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3.3. Regional average of hard coral (blue line, open circles) and fleshy algae (green line, closed circles) cover pre-and post-bleaching (mean and 95% confidence interval) (n = 131). Post-bleaching period is from July 2016 onwards and is represented by a dotted line, and pre-bleaching is a solid line.
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The third global coral bleaching event started in the North Pacific in the summer of 2014, and continued for a record 3 years, only dissipating in 2017. It affected the Western Indian Ocean (WIO) between January and May 2016, and was the strongest bleaching event to occur in the region since 1998.
The main objective of this report is to provide up...
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Citations
... These "unpublished" datasets can provide a wealth of information for the remote scientist, and their use for monitoring, assessment and publications are often highly desirable at the national or regional level (e.g. Gudka et al., 2018, Cowburn et al., 2021. ...
Modern-day coral reef conservation requires connections between researchers, decision-makers and stakeholders to achieve holistic ecosystem-based management (EBM), rooted in and supported by local communities. However, the COVID-19 pandemic, global political and financial instability and growing concerns over emissions from air travel have meant that face-to-face meetings and in-person fieldwork are increasingly difficult for many researchers at distant institutions. In this paper we discuss how to achieve EBM remotely, using a combination of freely available online data, remote fieldwork techniques and virtual communication and engagement tools. We highlight resources that have been useful in our work for components of overseas EBM and discuss lessons learned from those experiences.
There are benefits to remote working, including reduced carbon emissions and travel costs, the ability to record and re-use electronic training materials, the ability to reach a wider audience than through face-to-face meetings and an increased reliance and division of labour with local researchers and stakeholders. However, developing new relationships and gaining a deeper contextual understanding of the local site and culture is not easily replaced by online or remote methods. Post-COVID-19, it is likely that some aspects of remote working within coral reef conservation will continue, as in many other aspects of global collaboration. We propose a blended approach where much of the work and collaboration is conducted online, but with some in-person visits to develop the key relationships or decisions are needed.
... The global-scale coral bleaching event (GCBE) induced by the 2014-2016 ENSO has led to unprecedented coral mortality across regions throughout the tropical belt (Eakin et al., 2019 and references therein). During this period, the Western Indian Ocean (WIO) experienced its largest coral bleaching since the first global event was reported in 1998 (Obura et al., 2017;Gudka et al., 2018). ...
... The Seychelles suffered the most, with up to 90 % of the reefs affected by high or extreme bleaching, which was followed by Tanzania with up to 56 % of the reefs severely affected Gudka et al., 2020). While some regional-scale bleaching studies are existent for the Western Indian Ocean region (Gudka et al., 2018;Gudka et al., 2020;Cerutti et al., 2020), few studies have documented post-bleaching alterations and impacts of the 2014-2016 GCBE on individual local reef communities and beyond coral mortality. ...
We explored the extent of post-bleaching impacts, caused by the 2014–2016 El Niño Southern Oscillation (ENSO) event, on benthic community structure (BCS) and herbivores (fish and sea urchins) on seven fringing reefs, with differing protection levels, in Zanzibar, Tanzania. Results showed post-bleaching alterations in BCS, with up to 68 % coral mortality and up to 48 % increase in turf algae cover in all reef sites. Herbivorous fish biomass increased after bleaching and was correlated with turf algae increase in some reefs, while the opposite was found for sea urchin densities, with significant declines and complete absence. The severity of the impact varied across individual reefs, with larger impact on the protected reefs, compared to the unprotected reefs. Our study provides a highly relevant reference point to guide future research and contributes to our understanding of post-bleaching impacts, trends, and evaluation of coral reef health and resilience in the region.
... Furthermore, numerous initiatives exist to provide data and increase information flows. For example, the Nairobi Convention's Coral Reef Task Force (CRTF), which consists of two nodes of the Global Coral Reef Monitoring Network (GCRMN), has successfully compiled complementary ecological data from multiple contributors into consolidated datasets (Obura et al., 2017;Gudka et al., 2018). These datasets have been pivotal to recent regional reef status reporting (Ibid.) ...
... For projects or bilateral agreements, contracts are commonly used to establish formal data-sharing rules, e.g., creating a memorandum of understanding about when, how, and with whom data collected within a funded project should be shared. Projects involving multiple partners may employ initiative-specific data-sharing agreements with each data owner to facilitate sharing, as was the case for the Nairobi Convention's CRTF ecological data compilation(Obura et al., 2017;Gudka et al., 2018). Assigning data coordination and management responsibilities to a trusted non-governmental intermediary in the region 8 Flanders Marine Institute, available at http://www.vliz.be/en/publish ...
