Richard Dodge | Nova Southeastern University (original) (raw)

Papers by Richard Dodge

We analyzed spatial and temporal patterns of coral communities in the southeastern Arabian Gulf (... more We analyzed spatial and temporal patterns of coral communities in the southeastern Arabian Gulf (Abu Dhabi, Dubai, Sharjah) in response to temperature variability in one of the most extreme coral environments. We used IKONOS and Aster satellite imagery combined with 8 years of ecological monitoring data (line transects and photo-squares) and sea-surface temperature data (CoADS, HadISST1, NCAR). Analysis of SST confirms that the area is subjected to recurrent and cyclic temperature anomalies. We explore whether unusually low or high temperatures are the main forcing factor of coral mortality and whether links to ENSO via the Indian Ocean Zonal Mode/Dipole exist. Temperature extremes occur more frequently in the western area between Qatar and Abu Dhabi than in the eastern area between Abu Dhabi and Musandam. The spatial expression of coral assemblages near Jebel Ali (Dubai) on IKONOS imagery is consistent with what would be predicted if reef development was repeatedly ‘reset’ on a decadal time-scale by recurring episodes of coral mass mortality induced by severe positive or negative SST anomalies. Furthermore, a combination of remotely-sensed habitat mapping and bathymetric digital elevation model analysis revealed no evidence of any reefal framework development, suggesting that the cycle of temperature-induced mortality has been operating for a considerable time. We therefore suggest that the environment in the entire southeastern Arabian Gulf has not been conducive to biohermal framework production and that all coral areas have been subject to frequent mortality episodes. Increased global temperatures are likely to increase the frequency of extreme positive SST excursions and indeed the area has experienced bleaching events in 1996, 1998, and 2002, which is the fastest recurrence rate recorded on any reef system. While some evidence for phenotypic adaptation was observed (reduced bleaching in Acropora), further degradation of the system is expected

Elevated marine terraces of the Northwest Peninsula of Haiti have been investigated for geologic ... more Elevated marine terraces of the Northwest Peninsula of Haiti have been investigated for geologic structure, age, and height above sea level. The terraces are identified as constructional coral reefs each typically containing an Acropora palmata crest facies, lower A. cervicornis facies, and lower or interposed Montastrea annularis facies. Occasionally a beach sandstone facies is present shoreward of the A. palmata zone. From the town of Mole St. Nicholas 10-25 km eastward, 8 well-defined reefs rise to an elevation of 200m. These are linearly contiguous for at least 10 km and show little evidence of warping or differential uplift. Raised reefs continue at least 60 km eastward to Port-de-Paix and are also exposed on the island of Tortue. Eight additional constructional reef terraces are present from 200-600 m elevation around the area of Mare Rouge. A series of raised reefs are also present along the extreme west coast, Cap St. Nicholas area. The most prominent terrace cresting at 52 m gives Th-230/U-234 dates on unrecrystallized A. palmata which average 126,000 ±5,000 years B.P. Assuming a sea level of +6 m at 125,000 years ago, the data suggest an uplift rate of .37 m/1,000, making the Northwest Peninsula area of Haiti one of the highest reported uplifts in the Caribbean. The crest of the next lower reef stands at approximately 30.5 m elevation. The crest of the lowest reef (which is often the modern sea cliff) stands between 6 and 15 m. Dating of these reefs is now in progress

Coral skeletal density information is a useful growth parameter and may be coupled with extension... more Coral skeletal density information is a useful growth parameter and may be coupled with extension rates to determine calcification rates. The conventional process for density determination is often cumbersome and requires some parameters which are difficult to precisely specify (e.g., Mass absorption coefficients). We have developed a technique and windows based computer program which enables the rapid collection of coral density data. The coral skeleton slab is xradiographed with an aluminum wedge. Thickness and density of the aluminum wedge, thickness of the coral slab, density of pure coral aragonite, and digitized images of the coral and wedge x-radiographs provide necessary input. The program uses the wedge image and an empirically determined ratio of relative mass absorption coefficients, (thus removing difficulties with absolute values) in an equation relating wedge optic density and thickness to coral skeletal density. A transect is defined on the coral x-radiograph image, normal to growth band boundaries. Optic density of pixels are converted to skeletal density, averaged, and plotted. Variations of skeletal density along the transect are expressed as peaks and valleys corresponding to high and low density band portions. Measurements of extension, density, and calcification can be calculated for a variety of characterizations of annual and subannual band portions

Oceans 2003. Celebrating the Past ... Teaming Toward the Future (IEEE Cat. No.03CH37492), 2003

