Gut evacuation rate and grazing impact of the krill Thysanoessa raschii and T. inermis

To investigate the lack of tidal influence on the feeding dynamics of fiddler crabs, we used an in situ gut fluorescence technique to measure gut pigment content of Uca annulipes in the non-tidal mangrove habitat of the St Lucia Estuary. Measurements were taken over a 24-h cycle and in the two extreme seasons, austral summer and winter, to examine any diel and seasonal shifts in feeding. Three hour gut evacuation experiments were conducted to determine the gut evacuation rate and potential sexual differences in feeding. It was found that under lack of tidal fluctuations, U. annulipes feeding is influenced by diel rhythms. In summer, males displayed a bimodal pattern of feeding, becoming more active in the morning and late afternoon with a gut evacuation rate of 0.795h–1, whereas females remained generally inactive and displayed short bouts of feeding during the day with a gut evacuation rate of 0.322h–1. The summer grazing impact of U. annulipes on microphytobenthos was higher compared with winter. In winter both sexes were fairly inactive, but displayed a greater consumption efficiency (65% compared with 45% in summer). U. annulipes feeding dynamics in a non-tidal habitat are shown to vary seasonally, daily and among sexes.

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Diel periodicity of Subantarctic copepods: relationships between vertical migration, gut fullness and gut evacuation rate

Journal of Plankton Research ◽

10.1093/plankt/18.8.1387 ◽

1996 ◽

Vol 18 (8) ◽

pp. 1387-1405 ◽

Cited By ~ 38

Author(s):

A. Atkinson ◽

P. Ward ◽

E.J. Murphy

Keyword(s):

Vertical Migration ◽

Diel Periodicity ◽

Evacuation Rate ◽

Gut Fullness ◽

Gut Evacuation

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Ontogenetic variation of food intake and gut evacuation rate in larvae of the doncellaPseudoplatystoma punctifer, as measured using a non-destructive method

Aquaculture Research ◽

10.1111/j.1365-2109.2011.02982.x ◽

2011 ◽

Vol 43 (12) ◽

pp. 1764-1776 ◽

Cited By ~ 5

Author(s):

Etienne Baras ◽

Grace V. Montalvan Naranjos ◽

Dustin V. Silva del Aguila ◽

Fred Chu Koo ◽

Rémi Dugué ◽

...

Keyword(s):

Food Intake ◽

Ontogenetic Variation ◽

Evacuation Rate ◽

Gut Evacuation ◽

Non Destructive

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Consequences of model specification for the determination of gut evacuation rates: redefining the linear model

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f01-041 ◽

2001 ◽

Vol 58 (5) ◽

pp. 1032-1042 ◽

Cited By ~ 10

Author(s):

Alexander B Bochdansky ◽

Don Deibel

Keyword(s):

Linear Model ◽

Flow Reactor ◽

Plug Flow ◽

Exponential Model ◽

Plug Flow Reactor ◽

Gut Contents ◽

Gut Content ◽

Evacuation Rate ◽

Evacuation Model ◽

Gut Evacuation

The combination of gut contents and evacuation rate is an important tool to determine in situ feeding rates of many organisms. Traditionally used equations of gut evacuation models, however, have made a systematic comparison among models difficult. We changed the notation of the linear gut evacuation model to provide an algorithm compatible with the commonly used exponential model. Using examples from the literature, we demonstrate that prolonged retention of food after a true linear pattern of gut evacuation can be mistaken for an exponential pattern. In many of these examples, use of an exponential gut evacuation model causes overestimation of food consumption by approximately twofold. In situations where the entire gastrointestinal tract is examined instead of the stomach only, the time course of the gut content is best described by a plug-flow reactor for which the "input = output" rule applies. In contrast, the assumption of a "proportional release" must be met rigorously for the exponential model to be valid, which requires more complex feedback mechanisms than the simple plug-flow reactor. The new algorithm for the linear model is also consistent with the empirical observation that the gut evacuation rate is proportional to the initial gut content.

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