Poster Presentation Society for Freshwater Science 2026 Annual Meeting

Defining Blackwater Systems through the Examination of Physicochemical and Biological Parameters (136074)

Hazel Quarterman 1 , Victor Obi 1 , Asli Aslan 1
  1. Institute for Water and Health, Georgia Southern University , Savannah, Georgia, United States of America

Blackwater systems are traditionally defined as water bodies with a high concentration of tannins, low pH, dark color, and low levels of dissolved oxygen (DO); however, many freshwater systems considered “blackwater” do not fit this set of criteria. The lack of an operational definition for such a system is a pertinent issue in areas like the eastern United States, where blackwater systems dominate the coastal landscape but are poorly researched and defined.

 

The aim of this study is to select several methods to determine a set of physicochemical conditions and biological assemblages that most consistently distinguish blackwater systems from non-blackwater systems across the coastal plains of Georgia. By evaluating how physicochemical parameters traditionally used in observing blackwater streams may correlate with biological parameters such as species abundance, life history adaptations, and community composition, which are typically not included in blackwater monitoring efforts, we hope to broaden the definition of blackwater into a framework more definitive and comprehensive to better inform the classification and management of such systems by natural resource managers.

 

Through the development of this framework, aquatic organisms that specialize in or are endemic to blackwater systems, such as fish and macroinvertebrates, will serve as additional parameters to classify a blackwater system. The unique life history traits, community composition, and abundance of a species in a given system may be indicative of a biological assemblage unique to blackwater streams. Thus, designing an approach to collecting biological assemblage data in conjunction with traditional physicochemical traits of blackwater systems may prove vital to further informing management of these species and the conservation of their habitats. 

  1. Flotemersch J E., Blocksom K A., Herlihy A T., Kaufmann P R., Mitchell R M., and Peck D V. Distribution and Characteristics of Blackwater Rivers and Streams of the Contiguous United States. Water Resources Research. 2024; 60(2).
  2. Colvin S. A. R, Helms B. S., DeVries D. R., and Feminella J W. Environmental and Fish Assemblage Contrasts in Blackwater and Clearwater Streams. American Fisheries Society. 2020; https://academic.oup.com/tafs/article/149/3/335/7819427