Summary form only given. Coral reefs are the most imperiled ecosystem, with accelerating mortalit... more Summary form only given. Coral reefs are the most imperiled ecosystem, with accelerating mortality from globally increasing temperature, disease, and pollution. This threatens fisheries, tourism, shore protection, and biodiversity in over 100 countries. Oyster banks that once filled estuaries have almost vanished from over-harvesting and pollution. Corals and oysters are the only organisms building large wave-resistant frameworks that provide habitat for myriad other economically valuable organisms. We use very low voltage electrical currents to grow corals and oysters at faster rates than normal, even under normally lethal high temperatures and pollution, restoring these ecosystems where natural regeneration is impossible. The Biorock method directly provides energy for growth of skeleton and shells, leaving corals and oysters more energy for growth, reproduction, and resisting environmental stress. Field experiments in all oceans show that electrified corals and oysters grow faster and survive better, and quickly build up large populations of adult and larval fishes. Electric reefs can be constructed in any size or shape, allowing selective enhancement of desired fish and shellfish populations. This allows fishermen to grow reefs and sustainably harvest fish and shellfish instead of destroying wild populations. Hotels and dive shops can grow nearby reefs as beautiful tourism attractions that restore nearby fisheries and reduce pressure on natural reefs. Restoration of ecosystems and fisheries will be the major challenge of the coming century as increasing population and energy use cause global climate change and environmental degradation to accelerate.

The State of Coral Reef …, 2008

Chantal Collier1, Rob Ruzicka1, Ken Banks2, Luiz Barbieri3, Jeff Beal3, David Bingham3, James Boh... more Chantal Collier1, Rob Ruzicka1, Ken Banks2, Luiz Barbieri3, Jeff Beal3, David Bingham3, James Bohnsack4, Sandra Brooke5, Nancy Craig2, Richard Dodge6,7, Lou Fisher2, Nick Gadbois1, David Gilliam6,7, Lisa Gregg3, Todd Kellison4, Vladimir Kosmynin1, Brian ...

The State of Coral Reef …, 2005

Contributing Authors: Ken Banks3, Carl Beaver4, James Bohnsack5, Richard E. Dodge6,7, David Gilli... more Contributing Authors: Ken Banks3, Carl Beaver4, James Bohnsack5, Richard E. Dodge6,7, David Gilliam6,7, Walt Jaap4, Brian Keller8, V. Robert Leeworthy9, Tom Matthews4, Ramon Ruiz-Carus4, Deborah Santavy10, Richard Spieler6,7 ... Other Contributors: Jerald ...

Large-scale impacts on coral reefs due to global climatic change are projected to increase dramat... more Large-scale impacts on coral reefs due to global climatic change are projected to increase dramatically. Also suitability of many areas for reef growth is decreasing leading to the search for particular settings that might serve as refugia and maintain strong coral populations. We examine this hypothesis in Honduras. Dense coral thickets containing high numbers of endangered coral Acropora cervicornis occur on offshore banks but are rare on the fringing reef on nearby Roatan. Geomorphological setting and community dynamics were evaluated and monitored from 1996-2005. A model of population dynamics was developed to test assumptions derived from monitoring. Coral cover on the fringing reef declined in 1998 from \u3e30% to \u3c20%, but the banks maintained areas of very dense coral cover (32% cover by A. cervicornis on the banks but \u3c1% on the fringing reef). Bathymetry from satellite images showed the banks to be well-separated from the fringing reef, making asexual connectivity between banks and fringing reef impossible but protecting the banks from direct land-runoff during storms. Exposure to SE tradewinds also causes good flushing. Only four A. cervicornis recruits were recorded on the fringing reef over six years. Run-off associated with hurricanes caused greater mortality than did bleaching in 1998 and 2005 on the fringing reef, but not on the banks. Since 1870, our analysis suggests that corals on the banks may have been favored during 17 run-off events associated with tropical depressions and storms and potentially also during 5 bleaching events, but this is more uncertain. Our model suggest that under this disturbance regime, the banks will indeed maintain higher coral populations than the fringing reef and supports the assumption that offshore banks could serve as refugia with the capacity to subsidize depleted mainland populations

Reef Ball Deployment: In November of 2000, 160 concrete Reef BallTM modules (1.22m wide x 0.9m hi... more Reef Ball Deployment: In November of 2000, 160 concrete Reef BallTM modules (1.22m wide x 0.9m high) were deployed, at a depth of approximately 15 meters, between the Second and Third Reef tracts off Dania Beach, FL (Figures 1 and 2). The Reef Balls were grouped into 40 quads, with each quad containing four individual Reef Balls. One modified Reef Ball from each quad was designated as the ‘transplant’ ball, and was used as the receptacle for the coral transplants. The other three balls in each quad are part of a more comprehensive study. This multifactorial study is examining the effects of reef structure on fish assemblages, the effects of coral larval attractants on coral recruitment, and the interaction between fish assemblages and coral recruitment. The coral transplants are one such ‘coral larval attractant’ being examined. Coral transplants, and the donor colonies from which they were obtained, are being monitored for growth and survivorshi

