Updates – Sept & Oct 2019

More soon! 🙂

The lab is growing!

  • We welcome Jessie Moravek and Megan Pagliaro to the Ruhi Lab! Jessie is interested in studying the impacts of hydropower dams, and potential for mitigating them via reoperation and removal; and will be co-advised by Justin Brashares. Megan has been putting together an exciting research project on wetland restoration trajectories in the San Francisco Bay. Read more about them and their inspiring interests!
  • We also look forward to hosting Tadeu Siqueira, Brazilian sabbatical visitor who received a FAPESP grant to research metacommunity dynamics under environmental fluctuations; as well as Ph.D. student Zhenhua Sun, who is visiting this Fall from Sweden to study biodiversity benefits of stormwater ponds. Welcome all!

Busy Spring, exciting Summer

We got funding to study restoring wetlands!

The Ruhi Lab will receive funding from the California Department of Fish and Wildlife, for the project ‘Reconnecting Delta food webs: evaluating the influence of tidal marsh restoration on energy flow and prey availability for native fishes’. This Fall we will start a 3-year project combining analyses of community composition, stable isotopes, and sensor time-series data, in collaboration with USGS and ICF, via State Water Contractors. More soon!

Modeling river-reservoir dynamics

I am Tongbi Tu, a new postdoc in the lab.  I am working on a SESYNC Pursuit to study causal pathways and feedbacks within complex water management systems. This project integrates ecology, hydrology, and water law. The interdisciplinary team is composed of Sankar Arumugam (NCSU), Xiaoli Dong (UC Davis), Caitlin Dyckman (Clemson Univ.), Ted Grantham (UC Berkeley), Lars Olson (Univ. of Maryland), Benjamin Ruddell (Northern Arizona Univ.), Nicola Ulibarri (UC Irvine), and Albert Ruhi (UC Berkeley).

In this working group we will apply physically-based and time-series models to investigate how reservoirs can help provide engineered resilience to socio-environmental systems–especially during periods of drought. We will use a variety of approaches to detect direct and indirect causal pathways and feedbacks between hydrologic conditions, human uses, and downstream ecological outcomes in the Lower Colorado River basin. A better understanding of the complex dynamics of water systems can help advance sustainable freshwater management–a critical need in the face of increasing competition for scarce freshwater resources.

Major dams and regional water supply in the Lower Colorado River Basin (map modified from U.S. Department of Interior)

Drought and invertebrate community change in Californian streams

Hi there! My name is Guillermo de Mendoza and I am a postdoctoral researcher in the lab. Together with David Herbst (UC Santa Cruz) we are studying how stream invertebrate communities are changing over time and across the state of California. We are using a dataset collected via the Surface Water Ambient Monitoring Program (SWAMP). Our question concerns patterns of distance-decay of similarity–that is, dissimilarity in invertebrate communities across spatial and environmental distances.

DDS relationships are typically controlled by environmental gradients, dispersal barriers, and ecological drift. Here we are asking whether DDS can vary over time as well–in response to fluctuating hydrologic conditions. This research will show how drought influences spatial patterns of stream invertebrates (‘who is where’), and will help us further understand how freshwater biodiversity may respond to the multi-year droughts that characterize California’s hydroclimate.

Oct-Dec 2018 updates

  • Akira Terui, postdoc from the University of Minnesota, visited the lab in early November for an ongoing collaboration on the Moran effect.
  • Xavier Benito, SESYNC Postdoc Fellow, visited the lab in mid November to analyze diatom community time-series data.
  • Albert gave a seminar at UC Riverside (Evolution, Ecology, & Organismal Biology Colloquium)
  • We participated at the American Geophysical Union Fall Meeting in Washington, D.C., with the presentation ‘Understanding the cumulative effects of dams on regional streamflow dynamics‘.

Emergent effects of warming on stream food webs

I am Kyle Leathers, a first-year PhD student interested in how aquatic communities are affected by environmental stressors, species interactions, and the combination between the two. My research investigates these topics, focusing on the effects of thermal regimes on stream food webs controlled by the predatory Coastal Giant Salamander (Dicamptodon tenebrosus).

I will apply observational, experimental, and modeling approaches to achieve realism, control, and generalizability in this research. Diverse pool-riffle sites throughout a watershed and artificial streams provide relevant scales for fieldwork and experiments respectively. I will use random forest algorithms to determine the relative importance of warming to community structure. Additionally, I will test food web stability using stable isotope analysis. My results will ultimately inform a Spatial Stream Network (SSN) model that predicts stream food-web structure and Coastal Giant Salamander abundance under future climate change scenarios. Understanding how food-web structure responds to increased water temperature can improve our ability to anticipate associated risks such as trophic cascades, pollutant bioaccumulation, and algal blooms.

A palaeocological perspective into resilience

Understanding how freshwater ecosystems respond to environmental change requires knowing whether recent changes are within the bounds of natural variation or if these systems are, instead, entering new states.

I am Xavier Benito-Granell, an aquatic ecologist and new SESYNC Postdoc Fellow working on questions that revolve around the long-term resilience of diatom communities and their ability to capture regime shifts in lakes. My project, co-developed with my external mentor Albert Ruhi, aims at identifying abrupt transitions in palaeoenvironmental records of high-elevation Andean lakes.

We are applying time-series methods on a unique combination of diatom community data, biophysical data (pollen and sediment geochemistry), and human data (archaeological records). This historical perspective combines data at decadal to millennial scales, and allows asking whether early-warning signals precede regime shifts–something that would be useful to try identify lakes that may be on the verge of a critical transition. We hope this work will advance our understanding of the long-term dynamics and trajectories of high-altitude lakes, and of their responses to ongoing anthropogenic and environmental change.

Paramo landscape around Lake Patoquinuas, Cajas National Park (Ecuador)