Victoria Hill

Victoria Hill
Old Dominion University | ODU · Department of Ocean and Earth Sciences

PhD

About

53
Publications
11,060
Reads
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2,266
Citations
Citations since 2017
21 Research Items
1186 Citations
2017201820192020202120222023050100150200250
2017201820192020202120222023050100150200250
2017201820192020202120222023050100150200250
2017201820192020202120222023050100150200250
Additional affiliations
February 2003 - present
Old Dominion University
Position
  • Research Assistant
January 2003 - present
Old Dominion University
Position
  • Research Assistant

Publications

Publications (53)
Article
Full-text available
Photorespiration, commonly viewed as a loss in photosynthetic productivity of C3 plants, is expected to decline with increasing atmospheric CO 2 , even though photorespiration plays an important role in the oxidative stress responses. This study aimed to quantify the role of photorespiration and alternative photoprotection mechanisms in Zostera mar...
Article
Full-text available
Novel observations of the seasonal evolution of an ice algal bloom on the Chukchi shelf were collected by two autonomous buoys deployed 180 km apart in first‐year drifting sea ice. High attenuation of blue light in the bottom of the ice indicated considerable accumulation of ice algae biomass with derived Chlorophyll‐a concentrations (Chl a) up to...
Article
Seagrass meadows are degraded globally and continue to decline in areal extent due to human pressures and climate change. This study used the bio-optical model GrassLight to explore the impact of climate change and anthropogenic stressors on seagrass extent, leaf area index (LAI) and belowground organic carbon (BGC) in St. Joseph Bay, Florida, usin...
Article
Full-text available
Oceanographic lidar measurements of the linear depolarization ratio, δ, contain information on the bulk characteristics of marine particles that could improve our ability to study ocean biogeochemistry. However, a scarcity of information on the polarized light-scattering properties of marine particles and the lack of a framework for separating sing...
Article
Full-text available
Seagrasses are globally recognized for their contribution to blue carbon sequestration. However, accurate quantification of their carbon storage capacity remains uncertain due, in part, to an incomplete inventory of global seagrass extent and assessment of its temporal variability. Furthermore, seagrasses are undergoing significant decline globally...
Article
Full-text available
Satellite image artefacts are features that appear in an image but not in the original imaged object and can negatively impact the interpretation of satellite data. Vertical artefacts are linear features oriented in the along-track direction of an image system and can present as either banding or striping; banding are features with a consistent wid...
Article
Seagrasses account for approximately 10% of the total carbon stored in the ocean, although photosynthesis of seagrasses is carbon-limited at present oceanic pH levels. Therefore, increasing atmospheric CO 2 concentration, which results in ocean acidification/carbonation, is predicted to have a positive impact on seagrass productivity. Previous stud...
Article
Full-text available
Satellite remote sensing offers an effective remedy to challenges in ground-based and aerial mapping that have previously impeded quantitative assessments of global seagrass extent. Commercial satellite platforms offer fine spatial resolution, an important consideration in patchy seagrass ecosystems. Currently, no consistent protocol exists for ima...
Article
Full-text available
The growth of phytoplankton at high latitudes was generally thought to begin in open waters of the marginal ice zone once the highly reflective sea ice retreats in spring, solar elevation increases, and surface waters become stratified by the addition of sea-ice melt water. In fact, virtually all recent large-scale estimates of primary production i...
Article
Full-text available
Seagrass form the basis for critically important marine ecosystems. Previously, we implemented a deep convolutional neural network (CNN) model to detect seagrass in multispectral satellite images of three coastal habitats in northern Florida. However, a deep CNN model trained at one location usually does not generalize to other locations due to dat...
Article
Full-text available
Coastal ecosystems are critically affected by seagrass, both economically and ecologically. However, reliable seagrass distribution information is lacking in nearly all parts of the world because of the excessive costs associated with its assessment. In this paper, we develop two deep learning models for automatic seagrass distribution quantificati...
Conference Paper
Full-text available
Seagrass form the basis for critically important marine ecosystems. Previously, we implemented a deep convolutional neural network (CNN) model to detect seagrass in multispectral satellite images of three coastal habitats in northern Florida. However, a deep CNN model trained at one location usually does not generalize to other locations due to dat...
Chapter
Full-text available
Seagrass is an important factor to balance marine ecological systems, and there is a great interest in monitoring its distribution in different parts of the world. This paper presents a deep capsule network for classification of seagrass in high-resolution multispectral satellite images. We tested our method on three satellite images of the coastal...
Chapter
Full-text available
Seagrass is a highly valuable component of coastal ecosystems ecologically and economically, yet reliable mapping of seagrass density is not available due to the high cost of data processing and spatial mapping. This paper presents a deep learning approach for quantification of leaf area index (LAI) levels of seagrass in coastal water using high re...
