Chagos Research Articles

Climate oscillation and the invasion of alien species influence the oceanic distribution of seabirds.

Spatial and temporal distribution of seabird transiting and foraging at sea is an important consideration for marine conservation planning. Using at‐sea observations of seabirds (n = 317), collected during the breeding season from 2012 to 2016, we built boosted regression tree (BRT) models to identify relationships between numerically dominant seabird species (red‐footed booby, brown noddy, white tern, and wedge‐tailed shearwater), geomorphology, oceanographic variability, and climate oscillation in the Chagos Archipelago. We documented positive relationships between red‐footed booby and wedge‐tailed shearwater abundance with the strength in the Indian Ocean Dipole, as represented by the Dipole Mode Index (6.7% and 23.7% contribution, respectively). The abundance of red‐footed boobies, brown noddies, and white terns declined abruptly with greater distance to island (17.6%, 34.1%, and 41.1% contribution, respectively). We further quantified the effects of proximity to rat‐free and rat‐invaded islands on seabird distribution at sea and identified breaking point distribution thresholds. We detected areas of increased abundance at sea and habitat use‐age under a scenario where rats are eradicated from invaded nearby islands and recolonized by seabirds. Following rat eradication, abundance at sea of red‐footed booby, brown noddy, and white terns increased by 14%, 17%, and 3%, respectively, with no important increase detected for shearwaters. Our results have implication for seabird conservation and island restoration. Climate oscillations may cause shifts in seabird distribution, possibly through changes in regional productivity and prey distribution. Invasive species eradications and subsequent island recolonization can lead to greater access for seabirds to areas at sea, due to increased foraging or transiting through, potentially leading to distribution gains and increased competition. Our approach predicting distribution after successful eradications enables anticipatory threat mitigation in these areas, minimizing competition between colonies and thereby maximizing the risk of success and the conservation impact of eradication programs.

Asymmetrical international law and its role in constituting empires: the ICJ Chagos Advisory Opinion

The ongoing relationship between the UK and the Chagos Archipelago raises a number of important questions about international law’s relationship with imperialism, more specifically, the ability of the international legal order to influence the fact and the manner of decolonisation. In this contribution, I explore some aspects of this problem. I begin by providing a brief overview of the proceedings of the International Court of Justice, summarising the basic legal consequences of the court’s Advisory Opinion, before discussing its implications from the standpoint of what it reveals about international law’s relationship with the residual British Empire. My argument is that, for all its apparent attempts to promote decolonisation and self-determination, the international legal order has been and continues to remain complicit in the maintenance of exactly the kind of asymmetrical legal relations that constitute empires. Thus, although the Chagos Advisory Opinion may well have long-term significance for the development of the international legal doctrine and the teachings of international law, given the UK’s current position, it will not have any immediate impact on the plight of the Chagossian people.

Status and phenology of breeding seabirds and a review of Important Bird and Biodiversity Areas in the British Indian Ocean Territory

SummarySeabirds are one of the most threatened avian taxa and are hence a high conservation priority. Managing seabirds is challenging, requiring conservation actions at sea (e.g. Marine Protected Areas - MPAs) and on land (e.g. protection of breeding sites). Important Bird and Biodiversity Areas (IBAs) have been successfully used to identify sites of global importance for the conservation of bird populations, including breeding seabirds. The challenge of identifying suitable IBAs for tropical seabirds is exacerbated by high levels of dispersal, aseasonal and asynchronous breeding. The western Indian Ocean supports ~19 million breeding seabirds of 30 species, making it one of the most significant tropical seabird assemblages in the world. Within this is the British Indian Ocean Territory (BIOT), encompassing 55 islands of the Chagos Archipelago, which supports 18 species of breeding seabird and one of the world’s largest no-take MPAs. Between January and March in 1975 and 1996, eight and 45 islands respectively were surveyed for seabirds and the data used to designate 10 islands as IBAs. A further two were proposed following an expedition to 26 islands in February/March 2006. Due to the historic and restricted temporal and spatial nature of these surveys, the current IBA recommendations may not accurately represent the archipelago’s present seabird status and distribution. To update estimates of the BIOT breeding seabird assemblage and reassess the current IBA recommendations, we used seabird census data collected in every month except September from every island, gathered during 2008–2018. The maximum number of breeding seabirds for a nominal year was 281,596 pairs of 18 species, with three species making up 96%: Sooty Tern Onychoprion fuscatus - 70%, Lesser Noddy Anous tenuirostris - 18% and Red-footed Booby Sula sula - 8%. Phenology was a complex species-specific mix of synchronous and asynchronous breeding, as well as seasonal and aseasonal breeding. Nine of the 10 designated IBAs and the two proposed IBAs qualified for IBA status based on breeding seabirds. However, not every IBA qualified each year because Sooty Terns periodically abandoned breeding islands and Tropical Shearwater Puffinus bailloni breeding numbers dropped below IBA qualifying criteria in some years. Further, one survey per year does not always capture the periodic breeding of some tropical seabirds. We propose therefore, that IBAs in BIOT are better designated at the island cluster level rather than by specific island and require two surveys six months apart per year. This work highlights the merits of long-term, systematic, versus incidental surveys for breeding tropical seabirds and the subsequent associated designation of IBAs.

