Show simple item record

dc.contributor.supervisorEmbling, Clare
dc.contributor.authorEager, Dannielle Sophie
dc.contributor.otherSchool of Biological and Marine Sciencesen_US

Topographic features, such as seamounts and atolls, are commonly identified as biodiversity hotspots that are key areas of productivity in an otherwise oligotrophic Indian Ocean. Whilst these sites of increased biomass are frequently identified, the oceanographic drivers that underpin the spatiotemporal distributions of biomass are not. If effective conservation measures are to be continued and implemented in regions such as the Chagos Archipelago Marine Protected Area (MPA) then the spatial variability of biomass and the physical drivers must be elucidated. This study presents case studies at Sandes seamount and Egmont atoll in the Chagos Archipelago identifying the distributions and behavioural responses of pelagic biota to oceanographic processes. Multifrequency fisheries acoustics data was combined with synoptically collected oceanographic sensor data to determine the oceanographic drivers of pelagic biota. In-situ sampling was also conducted to determine the composition of species over topographic features. Both regional and fine-scale physical processes were identified driving the distribution of biological aggregations over the different topographic features in the Chagos Archipelago. Around Sandes seamount, a joint climatic-oceanographic event, the Indian Ocean Dipole (IOD), affected sea surface temperatures and current velocities causing the deepening of the thermocline. This dramatically reduced the number of schooling fish over the summit of Sandes seamount re-distributing schools into deeper water around the flanks of the seamount. Analysis of the plankton distributions at Sandes seamount also highlighted the role of the thermocline in aggregating biota. At Egmont atoll, flow-topography interactions dictated the spatial distribution of schooling fish, with canyons and lagoons influencing fish behaviour. This research emphasises the biological importance of seamounts and atolls in the Chagos Archipelago. Understanding the spatial variability of biota around topographic features is vital to improve the efficiency and efficacy of marine spatial plans. By recognizing the behavioural responses of pelagic fish and plankton to oceanographic processes in the Chagos Archipelago this work can contribute to a wider understanding of biophysical interactions around topographic features globally.

dc.publisherUniversity of Plymouth
dc.rightsAttribution-NonCommercial-ShareAlike 3.0 United States*
dc.subjectBiological oceanographyen_US
dc.subjectIndian Oceanen_US
dc.subjectChagos Archipelagoen_US
dc.subjectIndian Ocean Dipoleen_US
dc.titleIdentifying and quantifying pelagic organisms around seamounts, atolls, and islands in the Chagos Archipelago in relation to local oceanographic processesen_US
dc.rights.embargoperiodNo embargoen_US
rioxxterms.funderBertarelli Foundationen_US
rioxxterms.funderGarfield Weston Foundationen_US
rioxxterms.identifier.projectFieldwork fundingen_US
rioxxterms.identifier.projectStudentship fundingen_US

Files in this item


This item appears in the following Collection(s)

Show simple item record

Attribution-NonCommercial-ShareAlike 3.0 United States
Except where otherwise noted, this item's license is described as Attribution-NonCommercial-ShareAlike 3.0 United States

All items in PEARL are protected by copyright law.
Author manuscripts deposited to comply with open access mandates are made available in accordance with publisher policies. Please cite only the published version using the details provided on the item record or document. In the absence of an open licence (e.g. Creative Commons), permissions for further reuse of content should be sought from the publisher or author.
Theme by 
Atmire NV