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Publication THE ROLE OF VEGETATIVE FRAGMENTS IN SEAGRASS CONNECTIVITY(2020-01-23) LAI WEN YA SAMANTHA; BIOLOGICAL SCIENCES; Peter Alan Todd; SITI MARYAM YAAKUBThe 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.Publication BIG SHOES TO FILL: THE POTENTIAL OF SEAWALLS TO FUNCTION AS ROCKY SHORE SURROGATES(2013-08-22) LAI WEN YA SAMANTHA; BIOLOGICAL SCIENCES; PETER ALAN TODDLand reclamation and coastal development have converted or degraded large areas of natural intertidal habitats in Singapore, resulting in the loss of coastal habitats and biodiversity. In their place, the total length of seawalls is set to increase, from 319.23 km of presently to more than 600 km by 2060. Given the ubiquity of seawalls and their potential for supporting coastal communities, it is important that conservationists embrace ecological engineering as an additional tool to conserve near shore biodiversity.This thesis (i) quantifies the significant coastal transformations over this period and evaluates the future of marine habitat conservation and sustainability in Singapore, (ii) compares the communities on seawalls with those of natural rocky shores to evaluate the artificial habitat?s potential as a surrogate of the natural one and (iii) uses stable isotope analyses to further elucidate the ecological causes for the community differences observed between seawalls and rocky shores. Main research findings show that seawalls currently fail to act as surrogate habitats of rocky shores, and suggests that the lack of primary productivity could be one of the root causes for the lower diversity observed in the artificial habitat.