scholarly journals In situ ingestion rates of appendicularian tunicates in the Northeast Water Polynya (NE Greenland)

1999 ◽  
Vol 186 ◽  
pp. 149-160 ◽  
Author(s):  
JL Acuña ◽  
D Deibel ◽  
AB Bochdansky ◽  
E Hatfield
Keyword(s):  
Ingestion Rates ◽  
Northeast Water Polynya

scholarly journals Diets and Seasonal Ingestion Rates of Aurelia coerulea (Cnidaria: Scyphozoa) Polyps by in situ Feeding Experiments in Jiaozhou Bay, China

2021 ◽  
Vol 8 ◽  
Author(s):  
Wang Pengpeng ◽  
Zhang Fang ◽  
Guo Dongjie ◽  
Sun Song
Keyword(s):  
Prey Capture ◽  
Prey Availability ◽  
Ingestion Rate ◽  
Jiaozhou Bay ◽  
Gut Contents ◽  
Natural Diet ◽  
Ingestion Rates ◽  
Aurelia Coerulea ◽  
Feeding Experiments

The benthic scyphopolyp population is an important stage in the scyphozoan lifecycle. Nevertheless, few studies have detailed the natural feeding and quantified the energy flux of polyps based on field research. To better understand the scyphopolyp natural diet and seasonal variation patterns in the ingestion rate, in situ feeding experiments were conducted on Aurelia coerulea polyps in Jiaozhou Bay, China from August 2018 to April 2019. The diet of A. coerulea polyps was determined by gut content analysis. Digestion rates were also measured. Ingestion rates, based on the gut contents and digestion rates, were assessed monthly. Copepods, copepod nauplii, and ciliates were identified in the guts of A. coerulea polyps. Copepods with the bulk of total prey intake in number are an important source of nutrition for A. coerulea polyps in Jiaozhou Bay. Prey capture of A. coerulea polyps (prey polyp–1) varied among months, and was highly dependent upon the abundance of planktonic prey in the habitat. Copepods and copepod nauplii were digested more rapidly as temperature increased. Carbon weight-specific ingestion rate exhibited an obvious seasonal change, with the mean value of 0.13 ± 0.12 μg C μg C–1 d–1. More rapid digestion of prey at higher temperatures and larger prey availability would cause a higher ingestion rate in polyps. Scyphopolyps are widely distributed predators in littoral ecosystems and they may play an important role in plankton–benthos coupling by transferring energy from the water column to the benthos. Massive scyphopolyps blooms may influence pelagic ecosystems.

scholarly journals Reassessment of the gut pigment method for estimating in situ zooplankton ingestion

2007 ◽  
pp. 305-307 ◽  
Author(s):  
Edward G. Durbin ◽  
Robert G. Campbell
Keyword(s):  
Ingestion Rate ◽  
Rate Curve ◽  
Disappearance Rate ◽  
Ingestion Rates ◽  
Chlorophyll Pigment ◽  
Gut Pigment

Correction for chlorophyll pigment destruction has been frequently used in calculation of copepod ingestion rates using the gut pigment method. We argue that tracers in the gut may be either digested and assimilated, or evacuated, and that both processes are taken into account when an evacuation (disappearance) rate curve is determined. As a result, any correction for gut pigment destruction in calculating ingestion rate is inappropriate.

scholarly journals Bacterivory Rate Estimates and Fraction of Active Bacterivores in Natural Protist Assemblages from Aquatic Systems

1999 ◽  
Vol 65 (4) ◽  
pp. 1463-1469 ◽  
Author(s):  
Juan M. González
Keyword(s):  
Experimental Data ◽  
Incubation Time ◽  
Aquatic Systems ◽  
Short Term ◽  
Ingestion Rates ◽  
Poisson Distributions ◽  
Time Period ◽  
Different Characteristics

ABSTRACT Unlike the fraction of active bacterioplankton, the fraction of active bacterivores (i.e., those involved in grazing) during a specified time period has not been studied yet. Fractions of protists actively involved in bacterivory were estimated assuming that the distributions of bacteria and fluorescently labeled bacteria (FLB) ingested by protists follow Poisson distributions. Estimates were compared with experimental data obtained from FLB uptake experiments. The percentages of protists with ingested FLB (experimental) and the estimates obtained from Poisson distributions were similar for both flagellates and ciliates. Thus, the fraction of protists actively grazing on natural bacteria during a given time period could be estimated. The fraction of protists with ingested bacteria depends on the incubation time and reaches a saturating value. Aquatic systems with very different characteristics were analyzed; estimates of the fraction of protists actively grazing on bacteria ranged from 7 to 100% in the studied samples. Some nanoflagellates appeared to be grazing on specific bacterial sizes. Evidence indicated that there was no discrimination for or against bacterial surrogates (i.e., FLB); also, bacteria were randomly encountered by bacterivorous protists during these short-term uptake experiments. These analyses made it possible to estimate the ingestion rates from FLB uptake experiments by counting the number of flagellates containing ingested FLB. These results represent the first reported estimates of active bacterivores in natural aquatic systems; also, a proposed protocol for estimating in situ ingestion rates by protists represents a significant improvement and simplification to the current protocol and avoids the tedious work of counting the number of ingested FLB per protist.

