THE ROLE OF VEGETATIVE FRAGMENTS IN SEAGRASS CONNECTIVITY

Abstract

The study of the movement ecology of seagrasses is critical to understanding how they disperse, exchange genetic material, and persist in changing environments. Seagrasses are widely known to disperse long distances via their buoyant fruits. However, what is less studied is the process of long-distance dispersal via vegetative fragments, which can re-establish elsewhere following detachment from the parent plant to create a new plant. The focus of this thesis is the demographic and genetic connectivity of seagrass meadows in Singapore, with an emphasis on the vegetative fragment dispersal mechanism. Through a series of mesocosm and flume experiments, I obtained a range of parameters describing how vegetative fragments behave during the dispersal process, and developed a novel agent-based model that allowed me to predict the dispersal distances and patterns of fragments released from Singapore’s meadows. To determine how this predicted dispersal is reflected in the seagrass populations, I elucidated the genetic diversity and structure of local meadows using microsatellite DNA markers. My findings revealed that fragments are potentially an effective mode of dispersal for seagrasses, and that effectiveness of this kind of dispersal is likely to differ across species.