Roy A. Armstrong

University of Puerto Rico System | UPRM · Department of Marine Sciences

Decreased water quality in coastal environments due to land alterations by human activities has caused stressed and degraded coral reefs worldwide. The consequences of decreased water quality are not limited to coral reefs but also affect the quality of people’s lives by increasing the incidence of diseases, so areas highly impacted have been prior...

Highly divergent estimates of benthic cover of sponges have been reported for Caribbean mesophotic reefs (90-100 m) based on quadrat point-intercept data collection using 2 methods: visual surveys conducted in situ by technical divers, and analyses of photographs taken by unmanned underwater vehicles (UUVs). The second method has been criticized fo...

A change detection analysis utilizing Very High-resolution (V.H.R.) satellite imagery was performed to evaluate the changes in coastal vegetation in La Parguera, southwestern Puerto Rico, attributable to the increased influx of pelagic Sargassum and its accumulations in cays, bays, inlets and near-shore environments. Imagery was co-registered, corr...

Land-based sediment stress represents a threat to many coral reefs in Puerto Rico primarily as a result of unrestricted land cover/land use changes and poor best management practices. The effects of such stresses have been documented along most coasts around the island. However, little attention has been paid to reefs located on the north coast, an...

Remotely sensed ocean color data are useful for monitoring water quality in coastal environments. However, moderate resolution (hundreds of meters to a few kilometers) satellite data are underutilized in these environments because of frequent data gaps from cloud cover and algorithm complexities in shallow waters. Aggregating satellite data over la...

Absorption of colored dissolved organic matter or detrital gelbstoff (aCDOM/ADG) and light attenuation coefficient (Kd490) parameters were studied at La Parguera Natural Reserve in southwestern Puerto Rico, before and following Hurricanes Irma (6–7 September) and María (20–21 September) in 2017. Water quality assessments involving Sentinel 3A ocean...

Seagrass ecosystems affected by climate change and anthropogenic disturbances require baseline characterization of their cover, distribution, and dynamics for effective conservation strategies. Caja de Muertos Island (CMI) is an important nature reserve in Puerto Rico where long-term trends in seagrass cover are unknown but where availability of hi...

Coral reefs are among the most biologically diverse ecosystems on Earth. In the last few decades, a combination of stressors has produced significant declines in reef expanse, with declining reef health attributed largely to thermal stresses. We investigated the correspondence between time-series satellite remote sensing-based sea surface temperatu...

African Dust from the Sahara and Sahel regions of Northern Africa is blown intercontinental distances and is the highest portion of atmospheric dust generated each year. During the Northern Hemisphere summer months (boreal summer), these dust events travel into the Caribbean and southern United States. While viability assays, microscopy, and bacter...

Coastal, benthic communities, such as coral reefs, are at particular risk due to poor water quality caused by hurricanes. In addition to the physical impacts from wave action and storm surge, hurricanes bring significant rainfall resulting in increased runoff from land. Hurricanes Irma and Maria caused record or near-record floods at many locations...

The development of advanced acoustic and optical imaging techniques along with autonomous underwater vehicles (AUVs) and remotely operated vehicles (ROVs) has enabled high-resolution benthic mapping and biological characterization of mesophotic coral ecosystems (MCEs) over large spatial scales. Underwater vehicles can be grouped into tethered and u...

Effective management of seagrass habitats requires detailed information about seagrass condition and distribution. This paper addresses the first step of a larger study to assess long-term changes in seagrass distribution within Caja de Muertos Island Nature Reserve, Puerto Rico. A high-spatial-resolution characterization of seagrass beds in the re...

Aerial photography and VHR satellite imagery have been used extensively for terrestrial landuse/landcover mapping using pixel-based classification, object based classification or visual interpretation. VHR satellite imagery and aerial photography have also been used for benthic mapping but due to challenges from cloud cover, water turbidity and dep...

The Operational Land Imager (OLI) onboard Landsat-8 satellite can provide remote sensing reflectance (Rrs) of aquatic environments with high spatial resolution (30 m), allowing for benthic habitat mapping and monitoring of bathymetry and water column optical properties. To facilitate these applications, accurate sensor-derived Rrs is required. In t...

Objective: Vitamin D blood levels have been shown to be partially dependent upon season in temperate climates, however, this same evaluation has not yet been reported in fully tropical climates. Herein, we assessed the vitamin D levels in the blood of Rhesus monkeys housed at the Puerto Rico Caribbean Primate Research Center collected in the islan...

NASA's Black Marble nighttime lights product suite (VNP46) is available at 500 m resolution since January 2012 with data from the Visible Infrared Imaging Radiometer Suite (VIIRS) Day/Night Band (DNB) onboard the Suomi National Polar-orbiting Platform (SNPP). The retrieval algorithm, developed and implemented for routine global processing at NASA's...

Modulated by global, continental, regional, and local scale processes, convective precipitation in coastal tropical regions is paramount in maintaining the ecological balance and socioeconomic health within them. The western coast of the Caribbean island of Puerto Rico is ideal for observing local convective dynamics as interactions between complex...