Effect of Current Velocity on Ingestion Rates of Black Fly Larvae

1994 ◽  
Vol 51 (7) ◽  
pp. 1615-1619 ◽  
Author(s):  
Bernadette Charpentier ◽  
Antoine Morin
Keyword(s):  
Current Velocity ◽  
Pest Species ◽  
Black Flies ◽  
Black Fly ◽  
Ingestion Rates ◽  
Major Pest ◽  
Effective Doses ◽  
Measured Field ◽  
In Situ Feeding

In situ feeding measurements were made to quantify the effect of current velocity on ingestion rates of larvae of the major pest species of black flies in southern Quebec (Simulium venustum/verecundum, S. tuberosum, and Prosimulium mixtum/fuscum) and to compare these results with those obtained in seminatural conditions (gutter system). Ingestion rates of all three species increased with current velocity by a factor of 2.5 (P. mixtum/fuscum) to 10 (S. tuberosum) between 25 and 100 cm∙s−1. Measured field rates were significantly correlated with those predicted for similar larval sizes, temperatures, and seston concentrations in gutters, although field rates were only 56–87% of those in gutters once corrected for differences in current velocity. These results suggest that the preference of these species for current velocities of about 100 cm∙s−1 reflect their ability to feed faster at these velocities. The effectiveness of larvicides can therefore be strongly affected by current velocities, and determinations of effective doses from gutter experiments may slightly underestimate the required quantity of larvicide.

scholarly journals The importance of protozoan bacterivory in a subtropical environment (Lobo-Broa Reservoir, SP, Brazil)

2014 ◽  
Vol 74 (3) ◽  
pp. 569-578 ◽  
Author(s):  
AS Mansano ◽  
KF Hisatugo ◽  
LH Hayashi ◽  
MH Regali-Seleghim
Keyword(s):  
Bacterial Community ◽  
Dry Season ◽  
Heterotrophic Nanoflagellates ◽  
Grazing Impact ◽  
Ingestion Rates ◽  
In Situ Experiments ◽  
One Year ◽  
Induced Changes ◽  
Subtropical Environment

This study evaluated the importance of heterotrophic nanoflagellates (HNF) and ciliates bacterivory in a mesotrophic subtropical environment (Lobo-Broa Reservoir, Brazil) by the quantification of their ingestion rates. The in situ experiments using fluorescently labelled bacteria (FLB) were carried out bimonthly over one year (three surveys in the dry season and three in the rainy one) at the sub-surface of two sampling points that have different trophic degrees. The ingestion rates for both ciliates and HNF were higher in the meso-eutrophic region (point 2) due to the higher water temperatures, which accelerate the metabolism of protozoans and the higher bacteria densities. Concerning total protozoan bacterivory, the HNF had the greatest grazing impact on bacterial community, especially the HNF <5µm. The data showed that HNF grazing, in addition to regulating the bacteria abundance, also induced changes to the bacterial community structure, such as increasing size and numbers of bacterial filaments. The ciliates were also important to the system bacterivory, especially in point 2, where there were high densities and ingestion rates. The protozoan bottom-up control was more important in the dry season and the top-down control was more important in the rainy season, so, these two forces are equally important to the bacterial abundance regulation in this reservoir in an annual basis.

Grazing activity of mesoplanktonic copepods in a shallow bay during an algal spring bloom (Marennes-Oléron Bay, France)

1999 ◽  
Vol 79 (1) ◽  
pp. 73-84 ◽  
Author(s):  
Benoît Sautour ◽  
Jacques Castel
Keyword(s):  
Spring Bloom ◽  
Feeding Activity ◽  
Spring Tide ◽  
Fluorometric Method ◽  
Ingestion Rates ◽  
Suspended Particulate ◽  
Temora Longicornis ◽  
Shallow Bay ◽  
Paracalanus Parvus

In situ grazing activity of mesoplanktonic copepods was investigated by the fluorometric method during an algal spring bloom in a zone of oyster farming in Marennes-Oléron Bay. The grazing activity of copepods was overall higher during the night than during the day for three species (Temora longicornis, Paracalanus parvus and Acartia clausi), but peaks also appeared during the day for all of them. Individual ingestion rates and daily rations were higher during neap tide (low suspended particulate matter (SPM) concentrations) than during spring tide (high SPM concentrations). During ebb tide (when SPM concentrations were the lowest) the feeding activity of T. longicornis, P. parvus and A. clausi was significantly negatively correlated with algal concentration. Our work suggests that during the algal spring bloom in the farming area of Marennes-Oléron Bay the pressure exerted by mesoplanktonic copepods on the algal stock was very low, as a consequence of: (i) high algal concentrations in the field (resuspension and high phytoplanktonic production); (ii) low ingestion rates when high algal concentrations were observed. The likely ingestion of non-fluorescent particles by copepods is discussed.

Rendez vous with Saturn's rings

1984 ◽  
Vol 75 ◽  
pp. 743-759 ◽  
Author(s):  
Kerry T. Nock
Keyword(s):  
Solar Energy ◽  
Electric Propulsion ◽  
Power Source ◽  
Propulsion System ◽  
Low Thrust ◽  
Ring Plane ◽  
The Earth ◽  
Total Impulse ◽  
Saturn's Rings

ABSTRACTA mission to rendezvous with the rings of Saturn is studied with regard to science rationale and instrumentation and engineering feasibility and design. Future detailedin situexploration of the rings of Saturn will require spacecraft systems with enormous propulsive capability. NASA is currently studying the critical technologies for just such a system, called Nuclear Electric Propulsion (NEP). Electric propulsion is the only technology which can effectively provide the required total impulse for this demanding mission. Furthermore, the power source must be nuclear because the solar energy reaching Saturn is only 1% of that at the Earth. An important aspect of this mission is the ability of the low thrust propulsion system to continuously boost the spacecraft above the ring plane as it spirals in toward Saturn, thus enabling scientific measurements of ring particles from only a few kilometers.

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