Modeling Fusconaia masoni and Villosa constricta habitat in the Upper Neuse River Basin using Geographical Information Systems
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2019-07
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MARSH, GORDON. ENVIRONMENTAL ASSESSMENT. Modeling Fusconaia masoni and Villosa constricta habitat in the Upper Neuse River Basin using Geographical Information Systems. As development continues across the state of North Carolina it is imperative that freshwater mussel species and their habitat are protected. Freshwater mussels provide essential ecological benefits to stream ecosystems. Some of these benefits include: filtering out algae and bacteria from the water system and providing food for mammals and invertebrates (Vaughn and Spooner, 2006; NRCS, 2007;). These benefits, along with their longevity, allow freshwater mussels to be classified as an ecological indicator for stream health (Grabarkiewicz and Davis, 2008). North Carolina is home to 60 freshwater mussel species, with 50% listed as endangered, threatened, or special concern (NCWRC, 2019). As government and private industries continue project development, knowledge of existing species occurrences and their viable habitat is crucial. Geographical information systems (GIS) can allow us to model potential areas of habitat for future conservation efforts.
This project used GIS to model mesohabitat for the freshwater mussels Fusconaia masoni and Villosa constricta in the Upper Neuse River basin by evaluating habitat parameters associated with existing occurrences of these species within one hydraulic unit code (HUC 03020201) located in the Neuse River basin. These parameters: velocity, erosion, and stream power were then used to calculate the range of each species as well as the habitat quality for 75 to 100 meter reaches within each species’ range. The effects anthropogenic barriers had on the distribution of these species within this HUC was extrapolated into the study are to further refine each species’ range.
The ranges for V. constricta and F. masoni spanned approximately 311 km and 203 km, respectively, in the Upper Neuse River basin. Habitat quality values ranged from -144.74 to 540, with the highest number representing the most viable habitat. These values were divided into a habitat quality ranking (HQR) system with values 1–5, where HQR 5 had the most viable qualities and HQR 1 had the least viable qualities. Villosa constricta occurrences from existing databases were observed in reaches with an overall habitat quality ranking (OHQR) of 3 or better. Fusconaia masoni occurrences from existing databases were observed in reaches with an OHQR of 4 or better. Within the total range of V. constricta (311 km), there was 258.48 km of viable habitat within the Upper Neuse River basin. Within the total range of F. masoni (203 km), 95.7 km within the Upper Neuse River basin was viable habitat.
Eleven sites were visited to field verify the GIS model: 4 sites within the Eno River basin, 3 sites within the Little River basin, and 4 sites within the Flat River basin. A total of 10 F. masoni individuals were located during the field surveys, 3 within the Eno River basin, 6 within the Flat River basin and 1 within the Little River basin. A total of 31 V. constricta individuals were located during the field surveys, 4 within the Eno River basin, 24 in the Flat River basin, and 3 within the Little River basin. Of the 10 F. masoni observed, 2 were observed within reaches with an HQR of 3. Six were observed within an HQR of 4. All F. masoni observed were located within OHQR of 4. Fourteen V. constricta were observed within reaches with an HQR of 3, and 17 were observed within reaches with an HQR of 4. Thirty V. constricta were observed in reaches with an OHQR of 4, 1 was observed in an OHQR of 3. There was no statistically significant difference between the number of observed F. masoni or V. constricta at HQR 3 versus HQR 4 at the reach level (p = 0.7577 and p = 0.3938, respectively). However, there was a significant difference in the OHQR for the F. masoni (p = 0.0187), but not for the V. constricta (p = 0.2528).