Big Powers, Small Islands, Real Displaced People. Response to Gettel, Eliza. Recognizing the Delians Displaced after 167/6 BCE. Humanities 2018, 7, 91

Eliza Gettel’s paper on the displacement of the Delians in the second century BCE does an excellent job of examining an ancient case study of displacement through the lens of contemporary conceptions of displacement and asylum. In this paper, I try, as a modern historian of asylum, to reflect on the applicability of modern classifications to a case study over 2000 years old. First, I discuss the compatibility of the ancient with the modern. Subsequently, I engage much more deliberately with the arguments Gettel presents in her paper. Finally, I introduce a contemporary case study involving the displacement of people from the Chagos Islands in the Indian Ocean that I argue shares some similarities with that of the Delians, with both cases highlighting the often-neglected agency of the displaced.

Evolutionary biogeography of the reef-building coral genus Galaxea across the Indo-Pacific ocean

Stony corals (Scleractinia) form the basis for some of the most diverse ecosytems on Earth, but we have much to learn about their evolutionary history and systematic relationships. In order to improve our understanding of species in corals we here investigated phylogenetic relationships between morphologically defined species and genetic lineages in the genus Galaxea (Euphyllidae) using a combined phylogenomic and phylogeographic approach. Previous studies revealed the nominal species G. fascicularis included three genetically well-differentiated lineages (L, S & L+) in the western Pacific, but their distribution and relationship to other species in the genus was unknown. Based on genomic (RAD-seq) and mitochondrial sequence data (non-coding region between cytb and ND2) we investigated whether the morphological taxa represent genetically coherent entities and what is the phylogenetic relationship and spatial distribution of the three lineages of G. fascicularis throughout the observed species range. Using the RAD-seq data, we find that the genus Galaxea is monophyletic and contains three distinct clades: an Indo-Pacific, a Pacific, and a small clade restricted to the Chagos Archipelago. The three lineages of G. fascicularis were associated with different RAD-seq clades, with the ‘L’ lineage showing some morphological distinction from the other two lineages (larger more asymmetrical polyps). In addition to these, three more genetic lineages in G. fascicularis may be distinguished – a Chagossian, an Ogasawaran, and one from the Indian-Red Sea. Among nominal taxa for which we have multiple samples, G. horrescens was the only monophyletic species. The mitochondrial non-coding region is highly conserved apart of the length polymorphism used to define L, S & L+ lineages and lacks the power to distinguish morphological and genetic groups resolved with genomic RAD-sequencing. The polyphyletic nature of most species warrants a careful examination of the accepted taxonomy of this group with voucher collections and their comparison to type specimens to resolve species boundaries. Further insight to the speciation process in corals will require international cooperation for the sharing of specimens to facilitate scientific discovery.

A review of Indian Ocean Foa cardinalfishes (Percomorpha: Apogonidae: Apogonichthyini), with a new species from Chagos Archipelago and the Maldives

A review of Indian Ocean Foa cardinalfishes (Percomorpha: Apogonidae: Apogonichthyini), with a new species from Chagos Archipelago and the Maldives

Mitochondrial genome of the silky shark Carcharhinus falciformis from the British Indian Ocean Territory Marine Protected Area

We present the first mitochondrial genome of Carcharhinus falciformis from the Chagos Archipelago in the British Indian Ocean Territory (BIOT) Marine Protected Area (MPA). The mitochondrial genome of C. falciformis is 16,701 bp in length and consists of 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes, and a non-coding control region (D-loop). GC content was at 40.1%. The control region was 1063 bp in length. The complete mitogenome sequence of C. falciformis from the BIOT MPA will enable improved conservation measures of the CITES listed species through studies of species distribution, population abundance, fishing pressure and wildlife trade.

