Underwater Videography Research Articles

Kinematic Analysis of Swimmers with Permanent Physical Disabilities

When the movement patterns of persons with permanent physical disabilities are observed from underwater, it is apparent that they have adapted unique variations in their swimming strokes to compensate for existing anatomic and neuromuscular deficits. Using underwater videotaping and subsequent analysis it is now possible to both identify and evaluate the movement mechanics of these swimmers. The purpose of this paper is to describe how motion analysis technology can be used in biomechanical research to examine the stroke mechanics of swimmers with permanent physical disabilities. In addition, we will identify the unique movement patterns of these swimmers, and, when applicable, discuss the limitations to their swimming efficiency. Aquatic exercise has been used extensively in the past 20 years as a rehabilitative and therapeutic modality for individuals with permanent physical disabilities. The freedom of movement in the water and the ability to exercise muscles which, on land, have difficulty overcoming gravitational constraints makes swimming and related aquatic activities invaluable for persons with a wide range of physically disabling conditions (Daly, 1999; Dummer, 1999; Prins, 1988). Since the primary intent of analyzing the swimming stroke mechanics of disabled swimmers is to improve instructional techniques, the first objective is to examine the underwater movement patterns of these swimmers. The methods for teaching and analyzing the swimming stroke mechanics of swimmers with permanent physical disabilities are similar to those used for assisting able-bodied swimmers. Stroke patterns are videotaped from above- and underwater and evaluated using digital video recorders. Slow motion and freeze-frame capabilities of the video recorders allow more detailed analysis; however, these assessments, no matter how detailed, remain somewhat subjective. With the advent of motion capture technology, which is used for research in biomechanics, it is now possible to determine motion more precisely by quantifying the results. Biomechanics is divided into two branches of study. Kinematics deals with the description of spatial and temporal parameters of movement measured as linear and angular displacements, velocities, and accelerations. Kinetics examines the forces that lead to the resulting kinematic changes (Griffiths, 2006; Kreighbaum, 1996). Using underwater videography and motion capture technology, the

Bottom Habitat Mapping Using Towed Underwater Videography: Subtidal Oyster Reefs as an Example Application

Abstract Towed underwater video has become a widely used method for bottom habitat mapping in coastal waters, but very little has been published on this relatively new and effective approach. We use a case study on two oyster reefs to illustrate the pros and cons of towed video, visualization techniques, and future research topics. Towed video is deployed in similar fashion to single-beam sonars, yielding narrow swaths of video imagery that are recorded concurrently with global positioning system (GPS) data for georeferencing. The major advantages over acoustic (sonar) methods are that image processing and interpretation are relatively simple, and there is little or no need for subsequent ground-truthing. The system used in the present study consists of an underwater black and white camera mounted on a steel frame, differential GPS unit, and digital video camera for recording. It was assembled from off-the-shelf items, and total cost was approximately $3500 (2006 US$). The imagery from both study reefs wa...

Seagrass monitoring by underwater videography: Disturbance regimes, sampling design, and statistical power

Surface-based underwater videography with submeter-accuracy differential GPS is a method with several advantages, including high spatial and visual resolution, effectiveness at all depths at which seagrasses occur, non-destructive sampling, and rapid data collection in the field. Here I investigate the statistical power of this method applied to a natural meadow and to virtual meadows created by a spatially explicit model of seagrass disturbance, regrowth, and colonization. The approach is found to detect a 5–10% loss in short timespans at 80% probability, with a sampling design emphasizing long transects ( ≅ 400 m or greater) and a paired analysis in which the same permanent transects are followed each monitoring event. A field effort function shows that this precision is possible within a single working field day for sampling regions ≅ 1 km 2. These conclusions hold regardless of the presence of positional error in remonitoring previous transects by submeter DGPS navigation.

Terrestrial and Submerged Aquatic Vegetation Mapping in Fire Island National Seashore Using High Spatial Resolution Remote Sensing Data

The vegetation communities and spatial patterns on the Fire Island National Seashore are dynamic as the result of interactions with driving forces such as sand deposition, storm-driven over wash, salt spray, surface water, as well as with human disturbances. We used high spatial resolution QuickBird-2 satellite remote sensing data to map both terrestrial and submerged aquatic vegetation communities of the National Seashore. We adopted a stratified classification and unsupervised classification approach for mapping terrestrial vegetation types. Our classification scheme included detailed terrestrial vegetation types identified by previous vegetation mapping efforts of the National Park Service and three generalized categories of high-density seagrass, low-density seagrass coverages, and unvegetated bottom to map the submerged aquatic vegetation habitats. We used underwater videography, GPS-guided field reference photography, and bathymetric data to support remote sensing image classification and information extraction. This study achieved approximately 82% and 75% overall classification accuracy for the terrestrial and submnerged aquatic vegetations, respectively, and provided an updated vegetation inventory and change analysis for the Northeast Coastal and Barrier Network of the National Park Service.

