Understanding cold-water corals’ health and ecosystems on the Irish margin, NE Atlantic; a critical look into the ecology, geology, hydrodynamic processes and human impacts

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dc.availability.bitstreamopenaccess
dc.contributor.advisorWheeler, Andrew
dc.contributor.advisorRamsay, Ruth
dc.contributor.advisorLim, Aaron
dc.contributor.authorAppah, John
dc.contributor.funderScience Foundation Irelanden
dc.date.accessioned2023-05-16T15:30:57Z
dc.date.available2023-05-16T15:30:57Z
dc.date.issued2022-08
dc.date.submitted2022-08
dc.description.abstractCold-water corals (CWCs) have come under threat from climate change and anthropogenic activities such as fishing and marine litter pollution despite, being ecological engineers that support high biodiversity, and as a result are protected in Europe under the EU Habitats Directive with some designated as Special Areas of Conservation (SACs). Abiotic (low pH, macro and microplastics) and biotic (pathogens and harmful microbes) factors, due to climate change and human activities, can stress CWCs, disrupting the coral holobiont with dire consequences on the energy allocation processes, coral health and diseases, growth and survival, resilience as well as biodiversity in deep sea corals. CWCs are azooxanthellate, filter feed and exist withing temperature limits of 4-13 °C. Using a habitat mapping approach, coupled with CWC histology and studies of the coral microbiome, this PhD research investigates the CWCs’ ecosystem health and environmental processes that influence biodiversity in the two SACs, upper Porcupine Bank Canyon (uPBC) and the western Belgica Mound Province (wBMP), on the Irish continental margin, northeast Atlantic. Chapter one provides a general introduction to cold-water corals, the objectives of the research and the threats to ocean environmental health and consequent organismal health, while chapter two maps the spatial distribution of CWCs within one of the largest submarine canyons on the Irish margin, the uPBC, highlighting importantly habitat heterogeneity in reef habitats and the hydrographic factors that influence the pattern of CWCs distribution in the canyon. Chapter three mapped the distribution of marine litter in two special areas of conservation (PBC and BMP) on the Irish margin and its impact on CWCs’ distribution as well as to determine if the SACs are serving their purpose and their usefulness against litter entry. In chapter four, the study assessed the distribution and roles of the coral holobiont in the uPBC using molecular techniques whilst chapter five uses a combination of histological and molecular techniques to assess Haplosporidia and Vibrio spp. in main framework-forming corals in the uPBC. Chapter six synthesizes the data obtained and concludes on the distribution and status of the cold-water corals in the uPBC in the face of climate change and anthropogenic pressures. In the analysis, five different substrates were characterized in the uPBC and resolved into non-reef (sediment, sediment & dropstones and bedrock) and reef and rubble (live/dead coral and coral rubble) habitats, including the terrain features observed in the canyon, and these generally contributed to the high biodiversity. High benthic megafaunal diversity (higher number of taxa identified), although not significantly different from the Shannon’s diversity observed in reef and rubble habitats, was detected in the non-coral habitats compared to the reef and rubble habitats in the upper PBC. Percentage estimates of Shannon’s diversity for non-coral and reef and rubble habitats were (H’non-reef =2.38; H’reef and ruble = 2.16) and Pielou’s evenness (J’non--reef =0.71; J’ reef and ruble = 0.65) respectively whilst density estimates of Shannon’s diversity for non-coral and reef and rubble habitats were (H’non-reef =1.72; H’reef and ruble = 1.14) and Pielou’s evenness (J’non--reef =0.54; J’ reef and ruble = 0.43) respectively. Geomorphology and hydrography were noted to affect the distribution of litter in the SACs. Another striking finding was that fishing gear (uPBC=80.7%, wBMP = 14.3% buoys) and plastics (uPBC = 11.3%, wBMP = 55.1%) were detected in relatively high abundance, suggesting that anthropogenic activities such as fishing (>60% vessels) are ongoing in the PBC and BMP despite being a SACs. It is unclear, however, if the observed fishing gear in the uPBC and wBMP may have drifted into them by deep-sea currents or were dumped before they were designated an SAC, as the SACs are closed to fishing. Additionally, the results reveal the upper canyon as a high energy environment with sufficient mixing of materials and community composition among the corals, water and sediment samples. Shannon’s index (H = 2.19, P = 0.33) and species evenness (J’ = 1.66, P = 0.43) among the groups of samples, respectively, were not significantly different. A positive note is that the corals generally appear to be in good health with low Haplosporidia (0.03%) and Vibrio (0.03%) infections in a single L. pertusa individual from the canyon head respectively, although we risk losing the corals due to bottom fishing and the current trend of climate change. A total of 40% Rickettsiales-like organisms (RLOs), with 26.7% observed in the south branch and 13.3% observed in the canyon head were detected. Despite the many threats and pressures such as marine litter pollution, changing pH, sedimentation and bottom trawling, the CWCs on the Irish margin, are associated with high biodiversity and appear to be resilient, well adapted to the deep-sea environment. However, regular monitoring campaigns and health screening studies are advocated. Although continuous monitoring through research and management activities would be the way forward, it is recognised that the cost of such deep-sea surveys/expeditions are huge and require sufficient funding from the various funding bodies. It is believed that the findings of this research will inform policy makers and management on how to effectively protect the vulnerable ecosystems of these deep seas.en
dc.description.statusNot peer revieweden
dc.description.versionAccepted Versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.citationAppah, J. K. M. 2022. Understanding cold-water corals’ health and ecosystems on the Irish margin, NE Atlantic; a critical look into the ecology, geology, hydrodynamic processes and human impacts. PhD Thesis, University College Cork.en
dc.identifier.endpage264en
dc.identifier.urihttps://hdl.handle.net/10468/14468
dc.language.isoenen
dc.publisherUniversity College Corken
dc.relation.projectinfo:eu-repo/grantAgreement/SFI/SFI Investigator Programme/16/IA/4528 MI (N)/IE/Mapping, Modelling and Monitoring Key Processes and Controls on Cold-water Coral Habitats in Submarine Canyons (MMMonKey_Pro)/
dc.relation.projectinfo:eu-repo/grantAgreement/EC/H2020::RIA/818123/EU/Integrated Assessment of Atlantic Marine Ecosystems in Space and Time/iAtlantic
dc.rights© 2022, John Kwame Mensah Appah.en
dc.rights.urihttps://creativecommons.org/licenses/by-nc-nd/4.0/en
dc.subjectCold-water coralsen
dc.subjectPorcupine Bank Canyonen
dc.subjectBelgica Mound Provinceen
dc.subjectBiodiversityen
dc.subjectMarine litteren
dc.subjectHealth screeningen
dc.subjectPathogensen
dc.subjectDeep seaen
dc.titleUnderstanding cold-water corals’ health and ecosystems on the Irish margin, NE Atlantic; a critical look into the ecology, geology, hydrodynamic processes and human impactsen
dc.typeDoctoral thesisen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD - Doctor of Philosophyen
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