Investigations of instream incubation conditions on the development of Atlantic Salmon (Salmo salar) embryos in a northern New Brunswick river
University of New Brunswick
The spatial distribution of landscape characteristics within a watershed can influence instream water quality conditions and impact the growth and development of incubating Atlantic Salmon (Salmo salar) embryos as they incubate within substrates (i.e., redds). With globally declining Atlantic Salmon populations it is becoming increasingly important to foster greater freshwater resilience, especially at very early stages of development when embryos are immobile and most sensitive to subtle changes in water quality conditions. However, relatively little is known on the prevalence of Atlantic Salmon embryo deformities, especially within Jordan/Scotty incubators, which represents an important data gap that could have important implications for the future viability of certain populations. It is my aim to investigate how landscape characteristics vary at multi-spatial scales at six incubation sites within the Serpentine River, New Brunswick and how this variation may influence water quality conditions that incubating embryos rely upon for proper growth and development. Performing a principal component analysis (PCA) of landscape characteristics and water quality conditions I explored what environmental factors were influencing variation in incubation habitat conditions. Using a combination of one-way ANOVAs and simple linear regressions, I also explored what site-level water quality conditions and bundle-level incubation conditions had a statistically significant influence on the mortality and deformity status of the 18 000 developing embryos. My PCA results indicate that natural landscape characteristics at the catchment-scale, such as relative percent forested area are primarily influencing changes in water quality conditions and substrate composition, such as fewer heavy metals (i.e., Fe) and finer substrates (i.e., proportion gravel) within downstream sites of the Serpentine River. Overall, the proportion deformities we observed (~2.6%) did not reflect the elevated proportions (~80%) observed within a previous study conducted in 2013, and although the proportion of mortalities we observed (~45%) were quite high, these findings were consistent with other similar in-situ incubation studies. ANOVA results indicated that there were no between field and control site differences in the proportion of either mortalities or deformities per incubator. Further investigation of between field site differences in the total number and proportion of embryo mortalities and deformities using site level water quality conditions (i.e., cumulative degree days and coefficient of variation in dissolved oxygen concentrations) and bundle-level incubation conditions (i.e., distribution of sand particles within incubators) were not statistically significant. Therefore, these findings suggest no environmental factors within the Serpentine River are influencing embryo survival or reducing their overall fitness and suggest in-stream incubation is an alternative to rearing within hatchery environments.