Adaptive feeding in the American oyster Crassostrea virginica: Complex impacts of pulsatile flow during pseudofecal ejection events

Abstract

Adaptive feeding is a strategy used by many organisms to maintain growth and reproduction success while encountering varying feeding conditions. Oysters are sessile benthic and non-siphon filter feeders. Oysters are well adapted to modify the ambient microenvironment through their pumping behavior and particle selection activity. Rejection of unsuitable food particulates bound in pseudofeces via ejection events are an integral part of oyster feeding during which oysters produced strong flow opposite to their inhalant feeding flow. The strong opposite pulsatile flow during the ejection event inevitably disrupts the oyster's normal feeding cycle, but how oysters restart their feeding and allocate their energy consumption during an ejection event has not been investigated. The present study used particle image velocimetry (PIV) to examine the impact of ejection events on the feeding of the American oyster, Crassostrea virginica. The strong pulsatile flow resulting from pseudofecal ejection altered the external flow fields by moving water away from the shell. The initial feeding zone after pseudofecal ejection was relatively narrow, possessed a low pulsatile flow, and did not exploit the full flow field. The feeding zone gradually expanded as the pulsatile flow weakened. The strong shear rate at the stable feeding zone then sustained the feeding flow that facilitated oyster feeding. Furthermore, the volumetric fluxes often increased after the ejection event, suggesting increase in feeding efficiency after ejection events. These PIV studies provide new insight on the interactions between feeding oysters and the surrounding physical environment at small yet ecologically relevant scales. Oysters commonly reside in the shallow intertidal and subtidal zones where they are exposed to a wide range of environmental conditions (Bartol et al. 1999; Grizzle et al. 2003; Rick et al. 2016). Although well adapted to the dynamic environmental conditions found in estuaries, oyster feeding rates and particle sorting efficiencies are sensitive to a variety of biological factors such as live algae composition and concentration (

Depuration of live oysters to reduce Vibrio parahaemolyticus and Vibrio vulnificus: A review of ecology and processing parameters

“…Oysters are adaptive feeders influenced by their environment and can filter up to 55 L of water per day (Pietros & Rice, 2003;Wang, Song, et al, 2020). To measure the effects of oyster to seawater ratio on VP reduction in Pacific oysters, Shen et al (2019) tested oysters in a recirculating depuration system for 5 days.…”

Hydrodynamic role of substrate attachment in shaping the suspension‐feeding current created by the marine gastropod Crepidula fornicata

“…At an exceedingly high concentration, quite a number of seeding particles were not retained by the gill but were instead left in the exhalant current, thereby enabling the PIV analysis there. A more common planar PIV technique, which uses a thin laser sheet to illuminate tracer particles, has been previously applied to measure the suspension‐feeding currents of bivalves (Du Clos et al, 2017; Frank et al, 2008; Nishizaki & Ackerman, 2017; Riisgård et al, 2011; Stamhuis et al, 2002; Troost et al, 2009; Wang et al, 2020). Instead of using a thin laser sheet, however, the present PIV setup simply made use of the thin depth‐of‐field at high magnification to achieve a planar PIV imaging (Gemmell et al, 2014).…”

“…Nonetheless, in a more general sense, lamellibranchs use their inhalant and exhalant apertures (some use siphons) to regulate and direct their suspension‐feeding currents. The functions include modulation of the pumping rate in response to environmental flow and food conditions (Foster‐Smith, 1976; Jørgensen et al, 1988; Newell et al, 2001; Riisgård et al, 2003), reduction of refiltration by effectively separating the inhalant and exhalant current (Du Clos & Jiang, 2018), and production of a strong, pulsed flow in the opposite direction of the normal inhalant current to reject unwanted particles or pseudofeces (Wang et al, 2020). By contrast, individuals of Crepidula have only one shell, do not have siphons, and must attach their foot to a solid substrate to form a complete inhalant chamber with a narrowed opening for effective feeding.…”

Microencapsulated Diets as an Alternative to Bivalve Feeding: Particle Size and Microalga Content Affect Feed Intake

“…Food particles are mostly collected through the inhalant siphon and sorted on the labial palps and gills, and unwanted particles (particularly sharp-edged particles) are rejected in pseudo-feces [ 6 ], except for oysters, a non-siphoned species. Oysters are well adapted through their pumping behavior and particle selection activity [ 7 ], using the gills to stick the particles and then move them up to the mouth [ 8 ].…”