Reproductive and developmental biology of marine invertebrates; deep-sea biology. I have been conducting long-term research on the factors controlling reproductive cycles in marine invertebrates, particularly those in bathyal and deep-water habitats. Much of my work involves the use of oceanographic research ships and manned submersibles. For the past twelve years, most of this research has been conducted in the Gulf of Mexico (methane sold seeps), the Bahama Islands, the Pacific ocean (hydrothermal vents) and the Gulf of Maine in collaboration with colleagues at the Univ. of Southampton (Britain) and Harbor Branch Oceanographic Inst. A good deal of my work focuses on the ultrastructural features of gametogenesis, especially oogenesis, and the mechanisms of yolk synthesis in the egg. Through the use of electron microscopy, I have been able to better understand how food drives egg production in deep water invertebrates that often have access to limited food supplies. Of particular interest are the factors that determine whether a deep sea species undergoes annual or continuous reproduction, often in the absence of environmental cues (light, food, temperature change) that influence the reproductive cycles of shallow water species.