Every time you look around you see species diversity around you: you can see many types of trees, animals, etc. The ocean is no different in this respect. You look around and you may see fishes, birds, sharks, or marine mammals (like the sea lion that decided to hang out with us during our night shift). But there is more diversity than meets the eye: in the microbial world!! It is likely that one of the first things that comes to mind about bacteria is their role in diseases and infections. Although that is true, it is only a small fraction of the diversity of microorganisms that we can find around us. They play very important roles in all ecosystems, and are a very important component of the oceans.
Microbes are extremely abundant in the oceans: on average we can find close to 1 billion bacterial cells – including hundreds of species- in a single liter of seawater. The microbial biomass in the world’s oceans has been estimated to be almost 90% of the total ocean biomass!!
Microorganisms play a very important role in cycling nutrients in the oceans. They also are able to sustain communities in environments such as volcanic vents or methane seeps. But, a relatively unexplored role for microorganisms in the marine environment is their direct relationship with the animals that live in it. Almost every animal, including ourselves, carries a different set of microbial species that live within us.
An especially interesting set of microorganisms is found in the gut. These microbes are adapted for life in gut conditions: they process the food ingested by the organism, gaining energy for themselves while also providing nutrients to their host that it would not otherwise be able to absorb. A common example is the community of microbes that lives in the gut of termites: they allow the insect to process the cellulose in wood. One of the questions that I want to investigate is how this type of relationship works in the marine environment. I’m looking at the microbial diversity within the gut of fishes that live in the Santa Barbara Basin, and using this information to get a better idea of the deep relationship between microbes, animals and their habitat. Do we see the same type of microorganisms in all fish species, or there are species-specific types? How might the diet of each fish affect this microbial diversity? Are there interesting metabolic functions that the microorganisms are doing inside the fish guts that are beneficial for the fishes?