Introduction to the Forthcoming Book: Decolonization and the International Court of Justice: New Directions From the Chagos Advisory Opinion

This is the introduction to a new book forthcoming with CUP. It introduces readers to the case of the Chagos Archipelago, the International Court of Justice's recent Advisory Opinion in the case and the 13 chapters included in the volume.

Complete mitochondrial genome of the whitetip reef shark Triaenodon obesus from the British Indian Ocean Territory Marine Protected Area

We present the first mitochondrial genome of Trianenodon obesus from the Chagos Archipelago in the British Indian Ocean Territory (BIOT) Marine Protected Area. The mitogenome was 16,702 bp in length and consisted of 13 protein-coding genes (PCGs), 22 tRNA genes, 2 rRNA genes, and a non-coding control region (D-loop). GC content was at 38.9%. The control region was 1064 bp in length. This mitogenome for the BIOT MPA T. obesus differed from the previously published T. obesus genome by 15 bp and the differences include a 2 bp insertion and 13 single nucleotide polymorphisms distributed across the mitogenome in the BIOT MPA sequence. Whole mitogenome sequence of T. obesus from the Chagos archipelago presented here fills existing gaps in genetic information on marine species from the BIOT MPA and provides additional tools for species specific assessments as to the effectiveness of MPA management. In addition, methods presented here lay the framework for genetic studies in remote locations with limited infrastructure.

Mitochondrial genome of the Silvertip shark, Carcharhinus albimarginatus, from the British Indian Ocean Territory

The Chagos archipelago in the British Indian Ocean Territory (BIOT) has been lacking in detailed genetic studies of its chondrichthyan populations. Chondrichthyes in Chagos continue to be endangered through illegal fishing operations, necessitating species distribution and abundance studies to facilitate urgent monitoring and conservation of the species. Here, we present a complete mitochondrial genome of the Silvertip Shark, Carcharhinus albimarginatus sampled in the Chagos archipelago. The mitochondrial genome of C. albimarginatus was 16,706 bp in length and consisted of 13 protein-coding genes, 22 tRNA genes, two rRNA genes, a replication origin and a D-loop region. GC content was at 38.7% and the control region was 1,065 bp in length. We expect that mitogenomes presented here will aid development of molecular assays for species distribution studies. Overall these studies will promote effective conservation of marine ecosystemes in the BIOT.

Mauritian sovereignty over the Chagos Archipelago? Strategic implications for Diego Garcia from a UK-US perspective

This article examines the implications for the U.S. military base in Diego Garcia, located in the Chagos Archipelago, in the event that sovereignty of the atoll is ceded from the U.K. to Mauritius. Diego Garcia has become a critically important military base, facilitating U.S. power projection into the Indian Ocean, Middle East and Africa. The legality and future of British sovereignty over the atoll was challenged in 2019 in both the International Court of Justice and United Nations General Assembly. This article finds that Mauritian sovereignty of Diego Garcia would have considerable adverse consequences for U.S. military activity, potentially prohibiting many of the core functions the facility currently performs, as under U.K. sovereignty. Further, this article examines the strategic utility in Diego Garcia for the U.S. and U.K. governments, which demonstrates why these two nations are willing to endure considerable reputational costs and international backlash for retention of the atoll.

