scholarly journals Reef benthos of Seychelles - A field guide

2021 ◽  
Vol 9 ◽  
Author(s):  
Nico Fassbender ◽  
Paris Stefanoudis ◽  
Zoleka Filander ◽  
Gilberte Gendron ◽  
Christopher Mah ◽  
...  
Keyword(s):  
Community Composition ◽  
Benthic Communities ◽  
Scuba Diving ◽  
Video Camera ◽  
Field Guide ◽  
Video Footage ◽  
Deep Reef ◽  
Camera Systems ◽  
Visual Identification ◽  
Marine Macrophytes

During the 2019 First Descent: Seychelles Expedition, shallow and deep reef ecosystems of the Seychelles Outer Islands were studied by deploying a variety of underwater technologies to survey their benthic flora and fauna. Submersibles, remotely operated vehicles (ROVs) and SCUBA diving teams used stereo-video camera systems to record benthic communities during transect surveys conducted at 10 m, 30 m, 60 m, 120 m, 250 m and 350 m depths. In total, ~ 45 h of video footage was collected during benthic transect surveys, which was subsequently processed using annotation software in order to assess reef biodiversity and community composition. Here, we present a photographic guide for the visual identification of the marine macrophytes, corals, sponges and other common invertebrates that inhabit Seychelles’ reefs. It is hoped that the resulting guide will aid marine biologists, conservationists, managers, divers and naturalists with the coarse identification of organisms as seen in underwater footage or live in the field. A total of 184 morphotypes (= morphologically similar individuals) were identified belonging to Octocorallia (47), Porifera (35), Scleractinia (32), Asteroidea (19), Echinoidea (10), Actiniaria (9), Chlorophyta (8), Antipatharia (6), Hydrozoa (6), Holothuroidea (5), Mollusca (2), Rhodophyta (2), Tracheophyta (2), Annelida (1), Crinoidea (1), Ctenophora (1), Ochrophyta (1) and Zoantharia (1). Out of these, we identified one to phylum level, eight to class, 14 to order, 27 to family, 110 to genus and 24 to species. This represents the first attempt to catalogue the benthic diversity from shallow reefs and up to 350 m depth in Seychelles.

scholarly journals Application of Shore-Based Video and Unmanned Aerial Vehicles (Drones): Complementary Tools for Beach Studies

2020 ◽  
Vol 12 (3) ◽  
pp. 394 ◽  
Author(s):  
Donatus Bapentire Angnuureng ◽  
Philip-Neri Jayson-Quashigah ◽  
Rafael Almar ◽  
Thomas Christian Stieglitz ◽  
Edward Jamal Anthony ◽  
...  
Keyword(s):  
Low Cost ◽  
Video Camera ◽  
Video Data ◽  
Camera System ◽  
Camera Systems ◽  
Camera View ◽  
Aerial Vehicle ◽  
One Year ◽  
Video Camera System ◽  
Good Agreement

Video camera systems have been used over nearly three decades to monitor coastal dynamics. They facilitate a high-frequency analysis of spatiotemporal shoreline mobility. Video camera usage to measure beach intertidal profile evolution has not been standardized globally and the capacity to obtain accurate results requires authentication using various techniques. Applications are mostly site specific due to differences in installation. The present study examines the accuracy of intertidal topographic data derived from a video camera system compared to data acquired with unmanned aerial vehicle (UAV, or drone) surveys of a reflective beach. Using one year of 15-min video data and one year of monthly UAV observations, the intertidal profile shows a good agreement. Underestimations of intertidal profile elevations by the camera-based method are possibly linked to the camera view angle, rectification and gaps in data. The resolution of the video-derived intertidal topographic profiles confirmed, however, the suitability of the method in providing beach mobility surveys matching those required for a quantitative analysis of nearshore changes. Beach slopes were found to vary between 0.1 and 0.7, with a steep slope in May to July 2018 and a gentle slope in December 2018. Large but short-scale beach variations occurred between August 2018 and October 2018 and corresponded to relatively high wave events. In one year, this dynamic beach lost 7 m. At this rate, and as also observed at other beaches nearby, important coastal facilities and infrastructure will be prone to erosion. The data suggest that a low-cost shore-based camera, particularly when used in a network along the coast, can produce profile data for effective coastal management in West Africa and elsewhere.

