Metabolism of mesopelagic and bathypelagic copepods in the western North Pacific Ocean

Ikeda, Tsutomu; Sano, Fumikazu; Yamaguchi, Atsushi; Matsuishi, Takashi

doi:10.3354/meps322199

Cited by 50 publications

(88 citation statements)

References 36 publications

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“…In contrast, Spinocalanus sp. is not a species commonly found at this site, and has been reported as inhabiting deeper waters (>1,000-m depth) in the western North Pacific (Ikeda et al, 2006). However, in our study this species was present with a high abundance in shallow waters, and was a representative species for this particular sampling event.…”

Section: Discussioncontrasting

confidence: 46%

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: Discussioncontrasting

confidence: 46%

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

et al. 2017

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“…For pelagic animals lacking visual perception systems, such as the calanoid copepods of this study, the visual interactions hypothesis predicts that the range of reaction should not change with increasing habitat depths, and thus neither their metabolic rates nor protein concentrations should be affected by depth. Contrary to that prediction, Ikeda et al (2006a) indicated that the respiration rates (normalized by temperature and body mass) of copepods decreased by about 30% between the epipelagic and upper-bathypelagic zones, and interpreted this as a result of reduction in predation pressure ('predation-mediated selection' hypothesis Ikeda et al 2006a). Furthermore, Ikeda et al (2006b) showed that N content of dried calanoid copepods declines with increased depth, as was observed for micronektonic fishes and crustaceans by Childress & Nygaard (1973, 1974.…”

Section: Habitat Depth Vs Rna:dna Ratiomentioning

confidence: 81%

“…Thus, the water temperature gradient toward greater depths in the North Pacific does not explain the depth-related pattern of RNA:DNA ratios of pelagic copepods observed in this study. It should be noted that the conclusions mentioned above regarding the decline in metabolic rates (Ikeda et al 2006a) and body N content (Ikeda et al 2006b) of calanoid copepods with depth are free from the effects of vertical temperature gradients, as the epipelagic data compared in the aforementioned studies were from similar thermal regimes, e.g. Antarctic/Arctic waters.…”

Section: Habitat Depth Vs Rna:dna Ratiomentioning

confidence: 99%

“…Depth-related declining patterns in RNA:DNA ratios (this study), metabolism (= oxygen consumption, Ikeda et al 2006a) and body N composition (Ikeda et al 2006a,b) of pelagic copepods in the North Pacific are shown in Fig. 3, in which the original epipelagic data (those of Arctic/Antarctic copepods) were replaced with those of copepods living in the epipelagic North Pacific and determined at near in situ temperatures (mean: 11°C).…”

Section: Habitat Depth Vs Rna:dna Ratiomentioning

confidence: 99%

“…The negative effect of MYEL presence on RNA:DNA ratios suggests lower protein synthetic activities for copepods with MYELs, as compared to those without MYELs and slow escape reactions. In our previous studies, copepods with MYEL have been shown to have higher metabolic rates (Ikeda et al 2006a) and higher C and N contents in the body (Ikeda et al 2006b). These results may imply that copepods with MYEL are characterized by a lower protein growth/ metabolism efficiency while achieving a larger deposition of organic matter; however full evaluation of phylogenetic patterns in energy/material budgets in copepods will not be possible until sufficient physiological data are available.…”

Section: Parameters Affecting Nucleic Acid Ratiosmentioning

confidence: 99%

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RNA:DNA ratios of calanoid copepods from the epipelagic through abyssopelagic zones of the North Pacific Ocean

Ikeda

Sano²,

Yamaguchi³

et al. 2007

Aquat. Biol.

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As indices of protein synthetic activity, RNA:DNA ratios were determined for > 80 copepod species caught from the epipelagic (0 to 500 m), mesopelagic (500 to 1000 m), upper bathypelagic (1000 to 2000 m), lower bathypelagic (2000 to 3000 m) and abyssopelagic (3000 to 5000 m) zones of the North Pacific Ocean. The copepods from the epipelagic zone exhibited higher RNA:DNA ratios compared to those from the mesopelagic through the abyssopelagic zones. Parameters (other than the depth zones) affecting the ratios were explored, by grouping the copepods into 4 developmentalstage/sex categories (C4, C5 and C6 females and males), 3 feeding types (carnivore, detritivore and suspension feeder), or 2 phylogeny-related reaction-speed groups in which detecting the presence or absence of myelinated sheath enveloping axons indicated fast or slow reacting species, respectively. Stage and sex data showed that RNA:DNA ratios were greater in C6 females than in other groups. Among the feeding-type data, carnivores exhibited the lowest RNA:DNA values. Reaction-speed data indicated that slow-reacting species are characterized by lower ratios than fast-reacting species. Taking into account all of these biological parameters as independent variables, stepwise multiple regression analysis revealed that the pattern of the reduction in RNA:DNA ratios toward greater depths was still valid. The typical interzonal copepods, Neocalanus spp., showed that non-feeding C6 females of N. plumchrus and N. flemingeri collected from the mesopelagic through the abyssopelagic zones had high RNA:DNA ratios comparable to those of the epipelagic-zone copepods. The present results, combined with recent reports on the depth-related decline in the metabolism and body nitrogen content of pelagic copepods downward, suggest overall slower life modes of deeper-living species. We think the 'predation-mediated selection' hypothesis explains this 'slow' life more effectively than limited food supply or colder temperatures in the deep sea.

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A Comprehensive Overview of SDG 14: Life Below Water_Final

Rossi¹

2022

SDG 14: Life Below Water

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Metabolism of mesopelagic and bathypelagic copepods in the western North Pacific Ocean

Cited by 50 publications

References 36 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

RNA:DNA ratios of calanoid copepods from the epipelagic through abyssopelagic zones of the North Pacific Ocean

A Comprehensive Overview of SDG 14: Life Below Water_Final

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