Geology topics

Oliver Patton

Publications and source records attributed to Oliver Patton.

4 recordsLinked to original sources

USGS2022

Underwater videographic observations of domesticated Delta smelt in field enclosures

The delta smelt ( Hypomesus transpacificus ) is a small, euryhaline fish species endemic to the Sacramento–San Joaquin Delta; it is protected under the U.S. and California Endangered Species Acts, and because of declines in population abundance, the delta smelt may be vulnerable to extinction. The California Department of Water Resources (DWR) is conducting studies to test the viability of using domesticated fish to supplement the wild population of delta smelt. These studies have focused on examining the health and survival of domesticated delta smelt placed inside enclosures (circular cages that are approximately 1.5 meters tall by 1 meter in diameter) into the wild. We completed two parts within this study using underwater cameras inside the enclosures to observe fish behavior and their responses to certain stimuli. In both parts of the study, delta smelt behaviors were broadly categorized into two basic categories: (1) normal and (2) alarm. Normal behavior was characterized as calm, non-polarized, and docile swimming behavior. Alarm behavior was characterized by sudden and rapid darting, polarized frantic swimming activity, and tighter schooling polarization of individuals. The first part of the study took place in a semi-controlled agricultural pond on the campus of the University of California, Davis. At this agricultural pond, we developed methods of observation and documented how fish behaved in response to enclosure disturbances associated with routine cleaning and service that is required during extended field deployments of the enclosures. We observed that delta smelt behavior changed from normal to alarm at the onset of an enclosure service and from alarm to normal within about 2 minutes after the service ended. The second part of the study was completed in cooperation with the DWR. In October 2019, DWR deployed three enclosures in the Sacramento River near Rio Vista, California. To monitor survival rate of delta smelt, DWR permitted us to deploy cameras in one enclosure to document the frequency and duration of alarm behaviors exhibited by delta smelt and the frequency, duration, and intensity of three types of disturbances: (1) noise generated from passing boats, (2) noise generated from the enclosure moving in response to wave energy, and (3) vertical movements of the enclosure generated from wave energy. Alarm behaviors averaged about 2 minutes in duration and occurred most frequently during the evening compared to midday or morning. Each disturbance variable exhibited substantial variability in duration and intensity and occurred least frequently during the morning and evening compared to midday. Alarm behaviors appeared to be most associated with high intensity enclosure noises and vertical movements; however, limited replicate samples prohibited developing a statistical relation. Alarm behaviors did not directly contribute to injury or mortality of individual delta smelt; however, indirect or sublethal effects of alarm behaviors were not examined.

California↗

USGS2020

Estuarine habitat use by White Sturgeon (Acipenser transmontanus)

White Sturgeon ( Acipenser transmontanus) , a species of concern in the San Francisco Estuary, is in relatively low abundance due to a variety of factors. The purpose of our study was to identify the estuarine habitat used by White Sturgeon to aid in the conservation and management of the species locally and across its range. We seasonally sampled sub-adult and adult White Sturgeon in the central estuary using setlines across a habitat gradient representative of three primary structural elements: shallow wetland channels (mean sample depth = 2 m), shallow open-water shoal (mean sample depth = 2 m), and deep open-water channel (mean sample depth = 7 m). We found that the shallow open-water shoal and deep open-water channel habitats were consistently occupied by White Sturgeon in spring, summer, and fall across highly variable water quality conditions, whereas the shallow wetland channel habitat was essentially unoccupied. We conclude that sub-adult and adult White Sturgeon inhabit estuaries in at least spring, summer, and fall and that small, shallow wetland channels are relatively unoccupied.

California↗

USGS2020

Hydrodynamics drive pelagic communities and food web structure in a tidal environment

Hydrodynamic processes can lead to the accumulation and/or dispersal of water column constituents, including sediment, phytoplankton, and particulate detritus. Using a combination of field observations and stable isotope tracing tools, we identified how hydrodynamic processes influenced physical habitat, pelagic communities, and food web structure in a freshwater tidal system. The pelagic habitat of a terminal channel differed spatially, likely aligning with differences in hydrodynamics. Three zones that we classified by exchange with downstream habitat had distinct water quality characteristics, supported different densities of zooplankton and nekton, and exhibited disparate support from benthic and pelagic trophic pathways to pelagic consumers. Hydrodynamically driven zones and their emergent characteristics appeared sensitive to hydrology, as elevated runoff was correlated with a shift in hydrodynamic habitat and organismal distributions. The results of our study highlight the relationship between hydrodynamic processes, biological responses, and climate, and suggest that understanding the physical process can improve understanding of pelagic habitats and communities.

California↗

USGS2019

Dissolved oxygen controls summer habitat of Clear Lake Hitch (Lavinia exilicauda chi), an imperilled potamodromous cyprinid

The Clear Lake Hitch is an imperiled minnow endemic to Clear Lake, Lake County, California, USA that is listed as threatened under the California Endangered Species Act (ESA) and is a candidate for listing under the United States ESA. It exhibits a potamodromous life cycle whereby adults, which reach up to 6+ years in age and over 350 mm in length, migrate into Clear Lake’s ephemeral tributaries briefly during spring to spawn. Conservation and management of Clear Lake Hitch is inhibited, in part, by a lack of information on the lacustrine distribution and habitat of non-breeding individuals within Clear Lake. To address this problem, we sampled Clear Lake Hitch with gill nets in a stratified random sampling design to determine the distribution and habitat associations in early summer 2017 and 2018. We identified abundance-habitat relationships for juvenile and adult Clear Lake Hitch using Bayesian zero-inflated negative binomial generalized linear mixed modeling. The results indicated that dissolved oxygen concentration was the most important habitat feature among those measured; both juvenile and adult Clear Lake Hitch were substantially more abundant in normoxic (> 2 mg l-1) than in hypoxic (< 2 mg l-1) habitat. Both life stages also exhibited weak positive relationships with chlorophyll fluorescence, suggesting that relatively productive habitats may support higher numbers of Clear Lake Hitch. Spatially, juveniles were most abundant in nearshore habitats while adults were ubiquitous, indicating an ontogentic habitat expansion that may be associated with a resource availability-predation risk tradeoff. Management actions undertaken to improve or alleviate water quality and hypoxia problems in Clear Lake would also improve Clear Lake Hitch habitat.

California↗