Spring has sprung– the ecological importance of the spring melt.
Today is the first day of spring and as the days get longer, people and critters will be expecting warmer temperatures and the resulting melting of snow from the landscape. For some homeowners, spring is a nerve-wracking time when flooding is more prevalent as local watercourses receive the snowmelt. But for the rivers themselves and the creatures that live there, floods are necessary because they are key contributing factors to freshwater biodiversity, life history characteristics, ecological traits of stream organisms and physical processes in streams. Rising waters fill neighbouring lands, renew soils, add valuable woody debris, and redistribute sediment creating crucial microhabitats for a range of species.
The freshet, the spring thaw resulting from snow and ice melt, is typically the most significant flood of the year in magnitude and importance to aquatic plant and animal life and humans. Some fish (like the Northern Pike) spawn in the floodplains that are flooded during this time. These areas are considered crucial fish nursery habitat, however, they are often threatened from poor land-use planning.
Empirical evidence and predictions suggest that many areas in Canada are warming which will affect the timing and size of the freshet and winter thaw flows. How fish and other aquatic organisms respond to changes in climate, temperature, and freshet timing is not clear and will depend on species-specific tolerances and resilience (Crozier et al., 2011).
River ecosystems are particularly vulnerable to a warming climate because (1) many species within these habitats have limited abilities to leave their environment as it changes, (2) water temperature and availability are climate-dependent, and (3) many systems are already exposed to numerous human-induced pressures (Pletterbauer, Melcher, Graf, 2018).
As the spring freshet recedes, TUC and our Chapters will be gearing up for warmer weather and we’ll be posting about up-coming volunteer opportunities across the country. You can find out which Chapter is closest to you on our website. We recommend checking to see if they have a Facebook Page, which is where most of our Chapters communicate their upcoming workdays and events. Come out and join us to help improve the quality and quantity of habitat for our stream-dwelling friends.
Crozier, L.G., MD. Scheuerrel and R.W. Zabel. 2011. Using time-series analysis to characterize the evolutionary and plastic response to environmental change: a case study of a shift toward earlier migration date in sockeye salmon. The American Naturalist 178: 755-773.
Pletterbauer, F., Melcher, A., Graf, W. 2018. Chapter 11: Climate Change Impacts in Riverine Ecosystems. Riverine Ecosystem Management: Science for governing towards a sustainable future.