Meeting Abstract
Native Caribbean seagrasses, like coral reefs, are able to support diverse and abundant marine organisms in part because their wide range of physical characteristics and epibiotic communities generates varied food and shelter resources. Invasion of a native seagrass bed by an exotic seagrass therefore has great potential to disrupt existing marine communities by replacing or altering vital habitats. The seagrass Halophila stipulacea spread to the Mediterranean Sea from the Indian Ocean over a century ago, but has only recently (2002) been introduced to the Caribbean region. Little is known about the specific changes made to Caribbean communities by the arrival of this seagrass. This study uses environmental DNA techniques to characterize fish and other communities associated with native versus invasive seagrass habitats in St. Thomas, U.S. Virgin Islands, where H. stipulacea was first observed in 2012. Our primary hypothesis is that the diversity and abundance of fish and other organisms will decline in heavily-invaded areas. However, there are also indications from prior research that alterations may be counterintuitive and/or complex; shifts in habitat utilization by different fish feeding guilds may arise, rather than substantial declines in standard diversity metrics. The environmental DNA approach applied here complements past and upcoming traditional trap-based studies, and provides a crucial level of detail about fish communities in native and invaded seagrass habitats.
