Regulation of diurnal filter feeding by a novel gill structure in Amblypharyngodon melettinus (Teleostei, Cyprinidae)

Abstract

A unique gill structure, apparently associated with filter feeding on phytoplankton and suspended microdetritus, has been found in Amblypharyngodon melettinus, an abundant small Cyprinidae of Sri Lanka. The gill lamellae, the site of gas exchange, are bordered by a double row of fine appendices which are spread over the interlamellar gaps during daytime, but folded up at night. A respiratory function of the appendices can be excluded. The changing position of appendices correlates with the diurnal pattern of feeding (day) and swimming (night). The mechanism for movement of the appendices consists of hinge-like joints formed from the basement membranes of pavement cells, driven by variation in lamellar blood pressure. Food collection is based on both an efficient hydrosol filter produced by dense populations of clavate mucous cells of the buccopharyngeal epithelia and the lamellar appendices which cause a slower and more turbulent water current in the buccopharyngeal cavity. This may ensure the proper contact of food particles with the sticky mucous surface before they leave the buccopharyngeal cavity. The uniqueness of this structure is that the filter can be switched off during periodically occurring periods of high oxygen demand (high swimming activity at night) probably benefiting the process of respiration.

A comparative analysis on the effects of river discharge on trophic interactions in two tropical streams

“…During the present study, it was evident that fine detritus (FDT) was a major food source for many fish species in YO‐DZ, especially during LDR. Hofer, Salvenmoser, and Schiemer, () have shown that A. melettinus exhibited a unique mechanism for filter feeding phytoplankton and FDT through a double row of fine appendices which were spread over the interlamellar gaps during daytime, but folded up at night. However, in EO‐WZ, where leaf litter decomposition rate is low (Walpola, Leichtfried, Amarasinghe, & Füreder, ), detritus was not a common source of food for fish so that this stream does not support high densities of detritivorous fish species.…”

Size‐selective feeding on phytoplankton by two morpho‐groups of the small freshwater fishAmblypharyngodon mola

“…Earlier, Hofer et al . () discussed a type of feeding mechanism in Amblypharyngodon melettinus (Valenciennes 1844) where the unique gill structure of the fish plays a significant role in filter feeding. To fish with such a feeding strategy, size selection at the ingestion level could be an added advantage, as evident from this study.…”

Sustainable aquatic resource management and inland fisheries in tropical Asia: Interdisciplinary and transdisciplinary approaches

“…In all the Sri Lankan reservoirs studied, Amblypharyngodon melettinus, a seston-filtering cyprinid feeding with a remarkable diurnal cycle in migration and filter-feeding (Hofer et al 2003 ), shows a dominance of over 50% of the biomass and even greater proportion of biological productivity (Pet et al 1996 ). Ubolratana reservoir is dominated numerically by the zooplanktivorous Thai river sprat ( Clupeichthyes aesarnensis ), a minute gobiid Gobiopterus chuno and many small-sized cyprinids (see Schiemer 2008 ).…”

“…2 : arrow 2a) by enhancing nutrient release from the bottom strata through faeces production and enhanced bacterial activity. Small-sized cyprinid species like A. melettinus tend to shift the phytoplankton community to cyanobacteria and, in turn, stimulate primary production and eutrophication (Hofer et al 2003 ).…”