The Dark Ocean Biosphere
By analyzing proteomes, diversity, and chemistry alongside stable isotope experiments we are revealing dark ocean processes.
Image: Alex working with the ROV and our deep sea sampling systems - being visited on the seafloor by this giant crab. Photo: M. Hamilton
The Dark Ocean Biosphere exists in a different energy dynamic than what we know from our own sunlit lives and it is encountered using robots and submersibles. The deep sea consists of microbial environments in the aphotic pelagic water column and in sediments, pore waters, hydrothermal vents and the upper basaltic crust. Depending on the quantity of particulate matter in the water, levels of sunlight sufficient for photosynthesis penetrate only a few tens to hundreds of meters into the ocean. In the mesopelagic “twilight zone” (~ 200 m – 900 m) and dark bathypelagic water layers (1000 m – 4000 m) the sources for organic material fueling the metabolism of deep oceanic microbes are not obvious – allowing for exciting discoveries that are fundamentally changing our understanding of the role of the dark ocean in the global Earth system and its biogeochemical cycles!
In the Worden Lab we primarily examine microbes involved in organic matter cycling and biogeochemistry in the ocean, especially of the elements carbon, nitrogen, sulfur and non-protein organic compounds like vitamins. We also study multicellular eukaryotic animals, like corals (Fig. 2) and zooplankton – particularly in connection to interacting microbes. We aim to understand the structure and dynamics of natural microbial communities – from the single cell level to organismal interactions and communities, including microbiomes, — that collectively comprise the biota of these dark environments.
Left Image: Alex and Victoria Orphan at sea in the Pacific by the ROV Doc Ricketts in the moonpool room of the R/V Western Flyer.
Right Image: Graduate student Rachel Harbeitner sampling sediment cores during her Ph.D. research
Image: A deep sea bubblegum coral (Paragorgia arborea) in the Eastern North Pacific. Photo: C Eckmann
We combine laboratory experiments and analyses with ship-going research. For microbial research some studies focus on genomic, transcriptomic, and proteomic technologies, single cell analyses to describe and explore the genomics, biochemistry, metabolism and ecology of marine Bacteria and Archaea, Protists, Viruses – and their effects on ecosystem processes. To this end the Worden Lab has developed two new types of deep sea experimental systems - Bird Bag Incubators (Fig. 3) and Deep Sea Sediment Injector (DSSI) samplers (Fig. 4). We’ve also shared these systems with collaborators Richards (Oxford), Orphan (CalTech), and Dekas Labs (Stanford).