The Smithsonian Marine Science Symposium was held on 15-16 November 2007 in Washington, D.C. It represented the first major dissemination of marine research results since the establishment of the Smithsonian Marine Science Network (MSN). The 39 papers in this volume represent a wide range of marine research studies that demonstrate the breadth and diversity of science initiatives supported by the MSN. The first section contains an overview of the MSN along with papers describing the multidisciplinary investigations spanning more than 37 years for the four Smithsonian marine facilities that constitute the Network: the Smithsonian Environmental Research Center at the Chesapeake Bay, Maryland; the National Museum of Natural History's Smithsonian Marine Station at Fort Pierce, Florida; the Caribbean Coral Reef Ecosystems Program, with its Carrie Bow Marine Field Station in Belize; and the Smithsonian Tropical Research Institute in Panama. Subsequent papers represent findings by Smithsonian scholars and their collaborators on overarching topics of marine biodiversity, evolution, and speciation; biogeography, invasive species, and marine conservation; and forces of ecological change in marine systems. Overview of Smithsonian Marine Science. Introduction to the Smithsonian Marine Science Network / Michael A. Lang ; Land-Sea Interactions and Human Impacts in the Coastal Zone / Anson H. Hines ; Smithsonian Marine Station at Fort Pierce : Thirty-Eight Years of Research on the Marine Biodiversity of Florida / Valerie J. Paul [and others] ; Caribbean Coral Reef Ecosystems : Thirty-Five Years of Smithsonian Marine Science in Belize / Klaus Rèutzler ; The Smithsonian Tropical Research Institute : Marine Research, Education, and Conservation in Panama / D. Ross Robertson [and others] -- Marine Biodiversity, Evolution, and Speciation. Protandric Simultaneous Hermaphroditism Is a Conserved Trait in Lysmata (Caridea: Lysmatidae) : Implication for the Evolution of Hermaphroditism in the Genus / J. Antonio Baeza ; Reconciling Genetic Lineages with Species in Western Atlantic Coryphopterus (Teleostei: Gobiidae) / Carole C. Baldwin [and others] ; Recent Insights into Cnidarian Phylogeny / Allen G. Collins ; Biodiversity and Abundance of Sponges in Caribbean Mangrove : Indicators of Environmental Quality / Maria Cristina Diaz, Klaus Rèutzler ; Internal Transcribed Spacer 2 (ITS2) Variation in the Gorgonian Coral Pseudopterogorgia bipinnata in Belize and Panama / Daniel Dorado, Juan A. Sánchez ; Obvious Invaders and Overlooked Infauna : Unexpected Constituents of the Decapod Crustacean Fauna at Twin Cays, Belize / Darryl L. Felder [and others] ; Imposex in One of the World's Busiest Shipping Zones / Carter Li, Rachel Collin ; Shorefishes of the Tropical Eastern Pacific Online Information System / D. Ross Robertson ; Nephasoma pellucidum : A Model Species for Sipunculan Development? / Anja Schulze, Mary E. Rice ; Mitochondrial Phylogeography of the Intertidal Isopod Excirolana braziliensis on the Two Sides of the Isthmus of Panama / Renate Sponer, Harilaos A. Lessios ; Stability and Change in the Indian River Area Bryozoan Fauna over a Twenty-Four Year Period / Judith E. Winston. Biogeography, Invasive Species, and Marine Conservation. The Turtles' Tale : Flagships and Instruments for Marine Research, Education, and Conservation / John G. Frazierian ; Latitudinal Gradients in Recruitment and Community Dynamics in Marine Epifaunal Communities : Implications for Invasion Success / Amy L. Freestone, Richard W. Osman, Robert B. Whitlatch ; Ex Situ Culture of Caribbean and Pacific Coral Larvae Comparing Various Flow-Through Chambers / Mary Hagedorn [and others] ; Worldwide Diving Discoveries of Living Fossil Animals from the Depths of Anchialine and Marine Caves / Thomas M. Iliffe, Louis S. Kornicker ; Decimating Mangrove Forests for Commercial Development in the Pelican Cays, Belize : Long-Term Ecological Loss for Short-Term Gain? / Ian G. Macintyre [and others] ; Using the Panama Canal to Test Predictions about Tropical Marine Invasions / Gregory M. Ruiz, Mark E. Torchin, Katharine Grant ; Ciguatera Fish Poisoning in the Caribbean / Patricia A. Tester [and others] -- Forces of Ecological Change in Marine Systems. History of Reef Coral Assemblages on the Rhomboid Shoals of Belize / Richard B. Aronson [and others] ; Climate and Hydrological Factors Affecting Variation in Chlorophyll Concentration and Water Clarity in the Bahia Almirante, Panama / Rachel Collin [and others] ; Nutrient and Chlorophyll Dynamics in Pacific Central America (Panama) / Luis D'Croz, Aaron O'Dea ; Growth and Nutrient Conservation in Rhizophora mangle in Response to Fertilization along Latitudinal and Tidal Gradients / Ilka C. Feller [and others] ; Underwater Spectral Energy Distribution and Seagrass Depth Limits along an Optical Water Quality Gradient / Charles L. Gallegos [and others] ; Interannual Variation in Gelatinous Zooplankton and Their Prey in the Rhode River, Maryland / Eileen S. Graham [and others] ; Patterns of Water Quality and Movement in the Vicinity of Carrie Bow Cay, Belize / Karen H. Koltes, Thomas B. Opishinski ; Global Change and Marsh Elevation Dynamics : Experimenting Where Land Meets Sea and Biology Meets Geology / J. Adam Langley [and others] ; Herbivory, Nutrients, Stochastic Events, and Relative Dominances of Benthic Indicator Groups on Coral Reefs : A Review and Recommendations / Mark M. Littler [and others] ; Impacts of Human Disturbance on Soil Erosion Potential and Habitat Stability of Mangrove-Dominated Islands in the Pelican Cays and Twin Cays Ranges, Belize / Karen L. McKee, William C. Vervaeke ; An Overview of Symbiont-Bleaching in the Epiphytic Foraminiferan Sorites dominicensis / Susan L. Richardson ; New Perspectives on Ecological Mechanisms Affecting Coral Recruitment on Reefs / Raphael Ritson-Williams [and others] ; Do Indian River Lagoon Wetland Impoundments (Eastern Florida) Negatively Impact Fiddler Crab (Genus Uca) Populations? / Bjorn G. Tunberg ; Dynamic Hydrology of a Mangrove Island : Twin Cays, Belize / Daniel W. Urish [and others] ; Ecological Characteristics of Batis maritima in Florida and Belize / Dennis F. Whigham [and others] ; Sponge Community Dynamics on Caribbean Mangrove Roots : Significance of Species Idiosyncrasies / Janie L. Wulff.