Water temperatures within spawning beds in two chalk streams and implications for salmonid egg development
✍ Scribed by R. M. Acornley
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 112 KB
- Volume
- 13
- Category
- Article
- ISSN
- 0885-6087
No coin nor oath required. For personal study only.
✦ Synopsis
Water temperatures within brown trout (Salmo trutta L.) spawning gravels were measured in two Hampshire chalk streams from October 1995 to April 1996 inclusive. During the winter, mean intra-gravel water temperatures were higher than those in the stream, and increased with depth in the gravel bed. The amplitude of diel ¯uctuations in water temperature decreased with depth in the gravel bed, although diel ¯uctuations were still evident at a depth of 30 cm. Dierences in intra-gravel temperature gradients between the two study sites were attributed to dierences in the amplitude of stream water temperature ¯uctuations and there was no evidence that either of the study sites were located in zones of upwelling groundwater. Published equations are used to predict, from temperature, the timing of important stages in the development of brown trout embryos (eyeing, hatching and emergence) for eggs spawned in the autumn and winter and buried at dierent depths in the gravel bed.