English   español  
Please use this identifier to cite or link to this item: http://hdl.handle.net/10261/183923
logo share SHARE logo core CORE   Add this article to your Mendeley library MendeleyBASE

Visualizar otros formatos: MARC | Dublin Core | RDF | ORE | MODS | METS | DIDL
Exportar a otros formatos:


Predatory and suspension feeding of the copepod Acartia tonsa in turbulent environments

AuthorsSaiz, Enric ; Kiørboe, Thomas
KeywordsEncounter rate
Issue DateJun-1995
PublisherInter Research
CitationMarine Ecology Progress Series 122: 147-158 (1995)
AbstractThe copepod Acartia tonsa exhibits 2 different feeding modes: when feeding on small phytoplankton cells it sets up a feeding current and acts as a suspension feeder; when feeding on motile prey it acts as an ambush feeder. We examined experimentally the effects of small-scale turbulence on feeding rates in these 2 modes. The different feeding behaviours were triggered by offering the copepods diatoms Thalassiosira weissflogii and ciliates Strombidium sulcatum, respectively. Turbulence at 5 different intensities (energy dissipation rate, epslion, between 4 x 10-3 and 3.7 x 101 cm2 s-3) was generated by an oscillating grid. In ambush feeding mode, low (realistic) intensities of turbulence (epslion = 10-3 to 10-2 cm2 s-3) enhanced clearance rates by up to a factor of 4 above those observed in calm water. Higher intensities of turbulence (epslion = 10-1 to 101 cm2 s-3) resulted in a depression of clearance rates, although the rates were still significantly higher than those observed in calm water. The depression of clearance rates at high turbulence intensities was due partly to a decline in capture success, but mainly to a decrease in reactive distance, because turbulence interferes with prey perception by disturbing the hydrodynamical signal generated by motile prey. The negative effects were evident only at turbulence intensities exceeding those normally encountered by A. tonsa in its natural habitat. In suspension feeding mode, low intensities of ambient turbulence (epslion = 10-3 to 10-2 cm2 s-3) had negligible effects on clearance rates, while at higher turbulence intensities (epslion = 10-1 to 101 cm2 s-3) we observed a negative effect (depression of clearance rate). The negative effects become evident when ambient turbulent fluid shear approaches the maximum shear rate of the copepod's feeding current, and we hypothesize that at these intensities the feeding current is eroded. Again the negative effects were observed only at turbulence intensities higher than those typically experienced by A. tonsa in the sea. The differential response to turbulence of the 2 feeding behaviours, including the negative effects, were accurately predicted by encounter rate and feeding behaviour models proposed by Kiørboe & Saiz (1995; Mar Ecol Prog Ser 122:135-145). Because feeding behaviour is specific to the prey (phytoplankton vs motile prey), and because ambush-mode feeding is much more dependent on turbulence than suspension-mode feeding, our findings suggest that prey selection in A. tonsa may be partly governed by turbulence in the ocean. This may explain why microzooplankton at times dominates the diet of A. tonsa and other copepods, even though it is numerically scarce relative to phytoplankton in the environment
Description12 pages, 7 figures, 5 tables
Publisher version (URL)https://dx.doi.org/10.3354/meps122147
Identifiersdoi: 10.3354/meps122147
issn: 0171-8630
e-issn: 1616-1599
Appears in Collections:(ICM) Artículos
Files in This Item:
File Description SizeFormat 
Saiz_et_al_1995.pdf1,11 MBAdobe PDFThumbnail
Show full item record
Review this work

Related articles:

WARNING: Items in Digital.CSIC are protected by copyright, with all rights reserved, unless otherwise indicated.