Science Article

Before collecting samples, please remember to read the safety information.

You will collect samples from two stream sites. The length of the first stream site is defined as 10 times the average stream width. The second stream site is determined by the length of the first site and will be located two lengths away from the first site. Conducting investigations above and below areas of concern can save time and lead from symptoms to causes.

The number of sample sites
To quantify habitat complexity, you will be required to set up an evenly spaced framework that you will use to sample the entire pond. A pond site is defined as less than 2 m (6.5 ft) deep. Where asked to do sub-surveys to obtain data that are statistically reasonable, we suggest that your group try to do as many samples as you can (up to 30). If there are significant variables in the conditions, you may need more.

When to take samples
Some investigations are seasonal or time dependent. Please obey safety, environmental, and landownership rules when collecting samples. Not every student needs to tramp sensitive areas to look for biological materials.

Identifying redds
Redds are salmon or trout egg nests; a female fish digs a depression in the gravel streambed and lays her eggs there. A valuable skill for anyone walking or working in streams and rivers in the fall and spring is the ability to identify redds. The female fish will cover them with more gravel to protect them from predators and to keep them from being washed away. The result is an oblong mound of cleaned and sorted gravel, depending on the size of the depression.

Do not disturb redds, do not step on them, and do not dig them up. Avoid working near them if possible. Also, avoid causing erosion upstream of them, because silt can clog redds and smother the eggs inside by preventing water from flowing through the gravel. The eggs are most vulnerable in the first two weeks after being laid, when the gravel is still very clean.