The Coral X-radiograph Densitometry System (CoralXDS) is a Windows-based program which provides a... more The Coral X-radiograph Densitometry System (CoralXDS) is a Windows-based program which provides a tool for measurement of linear extension, density, and calcification from coral X-radiographs. These quantities are determined for high-density, low-density, and annual bands. CoralXDS operates in two modes : full mode and extension/luminance mode. Full mode measures linear extension, density, and calcification, while extension/luminance mode measures only linear extension. Extension/luminance mode requires only a coral image with scaling information. CoralXDS allows user specification of transect location and orientation on the coral image, and provides several options for automated and manual band selection. The output measurements are provided as plots and datasets

An ultraviolet laser was used to study the fluorescence spectrum of coral skeletons. Montastrea a... more An ultraviolet laser was used to study the fluorescence spectrum of coral skeletons. Montastrea annularis heads growing near the mouth of the New River Canal, Florida, had unusual three-part growth and fluorescence records: 1918-1944. High growth, annual fluorescence peak. 1945-1969. Low growth, high fluorescence, except during drought years 1970-1983. High growth, annual fluorescence peak. The first change followed opening of the New River Canal to drain the Everglades-Lake Okeechobee Agricultural Area for sugar cane cultivation. In 1969 canal flows were sharply reduced, and urban and agricultural waste waters pumped into diked conservation areas in order to increase infiltration into a dangerously lowered aquifer

The occurrence of power-law relationships between frequency and size of facies patches has been i... more The occurrence of power-law relationships between frequency and size of facies patches has been identified in both modern and ancient carbonate depositional bodies. However, quantification of the lateral extent of facies distribution in such systems, which vary on scales of centimeters to tens of kilometers, is notoriously difficult and remote sensing methods are increasingly becoming the tool of choice. In this study, facies patterns and their spatial relationships were quantitatively investigated in an Arabian Gulf shallow subtidal carbonate ramp setting in Dubai using a synergy of IKONOS satellite imagery and vessel-based acoustic bathymetry survey. The spatially detailed bathymetry was used as input into an empirical correction for the effect of the water column on the satellite imagery, facilitating classification of eight dominant facies types, using a classifier trained exclusively by hyperspectral in situ optical measurements of substrate reflectance. Secondly, the bathymetry was interpolated to represent a model of seafloor topography, which, when combined with the classified IKONOS imagery, yielded a three-dimensional model of facies distribution on the seabed. Both ground-verification and the predictive map derived for the IKONOS imagery confirm the fragmented nature of carbonate benthos in the study area, with patch sizes found to vary between 16m2 (the spatial resolution of the imagery) and 900 m2. The patch distribution of three assemblages of live and dead corals on extensive (but also fragmented hardground pavements was investigated using a variety of spatial statistics and it was found that the relationship between patch size and frequency approximate to a power-law relationship (linear in the log-log domain) over several orders of magnitude. The area is known to be subjected to recurrent and cyclic thermal induced mass mortality events on a decadal time scale, inhibiting reef framework development and likely to be a controlling mechanism in the patchiness of the coral communities

Measurement of coral extension rate is facilitated by x-radiography of medial slabs of coral skel... more Measurement of coral extension rate is facilitated by x-radiography of medial slabs of coral skeletons which contain annual density banding. Densitometer analysis of film optic density with calibration to skeletal density can also provide calcification rate and density, but is time consuming and restricted to thin transects equal in width to the densitometer beam. Coral density and calcification data are useful because they provide skeletal growth information additional to extension rate. A microcomputer system has been assembled and a BASIC program has been written to rapidly and accurately obtain extension, density, and calcification measurements from x-radiograph revealed coral skeletal growth bands. The hardware consists of: an IBM-PC microcomputer, internal digitizing board providing resolution of 256 x 256 picture elements (pixels) by 256 grey levels, closed circuit TV camera, and an evenly distributed back-light source. The software (BASIC program) is written to incorporate actual scale of the x-radiograph. Initially, film optic density is calibrated to skeletal density by digitizing the image of an aluminum wedge included in the x-radiograph. Appropriate formulas (Buddemeier, 1974) and mass absorption coefficients are utilized. Next, the coral x-radiograph is digitized and a transect perpendicular to growth band boundaries is defined. The transect dimensions are selectable by the operator. Pixel values of optic density within the transect are converted to skeletal density through the wedge calibration. These values are averaged parallel to band boundaries and graphed to produce a chart of peaks and valleys representing high and low density portions within each band. The program finds midpoints of each peak and valley along the graph. Linear distance between these points for each couplet gives annual extension rate. Density is found by integration of the area under peaks and valleys. Mass or calcification rate is calculated by the product of extension and density. Extension, density, and mass are also available for subannual band portions. Depending upon skeletal growth rate, the program can analyze up to 12 years on a single digitization. The image (and transect) can also be printed on a dot matrix printer making it possible to overlap and continue transects along the entire portion of the coral desired. Conventional image analysis systems cost in the 40,000pricerange.Themicrocomputersystemdescribedherecanbeimplementedforlessthan40,000 price range. The microcomputer system described here can be implemented for less than 40,000pricerange.Themicrocomputersystemdescribedherecanbeimplementedforlessthan5,000. The method provides relatively rapid, accurate, and objective measurements of the three skeletal growth parameters: extension, density, and calcification (mass). Investigations continue into the precision and reproducibility of the technique as well as for hardware to obtain greater resolution

