Effects of Nutrient Loading and Native Invaders on Structure and Function of Seagrass Ecosystems

EPA Grant Number: FP917368
Title: Effects of Nutrient Loading and Native Invaders on Structure and Function of Seagrass Ecosystems
Investigators: Stoner, Elizabeth W
Institution: Florida International University
EPA Project Officer: Lee, Sonja
Project Period: August 1, 2011 through July 31, 2014
Project Amount: $126,000
RFA: STAR Graduate Fellowships (2011) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Fellowship - Ecosystem Services: Aquatic Systems Ecology


The effects of anthropogenic nutrient loading on seagrass ecosystems have been well documented, with several impacts clearly identified, including a loss of seagrass biomass, changes in seagrass species present and an increase in opportunistic algae. However, little is known about the effects of increased native invaders, or endemic organisms that proliferate and expand their range as a result of human disturbance, on seagrass ecosystems. The objective of this research is to address whether increased densities of the potential native invader, Cassiopea spp., previously shown to be more abundant in nutrient-enriched coastal habitats, leads to a shift in sub-tropical seagrass benthic community structure and ecosystem function.


This research question will be broken into two major components. The first is to use a series of descriptive surveys to address whether a natural gradient in Cassiopea densities correspond to altered benthic community structure and seagrass health. Several parameters will be evaluated in this component, including epiphyte community composition and biomass, seagrass blade height, benthic invertebrate community structure and zooxanthellar densities within Cassiopea jellyfish tissue. The second component of this research will be to experimentally manipulate Cassiopea densities in seagrass ecosystems using a press design to remove jellyfish, and add jellyfish to two, extensive seagrass meadows. Benthic community structure and ecosystem function of the seagrass beds will be examined a priori, as well as at the conclusion of the study.

Expected Results:

As little is known about the role of anthropogenic nutrient loading and benthic jellyfish as native invaders in seagrass ecosystems, this research will provide a better understanding of how anthropogenic nutrients may lead to widespread shifts in seagrass community structure and functioning. In both the surveys and manipulative experiments, it is expected that there will be reduced species richness and abundance, decreased seagrass health and altered seagrass ecosystem functioning as a result of increased jellyfish densities.

Potential to Further Environmental/Human Health Protection

Cassiopea jellyfish and anthropogenic nutrient loading are prevalent in coastal habitats in several parts of the world. Therefore, this research has broad-reaching implications for many coastal ecosystems that are under the threat of nutrient pollution, as the subsequent proliferation of Cassiopea among other jellyfish, may result in a decline in coastal ecosystem integrity. Humans rely substantially on coastal ecosystems for many commercially viable species, as well as revenue from tourism, which can be affected by native invaders. Ultimately, this research may elucidate ways to mitigate effects of nutrient pollution and native invaders on coastal ecosystems.

Supplemental Keywords:

native invaders, nutrient pollution, benthic, Cassiopea spp., seagrass, ecosystems, communities, function, estuaries, sub-tropics, jellyfish

Progress and Final Reports:

  • 2012
  • 2013
  • Final