Egg production of the copepod Acartia bifilosa in two contrasting European estuaries in relation to seston composition

Burdloff, Didier; Gasparini, Stéphane; Villate, Fernando; Uriarte, Ibon; Cotano, Unai; Sautour, Benoît; Etcheber, Henri

doi:10.1016/s0022-0981(02)00133-8

Cited by 24 publications

(10 citation statements)

References 61 publications

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“…Nevertheless, the ranges in egg production and body size were similar to those found for this species in other studies conducted during summer seasons in the Baltic (Schmidt et , Koski & Kuosa 1999, as well as in other temperate estuaries (Uriarte et al 1998, Burdloff et al 2002. However, significant seasonal and geographical variations in all of these variables have been observed for Acartia bifilosa in the Baltic Sea (Viitasalo et al 1995).…”

Section: Discussionsupporting

confidence: 87%

Relationships between nucleic acid levels and egg production rates in Acartia bifilosa: implications for growth assessment of copepods in situ

Gorokhova¹

2003

Mar. Ecol. Prog. Ser.

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To evaluate the applicability of RNA-based indices in copepod growth assessment, concentrations of nucleic acids in Acartia bifilosa were calibrated against growth rates estimated via egg production experiments, and the relationships between levels of RNA, DNA, and the RNA:DNA ratio and growth rates were examined. Furthermore, to investigate effects of temperature and food availability on the relationships between weight-specific fecundity and nucleic acid levels, incubations were carried out at 9 and 16°C, each at 3 food concentrations. There were positive relationships between nucleic acid concentrations and their ratios and weight-specific egg production rates. Overall, RNA concentration was the best predictor of specific growth rate. No correlations between either of the measured variables and female body size were observed. When egg production was elevated by manipulating the feeding regime, RNA concentration and the RNA:DNA ratio increased in concert. Neither growth nor RNA indices were significantly affected by temperature, while a significant increase in DNA concentrations was observed at high food levels and low temperatures. The lack of temperature dependence in RNA-growth relationships allows their direct application for in situ growth estimates in summer populations of A. bifilosa in the northern Baltic Proper.KEY WORDS: Nucleic acid concentrations · RNA:DNA · Growth rate · Egg production · Weight-specific fecundity · Baltic · Acartia bifilosa Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 262: [163][164][165][166][167][168][169][170][171][172] 2003 tested the applicability of nucleic acid analysis for growth rate assessment using RNA concentrations (Dagg & Littlepage 1972, Ota & Landry 1984, Båmstedt & Skjodal 1980 or RNA:DNA values (Wagner et al. 1998(Wagner et al. , 2001) of mono-or multispecies zooplankton samples. Although most of the early studies focused on using RNA:DNA ratios as an index of nutritional condition (Wagner et al. 1998), a calibration of zooplankton growth rates against nucleic acid content has also been attempted, and linear relationships have been found between growth rate and RNA content (and/or RNA:DNA ratio) for various species of marine copepods (Nakata et al. 1994, Saiz et al. 1998, Wagner et al. 2001) and freshwater cladocerans (Vrede et al. 2002). In some cases, however, the relationship between RNA content and growth rate has been found to lack sufficient predictability (Dagg & Littlepage 1972, Ota & Landry 1984. Of great interest, therefore, are the 'rules' used to estimate growth from nucleic acid measurements, and these need to be defined. For example, it has been shown that temperature influences the relationship between RNA and growth in copepods (Saiz et al. 1998, Wagner et al. 2001) and lobsters (Juinio et al. 1992), while a correlation was found between body size and the RNA:protein ratio in squid (Moltschaniwskyj & Jackson 2000), and between developmental stage and RNA-based indices in copepods (Wa...

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Section: Discussionsupporting

confidence: 87%

Relationships between nucleic acid levels and egg production rates in Acartia bifilosa: implications for growth assessment of copepods in situ

Gorokhova¹

2003

Mar. Ecol. Prog. Ser.

