Deep sea environments, particularly regions near hydrothermal vents, harbor communities of organisms that are exposed to extreme environmental conditions of pressure, temperature, oxygen and other variables. Oceanographers have accumulated considerable knowledge regarding the assemblages of large animals that live in these environments and the archaea and bacteria that produce organic material to support these animals, but there are still few data on the abundances, diversity and ecological roles of protists that inhabit the deep sea. The discovery of deep-sea hydrothermal vents approximately four decades ago opened a window into a largely unknown and unexplored segment of the biosphere that changed our fundamental views about the distribution and limits of life within the oceans and the origins of all life. One of the most startling discoveries of these studies was that thriving, diverse metazoan communities appeared to be solely supported on carbon originating from bacterial and archaeal chemoautotrophy (organic material produced using chemical energy made available from the vents) thereby changing the conception that all primary productivity on earth is driven by sunlight. Protists play a pivotal role in other bacterial-based food webs within the ocean, and it is likely that they play similar roles in the deep sea. Yet, little work has been done to document or explore this ecological role.
The goal of this research project was to address fundamental questions regarding the species diversity, abundances of protistan taxa, and the trophic activities of protists within the deep ocean, focusing largely on hydrothermal vents. Our research program was designed to:
- determine whether deep-sea communities harbor endemic (unique) species or assemblages of protists
- establish the identity of these species
- begin to establish the trophic activities of these species (what they eat, and how rapidly they grow)
Cruises conducted in October 2007 and November 2008 aboard the Research Vessel Atlantis provided the opportunity to dive to the deep-sea hydrothermal vent systems at Guaymas Basin in the Gulf of California and the ‘9° North’ dive site along the East Pacific Rise in the Deep Submersible Alvin. These cruises entailed numerous dives to obtain samples and conduct experiments that allowed us to survey the breadth of protistan diversity and activity across a wide range of deep-sea/vent habitat types. A variety of sampling techniques (water bottles, sediment cores), collection instruments and colonization substrates were employed (see our Deep-Sea Picture Gallery). Additionally, our goals included establishing cultures of deep-sea heterotrophic protists (ciliates, flagellates, amoebae) that were collected from the study sites for use in subsequent experiments in the lab.
