Effects of Environmental Factors and Sodium Hypochloriten Egg Embryonation and Hatching Success of Monogenea, Dendromonocotyle pipinna (Monogenea: Monocotylidae)
Date Issued
2009
Date
2009
Author(s)
Chen, Hui-Guan
Abstract
Monogenean intensities are usually low on wild blotched fantail ray (Taeniura meyeni) and that fish, when infected, appear to be healthy. But the rays kept in the aquarium during a period of time, the rays displayed skittish swimming behaviors and cloudiness on the dorsal surface around the eyes, spiracles and shoulder region. These symptoms and behaviors were attributed to high parasite loads. Monogeneans were removed directly by gently scraping and sucking a water conduit along the dorsal surface of a heavily infected specimen of T. meyeni.pecimens were stained with Semichon’s carmine or left unstained, dehydrated in an ethanol series, cleared in creosote and mounted in Permount. The parasite was identified as Dendromonocotyle pipinna according to published paper. Histological studies of infected Taeniura meyeni showed that there had holes and vacuoles between epidermal cells, and unicellular gland cell became less. Eggs were collected for the following experiments after laying by adult D. pipinna directly. Conditions of incubation at 26 ℃ and 35‰ salinity fitted for hatching and the embryonation of D. pipinna was recorded. The effects of temperature and salinity on the embryonation period and hatching success of eggs of D. pipinna were investigated. Temperature influenced embryonation period strongly; eggs first hatched 4 days after laying at 30 ℃, 16 days after laying at 16 ℃, 12 days after laying at 18 ℃, 9 days after laying at 20 ℃, 7 days after laying at 22 ℃and 5 days after laying at 24-28 ℃. Hatching percentages of D. pipinna eggs were similar for eggs incubated at 30, 35 and 40 ‰ salinity, but increased for eggs incubated at higher or lower salinities. More than 80 % of D. pipinna eggs hatched when they were incubated at salinities ranging from 30 to 40 ‰. Hatching success was lower at 25 and 45 ‰ salinity, and few or no eggs hatched at 10 and 15 ‰. Hatching success of D. pipinna eggs that were rehydrated and incubated after periods of desiccation from 1 min to 10 min, the percentage of eggs hatched were 1 min-72.67 %, 2 min-73.73 %, 3 min-10.56 % and 5 min-1.54 %. Hatching of D. pipinna eggs can be prevented by desiccation for 10 min. Sodium hypochlorite treatment tested for its ability to prevent hatching of D. pipina eggs. The percentage of control was 96.01 %. Hatching of D. pipinna eggs was similar for eggs by treatment with 5 ppm sodium hypochlorite for 6 to 24 hr,more than 80 %. Treatment with 10 ppm sodium hypochlorite for 6 and 12 hr, the percentage of eggs hatched were 46.99 and 29.45 %. Treatment with 15 ppm sodium hypochlorite for 6 and 12 hr, the percentage of eggs hatched were 10.65 and 1.17 %. Hatching of D. pipinna eggs can be prevented by treatment with 20 ppm sodium hypochlorite for 6 hr or by treatment with 10 ppm sodium hypochlorite for 18 hr.
Subjects
monogenea
Dendromonocotyle pipinna
Taeniura meyeni
temperature
salinity
desiccation
sodium hypochlorite
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