Groundwater Dependent Ecosystem (GDE) protection is increasingly being recognized as essential for the sustainable management and allocation of water resources. GDE services are crucial for human well-being and for a variety of flora and fauna. However, the conservation of GDEs is only possible if knowledge about their location and extent is availa...

Optical imaging of coral reefs and other benthic communities present below one attenuation depth, the limit of effective airborne and satellite remote sensing, requires the use of in situ platforms such as autonomous underwater vehicles (AUVs), remotely-operated vehicles (ROVs), towed platforms and drop cameras. High-resolution optical data from AU...

The spectral slope of the absorption coefficient of colored dissolved and detrital material (CDM), Scdm (units: nm−1), is an important optical parameter for characterizing the absorption spectral shape of CDM. Although highly variable in natural waters, in most remote sensing algorithms, this slope is either kept as a constant or empirically modele...

The use of passive satellite sensor data in shallow waters is complicated by the combined atmospheric, water, and bottom signals. Accurate determination of water depth is important for monitoring underwater topography and detection of moved sediments and in support of navigation. A Worldview 2 (WV2) image was used to develop high-resolution bathyme...

Reef corals typically contain a number of pigments, mostly due to their symbiotic relationship with photosynthetic dinoflagellates. These pigments usually vary in presence and concentration and influence the spectral characteristics of corals. We studied the variations in pigment composition among seven Caribbean shallow-water Scleractinian corals...

Percent of colonies from each species containing a particular pigment. (XLSX)

This work was conducted as part of a preliminary assessment of the condition of seagrassess in sourthern Puerto Rico. Stressors and recommendations were provided.

The radiance transmittance (Tr) is the ratio of the water-leaving radiance (Lw(0⁺)) to the sub-surface upwelling radiance (Lu(0⁻)), which is an important optical parameter for ocean optics and ocean color remote sensing. Historically, a constant value (~0.54) based on theoretical presumptions has been adopted for Tr and is widely used. This optical...

This work presents the results of a unique study conducted in Southern Puerto Rico. A fast and intensive region‐wide survey from Punta Jorobado to Punta Petrona was conducted to evaluate the extension and intensity of anthropogenic stressors on shallow seagrass habitats. This task was challenging because it covered a wide variety of ecosystems from...

Global assessments of ultraviolet radiation (UVR) by the end of the 20th century indicated worldwide increases in UVR. While with the implement of the Montreal Protocol ozone-depleting substances are starting to decrease, studies in coral reef platforms have shown a 1% increase in UVR during the past two decades. Despite the exponential light atten...

The effectiveness of management plans developed for responding to coral disease outbreaks is limited due to the lack of rapid methods of disease diagnosis. In order to fulfill current management guidelines for responding to coral disease outbreaks, alternative methods that significantly reduce response time must be developed. Hyperspectral sensing...

The benthic communities of the deep insular shelf at the Hind Bank marine conservation district (MCD), an important spawning aggregation site for groupers, were studied with the Seabed autonomous underwater vehicle (AUV) at depths between 32 and 54 m. Four digital phototransects provided data on benthic species composition and abundance of the insu...

The effects of enhanced ultraviolet radiation (280–400 nm: UVR) on the fecundity of Acropora cervicornis were measured in field-transplanted colonies from 20 m to 1 m depth and vice versa at La Parguera, Puerto Rico. Fecundity was estimated from histological sections made from tissue samples obtained at different time intervals during the experimen...

Mesophotic coral ecosystems (MCEs) can be defined as light-dependent coral, algal, and sponge communities that occur in the deepest half of the photic zone in tropical and subtropical regions. The distribution of MCEs in the US Caribbean and elsewhere, including ecologically relevant parameters such as percent living coral cover, reef rugosity, inc...

Shallow reef corals can frequently be subjected to high doses of ultraviolet radiation [280–400 nm (UVR)] and have developed mechanisms to cope with this. Nevertheless, slight changes in this stressor may impact their physiology and ultimately their survival. Here, we present results on the effects of artificially enhanced UVR on the growth, reprod...

The coloration of tropical reef corals is mainly due to their association with photosynthetic dinoflagellates commonly known as zooxanthellae. Combining High Performance Liquid Chromatography (HPLC), spectroscopy and derivative analysis we provide a novel approach to discriminate between the Caribbean shallow-water corals Acropora cervicornis and P...

This book started as an idea at the GeoHab meeting held in Noumea, New Caledonia, in May 2007. We noticed that multibeam bathymetry maps of geomorphic features, sometimes shown as 3D fly-thru movies, followed by detailed sampling and photographic data (including underwater videos) illustrating the substrate conditions and associated biota was a con...

This paper presents a general review of the distribution of mesophotic coral ecosystems (MCEs) in relationship to geomorphology in US waters. It was specifically concerned with the depth range of 30–100m, where more than 186,000km2 of potential seafloor area was identified within the US Gulf of Mexico/Florida, Caribbean, and main Hawaiian Islands....