Comprehensive and timely data-sharing is essential for effective ocean governance. This institutional analysis investigates pervasive data-sharing barriers in Kenya and Tanzania, using a collective action perspective. Existing data-sharing rules and regulations are examined in respect to boundaries, contextuality and incentive structures, compliance and settlement mechanisms, and integration across scales. Findings show that current institutional configurations create insufficient or incoherent incentives, simultaneously reducing and reproducing sharing barriers. Regional harmonisation efforts and strategically aligned data-sharing institutions are still underdeveloped. This article discusses proposals to increase capacities and incentives for data-sharing, as well as the limitations of the chosen analytical framework. The debate is extended to aspects beyond institutional issues, i.e., structural data-sharing barriers or ethical concerns. Key recommendations include the establishment of more compelling incentives structures for data-sharing, increased funding of capacity-building and sharing infrastructure, and further awareness creation on the importance of data-sharing.
... The coral bleaching event in 2016 was a global catastrophe on the reefs. Almost in the all tropical or subtropical coral ecosystem reported this phenomenon, including, in Indonesia region (Bachtiar and Hadi, 2019;Ampou et al., 2017;Putra et al., 2019;Wouthuyzen et al., 2018), the Great Barrier Reef (GBR) (Harvey et al., 2018;McMahon et al., 2019;Tebbett et al., 2019;Wismer et al., 2019;Wolanski et al., 2017), Maldives (Nizam et al., 2016), Brazil (Teixeira et al., 2019), Mexico (Johnston et al., 2019), Indian Ocean (Gudka et al., 2018;Head et al., 2019;Ranith and Kripa, 2019;Thinesh et al., 2019), Seychelles (Robinson et al., 2019), Guam (Raymundo et al., 2019), Japan (Nishiguchi et al., 2018), and several other locations that are widespread in the Indo Pacific Ocean. The bleaching phenomena in 2016 in Pieh MRP were largely caused by the increase of Sea Surface Temperature (SST) anomaly due to short duration climate pattern El Niño-Southern Oscillation (ENSO) (Booth and Beretta, 2002). ...
Highlight ResearchAfter bleaching disturbance and Acanthaster planci outbreaks, herbivore fishes species were dominated in MRP PiehThis explains the marine recreational activities in utilization zone MRP Pieh have no impact on reducing fish biomassAfter disturbance in MRP Pieh shows the coral reef fishes still endurance on bleaching event, and Acanthaster planci outbreak after disturbance in MRP Pieh shows the coral reef fishes still endurance on bleaching event and Acanthaster planci outbreak. However, the composition of corallivorous has decreased but has been an increase in herbivorous and carnivorous fish populationsAbstractPieh MRP encountered non-anthropogenic phenomena, precisely massive coral bleaching in 2016, 2017, and massive predators from Acanthaster planci outbreaks in 2018. This study aimed to understand the pattern of coral reef diversity in the core zone and utilization in the MRP area and compare it to non-MRPS locations that accept the same non-anthropogenic pressure conditions. Coral fish sampling using a UVC is categorized into three zones: the core zone, the utilization zone, and outside the MRP area. 8 Families of coral reef fishes were counted based on categories of level function in ecologies and economy. Taxonomic distinctiveness estimates were calculated mathematically for each sample, including species richness and taxonomic diversity were compared among zonation area. Pearson’s Coefficient Correlation Matrix was used to measure the correlation relationship between zonation areas. There are 91 species of fish and 3002 individuals found. The richest family in the MRP Core Zone and MRP Utility Zone was Acanthuridae with 20 species and non-MRP has a lower species richness and abundance of fish communities. The dominant species in Pieh MRP was Ctenochaetus striatus with average abundant per site (21.3 ± 7.62, n = 3). Acanthuridae represents 55.98% of the total biomass in MRP-Core Zone, 63.13% in MRP-Utility Zone, and 41.55% in Non-MRP Area. This study showed the number of species and populations from corallivores fishes have decreased but has been an increase in herbivorous and carnivore diversity. The diversity indices (H’) and ENS also shows no differ significantly between zonation.
... Estimates suggest coral reefs generate profits for the tourism industry worth US$ 356,000 per year, per km 2 (Spalding et al., 2017). In total, reefs could be worth US$ 2.5 billion per year or 4% of the Kenya GDP (Gudka et al., 2018). ...
