scholarly journals The ecological importance of habitat complexity to the Caribbean coral reef herbivore Diadema antillarum: three lines of evidence

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
M. D. V. Bodmer ◽  
P. M. Wheeler ◽  
P. Anand ◽  
S. E. Cameron ◽  
Sanni Hintikka ◽  
...  
Keyword(s):  
Habitat Complexity ◽  
Sea Urchins ◽  
Spatial Scales ◽  
Cost Effective ◽  
3D Models ◽  
Ecosystem Functions ◽  
Diadema Antillarum ◽  
Average Complexity ◽  
Caribbean Coral ◽  
Lines Of Evidence

AbstractWhen Caribbean long-spined sea urchins, Diadema antillarum, are stable at high population densities, their grazing facilitates scleractinian coral dominance. Today, populations remain suppressed after a mass mortality in 1983–1984 caused a loss of their ecosystem functions, and led to widespread declines in ecosystem health. This study provides three lines of evidence to support the assertion that a lack of habitat complexity on Caribbean coral reefs contributes to their recovery failure. Firstly, we extracted fractal dimension (D) measurements, used as a proxy for habitat complexity, from 3D models to demonstrate that urchins preferentially inhabit areas of above average complexity at ecologically relevant spatial scales. Secondly, controlled behaviour experiments showed that an energetically expensive predator avoidance behaviour is reduced by 52% in complex habitats, potentially enabling increased resource allocation to reproduction. Thirdly, we deployed a network of simple and cost-effective artificial structures on a heavily degraded reef system in Honduras. Over a 24-month period the adult D. antillarum population around the artificial reefs increased by 320% from 0.05 ± 0.01 to 0.21 ± 0.04 m−2 and the juvenile D. antillarum population increased by 750% from 0.08 ± 0.02 to 0.68 ± 0.07 m−2. This study emphasises the important role of habitat structure in the ecology of D. antillarum and as a barrier to its widespread recovery.

scholarly journals The sea urchin Diadema antillarum – keystone herbivore or redundant species?

2015 ◽  
Author(s):  
Lindsey L. Precht ◽  
William F. Precht
Keyword(s):  
Coral Reefs ◽  
Sea Urchin ◽  
Cost Effective ◽  
Caribbean Region ◽  
Diadema Antillarum ◽  
Natural Systems ◽  
Caribbean Coral ◽  
Reef Recovery ◽  
Caribbean Coral Reefs ◽  
Reef Tract

Two main hypotheses have been developed for describing the role and importance of the sea urchin Diadema antillarum on reefs of the Caribbean region in both space and time. The first and most crucial is whether D. antillarum was the most important “keystone” grazer on Caribbean reefs? The alternate to this hypothesis is that D. antillarum was merely a redundant species, playing a secondary role to herbivorious fishes which only came into dominance after herbivorous fishes had been removed by man through exploitive fishing practices. To resolve this debate, we pose the question: “What is the role of Diadema antillarum in altering the composition of the benthic community on Caribbean coral reefs in time and space?” The interpretation presented herein implies that D. antillarum was and is the most important shallow-water herbivore on Caribbean coral reefs. This is contrary to a prevailing model but in substantial agreement with the historical importance of the species. If correct, the continued and future recovery of this sea urchin may be the key ingredient to facilitating coral reef recovery throughout the region. In addition, on coral reefs where the natural recovery of Diadema has been delayed or is absent (e.g. the Florida Reef Tract); measures to actively restore these urchins may be the most efficient and cost-effective tool for conserving and enhancing the ecological function of reefs. This debate also emphasizes the requirement for implementing ecologically-based, not ideologically-based management of natural systems.

scholarly journals The sea urchin Diadema antillarum – keystone herbivore or redundant species?