The SCATMES Device for Measurement of Concentrated Solar Radiation

1999 ◽  
Vol 121 (2) ◽  
pp. 116-120 ◽  
Author(s):  
A. Neumann ◽  
A. Schmitz
Keyword(s):  
Solar Radiation ◽  
Measurement System ◽  
Flux Distribution ◽  
Optical Design ◽  
Video Camera ◽  
Solar Furnace ◽  
Camera Systems ◽  
Measurement Principle ◽  
Concentrated Solar Radiation ◽  
Compact Geometry

Video camera systems monitoring a diffuse reflecting target for measuring the flux distribution of concentrated solar radiation are quite common. This technique cannot be used if parts of the experimental setup screen the surface of the target. The development of a new measurement system with a compact geometry and a new optical design is described. With this system it is possible to measure the flux distribution behind parts of an experiment and at any position of the plane of measurement, without any alteration of the setup. The sources of error, especially those of the target and the camera, are described and discussed, and finally a comparison to the existing FATMES-System, which has been performed at the solar furnace of the DLR in Cologne, is presented. Due to its measurement principle the new system is called ’Scanning Camera and Target Measurement System‘ (acronym: SCATMES).

scholarly journals Depth moderates loss of marine foundation species after an extreme marine heatwave: could deep temperate reefs act as a refuge?

2020 ◽  
Vol 287 (1928) ◽  
pp. 20200709
Author(s):  
Ana Giraldo-Ospina ◽  
Gary A. Kendrick ◽  
Renae K. Hovey
Keyword(s):  
Transition Zone ◽  
Community Composition ◽  
Benthic Community ◽  
Benthic Communities ◽  
Foundation Species ◽  
Temperate Reefs ◽  
Environmental Extremes ◽  
Deep Reefs ◽  
Clear Shift ◽  
Western Australian

Marine heatwaves (MHWs) have been documented around the world, causing widespread mortality of numerous benthic species on shallow reefs (less than 15 m depth). Deeper habitats are hypothesized to be a potential refuge from environmental extremes, though we have little understanding of the response of deeper benthic communities to MHWs. Here, we show how increasing depth moderates the response of seaweed- and coral-dominated benthic communities to an extreme MHW across a subtropical–temperate biogeographical transition zone. Benthic community composition and key habitat-building species were characterized across three depths (15, 25 and 40 m) before and several times after the 2011 Western Australian MHW to assess resistance during and recovery after the heatwave. We found high natural variability in benthic community composition along the biogeographic transition zone and across depths with a clear shift in the composition after the MHW in shallow (15 m) sites but a lot less in deeper communities (40 m). Most importantly, key habitat-building seaweeds such as Ecklonia radiata and Syctothalia dorycarpa which had catastrophic losses on shallow reefs, remained and were less affected in deeper communities. Evidently, deep reefs have the potential to act as a refuge during MHWs for the foundation species of shallow reefs in this region.

The AirScope: A Novel Wireless Laparoscope

2012 ◽  
Vol 6 (4) ◽  
Author(s):  
John Lazarus
Keyword(s):  
Video Transmission ◽  
Fiber Optic ◽  
Video Camera ◽  
Video Monitor ◽  
High Definition ◽  
Experimental Prototype ◽  
Camera Systems ◽  
Wide Angle Lens ◽  
Expected Benefits

The modern laparoscope relies on Hopkins’ glass rod lenses, a fiber-optic light source, a video camera, and external cables. This paper discusses the feasibility of developing an experimental prototype of a completely wireless laparoscope by making use of the latest in electronic and optic miniaturization. Design requirements were defined to mimic a standard 10 mm adult laparoscope. An 8 mm diameter (CMOS) camera was used, which delivered standard definition TV resolution at an image refresh rate of 30 Hz. A wide-angle lens was chosen, and a focusing mechanism was designed. Instead of a fiber-optic cable, illumination was achieved using four miniature LED lights. A 2.4 GHz wireless transmission with adequate range for use in an operating theater was chosen. A wireless receiver on a standard personal computer was used to drive a video monitor using off the shelf image processing software. A built-in rechargeable battery powered the wireless laparoscope. Flicker-free in vitro wireless video transmission was achieved. The laparoscope was made waterproof with a front cover lens and can be gas or chemically sterilized. The prototype laparoscope weights 78 g as compared with 900 g for a typical 10 mm laparoscope, camera, fiber-optic, and camera cables. Drawbacks of the prototype include reduced resolution of the video image as compared to high definition (HD) TV quality available on the most recent commercial camera systems. This experimental prototype has illustrated the feasibility of wireless endoscopy systems. The expected benefits include improved ergonomic maneuverability, reduced weight, and decreased electric power requirements.

scholarly journals Impacts of bottom trawling on benthic trophic status and meiofauna in a deep-sea sedimentary environment (Gulf of Castellammare, southwestern Mediterranean Sea)