Oceanography

Gulf of Mexico (GOM) ecosystems are interconnected by numerous physical and biological processes.... more Gulf of Mexico (GOM) ecosystems are interconnected by numerous physical and biological processes. After the Deepwater Horizon (DWH) disaster, these ecological processes facilitated dispersal of oil-spill toxicants or were damaged and broken. A considerable portion of post-DWH research focused on higher levels of biological organization (i.e., populations, communities, and ecosystems) spanning at least four environments (onshore, coastal, open ocean, and deep benthos). Damage wrought by the oil spill and mitigation efforts varied considerably across ecosystems. Whereas all systems show prolonged impacts because of cascading effects that impacted functional connections within and between communities, deep-sea and mesopelagic environments were particularly hard hit and have shown less resilience than shallow environments. In some environments, such as marshes or the deep-sea benthos, products from the spill are still biologically accessible. Some shallow ecosystems show signs of recove...

The coral reefs of Broward County, southeast Florida, USA are located offshore a highly urbanized... more The coral reefs of Broward County, southeast Florida, USA are located offshore a highly urbanized area. Because of the close proximity of a major shipping port and its associated anchorage, Broward reefs have been impacted by more than 10 ship groundings over the last 15 years. These injuries usually require restoration to speed recovery and compensate for damage. However, the recovery process on injured sites is not well understood, and even less is known about how restoration aids in recovery. This study examines coral recruitment, growth, and mortality in permanent quadrats on injured sites to asses their potential for natural recovery. It also investigates substrate materials commonly used in reef restoration, including limestone, concrete, and terracotta, to determine their efficacy in attracting and retaining coral recruits. Lastly, transplantation of juvenile corals collected on settlement plates from areas of higher coral recruitment and of corals raised in the lab from the larval stage is examined as a potential method to enhance reef restoration. Preliminary results indicate coral recruitment rates to injured sites were higher compared to reference sites. Mortality rates at the injured sites were also higher than reference sites. After one year of deployment, more corals settled on limestone plates than on concrete or terracotta. Hence, recovery on injury sites may be hampered by high juvenile coral mortality rates, and the choice of substrate materials used in restoration may influence recovery

Massive Caribbean scleractinians are slow to replace themselves in the population due to long lif... more Massive Caribbean scleractinians are slow to replace themselves in the population due to long life spans, low recruitment, and slow growth rates. Disruption of reproductive synchronicity or reduced fecundity may adversely affect their ability to recover and repopulate degraded areas. Reproductive information on Siderastrea siderea, an abundant Caribbean broadcast spawning species, is particularly sparse. In order to track gametogenesis and identify the time of spawning, tissue samples from S. siderea were collected from August 2007 on a weekly basis until November, when a reduction in gametes, indicative of spawning, was observed. Estimated spawning time was compared with lunar phase as well as water temperature data obtained from permanent digital temperature recorders deployed throughout Broward County to determine if either of these environmental cues affected spawning time. Information on colony condition and presence of bleaching was obtained for each colony sampled. Tissue samples were processed for histological analysis and examined for late stage gametes. Fecundity was estimated from measurements of the volume of oocytes cm-2 tissue and was compared between bleached and unbleached colonies. Initial analysis suggests that S. siderea spawned between November 8 and 11, 2007 which coincided with the new moon on November 9th. Samples collected on the 8th contained both ova and spermaries extruded from the mesenteries into the gastrovascular cavity and un-spawned gametes absorbed by the gastrodermis. Further collections of S. siderea in 2008 will be used to corroborate spawning correlation of S. siderea with lunar period