While the distribution and status of shallow-water reefs in many parts of the world has been well documented in the last 40 years, benthic characterization studies and large-scale mapping of deep reef habitats, are very rare. Recent studies on mesophotic coral ecosystems (30 -100 m) in the eastern Puerto Rico Shelf describe abundant and structurall...

An Aerosol and Oceanographic Science Expedition (AEROSE) on the NOAA Ship Ronald H. Brown collected PM 2.5 particles from a Saharan dust storm in March 2004. High levels of PM 2.5 (120 mg m3) were measured during this Saharan storm over the Atlantic Ocean. The particles were characterized for trace element content, with Al and Fe the most abundant...

Although remote sensing technology is a useful tool for monitoring shallow (

NASA's airborne science assets have been used to fly over strategic coral reef sites in Puerto Rico to collect high resolution imagery to support coral reef ecosystem research. The goal is to better understand how light scatters and reflects in shallow aquatic ecosystems, so current and future remote sensing sensors and data can be optimized for co...

In December 2005, the Airborne Visible Infrared Imaging Spectrometer (AVIRIS) was flown over Puerto Rico and the U.S. Virgin Islands for assessment of the 2005 Caribbean coral reef bleaching event. The resulting hyperspectral imagery is being used as the foundation for evaluating coral distribution and health in these areas. Image processing for th...

Puerto Rico, the easternmost island (18°15' N and 66°30' W) of the Greater Antilles, is about 50 km wide and 180 km long on its east/west axis, and has a coastline of 1,384 km including the adjacent islands of Vieques, Culebra, Desecheo, and Mona (Fig. 9.1). Puerto Rico is a “high” island with a central mountain range running east/west with peak el...

The effects of increased UV radiation (UV-B [280-320 nm] + UV-A [320-400 nm]; hereafter UVR) on the growth, production of photosynthetic pigments and photoprotective mycosporine-like amino acids (MAAs) were studied in the threatened Caribbean coral Acropora cervicornis transplanted from 20 to 1 m depth in La Parguera, Puerto Rico. The UVR exposure...

Apoptosis involves a highly organized and programmed series of events aimed at maintaining genomic stability by eliminating defective host cells. The purpose of this study was to determine the threshold doses and environmental UV-A and UV-B exposure times necessary to produce apoptosis and necrosis in the normal cells of a human fibroblast cell lin...

Ozone and UV radiation were analyzed at eight stations from tropical to sub-Antarctic regions in South America. Ground UV irradiances were measured by multichannel radiometers as part of the Inter American Institute for Global Change Radiation network. The irradiance channels used for this study were centered at 305 nm (for UV-B measurements) and 3...

The University of Puerto Rico at Mayaguez (UPRM), one of the core academic partners in the NSF sponsored Bernard M. Gordon Center for Subsurface Sensing and Imaging Systems (Gordon- CenSSIS), is developing algorithms using hyperspectral, multispectral and other sensing modalities to extract subsurface information in aquatic environments. As part of...

The NOAA Center for Atmospheric Sciences (NCAS) is one of the four NOAA cooperative centers established in 2001. The organization's main mission is to enhance the production of well-educated and highly qualified meteorology/atmospheric sciences graduates from traditionally underrepresented groups and to improve their representation in NOAA's workfo...

To adequately image through a water column and to delineate variation in coral reef ecosystem benthic types, sensors having high spatial, e.g., a Cirrus digital camera system (DCS), and spectral, e.g., the Airborne Visible Infrared Imaging Spectrometer (AVIRIS), resolution and high signal to noise are needed. Further, there is a need to better unde...

The quantitative characterization of the submerged biotopes of Enrique Reef, southwestern Puerto Rico, requires atmospheric and water column corrections of satellite data before performing classification algorithms. The Lyzenga (1978) method was used for deriving three depth-invariant bands based on the visible bands of IKONOS imagery. The spectral...

An estimated three billion metric tons of mineral aerosols are injected into the troposphere annually from the Saharan desert [Prospero et al., 1996]. Additionally, smoke from biomass burning sites in the savanna grasslands in sub-Saharan Africa contribute significant quantities of smaller-sized aerosols [e.g., Hobbs, 2000]. These windswept aerosol...

With the advent of new robotic technologies such as AUVs, a number of end user communities are being inundated with large amounts of data. The traditional techniques of manually counting and sorting out organisms in individual images are just not scaleable to the large datasets that are now being acquired. This paper examines the use of morphologic...

The main task of the Center for Subsurface Sensing and Imaging Systems (CenSSIS), funded by the National Science Foundation, is to develop appropriate techniques to separate complex subsurface signals. This multi-university Engineering Research Center aims to revolutionize the existing technology for detecting and imaging objects under different la...

Remote sensing is increasingly being used as a tool to quantitatively assess the location, distribution and relative health of coral reefs and other shallow aquatic ecosystems. As the use of this technology continues to grow and the analysis products become more sophisticated, there is an increasing need for comprehensive ground truth data as a mea...