2020 ◽  
Author(s):  
Antonio Pusceddu ◽  
Sarah Paradis ◽  
Davide Moccia ◽  
Pere Puig ◽  
Pere Masque ◽  
...  
Keyword(s):  
Community Composition ◽  
Deep Sea ◽  
Biochemical Composition ◽  
Benthic Communities ◽  
Sedimentary Environment ◽  
Sediment Cores ◽  
Organic Detritus ◽  
Bottom Trawling ◽  
Sedimentary Environments ◽  
The Impact

<p>The impacts of bottom trawling on the structure of benthic communities can be relatively non-selective, hitting biodiversity as a whole. This holds true also in the deep sea, where the impacts of trawling can be more severe and long-lasting than in shallow-waters, due to the reduced capacity for recovery and greater vulnerability of deep-sea organisms. For years, our knowledge of the impact of trawling on deep-water ecosystems has remained limited and has focused mainly on fish stocks and hard bottom systems. More recently, a number of studies have addressed the impacts of bottom trawling in the deep-sea sedimentary environments, and very few of them have focused on the impacts on meiofauna, though it is a key faunal component of deep-sea ecosystems.</p><p>We investigated the impact of bottom trawling on the quantity, biochemical composition and nutritional value of sedimentary organic matter and meiofauna along the Sicilian Margin (Gulf of Castellammare, southwestern Mediterranean) at ca. 550 m depth, during the summer of 2016. Amount, biochemical composition and freshness of sedimentary OM, as well as the abundance and community composition of meiofauna were determined in sediment cores taken at both trawled and untrawled grounds. The continuous erosive processes in the trawled site have led, generally, to the depletion of OM contents (20-60% lower than those in the untrawled site), as well as to statistically significant differences from the untrawled site in its biochemical composition. Nevertheless, the upper 2 cm of the trawled site consisted of recently accumulated sediments, enriched in phytopigments, and bulk OM contents similar to those in the untrawled one, interpreted as a very recent input of fresh OM from the upper water column. The abundance of meiofauna in trawled grounds was significantly higher than that in untrawled ones, whereas no differences were observed between trawled and untrawled grounds deeper in the sediment. Differences in the meiofaunal community composition among sediment layers in each site were larger than those among sites.</p><p>As previously reported, deep bottom trawling in the Gulf of Castellammare erodes large volumes of sediment, exposing old compacted sediment that is depleted in OM. This erosive action generally prevents the accumulation of fresh sediment. However, the episodic short-lived deposition of fresh organic detritus between hauls can lead to a temporary accumulation of fresh and bioavailable OM which, in turn, can induce a positive response in meiofauna abundance.</p><p>These results pinpoint the need of considering the impacts of bottom trawling on the benthic communities of deep-sea sedimentary environments at temporal scales shorter than previously done.</p>

scholarly journals Social Distancing for Covid-19 Monitoring System

2021 ◽  
pp. 49-61
Author(s):  
Raj Kushwaha ◽  
Kismat Khatri ◽  
Yogesh Mahato
Keyword(s):  
Real Time ◽  
Safe Distance ◽  
Public Places ◽  
Cascade Algorithm ◽  
Facial Mask ◽  
Social Distancing ◽  
Video Footage ◽  
Camera Systems ◽  
Haar Cascade ◽  
Increasing Demand

The battle of corona-virus and mankind is possible to be tackled as long as we maintain the basic norm of social distancing and wearing masks amongst ourselves as it is through our droplets from the respiratory tract that the virus spreads. With the increasing demand for man-force and people requiring to go to their workplaces post lockdown, it is very necessary that we save each other from the virus. In this project, we will go through a detailed explanation of how we can use Python, AI and Deep Learning to monitor social distancing at public places and workplaces are keeping a safe distance from each other by analyzing real-time video streams from the camera and also detect facial mask monitoring using OpenCV and Python. To ensure if people are following social distancing protocols in public places and workplaces, we wanted to develop a tool that can monitor if people are keeping a safe distance from one another, wearing masks or not by processing real-time video footage from the camera. People at workplaces, factories, shops can integrate this tool into their security camera systems and can monitor whether people are keeping a safe distance from each other or not along with that we detect facial mask monitoring using Python with help of haar-cascade algorithm to see whether a person is wearing a mask or not. We are also planning to include thermal screening detection to measure the temperature of the subjects, a dashboard which will display a live report of corona cases around the world. We will also include an alert system that will send a notification to the authorities if the social distancing is not followed or if the temperature exceeds the threshold. The authorities can take suitable measures to isolate the subject and thus prevent the spread of Covid-19.

scholarly journals Twenty years of change in benthic communities across the Belizean Barrier Reef