We analyzed spatial and temporal patterns of coral communities in the southeastern Arabian Gulf (... more We analyzed spatial and temporal patterns of coral communities in the southeastern Arabian Gulf (Abu Dhabi, Dubai, Sharjah) in response to temperature variability in one of the most extreme coral environments. We used IKONOS and Aster satellite imagery combined with 8 years of ecological monitoring data (line transects and photo-squares) and sea-surface temperature data (CoADS, HadISST1, NCAR). Analysis of SST confirms that the area is subjected to recurrent and cyclic temperature anomalies. We explore whether unusually low or high temperatures are the main forcing factor of coral mortality and whether links to ENSO via the Indian Ocean Zonal Mode/Dipole exist. Temperature extremes occur more frequently in the western area between Qatar and Abu Dhabi than in the eastern area between Abu Dhabi and Musandam. The spatial expression of coral assemblages near Jebel Ali (Dubai) on IKONOS imagery is consistent with what would be predicted if reef development was repeatedly ‘reset’ on a decadal time-scale by recurring episodes of coral mass mortality induced by severe positive or negative SST anomalies. Furthermore, a combination of remotely-sensed habitat mapping and bathymetric digital elevation model analysis revealed no evidence of any reefal framework development, suggesting that the cycle of temperature-induced mortality has been operating for a considerable time. We therefore suggest that the environment in the entire southeastern Arabian Gulf has not been conducive to biohermal framework production and that all coral areas have been subject to frequent mortality episodes. Increased global temperatures are likely to increase the frequency of extreme positive SST excursions and indeed the area has experienced bleaching events in 1996, 1998, and 2002, which is the fastest recurrence rate recorded on any reef system. While some evidence for phenotypic adaptation was observed (reduced bleaching in Acropora), further degradation of the system is expected

Elevated marine terraces of the Northwest Peninsula of Haiti have been investigated for geologic ... more Elevated marine terraces of the Northwest Peninsula of Haiti have been investigated for geologic structure, age, and height above sea level. The terraces are identified as constructional coral reefs each typically containing an Acropora palmata crest facies, lower A. cervicornis facies, and lower or interposed Montastrea annularis facies. Occasionally a beach sandstone facies is present shoreward of the A. palmata zone. From the town of Mole St. Nicholas 10-25 km eastward, 8 well-defined reefs rise to an elevation of 200m. These are linearly contiguous for at least 10 km and show little evidence of warping or differential uplift. Raised reefs continue at least 60 km eastward to Port-de-Paix and are also exposed on the island of Tortue. Eight additional constructional reef terraces are present from 200-600 m elevation around the area of Mare Rouge. A series of raised reefs are also present along the extreme west coast, Cap St. Nicholas area. The most prominent terrace cresting at 52 m gives Th-230/U-234 dates on unrecrystallized A. palmata which average 126,000 ±5,000 years B.P. Assuming a sea level of +6 m at 125,000 years ago, the data suggest an uplift rate of .37 m/1,000, making the Northwest Peninsula area of Haiti one of the highest reported uplifts in the Caribbean. The crest of the next lower reef stands at approximately 30.5 m elevation. The crest of the lowest reef (which is often the modern sea cliff) stands between 6 and 15 m. Dating of these reefs is now in progress

Coral skeletal density information is a useful growth parameter and may be coupled with extension... more Coral skeletal density information is a useful growth parameter and may be coupled with extension rates to determine calcification rates. The conventional process for density determination is often cumbersome and requires some parameters which are difficult to precisely specify (e.g., Mass absorption coefficients). We have developed a technique and windows based computer program which enables the rapid collection of coral density data. The coral skeleton slab is xradiographed with an aluminum wedge. Thickness and density of the aluminum wedge, thickness of the coral slab, density of pure coral aragonite, and digitized images of the coral and wedge x-radiographs provide necessary input. The program uses the wedge image and an empirically determined ratio of relative mass absorption coefficients, (thus removing difficulties with absolute values) in an equation relating wedge optic density and thickness to coral skeletal density. A transect is defined on the coral x-radiograph image, normal to growth band boundaries. Optic density of pixels are converted to skeletal density, averaged, and plotted. Variations of skeletal density along the transect are expressed as peaks and valleys corresponding to high and low density band portions. Measurements of extension, density, and calcification can be calculated for a variety of characterizations of annual and subannual band portions

Oceans 2003. Celebrating the Past ... Teaming Toward the Future (IEEE Cat. No.03CH37492), 2003