Conference Paper
Full-text available
Seagrass habitats are becoming extremely vulnerable due to human intrusion to seagrass meadows, which results in unbalanced marine ecosystems and extinction of marine animals. Traditionally, manual scarring has been used to identify and quantify seagrass propeller scars. However, this method requires site visitation and it is cost ineffective. In t...
Article
Passive ocean color remote sensing has revolutionized our ability to quantify the horizontal distribution of phytoplankton across the ocean surface. Lidar technology can provide remotely sensed estimates of the vertical distribution of optical properties and suspended particles in natural waters, significantly improving our ability to model upper o...
Article
The proximity of seagrass meadows to centers of human activity makes them vulnerable to a variety of habitat degrading insults. Physical scarring has long been recognized as an important but difficult-to-quantify source of habitat fragmentation and seagrass loss. We present a pixel-based algorithm to detect seafloor propeller seagrass scars in shal...
Article
Observations of the seasonal light field in the upper Arctic Ocean are critical to understanding the impacts of changing Arctic ice conditions on phytoplankton growth in the water column. Here we discuss data from a new sensor system, deployed in seasonal ice cover north-east of Utqiaġvik, Alaska in March 2014. The system was designed to provide ob...
Article
CO2 is a critical and potentially limiting substrate for photosynthesis of both terrestrial and aquatic ecosystems. In addition to being a climatewarming greenhouse gas, increasing concentrations of CO2 will dissolve in the oceans, eliciting both negative and positive responses among organisms in a process commonly known as ocean acidification. The...
Article
This paper provides a synthesis of available in situ primary production (PP) measurements from the Pacific Arctic Region (PAR), collected between 1950 and 2012. Seasonal integrated primary production (IPP) across the PAR was calculated from 524 profiles, 340 of which were also analyzed to determine the average vertical distribution of PP rates for...
Article
The absorption of solar energy by colored dissolved organic material (CDOM) in Arctic surface waters during the springtime is increasingly recognized as having profound impacts on seasonal retreat of ice from the Arctic Ocean. This study observed the production of CDOM within first year landfast sea ice, its contribution to light absorption within...
Article
Isotopic discrimination against 13 C during photosynthesis is determined by a combination of environmental conditions and physiological mechanisms that control delivery of CO 2 to RUBISCO. This study investigated the effects of light, flow, dissolved inorganic carbon (DIC) concentration, and its speciation, on photosynthetic carbon assimilation of...
Article
Although environmental requirements of seagrasses have been studied for years, reliable metrics for predicting their response to current or future conditions remain elusive. Eelgrass (Zostera marina L.) populations of the Chesapeake region lie near the southern limit of their range in the Western North Atlantic, exposing them to increasing thermal...
Article
Full-text available
A coupled biophysical model is used to examine the impact of changes in sea ice and snow cover and nutrient availability on the formation of massive under-ice phytoplankton blooms (MUPBs) in the Chukchi Sea of the Arctic Ocean over the period 1988–2013. The model is able to reproduce the basic features of the ICESCAPE (Impacts of Climate on EcoSyst...
Article
Full-text available
Seagrasses provide a number of critical ecosystem services, including habitat for numerous species, sediment stabilization and shoreline protection. Ariel photography is a useful tool to estimate the areal extent of seagrasses, but recent innovations in radiometrically calibrated sensors and algorithm development have allowed identification of bent...
Article
Full-text available
We present a two-step algorithm for the detection of seafloor propeller seagrass scars in shallow water using panchromatic images. The first step is to classify image pixels into scar and non-scar categories based on a sparse coding algorithm. The first step produces an initial scar map in which false positive scar pixels may be present. In the sec...
Chapter
Full-text available
The lower trophic level taxa underpin the marine ecosystems of the Pacific Arctic Region (PAR). Recent field observations indicate that range shifts, and changes in the relative abundance of particular taxa have occurred within the last decade. Here we provide a region wide survey of the diversity and distribution of viruses, bacteria, archaea, aut...
Poster
Full-text available
A comparison was made of the combined impacts of temperature and CO2 on photosynthesis, growth and survival of seagrass populations from a cold water environment in Puget Sound, WA (USA) (10º C), to those from a population in South Bay, VA (USA), that grow at 25° C or more. Plants were maintained in outdoor aquaria at different CO2 concentrations,...
Article
Full-text available
A coupled biophysical model is used to examine the impact of the great Arctic cyclone of early August 2012 on the marine planktonic ecosystem in the Pacific sector of the Arctic Ocean (PSA). Model results indicate that the cyclone influences the marine planktonic ecosystem by enhancing productivity on the shelves of the Chukchi, East Siberian, and...
Article
