<h2>
	BEFORE YOU START</h2>
<h3>
	<a name="TOC-Key-Ideas-Introduced-in-this-Unit:"></a>Key Ideas Introduced in this Unit:</h3>
<ul>
	<li>
		Mercury bioaccumulates</li>
	<li>
		Mercury amounts in organisms increase at higher trophic levels</li>
	<li>
		Mercury is toxic to humans and other organisms</li>
	<li>
		Dragonflies are a key part of the aquatic food web and are exposed to mercury</li>
</ul>
<h3>
	<a name="TOC-Concepts-and-Relationship:"></a>Concepts and Relationship:</h3>
<ul>
	<li>
		Mercury can enter organisms in several ways</li>
	<li>
