obbles"</span>, <span class="st">"Periphyton"</span><span class="op">)</span><span class="op">]</span></span>
<span><span class="co">#&gt;   Fine_gravel Coarse_gravel Sand_1_2_mm  Mud Cobbles_64_257_mm Boulders_257_mm</span></span>
<span><span class="co">#&gt; 1          40            40          10 &lt;NA&gt;              &lt;NA&gt;              10</span></span>
<span><span class="co">#&gt; 2          40            40          10 &lt;NA&gt;              &lt;NA&gt;              10</span></span>
<span><span 