Projects Worked On
|, , , , , , , , , , , , ,||Arc of Native Fishes||
This study is a unique examination of how local, regional and broad-scale environmental conditions influence fish recruitment, rearing, and reproduction in diverse habitats, including restored wetlands. It will produce essential background information needed to inform how well tidal marsh restoration projects work to support native fish populations in the CLC. We employ an interdisciplinary approach that couples hydrodynamic and particle tracking models with empirical data on distribution and abundance of phytoplankton, zooplankton, epibenthic invertebrates, and juvenile and adult fishes across habitat types. Monthly and continuous data on water quality and flows will be used to inform a developing regional hydrodynamic model which will be implemented. The model will characterize spatial and temporal changes in water quality due to tidal cycles, local inputs and exports. Monthly cruises will collect additional data on water quality, nutrients and chlorophyll-a. Zooplankton and epibenthic invertebrate are sampled by plankton and otter trawls. Fish are sampled using otter trawling, beach seining, and boat electrofishing. All data are collected concurrently to assess prey availability across species’ life histories. Analysis includes hydrodynamic, spatial and statistical approaches.
We are interested in learning how:
1. Increased overland flow and Delta outflow (from precipitation) pushes environmental conditions to favor certain native and pelagic species in the north Delta.
2. Hydrodynamic variability, including spring/neap tide cycles and overland flow, creates conditions that support biomass accumulation and periodic export in terminal sloughs, causing episodic “pulses” of increased food availability to pelagic organisms.
3. Timing of food pulses affects the community composition of fishes by favoring species that are recruiting concurrently with food pulses.
4. Differences in the fish community composition of sloughs is driven by species’ phenology and food web structure.
5. Restoration outcomes for pelagic fishes depend upon the influence of hydrodynamic and geomorphic characteristics on food webs.
|, , , , , , ,||The Complete Marsh Project||
Tidal wetland restoration success in Suisun Marsh requires science-based decision support from gathering and synthesis of pre-restoration baseline data. It also relies on a mechanistic understanding of the influence of hydrogeomorphology (flow, tidal prism, channel structure) on foodweb dynamics. Long term data from that project suggest that tidal wetlands in Suisun Marsh function as nurseries for recruiting juvenile fish, presumably because juvenile fish can utilize both pelagic and benthic food webs during this critical period of growth and survival. This project study mechanisms for creating favorable rearing conditions for juvenile estuarine and migratory fishes that rely on tidal wetlands for food and refuge during this critical period of growth and survival, especially in drought years when suboptimal conditions occur further upstream in the Delta. By modeling food web responses to hydrologic change, and differential resource use among native and alien juvenile fish, we gain a better understanding of how management scenarios can promote fish recruitment. We employ empirically-derived hydrodynamic modeling in conjunction with stable isotope modeling of aquatic food webs and patterns of juvenile fish foraging and growth. We hypothesize that (1) hydrology influences productivity and food availability in tidal wetlands, (2) juvenile fish foraging and growth varies as a function of food availability, and (3) juvenile fish resource use varies as a function of life stage and life history strategy (benthic vs. pelagic). Understanding how tidal wetland food webs support juvenile fish improve designs of tidal wetland restoration projects aiming to increase food availability to juvenile native fishes.