Effects of sediment burial on grass carp,Ctenopharyngodon idella(Valenciennes, 1844), eggs

Abstract

It is thought that grass carp (Ctenopharyngodon idella) eggs must remain suspended in the water column in order to hatch successfully. Using sand, the effects of varying sediment levels on grass carp eggs were tested at different developmental states and temperatures. Survival was high (15-35%, depending on temperature and trial) in the unburied treatment where eggs rested on a sand bed but were not covered by sediment. Survival was lower in the partial burial (5-10%) and very low (0-4%) in the full burial treatment. In all treatments, delayed hatching (organisms remaining in membranes past the stage of hatching competence) was noted. Deformities such as missing heads and pericardial edema occurred at high rates in the partial and full burials. Eggs that come in contact with the benthos and are resuspended in the water column should be considered in embryonic drift models.

Ontogenetic changes in swimming speed of silver carp, bighead carp, and grass carp larvae: implications for larval dispersal

“…We do not know the reason for this slower development, but we speculate that it may have been due to crowding or food scarcity. The other two species showed faster development and growth under similar conditions, and were similar to model predictions of developmental rate ( George et al, 2015 ). Silver carp in tanks did not advance past the notochord tip lifting stage (stage 41) during those first two weeks, and bighead and grass carp larvae in tanks achieved stage 43 (two chamber gas bladder) in a similar interval.…”

“…Horizontal swimming begins as soon as two days after hatch (upon the emergence of the gas bladder). George & Chapman (2013) and George et al (2015) further reported coarsely measured vertical swimming speeds, and water column location for vertical and horizontally swimming grass carp and bigheaded carp larvae.…”

“…The eggs of these fishes are semi-buoyant, and their survival is believed to require a length of river in which they drift downstream before hatching, and a minimum turbulence or velocity to keep the eggs from settling and being covered by sediment ( Kolar et al, 2007 ; George et al, 2015 ). Previous works have often assumed the requisite river length is approximately 100 km and minimum velocity to be around 0.7 m/s ( Soin & Sukhanova, 1972 ; Krykhtin & Gorbach, 1981 ; Kolar et al, 2007 ; Kocovsky, Chapman & McKenna, 2012 ).…”

“…However, larval drift dynamics are more complicated than those of passive particles because of the behavior of the larvae. The swimming capabilities of larvae change during ontogeny, in a transition marked by both behavioral (from vertical swimming to horizontal swimming) and anatomical (gas bladder emergence) changes ( Chapman & George, 2011 ; George & Chapman, 2013 ; George et al, 2015 ), that allow larvae to move laterally and hold position within the water column. Behavior, swimming kinematics, and swimming capabilities become complex factors that are seldom considered in larval dispersal or particle transport models.…”

Survival and drifting patterns of grass carp eggs and larvae in response to interactions with flow and sediment in a laboratory flume

“…nobilis ) which are also considered highly undesirable invaders in the United States and highly beneficial in Asia, can spawn hundreds of thousands of eggs at a time in turbulent flows of large rivers and their tributaries. Eggs subsequently develop and hatch while drifting in the currents [13–15]. Therefore, understanding grass carp and bigheaded carp response to flow and turbulence regimes at early life stages is fundamental to monitoring and controlling their dispersal and drift.…”