Journal of Freshwater Ecology (Jan 2020)
Water chemistry and light effects on survival of hatching salmonids in spring channels
Abstract
This study informs the restoration and development of salmonid fisheries and aquaculture facilities regarding water quality and light effects on hatching survival in spring channels. Brook trout Salvelinus fontinalis eggs were hatched in springs from karst and silica-clastic aquifers to determine whether survival was affected by water quality in differing geological areas. Nitrogen gas saturation (N2) was highest in karst springs and impacted survival, with a negative relationship between N2 and survival during hatching (> 110% N2 corresponded to 70.5% survival). A multiple regression model was developed to predict survival that included N2, acid neutralizing capacity (ANC), and light intensity (Light) following the equation: In a follow-up experiment, brook trout eggs were fertilized and hatched in hatching boxes in high and low levels of ultraviolet light (UV), fluorescent light, and complete darkness to test the effects of UV and light intensity on survival. Logistic regression was used to model the probability of mortality as a function of UV-B intensity. Results indicated freshly fertilized eggs were more severely impacted by light and UV than post-eyed eggs, and both UV and fluorescent light treatments experienced high mortality compared to the treatment in complete darkness. Karst springs with intermediate concentrations of calcium and increased ANC provide improved water quality for salmonids as compared to silica-clastic aquifers; however, high N2 can have negative effects on survival which, could be overcome by aeration within spring channels. Furthermore, using advanced aquaculture techniques, it may be possible to develop a brood stock that is resistant to the effects of N2. Effects of UV and light intensity pose additional challenges at early life stages for salmonids which, can be overcome by shading hatch boxes in the spring channel.
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