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“…affinis [54] and A . bifilosa [54] , [55] , respectively. Thus, the contribution of picocyanobacteria in the diet of these copepods may account for 8–35% and 10–47% of copepod total gut content, respectively.…”

Section: Discussionmentioning

confidence: 99%

Mesozooplankton Grazing on Picocyanobacteria in the Baltic Sea as Inferred from Molecular Diet Analysis

Motwani

Gorokhova

2013

PLoS ONE

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Our current knowledge on the microbial component of zooplankton diet is limited, and it is generally assumed that bacteria-sized prey is not directly consumed by most mesozooplankton grazers in the marine food webs. We questioned this assumption and conducted field and laboratory studies to examine picocyanobacteria contribution to the diets of Baltic Sea zooplankton, including copepods. First, qPCR targeting ITS-1 rDNA sequence of the picocyanobacteria Synechococcus spp. was used to examine picocyanobacterial DNA occurrence in the guts of Baltic zooplankton (copepods, cladocerans and rotifers). All field-collected zooplankton were found to consume picocyanobacteria in substantial quantities. In terms of Synechococcus quantity, the individual gut content was highest in cladocerans, whereas biomass-specific gut content was highest in rotifers and copepod nauplii. Moreover, the gut content in copepods was positively related to the picocyanobacteria abundance and negatively to the total phytoplankton abundance in the water column at the time of sampling. This indicates that increased availability of picocyanobacteria resulted in the increased intake of this prey and that copepods may rely more on picoplankton when food in the preferred size range declines. Second, a feeding experiments with a laboratory reared copepod Acartia tonsa fed a mixture of the picocyanobacterium Synechococcus bacillaris and microalga Rhodomonas salina confirmed that copepods ingested Synechococcus, even when the alternative food was plentiful. Finally, palatability of the picocyanobacteria for A. tonsa was demonstrated using uptake of 13C by the copepods as a proxy for carbon uptake in feeding experiment with 13C-labeled S. bacillaris. These findings suggest that, if abundant, picoplankton may become an important component of mesozooplankton diet, which needs to be accounted for in food web models and productivity assessments.

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“…Copepods do discriminate successfully between living phytoplankton cells and non-living detritus (Paffenhö-fer and Vansant 1985), and such selective feeding appears particularly important in turbid estuarine environments where non-living matter can comprise the bulk of the suspended matter pool (Tackx et al 2003). In fact, the nutritional quality of non-living components in suspended particulate matter is low compared with living phytoplankton cells, and this difference in quality has been shown to affect the reproductive success of copepod consumers (Burdloff et al 2002).…”

Section: Discussionmentioning

confidence: 99%

Can export of organic matter from estuaries support zooplankton in nearshore, marine plumes?

et al. 2008

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Marine and terrestrial ecosystems are connected via transfers of nutrients and organic matter in river discharges. In coastal seas, such freshwater outflows create prominent turbidity plumes. These plumes are areas of high biological activity in the pelagos, of which zooplankton is a key element. Conceptually, the increased biomass of zooplankton consumers in plumes can be supported by two alternative trophic pathways-consumption of fresh marine phytoplankton production stimulated by riverine nutrients, or direct trophic subsidies through the uptake of terrestrial and estuarine organic matter flushed to sea. The relative importance of these two pathways has not been established previously. Isotopic tracing (carbon and nitrogen) was used to measure the extent of incorporation of marine versus terrestrial matter into mesozooplankton consumers in the plumes off a small estuary in eastern Australia. Replicate zooplankton samples were taken during baseflow conditions with minimal freshwater influence to the sea, and during pulsed discharge events that generated turbidity plumes in coastal waters. Food sources utilized by zooplankton differed among locations and with the strength of freshwater flow. Terrestrial and estuarine carbon only made a sizeable contribution (47%) to the carbon demands of zooplankton in the lower estuary during pulsed freshwater flows. By contrast, in plumes that developed in nearshore marine waters, phytoplankton supplied up to 90% of the dietary carbon of zooplankton feeding in the plumes. Overall, it was ''fresh'' carbon, fixed by marine phytoplankton, the growth of which became stimulated by fluvial nutrient exports, that dominated energy flows in plume regions. The trophic role of terrestrial and estuarine organic exports was comparatively minor. The trophic dynamics of plankton in small coastal plumes is closely linked to variations in freshwater flow, but this coupling operates mainly through the enhancement of in-situ phytoplankton production rather than cross-boundary transfers of organic matter to marine food webs in the pelagos.

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Egg production of the copepod Acartia bifilosa in two contrasting European estuaries in relation to seston composition

Cited by 24 publications

References 61 publications

Relationships between nucleic acid levels and egg production rates in Acartia bifilosa: implications for growth assessment of copepods in situ

Relationships between nucleic acid levels and egg production rates in Acartia bifilosa: implications for growth assessment of copepods in situ

Mesozooplankton Grazing on Picocyanobacteria in the Baltic Sea as Inferred from Molecular Diet Analysis

Can export of organic matter from estuaries support zooplankton in nearshore, marine plumes?

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