Abstract
The Picayune Strand Restoration Project (PSRP) is located to the west of Fakahatchee Strand State Park Preserve in Collier County, Florida. This 55,000-acre restoration project is part of the Comprehensive Everglades Restoration Plan (CERP) and was one of the Acceler-8 projects initiated in 2004. The PSRP is intended to restore the hydrology of a system that was impacted by roads and canals constructed for a Gulf American Corporation development project; in order to assess the ecological success of the restoration, monitoring efforts occur periodically. The PSRP is ongoing: the roads have been removed of asphalt and mostly leveled off, two of the four canals have been filled, and two of the three pumping stations are complete. The key element now is determining whether or not the community structure of the restoration sites is progressing towards the reference sites i.e. if this restoration is succeeding. As potential indicators of hydrologic restoration, anuran, fish, macroinvertebrate, and plant communities have been surveyed. Amphibians are frequently used as an indicator of hydrologic restoration success, and a number of researchers have studied frog communities within the PSRP. One increasing issue on Florida’s landscape is the prominence of exotic invasive species – in the treefrog community, the Cuban treefrog (Osteopilus septentrionalis). Due to the growing Cuban treefrog population in Southwest Florida, there is a need to address this issue to ensure that the restoration is being successfully monitored to inform adaptive management. Anurans (i.e. treefrogs) were sampled monthly through the use of PVC pipes as refugia. They were then compared over time between restoration sites in the PSRP and reference sites in the Florida Panther National Wildlife Refuge (FPNWR) and the Fakahatchee Strand Preserve State Park (FSPSP), and among habitat types using univariate diversity indices. One-way ANOVAs were used to test for significant differences among treatments, habitats, and/or time. Results from the treefrog community indicate that the invasive O. septentrionalis is creating noise in the signal anurans provide of trends in restoration progress, however there are preliminary indications of restoration success that are most clearly identified within graminoid sites. Supplemental sampling shows that bimonthly sampling produces comparable anuran captures to monthly sampling, pipes with a cap closure rather than an elbow attract more anurans, and that larger pipes attract more anurans; however, these larger pipes may have a higher proportion of invasive species. Additionally, it is possible to determine a signal of restoration, however current methods may need to be adapted. This adaptation could include adding the use of anuran audio calls to better determine species assemblages, and/or focusing PVC-refugia sampling efforts on the graminoid habitats which provide a distinct signal of trends in restoration. Additional analyses were conducted on the various taxa utilized in the PSRP monitoring. While many restoration monitoring efforts utilize information from several different taxa, few researchers have looked at the impacts of utilizing a community approach to determining restoration progress by combining all of these taxa in their analyses. This study explores the efficacy of each of the four taxa involved in PSRP monitoring – anurans, fish, aquatic macroinvertebrates, and vegetation – by using cluster analyses, multidimensional scaling (MDS), and SIMPER analyses to determine which taxa are creating the greatest difference between treatments. Anurans were sampled using PVC pipe refugia, fish were sampled using Breder traps and throw traps, macroinvertebrates were sampled by dip netting, and vegetation was monitored along transects. To compare biotic communities across the restoration and reference sites, univariate analyses of biodiversity indices along with multivariate analyses, were performed within and across taxa. Results of these cross-taxa analyses indicate that aquatic macroinvertebrates, and vegetation community and structure are the two strongest differentiators between reference and restoration sites. Anuran similarity between reference and restoration habitats was due to the universal spread of O. septentrionalis, and while fish communities do indicate some level of difference – mainly due to the invasive exotic African jewelfish (Hemichromis letourneuxi) – they are not as powerful a tool as the invertebrates and vegetation. Future monitoring efforts may provide the best determination of restoration progress if they are focused on aquatic macroinvertebrates, and vegetation community and structure. These two taxa created the strongest signal between reference and restoration. Overall, the PSRP appears to be moving towards the reference sites in MDS space, although this pattern is most clear when combining all taxa.