& Controls on Cold-water Coral Habitats in Submarine ...
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The programme offers several key findings as well as a series of recommendations for studying difficult, deep water habitats, developing novel mapping techniques and for responsible practice within the area. To keep up to date with this research, visit the UCC Marine Geology Research Group website at http ://marinegeology.ucc.ie/ ROV -video data are acquired with downward- and oblique- facing camera. The data is converted into a 3D georeferenced orthomosaic (Fig. 2) and point via AgiSoft. This allows for 3D facies analyses across large areas of the canyon within a GIS. Fig. 1: i) Location of the Porcupine Bank Canyon (red); ii) distribution of its features; iii) overview of study sites used in Fig. 5; iv) mound development relative to current direction; v) major water masses in the PBC are Eastern North Atlantic Water (ENAW) and Mediterranean Outflow Water (MOW). Note: bathymetry source in Fig. 1 i) INFOMAR; in Fig. 1 ii) INFOMAR & UCC; and in Fig. 1 iii) & iv) - UCC Analysis of 3D coral habitat reconstructions show considerable variation throughout the canyon (Fig 5). Monitoring stations (‘Landers’) have been deployed via ROV within a number of these habitats. The Landers (Fig. 3) record current speed and direction, temperature and trap current-suspended particles. Results from the landers (Fig. 4) show that coral appear to thrive when the current flows directly towards the coral at lower flow speeds. This suggests that corals likely feed when the tide turns and is supported by findings from flume tanks. Conversely, areas with more coral rubble tend to have the highest flow speeds. ROV -mounted vibrocores were acquired through key habitats in the area (Fig. 9). Non-destructive Techniques Cores were scanned using dual- energy computed tomography (CT) at Cork University Hospital. The data sets were processed using Amira Software, to monitor CWC habitat development through geological time Destructive Techniques Sediment grain size from the CWC- bearing cores reveals the hydrodynamic control on the habitats. Sediment composition shows heterogenous patterns in carbonate and organic content. Stable isotope analysis on planktonic and benthic foraminifera constrain paleo-environmental conditions. C14 dating (AMS) was utilized to constrain key development stages Key points • Lophelia pertusa and the black coral Leiopathes glaberrima are the dominant cold-water corals in the PBC • Evidence of human activities include plastic litter and fishing gear (Fig. 7) • Depth & slope contribute the most to benthic fauna distribution in the PBC (Fig. 8) Submarine canyons are dynamic environments that support diverse biological communities including fisheries. The Porcupine Bank Canyon (Fig. 1), Ireland’s largest submarine canyon, is located along the Irish-Atlantic margin on the Porcupine Bank. It is designated as a Special Area of Conservation (SAC) and is disconnected from terrigenous influences, making it a site to study background European Atlantic conditions. Recent work has revealed cold-water coral (CWC) dominated habitats in the form of individual colonies, coral gardens, mounds and vertical cliff faces. The MMMonKey_Pro programme uses new Irish state-of-the-art exploration and analysis techniques to explore and monitor the PBC-CWC habitats and relate the findings to ocean-climate environmental dynamics. This project has two main aims: Aim 1: To develop an understanding of the interaction and mutual control of submarine canyon processes and CWC habitat functioning to better inform responsible interaction with this environment, and; Aim 2: To develop advanced methodologies to more effectively study deep-water heterogeneous dynamic biotic habitats including CWCs Fig 6: 1-A) and 2-A): Dense cloud of the coral mounds generated with photogrammetry 1-B) Example of Multiscale Geometrical classification(MGC). Blue: coral /Red: seabed 2- B) Example of Colour and Geometrical classification (CGC). Magenta: coral/Green: seabed 3-A) Orthomosaic generated with photogrammetry 3-B) Example of Object-Based image analysis (OBIA) with automated segmentation of objects 3-C) Manually classified objects. Green: coral; Red: seabed Point clouds, orthomosaics and digital elevation models were generated from the photogrammetry process to apply three novel classification workflows (Fig. 