A Conceptual Model of the Spread of the Introduced Crab Hemigrapsus sanguineus Using Behavioral, Field, and Genetic StudiesEPA Grant Number: U916132
Title: A Conceptual Model of the Spread of the Introduced Crab Hemigrapsus sanguineus Using Behavioral, Field, and Genetic Studies
Investigators: Park, Susan
Institution: University of Delaware
EPA Project Officer: Cobbs-Green, Gladys M.
Project Period: January 1, 2003 through January 1, 2006
Project Amount: $77,850
RFA: STAR Graduate Fellowships (2003) Recipients Lists
Research Category: Fellowship - Oceanography and Coastal Processes , Academic Fellowships , Aquatic Ecosystems
The objectives of this research project are to: (1) determine the behaviors of the larval Asian shore crab, Hemigrapsus sanguineus, that may affect transport; (2) determine the vertical distribution of larval H. sanguineus in the water column; (3) create a conceptual model of larval transport from behavioral and field data; (4) study the genetic population structure of H. sanguineus to infer the dynamics of the invasion event(s) as well as to shed light on basic evolutionary phenomena such as founder effects and genetic drift; and (5) combine the collected data into a conceptual model of range expansion along the western coast of the Atlantic for use in marine conservation and policy efforts.
H. sanguineus is a marine species native to the western Pacific that recently has been introduced to the Middle-Atlantic coast of North America. Although many ongoing studies of H. sanguineus in its new habitat are concentrating on the ecology of the adults and their potential effects on the ecosystem, no studies are addressing the issues of larval transport and range expansion. This research tests the hypothesis that the present infestation of H. sanguineus results from a single introduction in the Delaware Bay region and that the population has spread from the introduction site via larval dispersal. Corollaries to this hypothesis are that: (1) H. sanguineus possesses a repertoire of larval behaviors that facilitate long-distance transport in the coastal ocean; and (2) populations along the U.S. coast have similar genetic compositions.
The conceptual model of spread of H. sanguineus will be determined in three parts. The first two parts will focus on a conceptual model of larval transport. Larval transport models are most commonly determined by an examination of larval behavior and of the vertical distribution of larvae in the field. Many crustacean larvae express behavioral responses to environmental cues that regulate their vertical distribution in the water column. Because of vertical shear in currents, these behaviors will ultimately control the horizontal transport of the larvae. Therefore, an examination of the behavioral responses of H. sanguineus to various environmental stimuli is a first step in understanding dispersal mechanisms of this species. Field confirmation will be used to verify the laboratory behavioral experiments. The final phase of the model will be to ascertain the relative importance of multiple invasions by examining the population genetics of H. sanguineus in North America. If genetically distinct subpopulations are found along the coast, it could indicate the existence of multiple invasion sites.