Oxbow on the Columbia

Columbia River & Wetlands April 29,2013 - by Larry Halverson

One of the best examples of an Oxbow on the Columbia River can be seen from the view points on the mile hill at Radium Hot Springs.

Oxbows are formed when a river creates a meander by river's eroding the bank through hydraulic action. After a long time, the meander becomes very curved, and eventually the neck of the meander will become narrower and the river will cut through the neck usually at flood time.

After the river finds a different, shorter, course. The meander becomes an oxbow lake along the side of the river.

It would make an interesting photo story if pictures were taken of this process over time.

Columbia Spotted Frog Eggs

Columbia Spotted Frog egg mass in the Columbia Valley near Brisco - by Larry Halverson

Hatchlings on top of egg mass by Larry Halverson

Females lay eggs in communal masses at the water surface, either freely floating or loosely tangled around emergent vegetation. You can tell that these eggs just hatched because the tadpoles have no eyes and the gills are visible.  The hatchling stage of clinging to the egg mass only last a day or two before they become tadpoles. 

Water temperature was 22 degrees C which likely why the hatching is earlier in the Columbia Valley than Kootenay National Park where the water temp was 0 degrees C on May 1.

Compton Tortoiseshell - An Early Flyer

Compton Tortoiseshell - April 28, 2013 by Larry Halverson

Compton Tortoiseshells overwinter as adults so they are one of the earliest butterflies seen each spring.  However, they won’t be flying too much longer as they’ll soon lay eggs and die. Look for them along stream sides and clearings particularly where birch, willows and aspen are growing. 

If you miss them, there will be another flight from late July until they enter hibernation in October.

Mule Deer above Lake Windermere, April 22, 2013 by Larry Halverson

Mule deer are taking advantage of the valley bottoms where the grass greens first.

Prevent the Pathway!

Look at the following picture and identify 10 ways in which Aquatic nuisance species are introduced or spread into local aquatic ecosystems.

Let's take a look at the different ways some of these species invade or spread to new areas.

Aquatic nuisance species (ANS) can come from any country in the world and may be introduced into new ecosystems in a variety of ways.  The means and routes by which ANS are introduced into an aquatic ecosystem are called introduction pathways.  Some species migrate into new areas on their own (volitional movement), while others may be carried into new areas by natural events such as hurricanes or floods.  The vast majority of invasive species are spread into new water bodies as a direct result of human activities.  Whether intentionally or by accident, once an ANS is introduced and becomes established in a new ecosystem, it is very costly and difficult to control or eradicate them.  Often the best approach to preventing the introduction or further spread of ANS is to educate the public on the potential pathways of introduction and steps each person can take to stop the spread of ANS in their local community. 

From The Dish on Fish  http://fish-notes.blogspot.ca/2013/03/prevent-pathway.html