It was long thought that dark, oxygen-poor habitats, such as much of the deep sea, were largely devoid of life and housed low density, yet diverse assemblages of endemic fauna. The discovery of hydrothermal vents in the 1970s and subsequent realization that non-light based energy sources fuel a variety of marine foodwebs via chemosynthesis in extreme environments have since revolutionized ecological thinking about such ecosystems. They are now known to be highly productive, exhibiting greater macrofaunal biomass, yet lower organismal diversity, than neighboring areas devoid of chemosynthetic influx. Pakes? research provides preliminary evidence that such a pattern may exist in another extreme ecosystem- underwater anchialine caves, in which a discrete marine layer rests beneath one or more isolated layers of brackish or freshwater. Most anchialine caves contain low densities of invertebrates, yet some have inexplicably large biomasses of shrimp and members of the Remipedia, a rare crustacean class discovered in 1981 and found only in subtropical anchialine caves. It is the aim of Pakes? dissertation to integrate studies of geochemistry, microbiology, invertebrate food web dynamics, and behavior to better understand whether chemosynthesis correlates with macrofaunal density and diversity as well as remipede feeding behaviors in these extreme ecosystems.
." The field trip funded by this grant yielded ample material for analysis of the food web and behavior of crustaceans in a cave which exemplifies this extreme underwater ecosystem. In addition, concurent Carbon, Nitrogen, Sulfur Stable isotope Analysis development was completed in order to analyze cave samples. Both stable isotope and video analyses indicated that Remipedes were feeding on shrimp in the system and that the caves were dependent on a chemosynthetic source of energy as hypothesized. Bayesian analyses of stable isotope data suggested that nutrional input likely varies spatially. Furthermore, video analyses were instrumental in advancing our knowledge of remipede swimming and behavior with respect to their patchy environments in situ. BROADER IMPACTS: Stable Isotope Analyses developed by this study are currently being used by a variety of researchers studying terrestrial and marine systems. Findings supported by this grant have been presented at several international congresses during the fellowship's tenure and are currently in press, in review, and in preparation. Undergraduates of underrepresented groups from both the US and Mexico were instrumental in the data collection for these projects during field and laboratory work. Several of these students have leveraged these experiences and resultant publications in their successful applications to graduate programs. In addition, research from this project has been highlighted on several university and nonprofit websites in order to educate the public about cave research and conservation. Lastly, this study has begun a strong collaboration between the PI and University of Quintana Roo, Mexico at Cozumel, faciliating preliminary data aquisition that paved the way for a recently accepted cave investigation grant.