2015 ◽  
Author(s):  
Lindsey L. Precht ◽  
William F. Precht
Keyword(s):  
Coral Reefs ◽  
Sea Urchin ◽  
Cost Effective ◽  
Caribbean Region ◽  
Diadema Antillarum ◽  
Natural Systems ◽  
Caribbean Coral ◽  
Reef Recovery ◽  
Caribbean Coral Reefs ◽  
Reef Tract

Two main hypotheses have been developed for describing the role and importance of the sea urchin Diadema antillarum on reefs of the Caribbean region in both space and time. The first and most crucial is whether D. antillarum was the most important “keystone” grazer on Caribbean reefs? The alternate to this hypothesis is that D. antillarum was merely a redundant species, playing a secondary role to herbivorious fishes which only came into dominance after herbivorous fishes had been removed by man through exploitive fishing practices. To resolve this debate, we pose the question: “What is the role of Diadema antillarum in altering the composition of the benthic community on Caribbean coral reefs in time and space?” The interpretation presented herein implies that D. antillarum was and is the most important shallow-water herbivore on Caribbean coral reefs. This is contrary to a prevailing model but in substantial agreement with the historical importance of the species. If correct, the continued and future recovery of this sea urchin may be the key ingredient to facilitating coral reef recovery throughout the region. In addition, on coral reefs where the natural recovery of Diadema has been delayed or is absent (e.g. the Florida Reef Tract); measures to actively restore these urchins may be the most efficient and cost-effective tool for conserving and enhancing the ecological function of reefs. This debate also emphasizes the requirement for implementing ecologically-based, not ideologically-based management of natural systems.

scholarly journals The sea urchin Diadema antillarum – keystone herbivore or redundant species?

2015 ◽  
Author(s):  
Lindsey L. Precht ◽  
William F. Precht
Keyword(s):  
Coral Reefs ◽  
Sea Urchin ◽  
Cost Effective ◽  
Caribbean Region ◽  
Diadema Antillarum ◽  
Natural Systems ◽  
Caribbean Coral ◽  
Reef Recovery ◽  
Caribbean Coral Reefs ◽  
Reef Tract

Two main hypotheses have been developed for describing the role and importance of the sea urchin Diadema antillarum on reefs of the Caribbean region in both space and time. The first and most crucial is whether D. antillarum was the most important “keystone” grazer on Caribbean reefs? The alternate to this hypothesis is that D. antillarum was merely a redundant species, playing a secondary role to herbivorious fishes which only came into dominance after herbivorous fishes had been removed by man through exploitive fishing practices. To resolve this debate, we pose the question: “What is the role of Diadema antillarum in altering the composition of the benthic community on Caribbean coral reefs in time and space?” The interpretation presented herein implies that D. antillarum was and is the most important shallow-water herbivore on Caribbean coral reefs. This is contrary to a prevailing model but in substantial agreement with the historical importance of the species. If correct, the continued and future recovery of this sea urchin may be the key ingredient to facilitating coral reef recovery throughout the region. In addition, on coral reefs where the natural recovery of Diadema has been delayed or is absent (e.g. the Florida Reef Tract); measures to actively restore these urchins may be the most efficient and cost-effective tool for conserving and enhancing the ecological function of reefs. This debate also emphasizes the requirement for implementing ecologically-based, not ideologically-based management of natural systems.

Worldview-2 and Landsat 8 Satellite Data for Seaweed Mapping along Karachi Coast

2016 ◽  
Vol 5 (2) ◽  
Author(s):  
Muhammad Danish Siddiqui ◽  
Arjumand Z Zaidi
Keyword(s):  
Satellite Data ◽  
Spatial Scales ◽  
Economic Value ◽  
Vegetation Indices ◽  
Cost Effective ◽  
Geographical Information ◽  
Landsat 8 ◽  
Coverage Area ◽  
Breeding Sites ◽  
Marine Plant

<span>Seaweed is a marine plant or algae which has economic value in many parts of the world. The purpose of <span>this study is to evaluate different satellite sensors such as high-resolution WorldView-2 (WV2) satellite <span>data and Landsat 8 30-meter resolution satellite data for mapping seaweed resources along the coastal<br /><span>waters of Karachi. The continuous monitoring and mapping of this precious marine plant and their <span>breeding sites may not be very efficient and cost effective using traditional survey techniques. Remote <span>Sensing (RS) and Geographical Information System (GIS) can provide economical and more efficient <span>solutions for mapping and monitoring coastal resources quantitatively as well as qualitatively at both <span>temporal and spatial scales. Normalized Difference Vegetation Indices (NDVI) along with the image <span>enhancement techniques were used to delineate seaweed patches in the study area. The coverage area of <span>seaweed estimated with WV-2 and Landsat 8 are presented as GIS maps. A more precise area estimation <span>wasachieved with WV-2 data that shows 15.5Ha (0.155 Km<span>2<span>)of seaweed cover along Karachi coast that is <span>more representative of the field observed data. A much larger area wasestimated with Landsat 8 image <span>(71.28Ha or 0.7128 Km<span>2<span>) that was mainly due to the mixing of seaweed pixels with water pixels. The <span>WV-2 data, due to its better spatial resolution than Landsat 8, have proven to be more useful than Landsat<br /><span>8 in mapping seaweed patches</span></span></span></span></span></span></span></span></span></span></span></span></span></span><br /><br class="Apple-interchange-newline" /></span></span></span></span></span>