Airborne lidar sensing of massive stony coral colonies on patch reefs in the northern Florida reef tract

In this study we examined the ability of the NASA Experimental Advanced Airborne Research Lidar (EAARL) to discriminate cluster zones of massive stony coral colonies on northern Florida reef tract (NFRT) patch reefs based on their topographic complexity (rugosity). Spatially dense EAARL laser submarine topographic soundings acquired in August 2002 were used to create a 1-m resolution digital rugosity map for adjacent NFRT study areas characterized by patch reefs (Region A) and diverse substratums (Region B). In both regions, sites with lidar-sensed rugosities above 1.2 were imaged by an along-track underwater videography system that incorporated the acquisition of instantaneous GPS positions. Subsequent manual interpretation of videotape segments was performed to identify substratum types that caused elevated lidar-sensed rugosity. Our study determined that massive coral colony formation, modified by subsequent physical and biological processes that breakdown patch reef framework, was the primary source of topographic complexity sensed by the EAARL in the NFRT. Sites recognized by lidar scanning to be topographically complex preferentially occurred around the margins of patch reefs, constituted a minor fraction of the reef system, and usually reflected the presence of massive coral colonies in cluster zones, or their derivatives created by mortality, bioerosion, and physical breakdown.

Energetics of parental care in six syntopic centrarchid fishes

We studied parental behavior in six syntopically breeding species of centrarchid fishes to determine whether energetic costs could contribute to our understanding of the diversity of parental care. We used a combination of underwater videography, radio telemetry and direct observation to examine how the cost of parental care varied with both its duration and intensity. Duration of parental care, activity patterns, and energetic costs varied widely among species. Overall, the duration of care increased with parental size between species. When energetic costs were adjusted for species-specific differences in the duration of parental care, the cost of parental care also increased with mean size of the species. Species with extended parental care exhibited stage-specific patterns of activity and energy expenditure consistent with parental investment theory, whereas fish with short duration parental care tended to maintain high levels of activity throughout the entire period of parental care. The only apparent exception (a species with brief parental care but stage-specific behavior) was a species with multiple breeding bouts, and thus effectively having protracted parental care. These data suggest that some species with short duration parental care can afford not to adjust parental investment over stages of offspring development. Using our empirical data on parental care duration and costs, we reevaluated the relationship between egg size and quality of parental care. Variation in egg size explained almost all of the observed variation in total energetic cost of parental care, and to a lesser degree, duration-the larger the eggs, the more costly the parental care. This research highlights the value of incorporating energetic information into the study of parental care behavior and testing of ecological theory.

Assessment of Recent Habitat Conditions of Eastern Oyster Crassostrea virginica Bars in Mesohaline Chesapeake Bay

AbstractEastern oysters Crassostrea virginica in Chesapeake Bay, USA, have been subjected to intense harvest pressure since about 1850 and to disease epizootics since the 1950s. Combined, these processes have degraded the once extensive eastern oyster bottom; the remaining oyster shells, which are required as substrate for successful larval oyster settlement, are thus rendered increasingly susceptible to siltation. Between 1999 and 2001, we used an acoustic seabed classification system and underwater videography to assess oyster habitat conditions throughout Maryland's portion of Chesapeake Bay relative to eastern oyster recruitment and habitat restoration activities. We performed 16 surveys that covered a total of 39 km2 of bottom that were classified in 1911 as supporting productive oyster populations. Over 90% of this area has degraded from productive oyster bottom to mud, sand, or heavily sedimented oyster shell. Seventy percent of the locations we identified as containing unsedimented shell came from within the approximately 90 km2 of oyster bottom that had been subject to the management activity of spreading large volumes of shell at some time between 1960 and 1999. However, video observations of 49 of these locations that had been replenished with shell at various times indicated that any improvements in oyster habitat were short lived, as interstitial spaces in spread shell became highly sedimented after an average period of 5.5 years (n = 49; SE = 1.03). We conclude that the majority of oyster bottom in Maryland is extremely degraded and that no reasonable increase in the scale of present management practices will reverse this habitat decline.

