Quantifying the Effects of Plant Invasions on Aquatic Food Webs, Fish Condition, and Aquatic Ecosystem Function in the Northeast

EPA Grant Number: FP917100
Title: Quantifying the Effects of Plant Invasions on Aquatic Food Webs, Fish Condition, and Aquatic Ecosystem Function in the Northeast
Investigators: Lellis-Dibble, Kimberly A
Institution: University of Rhode Island
EPA Project Officer: Lee, Sonja
Project Period: September 1, 2010 through August 31, 2013
Project Amount: $111,000
RFA: STAR Graduate Fellowships (2010) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Fellowship - Ecosystem Services: Aquatic Systems Ecology


Invasive species are persistent biological pollutants that outcompete native species, alter community composition, and disrupt the flow of energy and materials through terrestrial and aquatic ecosystems. Numerous studies have documented a decline in habitat value for birds, mammals, and nekton (fish and swimming crustaceans) as invasive plants expand through ecosystems. However, few studies have focused on the effects of invasive plants on food webs and animal condition in the invaded ranges. The expansion of an invasive generalist plant (Phragmites australis australis) into disturbed wetland habitats, and the subsequent attempts to eradicate this weedy invader, provide an excellent model that I will use to quantify the impact of a nuisance species on overall ecosystem function.


This research quantifies the effect of a non-native plant invader on wetland ecosystems by examining alterations in food web dynamics and the condition, growth rate, and overall health of fauna residing in invaded habitats. Data will be generated using a variety of field and laboratory-based methods. The knowledge gained from this research can be applied beyond wetlands to more fully understand how invasive species affect native habitats and their associated plant and animal communities.


Specifically, my research will: 1) determine whether resources released by Phragmites are being incorporated into aquatic food webs; 2) quantify fish energy reserves, growth rate, and overall body condition in invaded, restoring, and reference marshes; and 3) investigate links between the dominant energy source and fish condition in invaded and restoring systems relative to reference marshes. I will analyze food web structure and dominant energy source via carbon, nitrogen, and sulfur stable isotopes in macrophyte, macroalgae, benthic microalgae, suspended particulate, and Fundulus heteroclitus (mummichog) samples. Lipids will be extracted from Fundulus to determine total energy reserves and will be compared with a morphometric index (Fulton’s K) to determine overall fish health. Sagittal otoliths will be removed from Fundulus to reveal recent growth rate and age structure of fish populations in each marsh system.

Expected Results:

This study will be the first study to directly compare and quantify fish condition in invaded and restoring marshes as compared to reference habitat. Results will extend beyond salt marsh systems to provide significant insights on how invasive plants affect habitats and their associated food webs, and whether restoration activities are in fact accomplishing their ecological goals. Since the invasion front of Phragmites continues to advance in the United States to the south and west, managers can use this information to make plant management decisions and prioritize habitat restoration projects before introduced Phragmites takes over other biologically diverse wetland ecosystems.

Potential to Further Environmental/Human Health Protection:

This research directly supports the Environmental Protection Agency’s mission to protect human health and the environment. Invasive species are arguably among the most persistent and widespread biological pollutants the Earth faces today. They pose a significant threat to ecosystems, biological security, and human well-being. They foul navigable waters and have significant economic costs. This research will provide critical information to better understand the full consequences of biological invasions, will help managers to prioritize restoration and control efforts, and will assist with the development of appropriate tools to control the spread of invasive species in order to better serve society.

Supplemental Keywords:

invasive species, fish, plant, Phragmites australis, Fundulus heteroclitus, wetland, energy reserves, growth rate, stable isotopes, otolith, lipid, food web,

Progress and Final Reports:

  • 2011
  • 2012
  • Final