scholarly journals Biogeography of acoustic biodiversity of NW Mediterranean coralligenous reefs

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lucia Di Iorio ◽  
Manon Audax ◽  
Julie Deter ◽  
Florian Holon ◽  
Julie Lossent ◽  
...  
Keyword(s):  
Large Scale ◽  
Spatial Scales ◽  
Western Mediterranean ◽  
Ecosystem Functions ◽  
Marine Biodiversity ◽  
Predator Species ◽  
The North ◽  
Mediterranean Habitats ◽  
Geographical Regions ◽  
Nw Mediterranean

AbstractMonitoring the biodiversity of key habitats and understanding the drivers across spatial scales is essential for preserving ecosystem functions and associated services. Coralligenous reefs are threatened marine biodiversity hotspots that are challenging to monitor. As fish sounds reflect biodiversity in other habitats, we unveiled the biogeography of coralligenous reef sounds across the north-western Mediterranean using data from 27 sites covering 2000 km and 3 regions over a 3-year period. We assessed how acoustic biodiversity is related to habitat parameters and environmental status. We identified 28 putative fish sound types, which is up to four times as many as recorded in other Mediterranean habitats. 40% of these sounds are not found in other coastal habitats, thus strongly related to coralligenous reefs. Acoustic diversity differed between geographical regions. Ubiquitous sound types were identified, including sounds from top-predator species and others that were more specifically related to the presence of ecosystem engineers (red coral, gorgonians), which are key players in maintaining habitat function. The main determinants of acoustic community composition were depth and percentage coverage of coralligenous outcrops, suggesting that fish-related acoustic communities exhibit bathymetric stratification and are related to benthic reef assemblages. Multivariate analysis also revealed that acoustic communities can reflect different environmental states. This study presents the first large-scale map of acoustic fish biodiversity providing insights into the ichthyofauna that is otherwise difficult to assess because of reduced diving times. It also highlights the potential of passive acoustics in providing new aspects of the correlates of biogeographical patterns of this emblematic habitat relevant for monitoring and conservation.

scholarly journals Utilization of desktop 3D printer-fabricated “Cost-Effective” 3D models in orthognathic surgery

2020 ◽  
Vol 42 (1) ◽  
Author(s):  
Masato Narita ◽  
Takashi Takaki ◽  
Takahiko Shibahara ◽  
Masashi Iwamoto ◽  
Takashi Yakushiji ◽  
...  
Keyword(s):  
Orthognathic Surgery ◽  
Cost Effective ◽  
3D Models ◽  
3D Printer

scholarly journals Spatial Variation in Canopy Structure across Forest Landscapes

2018 ◽  
Author(s):  
Brady S. Hardiman ◽  
Elizabeth A. LaRue ◽  
Jeff W. Atkins ◽  
Robert T. Fahey ◽  
Franklin W. Wagner ◽  
...  
Keyword(s):  
Temperate Forest ◽  
Forest Canopy ◽  
Spatial Scales ◽  
Canopy Structure ◽  
Ecosystem Functions ◽  
Lidar System ◽  
Stable Point ◽  
Eastern Usa ◽  
Forested Landscapes ◽  
Patch Scale