Oceanographic light detection and ranging (LIDAR) maps scattering layers, and relates their distributions to oceanographic processes. However, demonstrable links between this experimental technology and water column optical properties remain elusive. Theory shows the returned laser power (Pr) decays logarithmically as a function of depth-varying op...
Article
Full-text available
Water column optical properties of Greater Florida Bay were investigated in the context of their impacts on seagrass distribution. Scattering played an important role in light attenuation throughout the shallow water system. The northwest region was characterized by an absence of seagrasses and the highest scattering by particles, mostly from resus...
Article
Full-text available
1] The light absorption properties of particulate and dissolved materials strongly influence the propagation of visible light in oceanic waters and therefore the accuracy of ocean color algorithms. While the general absorption properties of these materials have been reported for Arctic waters, their seasonal variability remains unknown. We investig...
Article
The Arctic Ocean, including its regional shelf seas, is assumed to play an important role in the global carbon cycle. However, the true magnitude of annual production is unknown, as in situ data are sparse in time and space. Remote sensing technology has the potential to provide large scale estimates of phytoplankton biomass at much higher frequenc...
Article
Full-text available
We focus on the validation of a simplified approach to bathymetry retrieval from hyperspectral imagery (HSI) in the very shallow water limit (less than 1–2 m), where many existing bathymetric LIDAR sensors perform poorly. In this depth regime, near infra-red (NIR) reflectance depends primarily on water depth (water absorption) and bottom type, with...
Article
The role of mesozooplankton as consumers and transformers of primary and secondary production in the Beaufort and Chukchi Seas was examined during four cruises in spring and summer of both 2002 and 2004 as part of the western Arctic Shelf–Basin Interactions (SBI) program. Forty-seven grazing experiments using dominant mesozooplankton species and li...
Article
Standing stocks and production rates for phytoplankton and heterotrophic bacteria were examined during four expeditions in the western Arctic Ocean (Chukchi Sea and Canada Basin) in the spring and summer of 2002 and 2004. Rates of primary production (PP) and bacterial production (BP) were higher in the summer than in spring and in shelf waters than...
Data
Standing stocks and production rates for phytoplankton and heterotrophic bacteria were examined during four expeditions in the western Arctic Ocean (Chukchi Sea and Canada Basin) in the spring and summer of 2002 and 2004. Rates of primary production (PP) and bacterial production (BP) were higher in the summer than in spring and in shelf waters than...
Article
Full-text available
Recent observations show visible light attenuation in the Arctic Ocean to be greater than previously assumed. High attenuation observed during the period prior to ice melt and increased phytoplankton production, was attributed primarily to the high levels of absorption by chromophoric dissolved organic material (CDOM) present in these waters. Preli...
Conference Paper
Full-text available
A number of institutions, including the Naval Research Laboratory (NRL), have developed look up tables for remote retrieval of bathymetry and in-water optical properties from hyperspectral imagery (HSI) [6]. For bathymetry retrieval, the lower limit is the very shallow water case (here defined as < 2m), a depth zone which is not well resolved by ma...
Article
Full-text available
1] Particulate organic carbon (POC) export fluxes were estimated in the shelf-slope region of the Chukchi Sea using measurements of 234 Th À238 U disequilibria and the POC/ 234 Th ratio in large (>53-mm) particles. These export fluxes were used in conjunction with rates of primary productivity and benthic carbon respiration to construct a POC budge...
Article
The goal of this study was to explore how net community production (NCP) is influenced by the relationship between primary production and community respiration in the western Arctic Ocean. Plankton NCP and respiration were determined by measuring changes in oxygen in light and dark bottle incubations, respectively. Rates of NCP averaged over shelf,...
Article
In the spring and summer of 2002 primary production in the Chukchi Sea was measured, using 14C uptake experiments. Our cruise track encompassed the shelf and continental slope area of the Chukchi and Beaufort Seas progressing into deep water over the Canada Basin. The study area experienced upwards of 90% ice cover during the spring, with ice retre...
Article
Phytoplankton pigments and size-fractionated biomass in the Chukchi and Beaufort Seas showed spatial and temporal variation during the spring and summer of 2002. Cluster analysis of pigment ratios revealed different assemblages over the shelf, slope and basin regions. In spring, phytoplankton with particle sizes greater than 5 μm, identified as dia...
Article
Southampton Inst. degree validated by Nottingham Trent Univ. Thesis (Ph.D.)

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Projects

Projects (4)
Project
The goal of this project is to explore the relationship between oceanographic lidar depolarization, and the size, shape, and composition of particles in the ocean. In order to explore these aspects of lidar remote sensing, we have developed a polarized Monte Carlo radiative transfer model that considers particle size distribution and composition. We hope to be able to use this model to develop methods of retrieving these properties from shipboard polarized lidar returns.
Project
Describe the population dynamics of key zooplanton species and understand its main environmental drivers