The Effect of Spawning Salmon Presence on Riverbank Soil Organic Matter Content


  • Maya Bird
  • Ruwanya Pujitha Gunawardana
  • Alexandra McDonald
  • Gabrielle Vaillancourt-Ehling


The decomposition of salmon along riverbanks releases an abundance of nutrients, such
as nitrogen and phosphorus, into the surrounding soil. This leads to higher amounts of organic
matter absorbed into the soil which greatly benefits river ecosystems (Bilby et al., 2003). We
examined how the presence of spawning salmon affects the organic matter in soil found along
the riverbanks of three salmon spawning streams (Clayburn Creek, Capilano River, and
Serpentine River) in comparison to the soil organic matter content of three creeks that do not
support salmon (Poignant Creek, Coho Loop creek, and an unnamed creek in Meyer Glade, UBC
Botanical Gardens). We measured the mass of organic matter in the soil (%) obtained from
appropriate sampling locations, and predicted that the soil organic matter would be significantly
greater when spawning salmon are present compared to the soil organic matter present in creeks
that do not support salmon. Our statistical analysis showed that although on average the rivers
containing salmon had a higher percentage of organic material in the soil, the results were not
statistically significant and did not support our hypothesis that rivers that support spawning
salmon will have more organic matter (%) in the soil along the riverbank compared to rivers that
do not support spawning salmon.