Forest canopy structure (CS) controls many ecosystem functions and is highly variable across landscapes, but the magnitude and scale of this variation is not well understood. We used a portable canopy lidar system to characterize variation in five categories of CS along N = 3 transects (140&ndash;800 m long) at each of six forested landscapes within the eastern USA. The cumulative coefficient of variation was calculated for subsegments of each transect to determine the point of stability for individual CS metrics. We then quantified the scale at which CS is autocorrelated using Moran&rsquo;s I in an Incremental Autocorrelation analysis. All CS metrics reached stable values within 300 m but varied substantially within and among forested landscapes. A stable point of 300 m for CS metrics corresponds with the spatial extent that many ecosystem functions are measured and modeled. Additionally, CS metrics were spatially autocorrelated at 40 to 88 m, suggesting that patch scale disturbance or environmental factors drive these patterns. Our study shows CS is heterogeneous across temperate forest landscapes at the scale of 10&rsquo;s of meters, requiring a resolution of this size for upscaling CS with remote sensing to large spatial scales.

scholarly journals Evaluation of the Apple iPhone 12 Pro LiDAR for an Application in Geosciences

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Gregor Luetzenburg ◽  
Aart Kroon ◽  
Anders A. Bjørk
Keyword(s):  
High Resolution ◽  
Optical Sensors ◽  
Cost Effective ◽  
Point Clouds ◽  
3D Models ◽  
Absolute Accuracy ◽  
Wide Range ◽  
Financial Investments ◽  
Coastal Cliff ◽  
High Resolution Models

AbstractTraditionally, topographic surveying in earth sciences requires high financial investments, elaborate logistics, complicated training of staff and extensive data processing. Recently, off-the-shelf drones with optical sensors already reduced the costs for obtaining a high-resolution dataset of an Earth surface considerably. Nevertheless, costs and complexity associated with topographic surveying are still high. In 2020, Apple Inc. released the iPad Pro 2020 and the iPhone 12 Pro with novel build-in LiDAR sensors. Here we investigate the basic technical capabilities of the LiDAR sensors and we test the application at a coastal cliff in Denmark. The results are compared to state-of-the-art Structure from Motion Multi-View Stereo (SfM MVS) point clouds. The LiDAR sensors create accurate high-resolution models of small objects with a side length > 10 cm with an absolute accuracy of ± 1 cm. 3D models with the dimensions of up to 130 × 15 × 10 m of a coastal cliff with an absolute accuracy of ± 10 cm are compiled. Overall, the versatility in handling outweighs the range limitations, making the Apple LiDAR devices cost-effective alternatives to established techniques in remote sensing with possible fields of application for a wide range of geo-scientific areas and teaching.

scholarly journals MODELLING LANDSCAPE MORPHODYNAMICS BY TERRESTRIAL PHOTOGRAMMETRY: AN APPLICATION TO BEACH AND FLUVIAL SYSTEMS

2016 ◽  
Vol XLI-B8 ◽  
pp. 1175-1182 ◽  
Author(s):  
E. Sánchez-García ◽  
A. Balaguer-Beser ◽  
R. Taborda ◽  
J. E. Pardo-Pascual
Keyword(s):  
Morphological Changes ◽  
Spatial Scales ◽  
Cost Effective ◽  
Point Clouds ◽  
Field Work ◽  
Fluvial Systems ◽  
Natural Systems ◽  
3D Point Clouds ◽  
Pilot Channel ◽  
Terrestrial Photogrammetry

Beach and fluvial systems are highly dynamic environments, being constantly modified by the action of different natural and anthropic phenomena. To understand their behaviour and to support a sustainable management of these fragile environments, it is very important to have access to cost-effective tools. These methods should be supported on cutting-edge technologies that allow monitoring the dynamics of the natural systems with high periodicity and repeatability at different temporal and spatial scales instead the tedious and expensive field-work that has been carried out up to date. The work herein presented analyses the potential of terrestrial photogrammetry to describe beach morphology. Data processing and generation of high resolution 3D point clouds and derived DEMs is supported by the commercial Agisoft PhotoScan. Model validation is done by comparison of the differences in the elevation among the photogrammetric point cloud and the GPS data along different beach profiles. Results obtained denote the potential that the photogrammetry 3D modelling has to monitor morphological changes and natural events getting differences between 6 and 25 cm. Furthermore, the usefulness of these techniques to control the layout of a fluvial system is tested by the performance of some modeling essays in a hydraulic pilot channel.

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