Rainbow Trout Larvae Research Articles

Toxicity of eight solvent extraction chemicals and of cadmium to water fleas, Daphnia Magna, rainbow trout, Salmo Gairdneri, and Zebrafish, Brachydanio Rerio

1. The toxicity of 8 solvent extraction chemicals (Primene JM-T, Amberlite LA-1, Adogen 283, Adogen 383, Alamine 336, TBP and HDEHP) and of cadmium has been investigated in neonates of water fleas, Daphnia magna, embryos and larvae of rainbow trout, Salmo gairdneri, and in embryos, larvae and juveniles of zebrafish, Brachydanio rerio. 2. The importance of the threshold value for comparisons of toxicity data is discussed and the possibility of its determination at elevated temperature is suggested. 3. The toxicity data for cadmium, 48 hr LC 50 for water fleas 69 μg Cd/1 and embryo-larval toxicity for rainbow trout 5.0 μg Cd/1, agreed with previously reported data.

The post-hatching transition of erythrocytes from larval to adult type in the rainbow trout, Salmo gairdnerii irideus.

AbstractIn addition to typical, round disc‐like larval type erythrocytes (erythrocyte L) in pre‐hatching embryos as well as just‐hatched larva and the typical elliptic disc‐like adult type erythrocytes (erythrocyte A) in two‐year‐old fish, a third type of erythrocytes has been observed to appear in the peripheral blood of rainbow trout larvae during a short period (a few weeks) of erythrocyte transition from L to A. Analyses of the erythrocyte population at various stages of the transition have suggested that the third type erythrocytes may not be derived from erythrocyte L, but may be an independent population which will develop into erythrocyte A in the blood and therefore have been referred to as immature type erythrocyte A (erythrocyte ImA). Dynamics of erythrocyte replacement from one to the others during post‐hatching development is characterized by the rapid decrease in erythrocyte L and the compensatory appearance of erythrocyte ImA, which then will develop into the mature erythrocyte A in the peripheral blood.The three types of erythrocytes differ with respect to sensitivity to osmotic shock. A difference has also been observed between erythrocyte L and erythrocyte A including A concerning reactivity with concanavalin A and wheat germ agglutinin.

Respiratory and circulatory responses of rainbow trout larvae to carbon monoxide and to hypoxia.

ABSTRACT Larval trout undergo a transition from cutaneous respiration to gill respiration which at 10 °C is well advanced by the 18th day after hatching. Resting heart rate of newly hatched trout increases during the first few days, stabilizes for a while, and then drops between the 9th and 18th day after hatching. This drop may be the result of establishment of ‘vagal tone’. The basic breathing response of larval trout when hypoxic is an increase in fin movements and an increase in rate and amplitude of breathing, but breathing movements slow and weaken if environmental falls much below 40 mmHg. With trout up to 8 days after hatching hypoxia causes a tachycardia. At very low levels there is a drop in heart rate and in the amount of blood pumped by the heart. Upon restoring oxygen to very hypoxic larvae, the heart rate recovers slowly, unlike the quick abolition of bradycardia of adult fish. It appears that up to the age of 8 days from hatching, trout do not have a functional bradycardia reflex associated with hypoxia. The responses of larval trout to CO and to hypoxia, and of adult trout to CO, are similar in nature. It is proposed that the basic response to anoxaemia is an increase in breathing and circulation and that the adult bradycardia response to hypoxia is a superimposed mechanism which relates circulation to the quantity of oxygen presented to the gills.

Effect of the Organophosphate Dylox on Rainbow Trout Larvae

Organophosphate poisoning in fish and mammals has always been associated with the inhibition of acetylcholinesterase in both neuromuscular and brain tissues. This inhibition resulted in the apparent death of the organisms by asphyxia. Rarely have other effects been reported.In the present study, 1-inch rainbow trout larvae were treated for 16 hr with from 10 to 100 ppm Dylox, or for 40 hr with 5 ppm. This treatment produced a marked acetylcholinesterase inhibition that was reflected by their abnormal behaviour patterns. Histological examination revealed pathological changes in the heart, liver, blood cells, pseudogills, and muscular tissues; this pathology could not be explained on the basis of acetylcholinesterase inhibition.