White sturgeon (Acipenser transmontanus Richardson, 1836) larvae were reared at two temperatures (13.5 or 17.5°C) with or without gravel as a substrate to examine the effect of rearing environment on growth and whole body cortisol, an index of stress (initial weight 23.4 mg; four replicate tanks per treatment). Larvae were sampled 8, 16, and 24 days post-hatch. Larvae were larger when reared with substrate and at warmer temperatures. For whole body cortisol, a significant age by temperature interaction was observed with the highest values on day 16 for larvae from warm water treatments. Larvae reared in gravel consistently showed significantly lower whole body cortisol than larvae reared without substrate. In response to mechanical agitation, there was a significant effect of time following disturbance. Increased growth and reduced stress hormone levels make substrate rearing of yolksac larvae an important technique for enhancement efforts in artificial and natural environments. The positive effects of temperature on growth, however, with higher whole body cortisol, suggest that larval white sturgeon development may be better at cooler temperatures.
To investigate the role of substrate enrichment on larval growth and performance, white sturgeon, Acipenser transmontanus, were reared for 12 dph (the pre-feeding stage) in the presence and absence of enriched substrates (i.e. structurally complex media). Following this period, larval sturgeon were transferred to holding tanks with unenriched substrate (lacking structural complexity) and reared for an additional 30 days, during which time health and performance indicators (growth, U crit , startle response reaction time) and whole body lipid composition were assessed at 15 and 18°C. Sturgeon reared on unenriched substrates tended to grow more slowly (up to 40% reduced mass at 40 dph) with a lower condition factor (5-15% lower between 8 and 40 dph), but also exhibited delayed gut development and reduced rate of yolksac absorption (at 15 dph) than those reared with enriched substrates. Whole body lipid composition was significantly altered with substrate enrichment, although the biological relevance of these changes is unknown. White sturgeon reared without exposure to enriched substrates at some temperatures and developmental phases demonstrated modest reductions in aerobic (~20-30% lower U crit ) and startle response performance (~5-10% slower reaction time) at 15 and 30 dph. Overall, most effects were influenced by rearing temperatures and parentage, such that differences were not statistically significant under all conditions. Clearly, however, substrate enrichment plays an important role in development of white sturgeon during early life stages. U.S.
The effect of substratum on growth and metabolic rate was assessed in larval white sturgeon Acipenser transmontanus. Yolk-sac larvae (YSL) were reared in bare tanks or tanks with gravel as substratum from hatch until approximately 16 days post hatch (dph). The effect of an artificial substratum was also evaluated on growth alone. Substratum had a significant effect on mass, with larvae reared in gravel and artificial substrata being larger than those reared without substratum. Routine metabolic rates were significantly lower and relative aerobic scope (the difference between maximum and routine metabolic rate) was significantly higher for YSL and feeding larvae (FL) reared in gravel relative to those reared in bare tanks, particularly before fish started feeding exogenously. Furthermore, gravel-reared larvae had higher whole-body glycogen concentrations relative to bare-tank-reared larvae. Routine factorial scope (maximum metabolic rate divided by routine metabolic rate) was relatively low in all treatments (< 1·7) indicating a limited ability to elevate metabolic rate above routine early in development and mass exponents for metabolic rate exceeded 1. Taken together, these data indicate that YSL reared without substratum may divert more of their energy to non-growth related processes impairing growth. This finding underscores the importance of adequate rearing substratum for growth of A. transmontanus and may provide support for habitat restoration and alternative hatchery rearing methods associated with sturgeon conservation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.