Halophila stipulacea: survival under adverse conditions.

Halophila stipulacea is an invasive seagrass species originally native to the Indian Ocean. It invaded the Mediterranean Sea shortly after the opening of the Suez Canal, and has recently been found in the Caribbean. It has been suggested that it arrived in the Mediterranean attached to small pleasure craft, fishing craft, or small cargo vessels. This research examines the feasibility of these methods of transport and the possibility that arrived transported by ocean currents. To investigate potential transport vectors, we collected rooted samples of H. stipulacae from Brewers Bay on the island of Saint Thomas, USVI, and exposed them to conditions that would be experienced under each alternative method of transport. The health of the samples was monitored using a FLOURPEN FP 100 portable fluorometer. Rhizomes, and associated leaf pairs declined rapidly when exposed to air, submersed in freshwater, or kept damp in a towel soaked in seawater, but survived for more than 5 weeks when left floating in a bucket submersed in a seawater tank. Water temperature ranged between 27C and 30C during the experiment. This suggests that it might be possible for H. stipulacae to cross the Atlantic aided by currents.