Effect of turbulence on feeding intensity and survival of Japanese flounder Paralichthys olivaceus pelagic larvae

Abstract

Three-day rearing experiments were conducted to study the effect of turbulence on the feeding intensity and survival of pelagic larvae of Japanese flounder Paralichthys olivaceus. Four levels of turbulence as control (10(-7.2) m2 s(-3)), low (10(-6.2) m2 s(-3)), mid (10(-5.6) m2 s(-3)) and high (10(-5.0) m2 s(-3)) were set by changing the flow rate of water pumped through pipes set on the bottom of the tanks. In B-stage larvae, defined as having buds of elongated dorsal fin rays, the feeding intensity and growth were higher in the low and mid turbulence levels, while survival was highest in the control level. Most of the larvae surviving in the control level, however, were judged to be in a seriously starved condition leading to subsequent high mortality. Because the three-day span of the rearing experiments was thought to be a little shorter than the periods before starvation-induced, high mortality occurs. In contrast, for D-stage larvae, their feeding and growth were optimal in the control and low levels. Feeding was more adversely affected in the high level for D-stage larvae compared with B-stage larvae. This is probably due to the compressed body shape and elongated dorsal fin rays of D-stage larvae, which may be more strongly affected by turbulence and, as a consequence, the larval feeding behaviour such as pursuit and capture of prey organisms becomes less efficient than in lower turbulence. Considering the vertical distribution of B and D-stage larvae in the oceanic water column, the optimum turbulence level range found in the present study corresponded to a wind speed of 7-10 m s(-1). Therefore, moderate weather conditions of this wind speed range are considered to potentially enhance survival of early larval stages of P. olivaceus.

A Day in the Life of Fish Larvae: Modeling Foraging and Growth Using Quirks

“…At the parameterized effective speeds of >4 mm s −1 the net influence of turbulence was always negative (Figure 5). In the laboratory, optimal intermediate turbulence has also been demonstrated only for small (poorly developed, slow) larvae [78]–[80]. In one study, small (<5 mm L , 7–9 d post hatch) Japanese flounder ( Paralichthys olivaceus ) larvae benefited significantly from turbulent kinetic energy dissipation rates between 10 −7 and 10 −5 W kg −1 , while slightly larger individuals (<7 mm, 12–14 d) did not [80].…”

“…In the laboratory, optimal intermediate turbulence has also been demonstrated only for small (poorly developed, slow) larvae [78]–[80]. In one study, small (<5 mm L , 7–9 d post hatch) Japanese flounder ( Paralichthys olivaceus ) larvae benefited significantly from turbulent kinetic energy dissipation rates between 10 −7 and 10 −5 W kg −1 , while slightly larger individuals (<7 mm, 12–14 d) did not [80]. A pattern of diminishing benefits of turbulence with increasing size (development, speed) also emerges from most models, with the pattern of decline depending on assumptions regarding visual field geometry, foraging behavior, pursuit success, and relative turbulent velocity w between predator and prey [67], [81]–[83].…”

Lemon sole Microstomus kitt in the northern North Sea: a multidisciplinary approach to the early life‐history dynamics

“…Because day length is not altered in any climate‐change scenario, the available feeding time for visual predators such as small juvenile and larval fish remains limited in autumn and winter. In addition, other aspects such as increased “storminess” (Hinder et al ., 2012) may disrupt dispersal patterns (Lacroix et al ., 2018) and feeding (Oshima et al ., 2009; Utne‐Palm, 2004).…”