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Biologically rich and under threat, yet understudied

Key findings

  • A systematic survey of the scientific literature on marine environments in the UK Overseas Territories (UKOTs) was published this month in Biodiversity and Conservation.
  • The geographic disparities between the fourteen UKOTs are reflected in the varied coverage of the current scientific evidence base.
  • Only 10% of research papers had management or conservation implications as their main focus, knowledge gaps hamper attempts to implement evidence-based policy. The vast majority of research undertaken has focussed upon single species, biological studies.
  • All UKOTs are threatened by climate change, particularly sea level rise.
  • UK Government funding commitments through the Blue Belt Programme are admirable but must continue in order to tackle information gaps and risks of illegal, unreported and unregulated (IUU) fishing.

The UK Government is responsible for 14 UKOTs, which together comprise over 94% of the unique biodiversity managed by the UK. Recently published research, commissioned by Great British Oceans and led by Dr Bethan O’Leary and colleagues from the Universities of York and Greenwich, presents a review of studies on marine biodiversity across the UKOTs.

Fig. 1 Marine areas of the United Kingdom’s Overseas Territories (UKOTS). World exclusive economic zones are shown in grey scale in map (a). Note that several of the UKOTs are subject to disputes by other countries and that the British Antarctic Territory legally has no marine waters in accordance with the Antarctic Treaty. Sovereign Base Area is abbreviated to SBA in (d). Figure reproduced from O’Leary et al 2019 in accordance with a Creative Commons Attribution 4.0 International License.

The authors reviewed all journal articles relating to UKOT marine environments published in academic journals since 2007 They assessed the 660 relevant articles according to their geographic and topic area coverage, and also assessed global publicly available spatial threat data for each UKOT.

Geographic coverage

Published research on the UKOTs has been consistent but low across this period, with the majority of studies focusing on territories frequented by research vessels or with existing research infrastructure, e.g. the Falkland Islands and South Georgia and the South Sandwich Islands.

“…many of the UKOTs are remote and are difficult and expensive to travel to with most lacking essential research platforms such as survey vessels, although if work can be done locally or in partnership with local communities then costs may be reduced and associated in-country benefits will be greater as local expertise develops.”

O’Leary et al 2019

Some UKOTs are particularly under-represented, for example St Helena in the South Atlantic, which was the focus of just eight articles. This is despite the fact it has the highest number of endemic species (species not found anywhere else) of any island OT (502 endemic terrestrial and marine species were recorded in a recent survey by RSPB). However, St Helena has been the focus of research projects by governments, NGOs and others which are not always published in scientific journals.

Topic area coverage

The majority of studies focused on seabirds, fish (including sharks) and plankton, and mainly concerned their biology (e.g. diet and reproduction) and distribution. Ecosystem-wide studies were less common but are likely to be key in generating information for marine managers. An increased understanding of territory-specific threats was also identified as being much needed.

Despite the high priority of the UKOTs in current UK Government marine policy (in 2016 the UK committed to creating 4 million square kilometres of marine protected areas around seven UKOTs), very little of the available research concerned management, conservation considerations or human-induced threats. Disappointingly, only 10% of articles explicitly considered management or conservation implications as their main focus.

Threat data

Using freely available spatial data on climate, fishing and other human stressors in the marine environment, each UKOT was assessed and given a threat score. The dominant ‘climate change associated’ stressor was sea level rise and human stressors included ocean pollution, shipping and invasive species. Fishing stressors varied depending on the region, with artisanal fishing acting as a greater stressor in populated territories, and bycatch of non-target species by commercial fishing vessels was of concern in most territorial waters.

Fig. 2: Additive threat models for a ‘climate change associated’, b ‘fishing’, and c ‘other human’ stressors experienced by UK Overseas Territories. Figure reproduced from O’Leary et al 2019 in accordance with a Creative Commons Attribution 4.0 International License.

Gibraltar had the highest average threat score, and South Georgia and the South Sandwich Islands the lowest. This score largely reflects those areas with greatest human pressure and does not account for threats in regions adjacent to UKOT waters. However, the authors cautioned that,

“…many of the UKOTs had no data for one or more areas within their associated waters. Where this occurs, it will lower the mean level of threat for the area concerned and thus make specific locations appear less threatened than others.” [Furthermore] “site specific research to ground truth these findings and provide additional threat data to better inform spatial management is required”

O’Leary et al 2019

Table 1 Contribution of each component threat to the mean ‘climate change associated’, ‘fishing’ and ‘other human’ threat scores for each UK Overseas Territory. Black cells represent cases where the component threat contributed > 50% of the mean threat score for the territory in question, dark grey 30–50%, midgrey 20–30%, light grey 10–20%, and white < 10%. Dashed horizontal lines group territories into ocean regions. Abbreviations: UKOT UK Overseas Territory, BVI British Virgin Islands, Is. Island(s), TCI Turks and Caicos Islands, Tristan Tristan da Cunha, SGSSI South Georgia and South Sandwich Islands, BIOT British Indian Ocean Territory, and SBAs Akrotiri and Dhekelia Sovereign Base Areas. Note that fishing is no longer legally permitted around BIOT and the Pitcairn Islands. ‘Pelagic, low bycatch’ fishing is shown as contributing > 50% of the mean ‘fishing’ threat score for each of these UKOTs, however this is concentrated around exclusive economic zone (EEZ) boundaries (Fig. 2) and likely represents overlap between high seas and EEZ boundaries. Figure reproduced from O’Leary et al 2019 in accordance with a Creative Commons Attribution 4.0 International License.

This study provides a useful indication of the main threats faced by each UKOT and plots key gaps in the current state of knowledge relevant to the effective management of UKOT marine environments.


Recent investments (e.g. the UK Government’s Blue Belt Programme and the Bertarelli Programme in Marine Science, focusing on the British Indian Ocean Territory (BIOT)) will help to enhance evidence for managers. However, the authors stressed that “additional and continued investment in research and management is therefore required in the Overseas Territories”, particularly in relation to illegal, unreported and unregulated (IUU) fishing.


Securing funding for the surveillance and monitoring of the UKOTs beyond the end of the Blue Belt Programme in 2020 will be an important next step for the UK Government to address these research and management gaps.

Associated research paper

Evidence gaps and biodiversity threats facing the marine environment of the United Kingdom’s Overseas Territories published by Dr Bethan O’Leary and colleagues*. This work is open access and available to download for free from the journal Biodiversity and Conservation.


*Citation: O’Leary, B.C., Fieldhouse, P., McClean, C.J. et al. Biodivers Conserv (2019) 28: 363.