Imaging Fall Chinook Salmon Redds in the Columbia River with a Dual-Frequency Identification Sonar

We tested the efficacy of a dual-frequency identification sonar (DIDSON) for imaging and enumeration of fall Chinook salmon Oncorhynchus tshawytscha redds in a spawning area below Bonneville Dam on the Columbia River. The DIDSON uses sound to form near-video-quality images and has the advantages of imaging in zero-visibility water and possessing a greater detection range and field of view than underwater video cameras. We suspected that the large size and distinct morphology of a fall Chinook salmon redd would facilitate acoustic imaging if the DIDSON was towed near the river bottom so as to cast an acoustic shadow from the tailspill over the redd pocket. We tested this idea by observing 22 different redds with an underwater video camera, spatially referencing their locations, and then navigating to them while imaging them with the DIDSON. All 22 redds were successfully imaged with the DIDSON. We subsequently conducted redd searches along transects to compare the number of redds imaged by the DIDSON with the number observed using an underwater video camera. We counted 117 redds with the DIDSON and 81 redds with the underwater video camera. Only one of the redds observed with the underwater video camera was not also documented by the DIDSON. In spite of the DIDSON's high cost, it may serve as a useful tool for enumerating fall Chinook salmon redds in conditions that are not conducive to underwater videography.

Comparing Fish Screen Performance to Physical Design Criteria

Fish screens associated with irrigation diversion structures perform a vital function by protecting rearing and migrating fishes. Irrigation diversions in the western United States were developed in the late 1800s and early 1900s with little regard to how they might affect fish populations. Fish screens were installed on some diversions beginning in the 1930s but were often ineffective. Beginning in the 1980s a “modern-era” fish screening program was initiated in the Yakima River basin in Washington State. A systematic phased approach was employed, with federal funding, to replace antiquated screens and to install screens where there had not previously been fish protection devices. Also during this time, the federal and state agencies responsible for protecting the fish resources developed regional criteria to guide design of these facilities. These criteria, developed by the National Marine Fisheries Service and used by the Washington Department of Fish and Wildlife, dictated physical metrics such as approach velocity (and mesh size) for fish screen facilities. Scientists at the Pacific Northwest National Laboratory (PNNL) developed methods for evaluating new fish screen facilities as they came “on line” to document whether the facilities were designed, constructed, operated, and maintained to be within the fish passage criteria. PNNL uses a combination of water velocity measurements, visual inspection, and underwater videography to determine whether fish screen sites are within the fish protection criteria. This annual evaluation schedule (most sites are evaluated three times/year) is a vital tool to ensure that the large initial capital investment (over $75 million USD) is being operated and maintained to protect fish.

REPRODUCTIVE AND TERRITORIAL BEHAVIOR OF COMANCHE SPRINGS PUPFISH (CYPRINODON ELEGANS) IN SAN SOLOMON SPRING POOL, BALMORHEA STATE PARK, REEVES COUNTY, TEXAS

Abstract While much is known about the behavioral ecology of some species of pupfish (Cyprinodon), virtually nothing is known about the reproductive and territorial behavior of the Comanche Springs pupfish (C. elegans). Using SCUBA and underwater videography, observations were made of the reproductive and territorial behavior of C. elegans in the source pool of San Solomon Spring, Balmorhea State Park, Texas. We constructed time budgets of territorial males and manipulated territorial landmarks. Cyprinodon elegans exhibited courtship and agonistic behaviors, including territorial disputes similar to other Cyprinodon species. Additionally, C. elegans used visual cues as a means for identifying territory, as do other species of Cyprinodon.

Determination of fish community composition in the untempered regions of a thermal effluent canal--the efficacy of a fixed underwater videography system.

High flows and deep waters associated with thermal discharge canals invoke safety concerns and preclude the use of conventional fish sampling methodologies. Despite these challenges, it is critical that assessments of thermal effects from power generation do not rely solely on data collected in the plume, but also focus on fish living in the canal, particularly in regions above the zone of tempering influence. We deployed a fixed underwater videography apparatus to monitor the community composition and abundance patterns of fish in the Nanticoke thermal generating discharge canal on the north shore of Lake Erie from February 1, 1999 until July 31, 1999. We also compared the number of species observed using video to angling surveys, visual observations through the air/water interface and two modified netting procedures. Our results indicate that videography permitted the detection of the most species and the highest number of individuals. Variable visibility was the largest limitation of this approach. The addition of infrared lighting for low light conditions and a series of cameras positioned at several depths would be a cost effective, safe, and efficient method of assessing community structure and behaviour of fish in thermal discharge canals.