Summary form only given. Coral reefs are the most imperiled ecosystem, with accelerating mortalit... more Summary form only given. Coral reefs are the most imperiled ecosystem, with accelerating mortality from globally increasing temperature, disease, and pollution. This threatens fisheries, tourism, shore protection, and biodiversity in over 100 countries. Oyster banks that once filled estuaries have almost vanished from over-harvesting and pollution. Corals and oysters are the only organisms building large wave-resistant frameworks that provide habitat for myriad other economically valuable organisms. We use very low voltage electrical currents to grow corals and oysters at faster rates than normal, even under normally lethal high temperatures and pollution, restoring these ecosystems where natural regeneration is impossible. The Biorock method directly provides energy for growth of skeleton and shells, leaving corals and oysters more energy for growth, reproduction, and resisting environmental stress. Field experiments in all oceans show that electrified corals and oysters grow faster and survive better, and quickly build up large populations of adult and larval fishes. Electric reefs can be constructed in any size or shape, allowing selective enhancement of desired fish and shellfish populations. This allows fishermen to grow reefs and sustainably harvest fish and shellfish instead of destroying wild populations. Hotels and dive shops can grow nearby reefs as beautiful tourism attractions that restore nearby fisheries and reduce pressure on natural reefs. Restoration of ecosystems and fisheries will be the major challenge of the coming century as increasing population and energy use cause global climate change and environmental degradation to accelerate.

The State of Coral Reef …, 2008

Chantal Collier1, Rob Ruzicka1, Ken Banks2, Luiz Barbieri3, Jeff Beal3, David Bingham3, James Boh... more Chantal Collier1, Rob Ruzicka1, Ken Banks2, Luiz Barbieri3, Jeff Beal3, David Bingham3, James Bohnsack4, Sandra Brooke5, Nancy Craig2, Richard Dodge6,7, Lou Fisher2, Nick Gadbois1, David Gilliam6,7, Lisa Gregg3, Todd Kellison4, Vladimir Kosmynin1, Brian ...

The State of Coral Reef …, 2005

Contributing Authors: Ken Banks3, Carl Beaver4, James Bohnsack5, Richard E. Dodge6,7, David Gilli... more Contributing Authors: Ken Banks3, Carl Beaver4, James Bohnsack5, Richard E. Dodge6,7, David Gilliam6,7, Walt Jaap4, Brian Keller8, V. Robert Leeworthy9, Tom Matthews4, Ramon Ruiz-Carus4, Deborah Santavy10, Richard Spieler6,7 ... Other Contributors: Jerald ...

Large-scale impacts on coral reefs due to global climatic change are projected to increase dramat... more Large-scale impacts on coral reefs due to global climatic change are projected to increase dramatically. Also suitability of many areas for reef growth is decreasing leading to the search for particular settings that might serve as refugia and maintain strong coral populations. We examine this hypothesis in Honduras. Dense coral thickets containing high numbers of endangered coral Acropora cervicornis occur on offshore banks but are rare on the fringing reef on nearby Roatan. Geomorphological setting and community dynamics were evaluated and monitored from 1996-2005. A model of population dynamics was developed to test assumptions derived from monitoring. Coral cover on the fringing reef declined in 1998 from \u3e30% to \u3c20%, but the banks maintained areas of very dense coral cover (32% cover by A. cervicornis on the banks but \u3c1% on the fringing reef). Bathymetry from satellite images showed the banks to be well-separated from the fringing reef, making asexual connectivity between banks and fringing reef impossible but protecting the banks from direct land-runoff during storms. Exposure to SE tradewinds also causes good flushing. Only four A. cervicornis recruits were recorded on the fringing reef over six years. Run-off associated with hurricanes caused greater mortality than did bleaching in 1998 and 2005 on the fringing reef, but not on the banks. Since 1870, our analysis suggests that corals on the banks may have been favored during 17 run-off events associated with tropical depressions and storms and potentially also during 5 bleaching events, but this is more uncertain. Our model suggest that under this disturbance regime, the banks will indeed maintain higher coral populations than the fringing reef and supports the assumption that offshore banks could serve as refugia with the capacity to subsidize depleted mainland populations

Reef Ball Deployment: In November of 2000, 160 concrete Reef BallTM modules (1.22m wide x 0.9m hi... more Reef Ball Deployment: In November of 2000, 160 concrete Reef BallTM modules (1.22m wide x 0.9m high) were deployed, at a depth of approximately 15 meters, between the Second and Third Reef tracts off Dania Beach, FL (Figures 1 and 2). The Reef Balls were grouped into 40 quads, with each quad containing four individual Reef Balls. One modified Reef Ball from each quad was designated as the ‘transplant’ ball, and was used as the receptacle for the coral transplants. The other three balls in each quad are part of a more comprehensive study. This multifactorial study is examining the effects of reef structure on fish assemblages, the effects of coral larval attractants on coral recruitment, and the interaction between fish assemblages and coral recruitment. The coral transplants are one such ‘coral larval attractant’ being examined. Coral transplants, and the donor colonies from which they were obtained, are being monitored for growth and survivorshi

