Prey features affecting ingestion rates by Acanthocyclops robustus (Copepoda: Cyclopoida) on zooplankton

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.

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

The Journal of Foraminiferal Research ◽

10.2113/gsjfr.49.1.3 ◽

2019 ◽

Vol 49 (1) ◽

pp. 3-10 ◽

Cited By ~ 3

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.

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