Cardiac and metabolic physiology of early larval zebrafisl (Danio rend) reflects parental swimming stamina

Abstract

Swimming stamina in adult fish is heritable, it is unknown if inherited traits that support enhanced swimming stamina in offspring appear only in juveniles and/or adults, or if these traits actually appear earlier in the morphologically quite different larvae. To answer this question, mature adult zebrafish (Danio rerio) were subjected to a swimming performance test that allowed separation into low swimming stamina or high swimming stamina groups. Adults were then bred within their own performance groups. Larval offspring from each of the two groups, designated high (L HSD) ar)d low stamina-derived larvae (L LSD), were then reared at 27 oC in aerated water (21 % O 2). Routine (f H,r) and active (f H,a) heart rate, and routine (Mo 2, r) and active (Mo 2,a) mass-specific oxygen consumption were recorded from 5 days post fertilization (dpf) through 21 dpf, and gross cost of transport and factorial aerobic metabolic scope were derived from M0 2 measurements. Heart rate generally ranged between 150 and 225 bpm in both L HSD and L LSD populations. However, significant (P < 0.05) differences existed between the L LSD and L HSD populations at 5 and 14 dpf in f H,r and at days 10 and 15 dpf in f H,a. M0 2, r was 0.04-0.32 μmol mg~1 h 1, while M0 2, a was 0.2-1.2 μmol mg -1 h -1. Significant (P < 0.05) differences between the L LSD and L HSD PoP- ulations in M0 2, r occurred at 7, 10, and 21 dpf and in M0 2, a at 7 dpf. Gross cost of transport was ~6-10μmol O 2 μg -1 m -1 at 5dpf, peaking at 14-19 μmol O 2 μg -1 m -1 at 7-10 dpf, before falling again to 5-6 μmol O 2 μg -1 m -1 at 21 dpf, with gross cost of transport significantly higher in the L LSD population at 7 dpf. Collectively, these data indicate that inherited physiological differences known to contribute to enhanced stamina in adult parents also appear in their larval offspring well before attainment of juvenile or adult features. © 2012 Gore and Burggren.