Factors Affecting Foraging Patterns of Juvenile Bluegill (Lepomis macrochirus) in Vegetated Habitats of a Wisconsin Lake

ABSTRACT We collected behavioral data of juvenile bluegill in vegetated habitats with underwater videography in a Wisconsin lake to gain a better understanding of how juvenile bluegill foraging patterns are influenced by environmental and/or biotic variables characteristic of vegetated habitats. Relationships among foraging patterns and invertebrate density, aquatic plant stem densities, water quality, water depth, and light were determined. Three plant species (Potamogeton illinoensis, P. robbimii and Ceratophyllum demersum), as well as invertebrate density, water temperature, and percent of light transfer in the water column were associated with foraging duration of blued. We suggest these data are useful in determining the habitat required for enhancement of bluegill populations and recruitment of young fishes.

Physical activity and behavior of a centrarchid fish, Micropterus salmoides (Lacépède), during spawning

Abstract – The spawning behavior of male and female largemouth bass Micropterus salmoides (Lacépède) was studied in central Illinois during the spring of 1998 to examine patterns of muscular activity associated with different spawning related behaviors and to evaluate whether electromyogram (EMGi) telemetry could be used to detect spawning activity. Fish were implanted with EMGi transmitters (8 females, 16 males) on April 7, prior to the initiation of spawning, and were released in four 0.10‐ha earthen research ponds. Continuous EMGi records, underwater videography and additional visual observations for one pair of EMGi tagged fish were collected throughout the entire spawning event, allowing us to quantify behavioral correlates of physical activity. Male EMGi activity patterns were only correlated with female patterns during courting and periods of male aggression toward the female. Overall, EMGi activity was highest for the female during shuddering (gamete deposition), whereas male EMGi activity was similarly high during periods of nest excavation, shuddering and post‐spawn parental care activities. During spawning, female EMGi activity was positively correlated to shuddering. Average daily EMGi activities for females peaked on the day of spawning. As a result of their engagement in parental care activities, male activity continued to rise even after spawning was completed. EMGi telemetry appears to be a useful technique for monitoring the reproductive activity of largemouth bass, especially in areas of high cover or turbid water or during low light conditions. This technology permitted us to quantify and contrast the activity patterns associated with different spawning related activities, information that will be required to construct accurate, gender‐specific bioenergetics models for this species.

Pursuit plunging by northern gannets (Sula bassana) feeding on capelin (Mallotus villosus).

Northern gannets (Sula bassana) are considered to obtain prey usually by rapid, vertical, shallow plunge dives. In order to test this contention and investigate underwater foraging behaviour, we attached two types of data-logging systems to 11 parental northern gannets at Funk Island in the North-Wiest Atlantic. We documented, for the first time to the authors' knowledge, gannets performing long, flat-bottomed, U-shaped dives that involved underwater wing propulsion as well as rapid, shallow, V-shaped dives. The median and maximum dive depths and durations were 4.6 and 22.0 m and 8 and 38 s, respectively. Short, shallow dives were usually V-shaped and dives deeper than 8 m and longer than 10 s were usually U-shaped, including a period at constant depth (varying between 4 and 28s with median 8s). Diving occurred throughout the daylight period and deepest dives were performed during late morning. On the basis of motion sensors in the loggers and food collections from telemetered birds, we concluded that extended, deep dives were directed at deep schools of capelin, a small pelagic fish, and we hypothesized that V-shaped dives were aimed at larger, pelagic fishes and squids. Furthermore, these V-shaped dives allowed the birds to surprise their pelagic prey and this may be critical because the maximum swimming speeds of the prey species may exceed the maximum dive speeds of the birds.

Spawning Habitat Used by Fall Chinook Salmon in the Snake River

Literature describing spawning habitat used by fall-run chinook salmon Oncorhynchus tshawytscha is lacking for populations using large, main-stem rivers. A stable spawning flow regime in the Snake River below Hells Canyon Dam and enhanced survey capabilities using remote underwater videography allowed us to accurately describe spawning habitat used by fall chinook salmon within this large river. Water depth measured at 205 fall chinook salmon redds ranged from 0.2 to 6.5 m. Mean water column velocity at 145 redds ranged from 0.4 to 2.1 m/s, and substrate- level water velocity at 164 redds ranged from 0.1 to 2.0 m/s. Substrate size classifications from 112 redds indicated that areas having particle sizes that are relatively homogenous with diameters of 2.5–15.0 cm are used for spawning. During our study, spawning generally began as water temperatures dropped below 16.0°C, and concluded as temperatures approached 5.0°C. Our results corroborate earlier observations of fall chinook salmon spawning in deep, fast-velocity water in the Hanford Reach of the Columbia River and significantly expand current criteria used to model spawning habitat availability for these fish within large rivers.

