Hymenocallis coronaria (Rocky Shoals Spider Lily) is a threatened species endemic to Georgia, Alabama, and South Carolina. The purpose of this research is to study two existing populations of Rocky Shoals Spider Lilies along Stevens Creek in McCormick, South Carolina. One of the populations is healthy and thriving while the other has decreased in extent and vigor over the last 20 years. Following South Carolina’s Adopt-A-Stream water quality testing and habitat protocols, information on the quality of water was collected at both sites. An EPA macroinvertebrate rapid bioassessment was also done to further analyse habitat and water quality differences. Data on hypothesized herbivory impacts was collected by placing a game camera at each site. The goal of the project is to identify the driver of the reduction of extent and vigor in the Rocky Shoals Spider Lily population by comparing it to the healthy population. We hypothesize that one or more of the following variables; herbivory, water quality, or habitat quality are driving the decline in Rocky Shoals Spider Lily on Stevens Creek. Identifying the reason for the stunted growth could help determine the environmental parameters needed for a healthy population. In the future we hope to identify new sites to plant Rocky Shoals Spider Lily in based on the parameters identified in this research.
Results/Conclusions
The chemical and bacterial water quality data for each site was similar in all parameters except for E. coli levels. Although E. coli concentrations differed at each site over the sampling period, levels at both sites were low, with not enough difference between the sites to likely be significant. The macroinvertebrate samples taken from both sites indicated fair water quality for both visits. However, the soil samples from each site showed that there is a difference in micronutrients between the two sites. Site 2 had a population that was unhealthy compared to Site 1; the soil samples showed there were lower levels of micronutrients found in Site 2. In order to further investigate the role of micronutrients in lily growth, seed collection and propagation is the next step of this project. Cameras will continue to monitor the sites to see if herbivory is a factor during summer months, in addition to an inventory of the entire length of Stevens Creek to identify other potential populations of lilies.