Evaluation of habitat characteristics associated with Podostemum ceratophyllum Michx. (Hornleaf riverweed), a foundation species in eastern North American rivers

Abstract

Podostemum ceratophyllum Michx. (Podostemaceae) is the only macrophyte within the genus that inhabits mid-order montane and piedmont rivers in eastern North America. Podostemum is considered a “foundation species” because the plant strongly influences benthic habitat structure and function by increasing habitat heterogeneity for macroinvertebrates and fishes, contributing to food webs, and sequestering water column nutrients. The conservation status of Podostemum remains data deficient in many states (e.g. WV, PA), but some states, such as CT, KY, MA, ME, NY, and OH, classify Podostemum as threatened, endangered, or of special concern. Over the past 35 years, there has been documented local decline and extirpation of Podostemum in NH, VT, VA, and PA. The decline of Podostemum has been postulated to be the result of stream degradation, including excessive sedimentation, flow and water chemistry alteration, and nutrient enrichment. However, because no study has specifically investigated stream water physiochemical properties or environmental stressors associated with Podostemum, there is currently no reliable way to predict how water quality impacts the plant. The proposed study includes two primary objectives. The first objective is to determine the physiochemical and physical habitat characteristics conducive to the growth and survival of Podostemum. The second is to model the distribution and possible decline of Podostemum based on historical records and field surveys. Physiochemical and habitat surveys will be conducted in West Virginia mid-order rivers and will be analyzed using logistic regression modeling. The outcomes of this research will be put towards an updated conservation strategy for this foundation species.