2021 ◽  
Author(s):  
John F Bruno ◽  
Catherine Alves ◽  
Richard B. Aronson ◽  
Nadia Bood ◽  
Karl D. Castillo ◽  
...  
Keyword(s):  
Community Composition ◽  
Human Impacts ◽  
Coral Cover ◽  
Benthic Communities ◽  
Disease Outbreaks ◽  
Barrier Reef ◽  
Living Coral ◽  
The Caribbean ◽  
And Shifts ◽  
Benthic Composition

Disease, ocean warming, and pollution have caused catastrophic declines in the cover of living coral on reefs across the Caribbean. Subsequently, reef-building corals have been replaced by invertebrates and macroalgae, leading to changes in ecological functioning. We describe changes in benthic community composition and cover at 15 sites across the Belizean Barrier Reef (BBR) following numerous major disturbances—bleaching, storms, and disease outbreaks—over the 20-year period 1997–2016. We tested the role of potential drivers of change on coral reefs, including local human impacts and ocean temperature. From 1997 to 2016, mean coral cover significantly declined from 26.3% to 10.7%, while macroalgal cover significantly increased from 12.9% to 39.7%. We documented a significant decline over time of the reef-building corals Orbicella spp. and described a major shift in benthic composition between early sampling years (1997–2005) and later years (2009¬–2016). The covers of hard-coral taxa, including Acropora spp., M. cavernosa, Orbicella spp., and Porites spp., were negatively related to marine heatwave frequency. Only gorgonian cover was related, negatively, to our metric of the magnitude of local impacts (the Human Influence Index). Changes in benthic composition and cover were not associated with local protection or fishing. This result is concordant with studies throughout the Caribbean that have documented living coral decline and shifts in reef-community composition following disturbances, regardless of local fisheries restrictions. Our results suggest that benthic communities along the BBR have experienced disturbances that are beyond the capacity of the current management structure to mitigate. We recommend that managers devote greater resources and capacity to enforce and expand existing marine protected areas and that government, industry, and the public act to reduce global carbon emissions.

scholarly journals Nano- and microplastics affect the composition of freshwater benthic communities in the long term

2020 ◽  
Vol 6 (5) ◽  
pp. eaay4054 ◽  
Author(s):  
P. E. Redondo-Hasselerharm ◽  
G. Gort ◽  
E. T. H. M. Peeters ◽  
A. A. Koelmans
Keyword(s):  
Risk Assessment ◽  
Community Composition ◽  
Benthic Communities ◽  
Dry Weight ◽  
Community Effects ◽  
Positive Effects ◽  
Population Sizes ◽  
Over Time

Given the societal concern about the presence of nano- and microplastics in the environment, our nescience with respect to in situ effects is disturbing. Data on long-term implications under ecologically realistic conditions are particularly important for the risk assessment of nano- and microplastics. Here, we evaluate the long-term (up to 15 months) effects of five concentrations of nano- and microplastics on the natural recolonization of sediments by a macroinvertebrate community. Effects were assessed on the community composition, population sizes and species diversity. Nano- and microplastics adversely affected the abundance of macroinvertebrates after 15 months, which was caused by a reduction in the number of Naididae at the highest concentration (5% plastic per sediment dry weight). For some other taxa, smaller but still significant positive effects were found over time, altogether demonstrating that nano- and microplastics affected the community composition.

The Effects of Target Length on the Visual Control of Step Length for Hard and Soft Impacts

2002 ◽  
Vol 18 (1) ◽  
pp. 57-73 ◽  
Author(s):  
Elizabeth J. Bradshaw ◽  
W.A. Sparrow
Keyword(s):  
Video Camera ◽  
Step Length ◽  
Visual Control ◽  
Whole Body ◽  
Black And White ◽  
Video Footage ◽  
Digital Video Camera ◽  
Control Time ◽  
Approach Velocity ◽  
Speed Accuracy

Adjustments to gait were examined when positioning the foot within a narrow target at the end of an approach for two impact conditions, hard and soft. Participants (6 M, 6 F) ran toward a target of three lengths along a 10-m walkway consisting of two marker strips with alternating black and white 0.5-m markings. Five trials were conducted for each target length and impact task, with trials block randomized between the 6 participants of each gender. A 50Hz digital video camera panned and filmed each trial from an elevated position adjacent to the walkway. Video footage was digitized to deduce the gait characteristics. A linear speed/accuracy tradeoff between target length and approach time was found for both impact tasks (hard, r = 0.99, p < 0.01; soft, r = 0.96, p < 0.05). For the hard-impact task, visual control time increased linearly (r = 0.99, p < 0.05) when whole-body approach velocity decreased. Visual control time was unaffected by whole-body approach velocity in the soft-impact task. A constant tau-margin of 1.08 describes the onset of visual control when approaching a target while running, with the control of braking during visual control described by a tau-dot of –0.85. Further research is needed to examine the control of braking in different targeting tasks.

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