Species Diversity

In 2010, we found 21 species of SAV occurring across 106 sites in five coastal river deltas ranging from Mobile Bay, Alabama to Pearl River, Mississippi. They included saline-brackish seagrasses, brackish-fresh submerged SAV, freshwater submerged and floating-leaved species reported previously on the Mississippi Aquatic Plants Website. 

Table 1: Species list of the three SAV groups found in our surveys

To better understand the relationships among these different SAV species, we used hierarchical agglomerative clustering on the Euclidean distance matrix. Ward's algorithm was chosen as it is space conserving and has been found to perform best with community data. The resulting dendrogram looks like this:

Species that are more closely grouped on this diagram tended to occur together in similar sites. Two major branches in composition of the SAV communities occur at the top of the tree. The right branch is comprised of seagrasses and brackish-fresh submerged SAV found nearer to the ocean, while the left branch is populated by submerged and floating leaved species found in the upper reaches of the river delta.