Zooplankton as a compound mineralising and synthesizing system: phosphorus excretion

Gulati, R. D.; Martínez, Carmen Pérez; Siewertsen, K.

doi:10.1007/bf00028628

Cited by 21 publications

(14 citation statements)

References 40 publications

(42 reference statements)

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“…The dependence of the C:P ratios of the egesta on those of the food items (Fig. 7) is in qualitative agreement with field, laboratory, and model studies on individual predator-prey interactions (Elser et al 1988, Jü rgens and Gü de 1990, Sterner 1990, Urabe 1993, Gulati et al 1995.…”

Section: Remineralizationsupporting

confidence: 84%

“…However, taking an ecosystem perspective provides a different view on the availability of the P incorporated into daphnid biomass. In most natural systems, daphnids have a relatively high biomass turnover due to carnivores and thus a relatively high rate of remineralization of the P incor-ENERGY VS. NUTRIENT LIMITATION Gulati et al (1995) Olsen and Østgaard (1985) Peters (1975) Herbivorus crustaceans P rich 0.7-1.2 present study…”

Section: Remineralizationmentioning

confidence: 60%

“…Notes: Deviations among empirical investigations are partially attributable to the differences in the techniques employed to determine P (Gulati et al 1995). Priority was given to literature values providing simultaneous information on the C:P ratios measured in P-rich and P-depleted food.…”

Section: Remineralizationmentioning

confidence: 99%

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

Gaedke

Hochstädter

Straile

2002

Ecological Monographs

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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 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.

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Section: Remineralizationsupporting

confidence: 84%

Section: Remineralizationmentioning

confidence: 60%

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

Gaedke

Hochstädter

Straile

2002

Ecological Monographs

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“…Excretion of inorganic P by zooplankton alone may account for 4-239% of the P demand of primary producers, and this percentage varies among months (Gulati et al, 1995;Vanni, 2002). However, other analyses focused on rates of primary production that are corrected for loss of phytoplankton argue that biotic recycling is not sufficient to explain observed rates of production during the summer (Caraco et al, 1992).…”

Section: Introductionmentioning

confidence: 99%

Phosphorus sources and demand during summer in a eutrophic lake

et al. 2009

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In pelagic systems, phytoplankton biomass may remain abundant or near equilibrium while concentrations of the limiting nutrient are below detection. In eutrophic lakes, it has been thought that episodic algal blooms are due to mixing events that break down this equilibrium by adding nutrients to the mixed layer. Alternatively, rapid rates of biotic recycling among primary producers and heterotrophic consumers could maintain high phytoplankton biomass, yet the recycling process has been difficult to observe in situ. Here we use free-water oxygen measurements and an associated metabolic model to infer rates of phosphorus (P) uptake and biotic mineralization in the epilimnion of a eutrophic lake. The rates of uptake and mineralization were compared to "external" sources of P such as loading and entrainment. Also, model results were assessed using sensitivity analysis. We found that the majority of phytoplankton P demand during the period of low P availability could be accounted for by biotic mineralization, but that it was important to consider the effects of entrainment in order to account fully for P uptake. These general results were relatively insensitive to model parameterization, though the relative C:P ratio of material taken up versus mineralized was an important consideration. This study integrates modeling and measurement tools that monitor ecosystem processes at finer temporal resolution than has previously been possible, complementing other studies that use experimental incubation and elemental tracers. Extension of this approach could enhance models that aim to integrate biological and physical processes in assessment of water quality and prediction of phytoplankton biomass.

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“…Zooplankton can be considered "compound mineralizing and synthesizing systems" (Gulati et al 1995); that is, they function both to recycle nutrient elements ingested in their food and to sequester nutrients in their own biomass during individual growth and population biomass accrual. Considerable interest in recent years has focused on stoichiometric analysis of these processes, emphasizing the interplay between the elemental composition of herbivorous grazers and their algal food.…”

Section: Introductionmentioning

confidence: 99%

Effects of zooplankton on nutrient availability and seston C : N : P stoichiometry in inshore waters of Lake Biwa, Japan

et al. 2001

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Forty-eight-hour experimental manipulations of zooplankton biomass were performed to examine the potential effects of zooplankton on nutrient availability and phytoplankton biomass (as measured by seston concentration) and C : N : P stoichiometry in eutrophic nearshore waters of Lake Biwa, Japan. Increasing zooplankton, both mixed-species communities and Daphnia alone, consistently reduced seston concentration, indicating that nearshore phytoplankton were generally edible. The zooplankton clearance rates of inshore phytoplankton were similar to rates measured previously for offshore phytoplankton. Increased zooplankton biomass led to increased concentrations of nutrients (NH 4 -N, soluble reactive phosphorus [SRP]). Net release rates were higher than those found in previous measurements made offshore, reflecting the nutrient-rich nature of inshore seston. Zooplankton nutrient recycling consistently decreased TIN : SRP ratios (TIN ϭ NH 4 ϩ NO 3 ϩ NO 2 ). This effect probably resulted from the low N : P ratios of nearshore seston, which were lower than those commonly found in crustacean zooplankton and thus resulted in low retention efficiency of P (relative to N) by the zooplankton. Thus, zooplankton grazing inshore may ameliorate algal blooms due to direct consumption but tends to create nutrient supply conditions with low N : P, potentially favoring cyanobacteria. In comparison with previous findings for offshore, it appears that potential zooplankton effects on phytoplankton and nutrient dynamics differ qualitatively in inshore and offshore regions of Lake Biwa.

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Zooplankton as a compound mineralising and synthesizing system: phosphorus excretion

Cited by 21 publications

References 40 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

Phosphorus sources and demand during summer in a eutrophic lake

Effects of zooplankton on nutrient availability and seston C : N : P stoichiometry in inshore waters of Lake Biwa, Japan

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