OCE-RIG: Biological activity on particulate organic material in the coastal ocean

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Overview: Marine microbial populations exhibit characteristic distributions both seasonally and across ocean basins. Using natural spatial and temporal variability, oceanographers have sought to identify the ecological variables that drive the abundance and activity of microbial groups. However, in addition to large scale resource gradients with distance and depth, there are numerous small scale microenvironments in the ocean where rates and processes are likely distinct from those in bulk seawater. Using an on-going time series, the investigator will examine seasonal changes in total and phylotype-specific biological activity in the particulate and freeliving phases. This project supports an early-career investigator working at the Pivers Island Coastal Observatory (PICO). The PICO time series has been sampled weekly (or more frequently) over the last two years to capture physical, chemical and biological variability in the coastal ocean. This time series enables the investigator to collaborate with a number of researchers and will serve as a long-term research focus. Intellectual merit: There is a growing interest in considering the contributions of microscale processes to total biological activity in the marine environment. Using size-fractionated seawater, this investigator will assess the changing contribution of particles to biological activity. Experiments will reveal the biogeochemical importance of particle-attached microbes to bulk biological processes and how they change over the course of a yearly cycle and in response to environmental perturbations (e.g. storms). The investigator will also compare the phylogeny and specific activity of particle-attached and free-living bacteria using 16S rRNA and rDNA libraries to identify which clades are responsible for these changes in total activity. In addition to categorizing clades as particle-attached or free-living, this investigator will examine the time series for transitions between particles and planktonic lifestyles at both coarse (16S rDNA) and fine scales (ITS) of phylogenetic resolution. This work will contribute to a more complete understanding of the role of particulate organic material as a distinct marine microenvironment and clarify its role in biogeochemistry. Broader impacts: The project directly involves a minority graduate student and several undergraduate students (from Duke, Marine Science Education Consortium Schools, and the REU program in marine science) in research activities. This work will also facilitate advancement of early career faculty in oceanography through development of a Preparing Oceanography Future Faculty (POFF) program to encourage women and underrepresented minorities to make the critical jump from graduate students and postdoctoral researchers to tenure-track faculty. POFF will provide motivated graduate students with a background in charting their careers to developing skills important for academic positions. After teaching the course, curricula, lesson plans and open source readings will be made publically available on a website to enable faculty to teach similar courses at other oceanography schools. To expand this outreach beyond academia, graduate students in the course will gain experience in mentoring by supervising middle school oceanography students in a science fair project, providing tours of the marine lab, and taking the eighth graders on a "research" cruise.