6). Results were compared to an object-based image analysis method (OBIA) to analyse the difference between 2D & 3D classification results. Results show that 3D Multiscale Geometrical Classification (MGC) using Support Vector Machines outperforms Color and Geometrical Classification (GCG), a Gradient Boosted Trees based method, with overall accuracies of 74% and 58%, respectively. However, each method has benefits for specific applications pertinent to the wider marine scientific community . Results suggest that advancing from commonly employed 2D image analysis techniques to 3D methods provide a more realistic representation of coral reefs. Fig. 2: Example of an orthomosaic created in this study and example facies: a) close up example image from the SC (Leiopathes sp.) facies; b) close up example image from the CR facies; c) close up example image from the DCF facies; d) close up example from the LCF facies; e) full scale orthomosaic Mapping, Modelling and Monitoring Key Processes & Controls on Cold-water Coral Habitats in Submarine Canyons (MMMonKey_Pro) Study Site Fig. 7: ROV HD stills from the canyon seabed. Coral occurs on mounds, on exposed vertical bedrock, on the canyon lip and as individual colonies. Note: litter is a regular find in the canyon (top right) Mapping: ROV Photogrammetry Fig. 3: A lander deployed within the Porcupine Bank Canyon. Note: Arm of the Holland 1 ROV in foreground. The Lander is strategically placed on the summit of the mound Fig. 4: Live coral proportion organised by mean current speed when the current is flowing directly against the aspect of the coral based on currents facing the corals 1) School of Biological, Earth & Environmental Science, University College Cork, 2) iCRAG (Irish Centre for Research in Applied Geosciences), 3) University of São Paulo, Brazil, 4) Cork University Hospital Fig. 5: Surface facies coverage within each coral habitat measured at the Porcupine Bank Canyon. Coral habitats vary from predominately live to predominately dead. Highest abundances of coral rubble are found at habitats near the canyon ‘lip’ Wheeler, A.J. 1,2 , O’Reilly, L. 1 , Lim, A. 1 , Appah, J. 1 , Oliveira, L.M. 1 , Conti, L. 3 & O’Connor, O.J. 4 Monitoring: Benthic Landers Modelling: Semi-supervised facies classification A Modelling: Paleoenvironmental Analyses Conclusions Fig 9: Core CE18011_VC2 through CWC mound with CT- data, stable isotope data and sedimentological data A A B C B B 1. MGC Method 2. CGC Method 3. OBIA Method Monitoring: Species Distributions in Canyon Fig. 8: Relationship between bathymetry (slope, aspect, rugosity and depth), habitat, site locations and benthic taxa distribution The MMMonkey_Pro Programme
Transcript of & Controls on Cold-water Coral Habitats in Submarine ...
The programme offers several key findings as well as a series of recommendations forstudying difficult, deep water habitats, developing novel mapping techniques and forresponsible practice within the area.To keep up to date with this research, visit the UCC Marine Geology Research Groupwebsite at http://marinegeology.ucc.ie/
ROV-video data are acquired with downward- and oblique-facing camera. The data is converted into a 3Dgeoreferenced orthomosaic (Fig. 2) and point via AgiSoft.This allows for 3D facies analyses across large areas of thecanyon within a GIS.
Fig. 1: i) Location of the Porcupine Bank Canyon (red);ii) distribution of its features; iii) overview of study sites used inFig. 5; iv) mound development relative to current direction;v) major water masses in the PBC are Eastern North AtlanticWater (ENAW) and Mediterranean Outflow Water (MOW).Note: bathymetry source in Fig. 1 i) INFOMAR; in Fig. 1ii) INFOMAR & UCC; and in Fig. 1 iii) & iv) - UCC
Analysis of 3D coral habitat reconstructions showconsiderable variation throughout the canyon (Fig 5).Monitoring stations (‘Landers’) have been deployed via ROVwithin a number of these habitats. The Landers (Fig. 3)record current speed and direction, temperature and trapcurrent-suspended particles.
Results from the landers (Fig. 4) show that coral appear tothrive when the current flows directly towards the coralat lower flow speeds. This suggests that corals likely feedwhen the tide turns and is supported by findings from flumetanks. Conversely, areas with more coral rubble tend tohave the highest flow speeds.
ROV-mounted vibrocores wereacquired through key habitats in thearea (Fig. 9).
