Species Survey Efforts, Genetics, and Patches (individual populations)

Keppner and Keppner (2002), surveyed for PCC on Gulf Power rights-of-way between Star Avenue and Transmitter Road in 2002, and on St. Joe Lands (largest private lands owner in PCC range) east of Panama City in 2003 and 2004 (Keppner and Keppner 2004). These surveys defined the eastern/southeastern range of the PCC (Keppner and Keppner 2004). In 2003, the City of Panama City hired Dr. Frasier Bingham to conduct a PCC survey (Bingham 2003). Later in 2003, the Keppners surveyed this same general area (Keppner and Keppner 2004) and conducted resurveys at a few points in 2006 (Figure 1.1).

In 2012-2013, FWC led a survey effort in which FWC staff and partners resurveyed previously documented points on rights-of-way and public road edges and at undocumented points throughout the species’ range. In 2013, some 10 years after the original surveys by the Keppners, the St. Joe Company provided access for these surveys (Figure 1.1). Although these surveys documented new occurrences that further defined the PCC range, surveyors failed to confirm PCC at several previously documented occurrence points. Data collected from opportunistic surveys, environmental consultants, and annual surveys on PCC management areas are continually added to the PCC database. Occurrence data from these surveys formed the basis for determining the species’ range (Figure 1.1). PCC surveys are limited to rights-of-way, lands open to the public, or private lands where access is granted, so there remain lands where the PCC likely occurs but access remains unauthorized (Figure 1.1).

In 2016, FWS funded a genetic status and landscape connectivity analysis of the PCC throughout its range where access was allowed and occurrences known (Duncan et al. 2017). FWS and FWC biologists collected 170 PCC samples from the field in February-April and August-September 2016. Adequate DNA from 161 samples (some had insufficient quality from DNA degradation) was obtained (Duncan et al. 2017). The samples represented most of the areas with recent records of PCC, which allowed the researchers to evaluate trends in genetic diversity and differentiation.

Genetic sampling locations showed patterns of differentiation. There was a strong pattern of isolation-by-distance, where increasing geographic separation tended to reflect increasing genetic differentiation among sample locations. The largest differences occurred between the eastern and western portions of the range (Figure 3.6). The results of a landscape analysis, which will be described further below, also demonstrate the importance of core and secondary soils in describing this genetic differentiation. For this reason, we have summarized the availability of these “suitable” habitats within each patch’s polygon in Table 3.2 and Table 3.3 and again within each individual patch’s summary.

Table 3.2. Summary of western range of the PCC and habitats (resistance layers) located within one-quarter mile polygon surrounding genetic points and surrounding habitat categories.
Population
Core Soils–undeveloped
Secondary Soils–undeveloped
Possibly Suitable-right soils but disturbed
Undeveloped, other soils
Urban Open Land
Unsuitable
Developed
Total acres
Effective Population Size (Ne)
Inbreeding Coefficient
Shriners 21.02 8.2 15.91 12.16 26.69 58.49 142.48 32.6 0.359
Airport-north 9.87 9.25 8.72 36.97 83.52 148.32 0.214
Airport-south 6.7 11.87 0.38 38.03 58.7 82.38 198.06 61.3 0.344
Talkington 61.34 24.81 16.15 26.55 69.01 197.86 424.5 0.31
City of Lynn Haven 43.72 15.59 44.9 0.05 9.5 11.82 125.58
Industrial 13.16 5.53 0.06 8.82 63.93 74.84 166.33 0.395
St. Joe Mitigation 232.1 99.56 5.13 0.72 21.71 70.05 429.28 1638 0.348
College Point 3.2 1.99 0.97 29.9 89.52 125.58
TOTALS: 390.12 176.78 15.91 88.48 84.6 320.47 456.02 1533.37
Table 3.3. Summary of eastern range of the PCC and habitats (resistance layers) located within either one-quarter mile polygon surrounding genetic points or larger polygons that merged several associated genetic points and surrounding habitat categories.
Population
Core Soils–undeveloped
Secondary Soils–undeveloped
Possibly Suitable-right soils but disturbed
Undeveloped, other soils
Urban Open Land
Unsuitable
Developed
Total acres
Effective Population Size (Ne)
Inbreeding Coefficient
Highpoint 76.1 70.07 2.6 16.75 48.18 213.69 63.1 0.26
Deerpoint 585.4 258.45 213.09 84.71 56.86 1,198.51 9.4 0.448
231 north 143.73 133.99 14 29.28 8.65 329.65 0.396
Star Avenue 1,754.07 1,344.59 2.04 336.89 9.32 355.68 729.71 4,532.30 1450.9 0.493
231 South-St Joe 3,007.99 2,301.25 23.09 281.89 3.54 328.75 449.43 6,395 145.6 0.46
TOTALS: 5,567.29 4,038.28 25.13 915.94 15.46 815.17 1,292.83 12,669.15
Totals of
All Columns
5,958.40 4,215.08 41.04 1,004.41 100.05 1,135.67 1,748.94 14,202.64
PCC genetic sample locations
Figure 3.6. Map of PCC genetic samples and eastern-western differentiation break-out.

For ease of summarizing habitat status associated with each patch, the PCC were delineated by polygons using one-quarter mile circles around each core sample. When the populations were delineated and multiple patches were the same genetically, we merged the one-quarter mile polygons into one larger polygon. Lacking an exact minimum separation distance between sampling points, we used one-quarter mile (0.4 km). Literature on crayfish dispersal distances are largely based on migratory and often invasive species. NatureServe recommends a 2 km distance for movement across suitable and unsuitable habitats. The PCC is a small crayfish that does not have large migratory movements, especially through unsuitable habitats, so we erred on the side of caution and used one-quarter mile (0.40 km) separation distance. We did not remove isolated lands that may be separated by development within the polygons due to time constraints. With larger populations, where genetically similar sample sites were distributed across a broader landscape, polygons were drawn separating each population by using breaks in habitats deemed biological barriers to movements (i.e., stream or unsuitable soils). Also, for ease of delineation, roadways or the PCC range was used as a delineating boundary (Figures 3.6, 3.7 and 3.16). The individual population boundary colors correspond with the genetic analysis report (Duncan et al. 2017) (Figures 3.6, 3.7, and 3.16).

PCC patches in west Panama City
Figure 3.7. Eight different patches are located in the western part of the PCC range.

Summaries for each patch are separated into the Western and Eastern sets:

Landscape Genetics: Western Patches

Landscape Genetics: Eastern Patches