Investigating Kinetics in the Freestyle Flip Turn Push-Off

Thirty experienced male swimmers with body types ± 1 SD of the mean of selected body form parameters reported for elite male swimmers were recruited for the study. During three freestyle flip turns, selected kinetic, hydrodynamic, and kinematic variables of the push-off following a flip turn were recorded. Kinetics were recorded via a 2D vertically mounted forceplate that recorded peak push-off force and total impulse. The acceleration of each swimmer’s center of gravity and wall exit velocity were calculated from underwater videography. Hydrodynamic peak drag force and drag impulse were calculated from the kinetic and kinematic data using a derivative of Newton’s second law. A stepwise regression yielded peak drag force, peak propulsive force, and push-off time in the final regression equation (R = 0.80; R2 = 0.64). Beta values indicated that the peak drag force carried the highest weighting of the three variables. The results of the stepwise regression indicated that a combination of a low peak drag force high peak propulsive force, and increased wall push-off time produced the fastest final push-off velocity.

Determination of the submerged macrophyte coverage of greifswalder bodden

The extent to which a water body can support submerged macrophytic vegetation provides an indicator of its degree of eutrophication. Regular, quantitative assessment of macrophyte populations enables changes in the trophic state of the system to be observed. A combination of aerial photography and underwater videography has proved to be an efficient method for calculating macrophyte coverage of large coastal areas.

Estimating basal area coverage of subtidal seagrass beds using underwater videography

Although seagrasses have been identified as vital living marine resources, their distribution has not been rigorously quantified at many locations. This fact is often due to the high cost of sampling seagrass habitats, especially those with deep-water plants that cannot be sensed from aerial platforms. We present a cost-effective method of estimating basal area coverage of submersed vegetation that uses differential global positioning system data linked to underwater video images of the bottom. Our sampling design and statistical procedures are identical to estimating proportions using cluster sampling with unequal cluster sizes. This method has several advantages over other techniques: (1) confidence intervals around basal area coverage estimates permit hypothesis testing of changes over time; (2) sampling efficiency is better than simple random sampling with quadrats; (3) deep-water zones out of the range of aerial platforms can be sampled; (4) video images provide positive identification of plants which is not possible with acoustic techniques; and (5) the techniques provide a permanent archive of visual images that can be analyzed for other bottom attributes, such as other vegetation, macro-invertebrates, and gross sediment types. This method has some limitations: (1) it is not possible to sample extremely shallow or turbid waters and under some physical structures; (2) it is impractical to sample very large regions; (3) errors in differential global positioning system data must be accounted for; and (4) seagrass density must be measured subjectively. We illustrate our sampling methods and data analysis with an example from Puget Sound, Washington, USA.

Occurrence of Zebra Mussels in Near-shore Areas of Western Lake Erie

We measured biomass, percent coverage, and length-frequency of zebra mussels in near-shore areas of western Lake Erie between 16 September and 10 November 1993 as part of a larger study on the ecological relationship between diving ducks and zebra mussels. Wet weight biomass of zebra mussels, determined by SCUBA diving, ranged from 0 to 3,611 g/m 2 and averaged ( ± 1 SE) 1,270 ± 380 g/m 2 (n = 11). Percent coverage of lake bottom by zebra mussels ranged from 0 to 70% and averaged 17 ± 4.0% (n = 27). Percent coverage of zebra mussels was relatively high in the northern portion (28–70% coverage) and in the southwestern portion (18–40%), but relatively low ( < 5%) in the southeastern portion of the study area. Percent coverage by zebra mussels, determined from underwater videography, was highly correlated (r 2 = 0.96) with zebra mussel biomass. Analysis of length-frequency data indicated that there was prominent recruitment of juvenile zebra mussels at only three of eight sites. Average shell length ranged from 11 mm to 15 mm at the other five sites. The non-uniform distribution of zebra mussels, as determined from biomass and videography, may have important ramifications when assessing zebra mussel impacts on waterfowl. These data may also be used when assessing impact of zebra mussels on other aquatic organisms in the near-shore areas of western Lake Erie.

Body Roll and Handpath in Freestyle Swimming: An Experimental Study

The purpose of this study was to determine the influence of (a) body roll, and (b) the motion of the arm relative to the trunk, on the medial-lateral component of the path followed by the hand during the pull phase in freestyle swimming. Ten male swimmers swam three trials of freestyle at a long-distance workout pace. Three-dimensional (3D) underwater videography was used to record the body roll angle-time history and the path followed by the hand during the pull phase. A mathematical model was used to characterize the motion of a swimmer's right upper limb in accord with 3D data from the videotape images, and to determine what the path of the hand would have been as a result of body roll alone. The contribution of body roll to the actual handpath was found to be nearly equal to the contribution of medial-lateral motions of the hand relative to the trunk.