Non-destructive TechniquesCores were scanned using dual-energy computed tomography (CT) atCork University Hospital. The data setswere processed using Amira Software,to monitor CWC habitat developmentthrough geological time
Destructive TechniquesSediment grain size from the CWC-bearing cores reveals thehydrodynamic control on the habitats.Sediment composition showsheterogenous patterns in carbonateand organic content.Stable isotope analysis on planktonicand benthic foraminifera constrainpaleo-environmental conditions.C14 dating (AMS) was utilized toconstrain key development stages
Key points• Lophelia pertusa and the black coral Leiopathes
glaberrima are the dominant cold-water coralsin the PBC
• Evidence of human activities include plastic litterand fishing gear (Fig. 7)
• Depth & slope contribute the most to benthicfauna distribution in the PBC (Fig. 8)
Submarine canyons are dynamic environments that supportdiverse biological communities including fisheries. ThePorcupine Bank Canyon (Fig. 1), Ireland’s largestsubmarine canyon, is located along the Irish-Atlanticmargin on the Porcupine Bank. It is designated as a SpecialArea of Conservation (SAC) and is disconnected fromterrigenous influences, making it a site to studybackground European Atlantic conditions. Recent work hasrevealed cold-water coral (CWC) dominated habitats inthe form of individual colonies, coral gardens, mounds andvertical cliff faces. The MMMonKey_Pro programme usesnew Irish state-of-the-art exploration and analysistechniques to explore and monitor the PBC-CWChabitats and relate the findings to ocean-climateenvironmental dynamics. This project has two main aims:
Aim 1: To develop an understanding of the interaction andmutual control of submarine canyon processes and CWChabitat functioning to better inform responsible interactionwith this environment, and;Aim 2: To develop advanced methodologies to moreeffectively study deep-water heterogeneous dynamic biotichabitats including CWCs
Fig 6: 1-A) and 2-A): Dense cloud of the coral moundsgenerated with photogrammetry 1-B) Example of MultiscaleGeometrical classification(MGC). Blue: coral /Red: seabed 2-B) Example of Colour and Geometrical classification (CGC).Magenta: coral/Green: seabed 3-A) Orthomosaic generatedwith photogrammetry 3-B) Example of Object-Based imageanalysis (OBIA) with automated segmentation of objects 3-C)Manually classified objects. Green: coral; Red: seabed
Point clouds, orthomosaics and digitalelevation models were generated fromthe photogrammetry process to applythree novel classification workflows(Fig. 6). Results were compared to anobject-based image analysis method(OBIA) to analyse the differencebetween 2D & 3D classification results.
Results show that 3D MultiscaleGeometrical Classification (MGC) usingSupport Vector Machines outperformsColor and Geometrical Classification(GCG), a Gradient Boosted Trees basedmethod, with overall accuracies of 74%and 58%, respectively. However, eachmethod has benefits for specificapplications pertinent to the widermarine scientific community .
Results suggest that advancing fromcommonly employed 2D image analysistechniques to 3D methods provide amore realistic representation of coralreefs.
Fig. 2: Example of an orthomosaic created in this study andexample facies: a) close up example image from the SC(Leiopathes sp.) facies; b) close up example image from the CRfacies; c) close up example image from the DCF facies; d) closeup example from the LCF facies; e) full scale orthomosaic
Mapping, Modelling and Monitoring Key Processes & Controls on Cold-water Coral Habitats in Submarine Canyons (MMMonKey_Pro)
Study Site
Fig. 7: ROV HD stills from the canyon seabed. Coral occurs on mounds, on exposed vertical bedrock, on the canyon lip and as individual colonies. Note: litter is a regular find in the canyon (top right)
Mapping: ROV Photogrammetry
Fig. 3: A lander deployed within the Porcupine BankCanyon. Note: Arm of the Holland 1 ROV in foreground. TheLander is strategically placed on the summit of the mound
Fig. 4: Live coral proportion organised by meancurrent speed when the current is flowing directlyagainst the aspect of the coral based on currentsfacing the corals
1) School of Biological, Earth & Environmental Science, University College Cork, 2) iCRAG (Irish Centre for Research in Applied Geosciences), 3) University of São Paulo, Brazil, 4) Cork University Hospital
Fig. 5: Surface facies coverage within each coral habitat measured at the PorcupineBank Canyon. Coral habitats vary from predominately live to predominately dead.Highest abundances of coral rubble are found at habitats near the canyon ‘lip’
Wheeler, A.J.1,2
, O’Reilly, L.1
, Lim, A.1
, Appah, J.1
, Oliveira, L.M.1
, Conti, L.3
& O’Connor, O.J.4
Monitoring: Benthic Landers Modelling: Semi-supervised facies classification
A
Modelling: Paleoenvironmental Analyses
Conclusions
Fig 9: Core CE18011_VC2 through CWC mound with CT-data, stable isotope data and sedimentological data
A
A B C
B
B
1. MGC Method
2. CGC Method
3. OBIA Method
Monitoring: Species Distributions in Canyon
Fig. 8: Relationship between bathymetry (slope, aspect, rugosity anddepth), habitat, site locations and benthic taxa distribution
The MMMonkey_Pro Programme
