Grazing and ingestion rates of nauplii, copepodids and adults of the marine planktonic copepod Calanus helgolandicus

1971 ◽  
Vol 11 (3) ◽  
pp. 286-298 ◽  
Author(s):  
G. -A. Paffenh�fer
Keyword(s):  
Ingestion Rates ◽  
Planktonic Copepod ◽  
Calanus Helgolandicus

scholarly journals Key considerations for assessing soil ingestion exposures among agricultural workers

2021 ◽  
Author(s):  
Sara N. Lupolt ◽  
Jacqueline Agnew ◽  
Thomas A. Burke ◽  
Ryan David Kennedy ◽  
Keeve E. Nachman
Keyword(s):  
Indirect Measurement ◽  
Agricultural Workers ◽  
Qualitative Investigation ◽  
Soil Ingestion ◽  
Ingestion Rates ◽  
Exposure Science ◽  
Measurement Tools ◽  
Route Of Exposure ◽  
Science Methodology ◽  
Depth Interviews

Abstract Background Soil ingestion is a critical, yet poorly characterized route of exposure to contaminants, particularly for agricultural workers who have frequent, direct contact with soil. Objective This qualitative investigation aims to identify and characterize key considerations for translating agricultural workers’ soil ingestion experiences into recommendations to improve traditional exposure science tools for estimating soil ingestion. Methods We conducted qualitative in-depth interviews with 16 fruit and vegetable growers in Maryland to characterize their behaviors and concerns regarding soil contact in order to characterize the nature of soil ingestion in the agricultural context. Results We identified and discussed four emergent themes: (1) variability in growers’ descriptions of soil and dust, (2) variability in growers’ soil contact, (3) growers’ concerns regarding soil contact, (4) growers’ practices to modify soil contact. We also identified environmental and behavioral factors and six specific agricultural tasks that may impact soil ingestion rates. Significance Our investigation fills an important gap in occupational exposure science methodology by providing four key considerations that should be integrated into indirect measurement tools for estimating soil ingestion rates in the agricultural context. Specifically, a task-based framework may provide a structure for future investigations of soil contact that may be useful in other populations.

Lake acidification and the distribution of males and females of a planktonic copepod

2002 ◽  
Vol 28 (2) ◽  
pp. 992-995
Author(s):  
Jan-Erik Svensson ◽  
Ragnar Lagergren ◽  
Jan A. E. Stenson
Keyword(s):  
Lake Acidification ◽  
Planktonic Copepod ◽  
Males And Females

The Effect of Temperature and Food Concentration On Ingestion Rates of Quinqueloculina Seminula On the Diatom Nitzschia Closterium

2019 ◽  
Vol 49 (1) ◽  
pp. 3-10 ◽  
Author(s):  
Yanli Lei ◽  
Chengchun Li ◽  
Tiegang Li ◽  
Zhimin Jian
Keyword(s):  
Food Availability ◽  
Ingestion Rate ◽  
Food Concentration ◽  
Laboratory Culture ◽  
Effect Of Temperature ◽  
Clearance Rates ◽  
Organic Detritus ◽  
Local Conditions ◽  
Ingestion Rates ◽  
Nitzschia Closterium

Abstract The majority of sediment-dwelling foraminifera are thought to be deposit feeders. They use their reticulopodia to gather sediment with associated algae, organic detritus, and bacteria. Uptake of diatoms by foraminifera have been observed but rarely quantified. We measured the clearance (gathering) rate and ingestion rate of diatoms by the common benthic foraminifer Quinqueloculina seminula using Nitzschia closterium as prey under laboratory culture conditions. Grazing experiments were performed to evaluate the effects of temperature (at 12, 15, 18, 21, and 24°C) and food availability (10 to 800 cells mm−2) on uptake rates of diatoms. The clearance rates, estimated from the disappearance of food items, were variable (0.59–4.4 mm2 foram−1 h−1) and did not show a clear relationship with food availability. The maximum clearance rates increased from 1.80 ± 0.21 to 2.69 ± 0.32 mm2 foram−1 h−1 when temperature increased from 12 to 18°C and decreased to 2.28 ± 0.25 mm2 foram−1 h−1 at 24°C. Ingestion rates varied from 1.0 to 43 × 103 diatoms foram−1 h−1, following a hyperbolic response to food concentrations at all experimental temperatures. The maximum individual ingestion rates increased from 842 ± 180 to 1648 ± 480 (mean ± SE) cells foram−1 h−1 and then decreased to 316 ± 54 cells foram−1 h−1 as temperature increased from 12 to 24°C. Experimental results revealed that 12–18°C was the optimal temperature range for Q. seminula feeding for specimens adapted to local conditions. Our study indicates that Q. seminula plays an ecological role by feeding upon benthic diatoms in marine benthic ecosystems.

Secondary production of Calanus helgolandicus in the Western English Channel

2004 ◽  
Vol 313 (1) ◽  
pp. 29-46 ◽  
Author(s):  
Catherine Rey-Rassat ◽  
Delphine Bonnet ◽  
Xabier Irigoien ◽  
Roger Harris ◽  
Robert Head ◽  
...  
Keyword(s):  
Secondary Production ◽  
English Channel ◽  
Calanus Helgolandicus

On the Nutrition and metabolism of zooplankton IV. The forms of nitrogen excreted By Calanus

1967 ◽  
Vol 47 (1) ◽  
pp. 113-120 ◽  
Author(s):  
E. D. S. Corner ◽  
B. S. Newell
Keyword(s):  
Amino Acids ◽  
Positive Reaction ◽  
Laboratory Experiments ◽  
Long Island Sound ◽  
Acartia Tonsa ◽  
Nitrogenous Compounds ◽  
Nitrogenous Substances ◽  
Experimental Density ◽  
Island Sound ◽  
Calanus Helgolandicus

A study has been made of the nitrogenous compounds excreted by Calanus helgolandicus (Claus) collected at Plymouth.Most of the excreted nitrogen is in the form of ammonia which accounts for 60–100% (average 74.3%) of the total, and some of the remainder may be lost as urea. There is no evidence for the excretion of measurable amounts of amino acids.Whether the animals are starved or fed they are primarily ammonotelic, and the quantity of ammonia produced at 10° C (3.33 μg/g. dry body wt/day) is not significantly changed when the animals are used at an abnormally high experimental density. This latter condition does, however, lead to the production of large quantities of additional nitrogenous substances that give a positive reaction with ninhydrin.IntroductionThe amounts of nitrogen excreted by zooplankton have been measured by several workers. Harris (1959) used the method of Riley (1953) to estimate the copious quantities of ammonia produced by animals (mainly Acartia tonsa and A. clausi) collected from Long Island Sound; Beers (1964), in laboratory experiments with the chaetognath Sagitta hispida, estimated the excreted ammonia by the procedure of Kruse & Mellon (1952); and Corner, Cowey & Marshall (1965) determined the ammonia excreted by Calanus helgolandicus and C. finmarchicus, using a ninhydrin technique described by Moore & Stein (1954). The methods employed by Harris and by Beers are specific for ammonia: that used by Corner et al. estimates nitrogenous substances (e.g. amino acids) in addition to ammonia, but certain tests were made which seemed to exclude the possibility that these substances contributed significantly to the nitrogen excreted by the animals.

Comparison of four methods to estimate meiobenthic copepod Amonardia normani ingestion rates

2013 ◽  
Vol 160 (9) ◽  
pp. 2395-2404 ◽  
Author(s):  
Lília Pereira de Souza Santos ◽  
Jacques Castel
Keyword(s):  
Ingestion Rates
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