The Coral X-radiograph Densitometry System (CoralXDS) is a Windows-based program which provides a... more The Coral X-radiograph Densitometry System (CoralXDS) is a Windows-based program which provides a tool for measurement of linear extension, density, and calcification from coral X-radiographs. These quantities are determined for high-density, low-density, and annual bands. CoralXDS operates in two modes : full mode and extension/luminance mode. Full mode measures linear extension, density, and calcification, while extension/luminance mode measures only linear extension. Extension/luminance mode requires only a coral image with scaling information. CoralXDS allows user specification of transect location and orientation on the coral image, and provides several options for automated and manual band selection. The output measurements are provided as plots and datasets

An ultraviolet laser was used to study the fluorescence spectrum of coral skeletons. Montastrea a... more An ultraviolet laser was used to study the fluorescence spectrum of coral skeletons. Montastrea annularis heads growing near the mouth of the New River Canal, Florida, had unusual three-part growth and fluorescence records: 1918-1944. High growth, annual fluorescence peak. 1945-1969. Low growth, high fluorescence, except during drought years 1970-1983. High growth, annual fluorescence peak. The first change followed opening of the New River Canal to drain the Everglades-Lake Okeechobee Agricultural Area for sugar cane cultivation. In 1969 canal flows were sharply reduced, and urban and agricultural waste waters pumped into diked conservation areas in order to increase infiltration into a dangerously lowered aquifer

The occurrence of power-law relationships between frequency and size of facies patches has been i... more The occurrence of power-law relationships between frequency and size of facies patches has been identified in both modern and ancient carbonate depositional bodies. However, quantification of the lateral extent of facies distribution in such systems, which vary on scales of centimeters to tens of kilometers, is notoriously difficult and remote sensing methods are increasingly becoming the tool of choice. In this study, facies patterns and their spatial relationships were quantitatively investigated in an Arabian Gulf shallow subtidal carbonate ramp setting in Dubai using a synergy of IKONOS satellite imagery and vessel-based acoustic bathymetry survey. The spatially detailed bathymetry was used as input into an empirical correction for the effect of the water column on the satellite imagery, facilitating classification of eight dominant facies types, using a classifier trained exclusively by hyperspectral in situ optical measurements of substrate reflectance. Secondly, the bathymetry was interpolated to represent a model of seafloor topography, which, when combined with the classified IKONOS imagery, yielded a three-dimensional model of facies distribution on the seabed. Both ground-verification and the predictive map derived for the IKONOS imagery confirm the fragmented nature of carbonate benthos in the study area, with patch sizes found to vary between 16m2 (the spatial resolution of the imagery) and 900 m2. The patch distribution of three assemblages of live and dead corals on extensive (but also fragmented hardground pavements was investigated using a variety of spatial statistics and it was found that the relationship between patch size and frequency approximate to a power-law relationship (linear in the log-log domain) over several orders of magnitude. The area is known to be subjected to recurrent and cyclic thermal induced mass mortality events on a decadal time scale, inhibiting reef framework development and likely to be a controlling mechanism in the patchiness of the coral communities

Measurement of coral extension rate is facilitated by x-radiography of medial slabs of coral skel... more Measurement of coral extension rate is facilitated by x-radiography of medial slabs of coral skeletons which contain annual density banding. Densitometer analysis of film optic density with calibration to skeletal density can also provide calcification rate and density, but is time consuming and restricted to thin transects equal in width to the densitometer beam. Coral density and calcification data are useful because they provide skeletal growth information additional to extension rate. A microcomputer system has been assembled and a BASIC program has been written to rapidly and accurately obtain extension, density, and calcification measurements from x-radiograph revealed coral skeletal growth bands. The hardware consists of: an IBM-PC microcomputer, internal digitizing board providing resolution of 256 x 256 picture elements (pixels) by 256 grey levels, closed circuit TV camera, and an evenly distributed back-light source. The software (BASIC program) is written to incorporate actual scale of the x-radiograph. Initially, film optic density is calibrated to skeletal density by digitizing the image of an aluminum wedge included in the x-radiograph. Appropriate formulas (Buddemeier, 1974) and mass absorption coefficients are utilized. Next, the coral x-radiograph is digitized and a transect perpendicular to growth band boundaries is defined. The transect dimensions are selectable by the operator. Pixel values of optic density within the transect are converted to skeletal density through the wedge calibration. These values are averaged parallel to band boundaries and graphed to produce a chart of peaks and valleys representing high and low density portions within each band. The program finds midpoints of each peak and valley along the graph. Linear distance between these points for each couplet gives annual extension rate. Density is found by integration of the area under peaks and valleys. Mass or calcification rate is calculated by the product of extension and density. Extension, density, and mass are also available for subannual band portions. Depending upon skeletal growth rate, the program can analyze up to 12 years on a single digitization. The image (and transect) can also be printed on a dot matrix printer making it possible to overlap and continue transects along the entire portion of the coral desired. Conventional image analysis systems cost in the 40,000pricerange.Themicrocomputersystemdescribedherecanbeimplementedforlessthan40,000 price range. The microcomputer system described here can be implemented for less than 40,000pricerange.Themicrocomputersystemdescribedherecanbeimplementedforlessthan5,000. The method provides relatively rapid, accurate, and objective measurements of the three skeletal growth parameters: extension, density, and calcification (mass). Investigations continue into the precision and reproducibility of the technique as well as for hardware to obtain greater resolution

