Parameters influencing the dissolved oxygen in the boundary layer of rainbow trout (Oncorhynchus mykiss) embryos and larvae

Abstract

SUMMARY We investigated the influence of oxygen demand (developmental stage) and supply (hypoxia, water flow rate, the chorion and body movements) on the oxygen concentration within the boundary layer next to the chorion of embryos or skin of larvae of rainbow trout (Oncorhynchus mykiss). Oxygen microelectrodes were used to measure dissolved oxygen (DO) within the boundary layer of trout embryos and larvae. As the embryos and larvae developed, the DO gradient and the thickness of the boundary layer increased. The DO concentration within the boundary layer next to the chorion or skin surface decreased as the DO concentration in the free-stream water decreased. A decrease in water flow rate increased the magnitude of the gradient and thickness of the boundary layer. In normoxia, the DO in the perivitelline fluid inside the chorion was 16±3.0% saturation at 31 days post fertilization, indicating that the chorion was a significant barrier to oxygen diffusion. The number of body movements did not change when embryos were exposed to hypoxia before hatching, but after hatching, hypoxia resulted in a decrease in body movements of the larvae. Taken together, our data indicate that the oxygen boundary layer around trout embryos and larvae depends on both the oxygen demand and supply. The factors that significantly impacted boundary layer oxygen were developmental stage, free-stream oxygen levels, water flow rate, and the presence of the chorion.

Fish embryos on land: terrestrial embryo deposition lowers oxygen uptake without altering growth or survival in the amphibious fishKryptolebias marmoratus

“…We propose that the lower metabolic rate in the terrestrial environment is related in part to fewer opercular movements. In encapsulated fish embryos, relatively thick boundary layers develop in low flow environments that may impair oxygen transport in aquatic environments (Ciuhanda et al, 2007;Miller et al, 2008;Dhiyebi et al, 2013). We found evidence to support the hypothesis that embryos manipulate their micro-environment to maintain oxygen delivery.…”

Impacts of hypoxia on the structure and processes in pelagic communities (zooplankton, macro-invertebrates and fish)

“…Freshly hatched trout larvae, for example, decrease their number of movements by 60% when exposed to hypoxia to reduce their oxygen consumption and total metabolism (Ciuhandu et al, 2007). Juvenile white sturgeon (Acipenser transmontanus) decreased their activity by 70% when exposed to moderate hypoxia (Crocker and Cech, 1997).…”

The diving bell and the spider: the physical gill of Argyroneta aquatica

“…We were able to measure the difference in P O2 as the optode approached the diving bell on a scale much wider than 0.02mm. The layer around the gas gill of stationary corixid bugs (Agraptocorixa eurynome) is approximately 0.3mm (P. D. G. Matthews, personal communication) and the layer is approximately 0.4mm in the eggs, and 1mm to the skin of larvae, of trout (Oncorhynchus mykiss) (Ciuhandu et al, 2007). Much thicker boundary layers are evident in micro-O 2 electrode profiles near submerged larvae of the beetle Phaeoxantha klugii (Zerm et al, 2004), but the results may have been affected by O 2 uptake by the electrode, an effect not produced by optodes.…”