A New Model of Particle Retention and Branchial Sieve Adjustment in Filter-Feeding Bream (Abramis brama, Cyprinidae)

Abstract

A new model for filter feeding in bream (Abramis brama, Cyprinidae) is presented based on the three dimensional architecture of the branchial sieve. Transverse ridges on the upper surface of the gill arches form a system of channels in which food particles appear to be retained. These ridges are formed by a fleshy interconnection between the middle part of the gill arch and the bony parts of its gill rakers. Muscles attached to the rakers, present only on the lateral edge of the gill arch, indicate movability of the lateral bony raker element. If the fish is foraging on particles smaller than the channel diameter, movement of these gill rakers probably adjusts the sieve by reducing the channel diameter of the opposite channel. Selectivity of bream depends on available size classes of zooplanktons and changes in selectivity are attributed to adjustment of the branchial sieve. The channel model has been tested with feeding experiments and X-ray cinematography. The reconstructed paths of marked food particles show that particles follow the hypothesized path. Particle retention occurred mainly at the expected medial site of the arches. Our study strongly supports the channel model of particle retention.

Trophic morphology of five benthic-feeding fish species of a tropical floodplain

“…The selective retention of food by the gill rakers has been mentioned by Angelescu & Gneri (1949), Keenleyside (1975), and Hoogenboezem et al (1991). In the present study, adaptations of the gill rakers to the feeding regime were observed in all the species, most obviously when the size of the food ingested was compared to the space between the gill rakers.…”

Mucus function and crossflow filtration in a fish with gill rakers removed versus intact

“…Dead-end sieving by rakers and/or microbranchiospines, during which the fluid to be filtered passes perpendicularly through the pores between the rakers and/or the microbranchiospines while particles larger than the pores are retained on the sieve, is not used as a filtration method in any of these three species (Sanderson et al, 1996;Sanderson et al, 2001). While muscular control of rakers during feeding has been hypothesized to allow reduction in the diameter of the channels between rakers in common bream (Hoogenboezem et al, 1991;van den Berg et al, 1994), changes in channel diameter as a result of raker movement have not been observed to occur in endoscopic videotapes of tilapia species (Goodrich et al, 2000;Sanderson et al, 1996;Sanderson et al, 2001).…”

“…These fish belong to 21 families in 12 orders , and comprise a quarter of the world fish catch (Food and Agriculture Organization of the United Nations, 2000). Despite the ecological and economic importance of suspension-feeding fish, food particle retention mechanisms are known for only seven species, including two species of tilapia (Callan and Sanderson, 2003;Hoogenboezem et al, 1991;Sanderson et al, 2001).…”

“…Gill rakers attached to the branchial arches have been hypothesized to be a component of all filtration mechanisms in fish (Hoogenboezem et al, 1991;Sanderson et al, 1991;Sanderson et al, 1996;Sanderson et al, 2001). In tilapia, toothed projections (~150·m high) on the external faces of the arches, termed microbranchiospines, have also been proposed as filtering structures (Beveridge et al, 1988a;Beveridge et al, 1988b).…”

Tradeoffs between respiration and feeding in Sacramento blackfish, Orthodon microlepidotus

“…For example, the common bream, Abramis brama trap Daphnia in adjustable channels between gill rakers on adjacent gill arches (Hoogenboezem et al . 1990(Hoogenboezem et al . , 1991 .…”