Quantification of pumping rate of Chironomus plumosus larvae in natural burrows

Abstract

This paper investigates and compares experimentally determined water velocity field above natural macrozoobenthos burrows generated by Chironomus Plumosus larva during their bio-irrigation activity. All experiments were carried out using particle image velocimetry and performed in mesocosms filled with sediment burrowed by larvae, and the water velocity fields near the inlets and outlets of the U-shaped burrows were measured. From water velocity data the average volumetric flow rates between 54.6 and 61.1 mm 3 /s were calculated. Assuming an average burrow diameter of 2.25 mm, the volumetric flow rates suggest the average flow velocities through burrows during the pumping period between 13.7 and 15.4 mm/s. Two additional interesting phenomena could also be shown by analyzing the flow field generated by the larva. The analysis of the amount of tracers used for visualizations revealed that some of the tracer particles added to the water must have been consumed along their path from the inlet toward the outlet, hinting clearly to the so-called filter-feeding action of C. plumosus. The second phenomenon is due to the form of motion C. plumosus generates. By careful flow visualizations it was found that unlike other organisms such as Urechis caupo that use peristaltic body contractions, C. plumosus worms its body sinusoidally catapulting the fluid far into the overlying water body. This action is of ecological advantage for it avoids generating short oxygen circuits for their respiration and filter feeding.

Detection of artificial water flows by the lateral line system of a benthic feeding cichlid fish

“…This work showed that A. stuartgranti is quite sensitive to artificial flows, responding to flows with velocities as low as ∼1 mm s , which is slower than those generated by copepods and copepodids (van Duren and Videler, 2003;Catton et al, 2007), tethered krill (Yen et al, 2003), midge larvae in burrows (Morad et al, 2010), and the tethered brine shrimp used with A. stuartgranti in prior studies (Schwalbe et al, 2012).…”

“…Flow rates were calculated as V ¼ _ Q= A, where V is water velocity, _ Q is flow rate (controlled by the digital settings of the pump, in ml min −1 ) and A is the internal cross-sectional area of the tubing (31.67 mm 2 ). The pump flow rates selected based on this equation were 1.9, 4.8, 9.5, 19.0 and 38.0 ml min burrow (∼14 mm s −1 ; Morad et al, 2010) and tethered adult brine shrimp (2-7 mm s −1 ; Schwalbe et al, 2012). Digital particle image velocimetry (DPIV) was used to analyze the water flowing from the active holes.…”

Tube‐dwelling invertebrates: tiny ecosystem engineers have large effects in lake ecosystems

“…As a result, chironomids can be very efficient filter feeders, transporting significant amounts of particulate organic matter and nutrients into the sediment. Chironomids drastically reduce particle densities in the burrow outlet fluid compared to the inlet fluid (Morad et al 2010). Based on known pumping rates, filtration effects at the lake-wide scale might be comparable to the increased water clarity and shifts in phytoplankton communities associated with expanding dreissenid mussels (Strayer 2009).…”

What is bioturbation? The need for a precise definition for fauna in aquatic sciences

“…The mechanism and rate by which infauna ventilate burrows vary considerably within and among taxonomic groups. Many polychaetes and insect larvae use muscular sinusoid undulations or peristaltic movements of the body to move water head-or tailwards in the burrow (Barrow & Wells 1982, Riisgård & Larsen 2005, Morad et al 2010. Bivalves, heart urchins and some polychaetes are dependent on ciliary action (Specht & Lee 1989, Riisgård & Larsen 2005, while many crustaceans use forceful beating of pleopods to create the water currents (Forster & Graf 1995.…”