A quick, easy and non‐invasive method to quantify coral growth rates using photogrammetry and 3D model comparisons

Abstract Coral growth rates vary significantly with environmental conditions and are thus important indicators of coral health and reef carbonate production. Despite the importance of this metric, data are sparse for most coral genera and species globally, including for many key reef‐building species. Traditional methods to obtain growth rates, such as coral coring or staining with Alizarin are destructive and only work for a limited number of species and morphological growth forms. Emerging approaches, using underwater photogrammetry to create digital models of coral colonies, are providing novel and non‐invasive ways to explore colony‐scale growth patterns and to address existing knowledge gaps. We developed an easy‐to‐follow workflow to construct three‐dimensional (3D) models from overlapping photographs and to measure linear, radial and vertical extension rates of branching, massive and encrusting corals after aligning colony models from subsequent years. The method presented here was applied to measure extension rates for 46 colonies of nine coral species in the remote Chagos Archipelago, Indian Ocean. Proposed image acquisition and software settings produced 3D models of consistently high resolution and detail (precision ≤ 0.2 mm) and variability in growth measurements was small despite manual alignment, clipping and ruler placement (SD ≤ 0.9 mm). Measured extension rates for the Chagos Archipelago are similar to published rates in the Indo‐Pacific where comparable data are available, and provide the first published rates for several species. For encrusting corals, the results emphasize the importance of differentiating between radial and vertical growth. Photogrammetry and 3D model comparisons provide a fast, easy, inexpensive and non‐invasive method to quantify coral growth rates for a range of species and morphological growth forms. The simplicity of the presented workflow encourages its repeatability and permits non‐specialists to learn photogrammetry with the goal of obtaining linear coral growth rates. Coral growth rates are essential metrics to quantify functional consequences of ongoing community changes on coral reefs and expanded datasets for key coral taxa will aid predictions of geographic variations in coral reef response to increasing global stressors.

Coral mass mortalities in the Chagos Archipelago over 40 years: Regional species and assemblage extinctions and indications of positive feedbacks

The global decline of reef corals has been driven largely by several marine heatwaves. This has greatly reduced coral cover but has reduced coral diversity also. While there is a lack of data in most locations to detect coral species losses, reefs of the Chagos Archipelago, central Indian Ocean, have long term monitoring data extending back to the late 1970s. Severe declines in cover have occurred since the 1970s, with regional extinctions of some species and key species assemblages. There is a severe decline in coral settlement, along with a substantial loss of habitat quality which has reduced the habitat available for settlement. This is a clear precursor to positive feedback. Regional species extinctions here occur mainly when total coral cover is <10% of pre-warming levels. Climate models predict more frequent and more severe marine heatwaves, and even if this ecosystem recovers it will contain fewer species.

Self-Determination in Light of the International Court of Justice’s Opinion in the Chagos Case

In its Advisory Opinion in Legal Consequences of the Separation of the Chagos Archipelago from Mauritius in 1965, delivered in 2019, the International Court of Justice (ICJ) was of the view that the decolonisation of Mauritius by the United Kingdom had not been lawfully completed when it achieved independence in 1968. This was due to the separation of the Chagos Archipelago in 1965. After dismissing various challenges to the exercise of its advisory jurisdiction, including the argument that the issue at stake was a territorial dispute between the States and that its jurisdiction was, therefore, being misused to circumvent the UnitedKingdom’s lack of consent to contentious proceedings, the ICJ felt it necessary to explore the nature, scope and content of the right to self-determination and whether it had been validly exercised in this instance. The ICJ found that self-determination had become established as a legal right in the context of decolonisation by the time Mauritius was in the process of securing its independence in the 1960s and that a corollary of the right was that of the territorial integrity of a non-self governing territory, which had not been respected in the case of Mauritius. Accordingly, the United Kingdom’s continued administration of the Chagos Archipelago constituted an ongoing internationally wrongful act, entailing international responsibility, which the United Kingdom was under an obligation to put an end to as soon as possible. While it was for the United Nations (UN) General Assembly to determine how the decolonisation of Mauritius was to be realised, in view of the fact that the right to self- determination has an erga omnes character, the ICJ called on all States to co-operate with the UN to that end.

