MEB Graduate Student Seminars

Yi-Chun Yeh (PI: Dr. Jed Fuhrman)
Long-term dynamics of free-living and particle-associated prokaryotic communities at the San Pedro Ocean Time-series

Abstract: The free-living and particle-associated marine prokaryotes have been proved to differ in their diversity and composition, but drivers of their long-term dynamics are poorly understood. We thus investigated surface to bottom dynamics of free-living (0.2-1.2 µm) and particle-associated (1.2-80 µm) prokaryotes at the San Pedro Ocean Time Series (SPOT) during 2000-2018 by using ssu rRNA tag sequencing. We assessed factors influencing the temporal variation of community composition by canonical correspondence analysis (CCA), and community turnover by the β-nearest taxon index (βNTI), a measure designed to assess the extent of stochastic vs. deterministic drivers. The results showed free-living and particle-associated prokaryotic communities both have strong seasonality at the surface and the deep chlorophyll maximum (DCM), though seasonal variation decreased in warm years, notably after 2012. Moreover, the free-living fraction exhibited a relatively stable dynamic without decreasing in average similarity over time, whereas the particle-associated fraction was undergoing directional change.


Melissa DellaTorre (PI: Dr. Donal Manahan)
Mechanisms of food and temperature impacts on growth in the ocean

Abstract: Variations in sources of energy and temperature have major impacts on the survival and growth of organisms. For marine larval forms, the degree to which food availability can alter physiological tolerances to thermal stress remains unknown. In this presentation, the physiological mechanisms of growth that are impacted by food quantity and temperature will be analyzed, in addition to food-temperature interactions. The goal of these studies is to understand resilience potential to future scenarios of ocean change.


Ariel Levi Simons (PI: Dr. Sergey Nuzhdin)
Using 𝞪, 𝞫, and 𝞯 diversity in describing the health of stream-based benthic macroinvertebrate communities

Abstract: Ecological monitoring of streams has frequently focused on measures describing the taxonomic, and sometimes functional, α diversity of benthic macroinvertebrates (BMIs) within a single sampled community. However, as many ecological processes effectively link BMI stream communities there is a need to describe groups of communities using measures of regional diversity. Here we demonstrate a role for incorporating both a traditional pairwise measure of community turnover, β diversity, in assessing community health as well as ζ diversity, a more generalized framework for describing similarity between multiple communities. Using 4395 samples of BMI stream communities in California, we constructed a model using measures of α, β, and ζ diversity which could account for most of the among-watershed variation in the mean health of communities, as described by the California Streams Condition Index (CSCI).

Tuesday, April 23, 2019
12 PM
AHF 153 (Torrey Webb Room)