The Big Thicket National Preserve spans five counties in southeast Texas and contains ten distinct ecosystem types. The Big Thicket National Preserve contains numerous protected areas following the Neches River and its smaller tributaries and encompassing the surrounding riparian habitat. This study sought to inventory the mussels in each distinct unit of the Big Thicket while evaluating the differences in community structure between the small, intermediate, and large streams contained within the preserve. Freshwater pearly mussels (Order: Unionoida) are some of the most endangered organisms in North America with Texas containing 15 State listed threatened mussel species. Six of those are native to east Texas. The mussels of the Big Thicket Preserve were last surveyed in the late 1990’s and early 2000’s in limited reaches with no surveys in the last ten years. In addition, using the inventory data, this study sought to improve upon existing ecological niche models for threatened mussel species found in the Big Thicket through the addition of new presence points and the creation of a new environmental layer to quantify stream size based on cumulative drainage size. Forty-three sites were examined during the summers of 2013 and 2014 for species presence and abundance, covering each unit that contained perennial streams. 619 mussels of 23 species were recorded. Stream size did not have an effect on either richness or evenness of mussel populations. Additionally, no difference in community structure was seen between small, intermediate, and large streams. These results do not follow trends indicated by studies in other watersheds throughout North America, possibly due to the present study being restricted to the lower Neches River watershed. Ecological niche models did improve with both the addition of new presence points as well as the new stream size environmental layer. These models are an important step towards conservation of these threatened species as well as the improvement of mussel niche models worldwide through the inclusion of the stream environmental layer.

Date of publication

Spring 5-26-2015

Document Type

Thesis (Local Only Access)



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