Willette, D.A.

The loss of biodiversity by the replacement of invasive species could lead to the loss of functional traits that maintain certain ecosystem services (ES). The ES method provides a conceptual framework to value changes of functional traits related to this loss of biodiversity. The Caribbean Sea offers a multifaceted seascape to evaluate this approach as native seagrass species (Thalassia testudinum, Syringodium filiforme or Halodule wrightii) cohabit this region together with the invasive seagrass Halophila stipulacea, native to the Indian Ocean. The functional traits of native seagrass species in the Caribbean are compared to different traits of H. stipulacea observed worldwide with the aim of evaluating the dimensions of this change in terms of the ES that seagrass meadows provide in the Caribbean. Under a changing seascape due to climate change and anthropogenic pressures that have driven the disappearance of most seagrass meadows in the Caribbean, we explore how this invasive seagrass could play a role in restoration attempts as a pioneer species where native species have been lost. The potential unintended consequences of the presence of H. stipulacea to replace services of native species are also noted.

Abstract:

Halophila stipulacea (Hydrocharitaceae) is reported for the first time from Aruba, Curaçao, Grenadines (Grenada), St. Eustatius, St. John (US Virgin Islands), St. Martin (France), and St. Vincent and the Grenadines, bringing the total number of known occurrences from eastern Caribbean islands to 19. Native to the Red Sea and western Indian Ocean, H. stipulacea spread to the Mediterranean Sea in the late 1800s and became established in the eastern Caribbean in 2002. The species has dispersed north and south of its first sighting in Grenada and now spans a latitudinal distance of 6° (>700 km), most likely facilitated by a combination of commercial and recreational boat traffic. The continuing range expansion of H. stipulacea indicates the species has successfully acclimated to surviving in the Caribbean environment, warranting further investigation into its ecological interactions with the indigenous seagrasses.