... The Indian Ocean is warming (McClanahan, 2002;Pearce & Feng, 2007), and in the last two decades, the Seychelles has experienced two major coral bleaching events (Graham et al., 2006;Gudka et al., 2018). The 1997 to 1998 bleaching event was linked to ENSO, which recorded the highest SST since 1961 (Payet & Agricole, 2006). ...
... The 1997 to 1998 bleaching event was linked to ENSO, which recorded the highest SST since 1961 (Payet & Agricole, 2006). More than 90% of the live coral cover was lost around the inner islands (Sheppard, 2003), and in 2016, some inner islands reported a further 60% loss (Gudka et al., 2018). Such events change reef structure, composition, and diversity which have cascading effects within food webs (Graham et al., 2006). ...
en Historically, Cousine Island was used for agriculture and harvesting various seabird eggs, but following restoration efforts initiated in the 1990s, it has become an important nesting area for Seychelles seabirds. White-tailed tropicbird (Phaethon lepturus), white tern (Gygis alba), and lesser (Anous tenuirostris) and brown noddy (Anous stolidus) populations were monitored on Cousine Island between 1997 and 2017 to determine the long-term population responses to various environmental variables during the winter breeding season. White tern, brown noddy, and white-tailed tropicbird populations are increasing, indicating that island conditions for breeding have improved for these species in the last 20 years. Lesser noddy populations are in decline, but not significantly, with winter air temperature significantly adding to this trend. Lesser noddies are true colonial nesters and are therefore potentially more affected by climatic conditions that result in nest failures and nearshore prey shortages. The relationship between numbers of seasonally breeding species (lesser and brown noddies) and those of year-round breeders (white-tailed tropicbirds and white terns) was also examined. Brown noddy population trends significantly predicted white-tailed tropicbird and white tern winter breeding population trends, suggesting that these species populations respond similarly to local conditions. Data from this study establish a baseline for future population trend investigations and assessments of island conservation and management success.
Résumé
fr L’île Cousine était autrefois utilisée pour la production et la récolte d’œufs de divers oiseaux marins, mais suite aux efforts de restauration lancés dans les années 1990, elle est devenue une zone de nidification importante pour les oiseaux marins des Seychelles. Des populations de phaétons à queue blanche (Phaethon lepturus), de sternes blanches (Gygis alba), de noddi mariannes (Anous tenuirostris) et de noddi bruns (A. stolidus) ont fait l’objet d’un suivi sur l’île Cousine entre 1997 et 2017 afin de déterminer les réactions à long terme de ces mêmes populations face à diverses variables environnementales pendant la saison de reproduction hivernale. Les populations de sternes blanches, de nodules bruns et de phaétons à queue blanche sont en augmentation, ce qui indique que les conditions insulaires pour la reproduction se sont améliorées pour ces espèces au cours des 20 dernières années. Les populations de noddi marianne sont en déclin, mais cette baisse n’est pas significative, et la température de l’air en hiver joue un rôle considérable dans cette tendance. Le noddi marianne est un véritable nicheur colonisateur. Il est donc potentiellement plus affecté par les conditions climatiques, qui entraînent des échecs de nidification et des pénuries de proies à proximité du rivage. La relation entre le nombre d’espèces qui se reproduisent de façon saisonnière (noddi marianne et noddi brun) et celles qui se reproduisent tout au long de l’année (phaéton à queue blanche et sterne blanche) a également fait l’objet d’un examen. Les tendances des populations de noddi bruns prédisaient de manière significative celles des populations reproductrices hivernales de phaétons à queue blanche et de sternes blanches, suggérant que ces populations d’espèces réagissent de la même manière aux conditions locales. Les données obtenues grâce à cette étude établissent une base de référence pour les futures études portant sur les tendances des populations et les évaluations de l’efficacité des stratégies de conservation et de gestion des îles.
... Bleaching severity during the peak-bleaching assessment in May 2016 indicated obvious but limited paling and bleaching of coral cover, and corroborated previous studies indicating local bleaching when temperatures reach 28.8 • C and/or~4 DHW [13,60]. During 2016, widespread bleaching was recorded in the Western Indian Ocean when some sites experienced 15 DHW and 37% of these sites were affected by high or extreme bleaching [7,61]. Post-bleaching surveys in September 2016 detected no mortality and only negligible paling on the South African reefs, approximating pre-bleaching levels as expected, after degree heating weeks returned to zero in June, corresponding with the cooler austral winter months (Figures 4 and 6). ...
