Skip to main content
ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Invasive Species and Pollinator Health » Research » Publications at this Location » Publication #427677
Research Project: Integrated Weed Management and Restoration Strategies to Protect Water Resources and Aquatic and Wetland Ecosystems of the Far Western U.S.

Location: Invasive Species and Pollinator Health

Title: Tidally influenced water exchange characteristics of hydrilla invasion sites within the lower Connecticut River

Author
item HOWELL, ANDREW - North Carolina State University
item SPERRY, BENJAMIN - Us Army Engineer Research And Dvelopment Center
item Beets, Jens
item DURHAM, MICHAEL - Us Army Engineer Research And Dvelopment Center
item GLUECKERT, JONATHAN - University Of Florida
item RINER, AMBER - University Of Florida

Submitted to: Estuaries and Coasts
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/9/2025
Publication Date: 1/27/2026
Citation: Howell, A.W., Sperry, B.P., Beets, J.P., Durham, M.W., Glueckert, J.S., Riner, A.E. 2026. Tidally influenced water exchange characteristics of hydrilla invasion sites within the lower Connecticut River. Estuaries and Coasts. 49: Article 53. https://doi.org/10.1007/s12237-025-01653-7.
DOI: https://doi.org/10.1007/s12237-025-01653-7

Interpretive Summary: In response to a new invasive species rapidly spreading in the Connecticut River, a series of tidal dye studies were performed to understand the water exchange processes at several sites of severe infestation. These infestations threaten navigation, water delivery for irrigation, recreation and hydropower. Dye studies were performed to guide management practices and allow for efficient use of herbicides to combat this new invasion. These dye studies provided an initial understanding of potential off-target water movement and suggestions for which aquatic-approved herbicides might be most effective at each site.

Technical Abstract: The Lower Connecticut River (CR) is an ecologically and recreationally significant ecosystem within New England, but the river has become increasingly vulnerable to the intrusion of aquatic invasive species (AIS) like hydrilla (Hydrilla verticillata). The hydrilla population recently discovered in the Lower CR is genetically unlike former hydrilla clades present in the United States. The specific biological and management components of this unique clade-C hydrilla in comparison to its cohorts remains largely undetermined and the nature of management action to combat the submersed plant within the tidally influenced lotic system further complicates waterway resilience efforts due to high-water exchange. Because of the inherent environmental challenges attributed to lotic environs, the use of aquatic herbicides remains the primary management tool for selective and effective hydrilla control. However, knowledge of the site-specific water exchange processes at infested sites coupled with subspecies- and herbicide-specific concentration-exposure time (CET) requirements are essential for successful plant management. The primary goal of the present studies was to quantify bulk water exchange rates at five representative hydrilla infestation sites within the Lower CR using Rhodamine WT dye (RWT) to mimic prospective herbicide application operations. Dye monitoring indicated distinct variability among study site water exchange rates, with RWT half-lives ranging from 0.35 to 72.36 hours following application. Future management efforts deploying herbicide should consider these methods and findings when selecting appropriate herbicide active ingredients and use rates to achieve hydrilla control. While the present water exchange findings offer initial guidance, comparable dye studies will be compulsory as management programs target additional hydrilla invasion areas within the river.