Teleconnections reveal that drivers of inter-annual growth can vary from local to ocean basin scales in tropical snappers

Individual growth rate is one of the key traits that determine the productivity of populations. Chronological approaches that relate time series of growth and climate information present the opportunity to identify important climatic drivers of demography and thereby understand the likely impact of climate change. We constructed otolith chronologies (a proxy for somatic growth) to examine synchrony of growth patterns within and between two mesopredatory fishes (Lutjanus bohar and L. gibbus) in the remote Chagos Archipelago, Indian Ocean. We then used mixed-model and pathway analysis to relate growth responses to a suite of climatic and environmental factors to determine the extent to which variation in inter-annual growth could be predicted at individual and population levels. Our models explained up to half the variance associated with annual growth at the level of populations. Significant environmental drivers of growth differed between species, as did the spatial scale of these drivers: L. gibbus exhibited a strong relationship with regional ocean temperature, whereas growth of L. bohar was correlated with the Pacific Decadal Oscillation, suggesting influential teleconnections between ocean basins as an underlying predictor of productivity of fish populations. Our results demonstrate that (1) synchronous growth stemming from relationships with climate factors may be suppressed at very low latitudes; (2) closely related species may respond to very different environmental stimuli; and (3) within the same environment, the scale of influential drivers may be local in nature or reflect oceanographic processes stretching across entire ocean basins. We demonstrate that biochronological approaches are effective tools for reconstructing relationships between climate variability and fish growth even in tropical regions where seasonality is low, and these methods can be valuable for forecasting population-level responses to projected climate change.

Estimates of marine turtle nesting populations in the south-west Indian Ocean indicate the importance of the Chagos Archipelago

AbstractGlobal marine turtle population assessments highlight the importance of the south-west Indian Ocean region, despite data gaps for the Chagos Archipelago. The archipelago hosts nesting hawksbill Eretmochelys imbricata and green turtles Chelonia mydas, both heavily exploited for 2 centuries until protection in 1968–1970. We assessed available nesting habitat and spatial distribution of nesting activity during rapid surveys of 90% of the archipelago's coastline in 1996, 1999, 2006 and 2016. We quantified seasonality and mean annual egg clutch production from monthly track counts during 2006–2018 along a 2.8 km index beach on Diego Garcia island. An estimated 56% (132 km) of coastline provided suitable nesting habitat. Diego Garcia and Peros Banhos atolls accounted for 90.4% of hawksbill and 70.4% of green turtle nesting. Hawksbill turtles showed distinct nesting peaks during October–February, and green turtles nested year-round with elevated activity during June–October. Estimates of 6,300 hawksbill and 20,500 green turtle clutches laid annually during 2011–2018 indicate that nesting on the Chagos Archipelago has increased 2–5 times for hawksbill turtles and 4–9 times for green turtles since 1996. Regional estimates indicate green turtles produce 10 times more egg clutches than hawksbill turtles, and the Chagos Archipelago accounts for 39–51% of an estimated 12,500–16,000 hawksbill and 14–20% of an estimated 104,000–143,500 green turtle clutches laid in the south-west Indian Ocean. The improved status may reflect &gt; 40 years without significant exploitation. Long-term monitoring is needed to captureinterannual variation in nesting numbers and minimize uncertainty in population estimates.

Comparing Decisions of International Courts on the Separation of Chagos Archipelago from Mauritius and its Aftermath - focused on the Advisory Opinion of the ICJ in 2019 -

Comparing Decisions of International Courts on the Separation of Chagos Archipelago from Mauritius and its Aftermath - focused on the Advisory Opinion of the ICJ in 2019 -

