Shurin Lab in Ecology, Behavior and Evolution, UCSD
We study variation in the structure and function of aquatic ecosystems and its consequences for people. We are particularly interested in the interactive roles of climate, predators and resources, and the importance of evolutionary change for ecological processes. The questions of how ecological and evolutionary changes affect human well-being, and how best to maintain the value of ecosystem services, motivate our research.
Climate and ecosystems
Climate shapes all ecosystems, and climate change caused by human activities is redistributing the world’s biomes, creating new combinations of conditions and organisms that have never previously existed. The relationship between ecosystems and climate is variable and contingent on local conditions like chemistry of the air, water or soil, or the introduction of exotic species or extirpation of natives.
We ask how mountain lake ecosystems vary along elevational climate gradients depending on the introduction of fish predators or the supply of different organic or inorganic resources. We sample a series of lakes annually to ask how climate variability associated with elevation or inter-annual fluctuations affect organisms from bacteria to fish and ecosystem processes like primary production, decomposition and carbon uptake.
Art by Simone des Roches
Evolution and ecosystems
Diversity is the basis for ecosystem stability. Species with different traits, for instance the ability to tolerate changing temperatures, maintain ecosystem functioning in the face of environmental change. However, resilience also depends on genetic and plastic changes within populations where different conditions favor different genes or phenotypes. We ask how populations vary among habitats, for instance fish living in lakes vs. streams, and how these differences affect the impact of these species on their environment. Hank Baker’s Ph.D. thesis studying adaptation by the enigmatic Tui Chub, a minnow with both threatened and invasive sub-species throughout western North America, is an excellent example.
Species invasions and ecosystems
Humans constantly reshape the earth’s biogeography, extirpating some species while promoting the spread of others. Some of these species are viewed fondly and form the basis for valuable enterprises such as fisheries. Others, not so much. Our research studies the impact of colonization of mountain lakes by prized sports fishes such as trout that endanger other species, particularly amphibians.
The recovery of threatened sea otter populations and its impact on coastal shellfish and finfish populations is another example. Otters reduce catches of prized invertebrates like urchins, clams and crabs, but create habitat for fishes by promoting kelp forest expansion. Ed Gregr estimated a net positive impact of otter recovery due to the value of fisheries, tourism and carbon uptake that exceed the loss of shellfish.
The upward expansion of river otters from the Central Valley to the Merced River in Yosemite Valley, starting in 2014, represents colonization of new habitat by a native species. Otters may impact exotic species like crayfish, native (Sacramento Sucker and Rainbow Trout) and exotic (Brown Trout) fish, and endangered frogs and turtles. Stephanie Li and Stefan Samu are studying the role of river otters in the Merced River and Yosemite Valley.
The world’s largest invasive animal, the common hippopotamus, is running amok in Colombia, South America. Options for controlling its expansion are limited by its charismatic appeal around the world and value as a local tourist attraction. We are collaborating with Colombian scientists to estimate the ecosystem and social role of hippos in the Magdalena River watershed.
Ecology and evolution of algae bioenergy systems
Burning fossil fuels threatens the stability of the climate and ecosystems that sustain every aspect of human life. Short of dramatic reductions in human population or standard or living, future generations will need to develop sources of energy that do not disrupt global climate. Algae (phytoplankton in ancient oceans) produced much of the fossil fuels that we use today, and their modern descendants can be cultivated to produce the same organic compounds the same way we grow food. However, the technology for growing algae to generate bioproducts, including oils for energy, is in its infancy. Ecological and evolutionary instability are two of the main problems in algae cultivation. We test how ecological and evolutionary principles can be used to design productive and resilient systems for the production of a variety of natural products including bioenergy. We partner with the U.S. Department of Energy and several commercial companies to understand the evolution and ecology of algae growing in large-scale industrial systems.
Some photos of past research projects:
Ash Meadows, Nevada
Mount Morrison Sunset
Which is the professor and which is the student? Nelson Aranguren and Daniel Duque
Sampling at Hacienda Napoles
Sampling Lago de Tota with Nidia Gil
Pavel Kratina and Rachel Abbott on Convict Lake
Entrance to Hacienda Napoles
with Anne Salomon and Chris Harley
Hippos don't respect barbed wire
on the mighty Magdalena