Oceanography

Gulf of Mexico (GOM) ecosystems are interconnected by numerous physical and biological processes.... more Gulf of Mexico (GOM) ecosystems are interconnected by numerous physical and biological processes. After the Deepwater Horizon (DWH) disaster, these ecological processes facilitated dispersal of oil-spill toxicants or were damaged and broken. A considerable portion of post-DWH research focused on higher levels of biological organization (i.e., populations, communities, and ecosystems) spanning at least four environments (onshore, coastal, open ocean, and deep benthos). Damage wrought by the oil spill and mitigation efforts varied considerably across ecosystems. Whereas all systems show prolonged impacts because of cascading effects that impacted functional connections within and between communities, deep-sea and mesopelagic environments were particularly hard hit and have shown less resilience than shallow environments. In some environments, such as marshes or the deep-sea benthos, products from the spill are still biologically accessible. Some shallow ecosystems show signs of recove...

The coral reefs of Broward County, southeast Florida, USA are located offshore a highly urbanized... more The coral reefs of Broward County, southeast Florida, USA are located offshore a highly urbanized area. Because of the close proximity of a major shipping port and its associated anchorage, Broward reefs have been impacted by more than 10 ship groundings over the last 15 years. These injuries usually require restoration to speed recovery and compensate for damage. However, the recovery process on injured sites is not well understood, and even less is known about how restoration aids in recovery. This study examines coral recruitment, growth, and mortality in permanent quadrats on injured sites to asses their potential for natural recovery. It also investigates substrate materials commonly used in reef restoration, including limestone, concrete, and terracotta, to determine their efficacy in attracting and retaining coral recruits. Lastly, transplantation of juvenile corals collected on settlement plates from areas of higher coral recruitment and of corals raised in the lab from the larval stage is examined as a potential method to enhance reef restoration. Preliminary results indicate coral recruitment rates to injured sites were higher compared to reference sites. Mortality rates at the injured sites were also higher than reference sites. After one year of deployment, more corals settled on limestone plates than on concrete or terracotta. Hence, recovery on injury sites may be hampered by high juvenile coral mortality rates, and the choice of substrate materials used in restoration may influence recovery

Massive Caribbean scleractinians are slow to replace themselves in the population due to long lif... more Massive Caribbean scleractinians are slow to replace themselves in the population due to long life spans, low recruitment, and slow growth rates. Disruption of reproductive synchronicity or reduced fecundity may adversely affect their ability to recover and repopulate degraded areas. Reproductive information on Siderastrea siderea, an abundant Caribbean broadcast spawning species, is particularly sparse. In order to track gametogenesis and identify the time of spawning, tissue samples from S. siderea were collected from August 2007 on a weekly basis until November, when a reduction in gametes, indicative of spawning, was observed. Estimated spawning time was compared with lunar phase as well as water temperature data obtained from permanent digital temperature recorders deployed throughout Broward County to determine if either of these environmental cues affected spawning time. Information on colony condition and presence of bleaching was obtained for each colony sampled. Tissue samples were processed for histological analysis and examined for late stage gametes. Fecundity was estimated from measurements of the volume of oocytes cm-2 tissue and was compared between bleached and unbleached colonies. Initial analysis suggests that S. siderea spawned between November 8 and 11, 2007 which coincided with the new moon on November 9th. Samples collected on the 8th contained both ova and spermaries extruded from the mesenteries into the gastrovascular cavity and un-spawned gametes absorbed by the gastrodermis. Further collections of S. siderea in 2008 will be used to corroborate spawning correlation of S. siderea with lunar period