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.
|, , ,||Blacklock Restoring Marsh||
Historically, the landscape of Suisun Marsh was dominated by tidal wetlands, with vast expanses of marsh plain that would flood during high tides (Moyle et al. 2014). In 1897, construction of a railroad through the western marsh facilitated rapid development of managed wetlands for waterfowl hunting (Arnold 1996). Today, approximately 340 km (210 miles) of constructed levees separate about 210 km2 (52,000 acres) of managed marsh from tidal waterways (Moyle et al. 2014). The Suisun Marsh Habitat Management, Preservation, and Restoration Plan mandates (1) conversion of 20-30 km2 (5,000- 7,000 acres) from managed wetlands to tidal wetlands and (2) the enhancement of 160-200 km2 (40,000- 50,000 acres) of managed wetlands (United States Department of the Interior Bureau of Reclamation 2013). Understanding how managed wetlands influence subtidal waterways is important for water management and the development of restoration designs that will benefit aquatic species. To address this knowledge gap, the UC Davis Blacklock Fish Study was initiated in October 2013 to collect and interpret information on the distribution and abundance of fishes in a restoring tidal marsh, a managed wetland, and adjacent tidal waterways. We used catch per unit effort (CPUE) of fishes collected during monthly trawl and beach-seine sampling conducted by the Blacklock Fish Study to evaluate differences in the distribution and abundance of fishes among a managed wetland, a restoring tidal wetland, and adjacent subtidal sloughs and embayments.
|, , , , , , ,||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.
|, , , , , , , , ,||Suisun Marsh Fish Study||
The University of California, Davis has been involved in fish and wildlife monitoring and research within Suisun Marsh for 35 years and has been instrumental in detecting important trends associated with naturally fluctuating environmental conditions as well as anthropogenic influences. Research has included a 35+ year time series on the fish and invertebrate communities of the slough networks, research on waterfowl nesting patterns and population biology, and research on the demography of salt marsh harvest mouse. The Suisun Marsh Fish Study anchors this effort as it is the longest established survey in Suisun marsh. It will continue the research of Professor Peter Moyle under the direction of John Durand, and will focus upon the detection of changes in the aquatic ecosystem in response to developing stressors in the San Francisco Estuary (SFE). This time series is designed to further our understanding of the ecology and function of the fish community residing within Suisun Marsh and the San Francisco Estuary (SFE), and acts as one of the key surveys with Interagency Ecological Program’s monitoring effort. Additional tasks will support other research, some of which is ongoing, and some of which is new. Funding for waterfowl studies will support and extend the research of Professor John Eadie, who has studied managed wetland production in Suisun Marsh for the past decade. Funding for mammal studies will support and extend the research of Professor Doug Kelt (UC Davis, Department of Wildlife, Fish and Conservation Biology), who has studied the ecology of saltmarsh harvest mouse in Suisun Marsh for the past 5 years. Funding for herpetological studies will support the research of Professor Brian Todd (UC Davis, Department of Wildlife, Fish and Conservation Biology), who is interested in Suisun Marsh managed wetlands as habitat for western pond turtles. These projects will help to improve management of Suisun Marsh to benefit multiple taxa across changing estuarine conditions. This is particularly important currently because of the effects of drought and climate change, which are likely related to the declines of smelt and salmon in the SFE and its watershed. Trawl catches of native fishes in recent years show less vulnerability in Suisun Marsh to the pelagic organism decline (POD) than in other parts of the SFE. Recent analyses suggest that the Marsh may act as a refuge/nursery for young fishes, buffering stressors that occur in other regions of the SFE. Likewise, Suisun Marsh is a known source of waterfowl production that affects bird populations across the state. The Marsh also functions as a refuge for other taxa, but little is known about these populations. Together, these projects will support an integrative understanding of the ecology of Suisun Marsh and its management practices. The fish study has traditionally been constrained to the slough networks surrounding managed wetlands. Waterfowl studies have focused on pond dynamics. Traditionally, each research domain has not been able to “cross the levees” to integrate their work horizontally across the entire system. However, emerging research supports the idea that certain types of pond management can support both native or desirable fish species and waterfowl. By working with local stakeholders and each other, the UCD research team can examine the effect of changing management strategies in an effort to maximize potential ecosystem benefits, as well as to advise tidal marsh restoration programs.