Potential impacts of Halophila stipulacea invasion on organic matter decomposition and storage in Caribbean seagrass meadows

In 2002, Halophila stipulacea (Forsskål and Niebuhr) Ascherson, a seagrass native to the Red Sea, Persian Gulf, and the Indian Ocean was identified in Flamingo Bay, Grenada (Caribbean Sea). The species has since spread to most of the Caribbean Islands, where it often forms large populations and displaces native seagrasses. This restructuring of Caribbean seagrass systems may reduce biodiversity, alter species interactions, and change organic matter storage and nutrient cycling. This study aimed to characterize and compare the contribution of organic matter to the food web and sediment pool by H. stipulacea and native Thalassia testudinum. Standing stock of seagrass and detritus (as coarse particulate organic matter) was quantified via biomass coring, while decomposition rates were estimated using a litter bag experiment.  Epiphytic biomass was also compared between the two seagrasses. Initial analysis indicated a slight positive correlation between detritus and T. testudinum biomass, but no correlation between detritus and H. stipulacea biomass was apparent. Finally, elemental analysis was conducted on seagrass detritus, epiphytes, and sediment cores to determine nitrogen and carbon content. H. stipulacea decomposed more rapidly than T. testudinum (7.3±0.2% and 4.3±0.2% material lost per day, respectively; mean±s.d.), suggesting that spread of non-native seagrass may reduce detrital pools and carbon storage in the sediments.  

Presentation Preference: Poster

Primary Presenter: Jonathan Herald, Kennesaw State University (jherald3@students.kennesaw.edu)

Authors:

Jonathan Herald, Kennesaw State University, 1000 Chastain Rd NW, Kennesaw, GA, USA  (jherald3@students.kennesaw.edu)

Troy Mutchler, Kennesaw State University, 1000 Chastain Rd NW, Kennesaw, GA, USA  (tmutchle@kennesaw.edu)

Kayla Gonzalez-Boy, Kennesaw State University, 1000 Chastain Rd NW, Kennesaw, GA, USA  (kgonza36@students.kennesaw.edu)

Ashlyn Stanalonis, Kennesaw State University, 1000 Chastain Rd NW, Kennesaw, GA, USA  (astanalo@students.kennesaw.edu)

Ángel Dieppa-Ayala, Jobos Bay Estuarine Research Reserve, Puerto Rico, USA  (adieppa@drna.pr.gov)

Milton Muñoz-Hincapié, Jobos Bay Estuarine Research Reserve, Puerto Rico, USA  (mmunoz@drna.pr.gov)

Mark McCarthy, Estonian University of Life Sciences, Tartu, Estonia  (mmccar49@kennesaw.edu)