-dependent predation, carbon transfer between trophic levels and size-biomass measurements determined in 5 independent field investigations. The community was separated into 10 different functional groups, which consisted mainly of pico-, nanoand micro-phytoplankton, bacteria, heterotrophic nanoflagellates, heterotrophic dinoflagellates, ciliates, nauplii, copepods and chaetognaths. The major carbon flow on all 5 occasions was consistent with a general conceptual food-web model, even though the study region was subjected to different oceanographic conditions -warm pool in 1990 to 1993, equatorial divergence in 1994. The 5 food webs showed distinct differences in structure, dependent on the size composition within each functional group, suggesting potential inherent non-steady-state dynamics at the intra-functional group level. The apparent stability of food-web dynamics in the equatorial plankton community may be a consequence of complex food-web interaction and resulting fluctuations, the effects of which neutralize each other over time.KEY WORDS: Pelagic food web · Equatorial Pacific · Size-dependent predation · Food-web complexity · Community stability · Functional group Resale or republication not permitted without written consent of the publisher

show abstract

Trophic Structure and Carbon Flow Dynamics in the Pelagic Community of a Large Lake

Cited by 29 publications

References 18 publications

Interplay between Energy Limitation and Nutritional Deficiency: Empirical Data and Food Web Models

Interplay between Energy Limitation and Nutritional Deficiency: Empirical Data and Food Web Models

Mapping trophic continua of benthic foodwebs:body size-δ15N relationships

Size-dependent carbon flow in the epipelagic food web of the Western Equatorial Pacific

Contact Info

Product

Resources

About