An update of proposed Sri Lanka warning system for east and west coast tsunamis

PurposeBased on the existing provisions/operations of tsunami warning in the Indian Ocean, authors observed that detection as well as arrival time estimations of regional tsunami service providers (RTSPs) could be improved. In particular, the detection mechanisms have been eccentrically focussed on Sunda and Makran tsunamis, although tsunamis from Carlsberg ridge and Chagos archipelago could generate devastating tsunamis for which inadequate provisions exist for detection and arrival time/wave height estimation. RTSPs resort to assess estimated arrival time/wave heights from a scenario-based, pre-simulated database. These estimations in terms of Sri Lanka have been found inconsistent. In addition, current warning mechanism poorly manages non-seismic tsunamis. Thus, the purpose of this study is to investigate these drawbacks and attempt to carve out a series of suggestions to improve them.Design/methodology/approachThe work initiated with data retrieved from global earthquake and tsunami databases, followed by an estimation of probabilities of tsunamis in the Indian Ocean with particular emphasis on Carlsberg and Chagos tsunamis. Second, probabilities of tsunami detection in each sub-region have been estimated with the use of available tide gauge and tsunami buoy data. Third, the difficulties in tsunami detection in the Indian Ocean are critically assessed with case studies, followed by recommendations to improve the detection and warning.FindingsProbabilistic estimates show that given the occurrence of a significant earthquake, both Makran and Carlsberg/Chagos regions possess higher probabilities to harbour a tsunami than the Sunda subduction zone. Meanwhile, reliability figures of tsunami buoys have been declined from 79-92 to 68-91 per cent over the past eight years. In addition, a Chagos tsunami is left to be detected by only one tide gauge prior to it reaching Sri Lankan coasts.Research limitations/implicationsThe study uses an averaged tsunami speed of 882 km/h based on 2004 Asian tsunami. However, using exact bathymetric data, Tsunamis could be simulated to derive speeds and arrival times more accurately. Yet, such refinements do not change the main derivations and conclusions of this study.Practical implicationsTsunami detection and warning in the Indian Ocean region have shown room for improvement, based on the inadequate detection levels for Carlesberg and Chagos tsunamis, and inconsistent warnings of regional tsunami service providers. The authors attempted to remedy these drawbacks by proposing a series of suggestions, including a deployment of a new tsunami buoy south of Maldives, revival of offline buoys, real-time tsunami simulations and a strategy to deal with landslide tsunamis, etc.Social implicationsIndian Ocean is prone to mega tsunamis as witnessed in 2004. However, more than 50 per cent of people in the Indian Ocean rim countries dwell near the coast. This is verified with deaths of 227,898 people in 14 countries during the 2004 tsunami event. Thus, it is of paramount importance that sufficient detection levels are maintained throughout the Indian Ocean without being overly biased towards Sunda tsunamis. With respect to Sri Lanka, Makran, Carlesberg or Chagos tsunamis could directly hit the most populated west coast and bring about far worse repercussions than a Sunda tsunami.Originality/valueThis is the first instance where the threats from Carlesberg and Chagos tsunamis to Sri Lanka are discussed, probabilities of tsunamis are quantified and their detection levels assessed. In addition, reliability levels of tsunami buoys and tide gauges in the Indian Ocean are recomputed after eight years to discover that there is a drop in reliability of the buoy data. The work also proposes a unique approach to handle inconsistencies in the bulletins of regional tsunami service providers, and to uphold and improve dwindling interest on tsunami buoys.

Multi-species co-operative hunting behaviour in a remote Indian Ocean reef system

ABSTRACTInter-specific hunting associations can occur across a range of marine species to facilitate prey capture through co-operative behaviour. Here we describe multiple transient cross-phyla associations between day octopus (Octopus cyanea) and three fish species, including peacock grouper (Cephalopholis argus), brown-marbled grouper (Epinephelus fuscoguttatus), and gold-saddle goatfish (Parupeneus cyclostomus), in the isolated reef system of the Chagos archipelago. Observations of such hunting associations are rare, and no similar observations have been recorded for this region. The remoteness of this study site may provide some explanation for these multiple sightings, allowing natural behaviours to occur undisturbed. However, given no previous sightings of such behaviour, the limitation of available food resources following two recent mass coral mortality episodes, may have necessitated the formation of these rare/novel hunting interactions. Intensified prey scarcity and increasingly degraded habitat structure following more frequent disturbance events may therefore lead to such indirect environmentally mediated behavioural responses becoming increasingly prevalent in reef-dwelling species.

SELF-DETERMINATION, THE CHAGOS ADVISORY OPINION AND THE CHAGOSSIANS

AbstractIn its Chagos Advisory Opinion, the International Court of Justice (ICJ) ruled that the UK's detachment of the Chagos Archipelago from the colony of Mauritius on the eve of independence constituted a violation of customary international law (CIL). This article analyses the Court's approach to establishing the emergence and content of the right to self-determination in this frustrated case of decolonisation. It goes on to examine the argument that self-determination's peremptory character has decisive consequences in this specific context—a contention which found favour with several judges in their Separate Opinions. The article explores the extent to which the claims and counterclaims, made during the advisory proceedings, turned on countervailing readings of not only the key sources of custom but also of the principle of inter-temporal law. The final sections consider the significance of the Chagos Opinion for the Chagossians, both in relation to the Archipelago's resettlement and for their outstanding appeal in the UK courts (where the European Convention on Human Rights performs a pivotal role).