Studies of the Release of Dissolved Free Amino Acids by Marine Zooplankton1

Webb, Katie; Johannes, R. E.

doi:10.4319/lo.1967.12.3.0376

Cited by 122 publications

(60 citation statements)

References 14 publications

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“…In the late-summer experiment, the predominant amino acid excreted was HIS, while in spring it was GLU. It has been reported that GLY and alanine (ALA) are the predominant amino acids excreted, while cysteine (CYS) was absent in almost all estimations (Webb and Johannes, 1967), in contrast with our results in which ALA was excreted, but at low rates, and MET was absent in both experiments (Figure 2). As with phosphorus, there are few studies available regarding DFAA excretion.…”

Section: Excretion Of Nitrogen and Phosphorus Compoundscontrasting

confidence: 56%

Dissolved Compounds Excreted by Copepods Reshape the Active Marine Bacterioplankton Community Composition

et al. 2017

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Copepods are important suppliers of bioreactive compounds for marine bacteria through fecal pellet production, sloppy feeding, and the excretion of dissolved compounds. However, the interaction between copepods and bacteria in the marine environment is poorly understood. We determined the nitrogen and phosphorus compounds excreted by copepods fed with two natural size-fractionated diets (<20-and 20-150-µm) in the upwelling zone of central/southern Chile in late summer and spring. We then assessed the biogeochemical response of the bacterial community and its structure, in terms of total and active cells, to enrichment by copepod-excreted dissolved compounds. Results revealed that copepods actively excreted nitrogen and phosphorus compounds, mainly in the form of ammonium and dissolved organic phosphorus (DOP), reaching excretion rates of 2.6 and 0.05 µmol L −1 h −1 , respectively. In both periods, the maximum excretion rates were associated with the 20-150-µm size fraction, but particularly during spring, when a higher organic matter quality was observed in excretion products compared to late summer. There were higher excretion rates of dissolved free amino acids (DFAAs) from copepods fed with the <20-µm size fraction, mainly histidine (HIS) in late summer and glutamic acid (GLU) in spring. A shift in the composition of the active bacterial community was observed between periods and treatments, which was associated with the response of the common seawater surface phyla Proteobacteria and Bacteroidetes. The specific bacterial activity (16S rRNA:rDNA) suggested a different response to the two size-fractionated diets. In late summer, Betaproteobacteria and Bacteroidetes were stimulated by the treatment enriched with excretion products derived from the 20-150-µm and <20-µm size fractions, respectively. In spring, Alphaproteobacteria were active in the treatment enriched with the excretion products of copepods fed with the <20-µm size fraction, whereas they were inhibited in the treatment enriched with excretion products in the 20-150-µm size fraction. Our findings indicate that different Valdés et al. Copepod Excretion and Bacterial Community Structure copepod diets can have a significant impact on the quantity and quality of their excretion compounds, which can subsequently generate shifts in the active bacterial composition. The bacterial response is probably associated with common-opportunistic sea surface microbes that are adapted to rapidly reacting to environmental offers.

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Section: Excretion Of Nitrogen and Phosphorus Compoundscontrasting

confidence: 56%

Dissolved Compounds Excreted by Copepods Reshape the Active Marine Bacterioplankton Community Composition

et al. 2017

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“…Used in conjunction with information on the life history, biochemical composition and food supply, an 0 : N ratio readily describes the nutritional status of natural populations and provides one of the few tools to assess zooplankton metabolism. Whether 0 : N ratios should be based on ammonia or total excretion, especially when large amounts of organic nitrogen are released (Webb & Johannes 1967, Eppley et al 1973, cannot be decided until the sources and mechanisms of such excretion are known. Because of this uncertainty, it is probably preferable to use only values of excreted ammonia to compute 0 : N ratios at this time.…”

Section: Discussionmentioning

confidence: 99%

O:N atomic ratio as a tool to describe zooplankton metabolism

Mayzaud¹,

Conover²

1988

Mar. Ecol. Prog. Ser.

289

190

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ABSTRACT. Use of the atomic 0 : N ratio as a metabolic index requires clarification of the biochemical complexities of zooplankton intermediary metabolism. We review the processes responsible for natural and experimentally-induced changes in the ratio and discuss their relative importance in relation to a variable natural environment. During starvation the 0 : N ratio is clearly linked to the availability of energy reserves and the use of body protein. Using theoretical computations, it can be shown that pure protein catabolism will yield 0 : N ratios in the range 3 to 16, while equal amounts of lipid and protein catabolism will correspond to values between 50 and 60. Under natural feeding conditions, the value of the ratio depends on the use by the animal of each biochemical fraction assimilated. Others factors, such as seasonal events in the life cycle, biochenlical composition of the body and food quality are of importance for correct interpretation of the variations. The concepts behind the rates are discussed, suggesting that such measurements reflect the adaptability of the animals to their total environment.

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“…Hence, fecal pellets in the gray deposit embedded in the interstices of tubes in the colony may provide a reservoir. Moreover, we assume that amino acids are released as metabolites of phytoplankton (Hellebust 1974) and zooplankton (Webb & Johannes 1967) attached to the colony. The source of DFAA is therefore obviously not restricted to individuals of H. elegans alone.…”

Section: Discussionmentioning

confidence: 99%

Induction of larval attachment and metamorphosis in the serpulid polychaete Hydroides elegans by dissolved free amino acids:isolation and identification

Harder¹,

Qian²

1999

Mar. Ecol. Prog. Ser.

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ABSTRACT. The calcareous tube-building polychaete Hydroides elegans (Haswell) is a major fouling organism in tropical waters around the world. In the marme environment, larvae of H. eleyans rapidly settle and metamorphose in response to acceptable surface-bound bio-organic films. In addition to biological inducers, previous investigations by our group have indicated chemical inducers for larval settlement and metamorphosis in H. elegans. Crude samples derived from adult H. elegans and colonies of the bryozoan Bugula neritina induced a high percentage of larval metamorphosis in laboratory assays. Here, we describe a bioassay-guided isolation and purification of larval metamorphic inducers originating from these samples. Biologically active HPLC-purified fractions of both samples were composed of free amino acids. The entire free amino acid composition was determined by quantitation with ortho-phthaldialdehyde (OPA) and was found to be comprised of aspartic acid, glutamic acid, serine. histidine, glycine, arginine, alanine, asparagine, glutarnine and taurine in concentrations ranging from 0.2 pM (histidine) to 5.6 pM (taurine). In the laboratory assay, the larval metamorphic response to an artificially prepared sample in identical concentrations of these amino acids was very simdar to the natural isolates.

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Studies of the Release of Dissolved Free Amino Acids by Marine Zooplankton1

Cited by 122 publications

References 14 publications

Dissolved Compounds Excreted by Copepods Reshape the Active Marine Bacterioplankton Community Composition

Dissolved Compounds Excreted by Copepods Reshape the Active Marine Bacterioplankton Community Composition

O:N atomic ratio as a tool to describe zooplankton metabolism

Induction of larval attachment and metamorphosis in the serpulid polychaete Hydroides elegans by dissolved free amino acids:isolation and identification

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