Dr. Matt Cohen, School of Forest Resources and Conservation – Riverine Nutrient Dynamics

Matt Cohen is an ecologist and hydrologist with particular interests in wetlands and rivers. He is an Assistant Professor in UF’s School of Forest Resources and Conservation. He teaches courses in Ecohydrology and Watershed Management. More information can be found at: http://sfrc.ufl.edu/ecohydrology

Goals of the Ecohydrology component - Evaluate and predict river network nutrient losses and transformations under varying environmental, geomorphic and hydrologic settings, to aid in setting downstream protective values (DPVs), a core component of NNC for lotic systems. Specific Ecohydrology goals include:

(1) Synthesize existing frameworks for predicting longitudinal and network-scale nutrient transformations
(2) Evaluate the applicability of these models (and embedded parameters) for Florida conditions (e.g., blackwater rivers, low-gradient systems, strong wetland interactions).
(3) Develop and implement techniques for the empirical estimation of river network nutrient processing to evaluate and improve existing models
(4) Translate findings into guidance documents that can be used as the empirical basis for regulatory establishment of downstream protective values.

A critical and underappreciated facet of the numeric nutrient standards in flowing waters is adoption of “downstream protective values” (DPVs) that would set nutrient criteria for rivers and streams to protect lakes and estuaries downstream, even where in-stream biological responses to nutrient enrichment are not obvious. During passage through a river network, nutrients are processed to a highly variable degree in response to variation in water chemistry, flow, channel morphology and riparian interactions; the proposed standards consider distance from a sensitive water body and assume a fixed rate of removal in time and space. Although longitudinal nutrient removal rates have become increasingly well constrained in other parts of the, particularly for small streams, there is very little information available for Florida, or for the large rivers that, per unit length, do most of the removal work. Localized study is required to establish the controls and process rates for both nitrogen and phosphorus. Emerging methods for quantifying nutrient uptake and recycling kinetics in streams and rivers will be applied to help establish these DPVs.