Coral reefs reach their southernmost limits in the southwestern Indian Ocean in Maputaland, South Africa. Here, we investigate the recent global coral bleaching event of 2016, the thermal dynamics of these marginal high-latitude reefs and the potential environmental factors regulating the responses of coral communities. Pre-, peak- and post-bleaching surveys of over 9850 coral colonies from 29 genera were undertaken over 3 years across 14 sites spanning 120 km of coastline using point-intercept and visual bleaching index survey methodologies. Bleaching data were related to several environmental variables including temperature, degree heating weeks (DHW), depth, latitude, and upwelling intensity. These reefs have experienced a history of relatively low thermal stress based on DHW. Long-term in situ temperature records nevertheless showed no obvious trend of increase. In situ temperatures also displayed poor relationships, with temperatures predicted by the Representative Concentration Pathway models. Mild coral bleaching with no significant mortality was recorded across sites with taxon-specific bleaching responses evident. Latitude and cumulative daily DHW were significantly related to the bleaching index whereas depth and interactions of depth with latitude and DHW were not. While upwelling of cooler water may offer some refuge to coral communities, especially in the Central and Southern Reef Complexes where it is more pronounced, this may only be transient as the upwelled water may also experience some degree of warming in future, thereby limiting such protection from global warming.
... Dive site visitations were dictated by local weather conditions and where divers had previously dived. Dive sites are characterized by carbonitic, granitic, and sandy-patch substrates with their reefs undergoing significant degradation due to the occurrence of multiple severe bleaching events in the last quarter of a century (Gudka et al., 2018;Harris et al., 2014;Khan & Amelie, 2015). ...
Determining the fundamental causes of scuba diver contact with coral reefs is vitally important for the marine tourism sector. This information can provide management authorities and dive operators with methods to promote and demonstrate sustainable dive practices in order to reduce physical interaction by divers on coral reefs. This study provides an insight into what variables influence physical contact by scuba divers on coral reefs around Praslin Island, Seychelles. Underwater behaviour was studied from 205 divers to identify what factors significantly influence contacts on coral reefs at dive sites. Male divers contacted the reef twice as much as female ones (0.25±0.04 versus 0.12±0.02 contacts min-1). Photographers contacted the reef significantly more than those divers without cameras (0.30±0.06 versus 0.10±0.02 contacts min-1), as did diving at midday versus in the morning (0.46±0.13versus 0.16±0.02 contacts min-1). Diver age had a significant effect on contact rates, with the 41-50 age category responsible for the highest amount contacts (0.31±0.07 contacts min-1). Dive operators need to be extra vigilant with these high-risk divers, utilising a combination of damage prevention methods for camera users, providing closer supervision for older divers and reminding divers about eco-friendly dive techniques who are completing more than one dive that day.
... Such peak values are lower than those recorded at Montgomery Reef (north-western Australia; 9.3 °C-weeks; Le Nohaı¨c Nohaı¨c et al. 2017) and Lisianski Island (northern Pacific;19.69 °C-weeks;Couch et al. 2017). The mismatch between the 3.4 °C-week NOAA-CRW value reported for Aldabra and the extent of benthic cover change observed here could be due to non-representativeness of the pure-water 50-km resolution virtual station for Aldabra, an atoll surrounded by deep cool oceanic waters ( Gudka et al. 2018). However, no substantial bleaching and mortality were expected based on in situ DHW, despite variations across reef location and depth. ...
... Following the 2014-2017 event, Aldabra's reefs have again suffered lower mortality than Seychelles' Inner Islands (e.g. 81% hard-coral cover loss at North Island; Obura et al. 2017;Gudka et al. 2018), where the bleaching risk was higher (DHW in Mahé peaked at 4.6 °C-weeks in April NOAA-CRW 2000). This pattern may partly be due to the neighbouring environment: in contrast to Aldabra surrounded by deep cool oceanic waters, shallow banks around the Inner Islands may enhance thermal stress ( Gudka et al. 2018). ...
... 81% hard-coral cover loss at North Island; Obura et al. 2017;Gudka et al. 2018), where the bleaching risk was higher (DHW in Mahé peaked at 4.6 °C-weeks in April NOAA-CRW 2000). This pattern may partly be due to the neighbouring environment: in contrast to Aldabra surrounded by deep cool oceanic waters, shallow banks around the Inner Islands may enhance thermal stress ( Gudka et al. 2018). Similarly, free from direct anthropogenic stressors, the Chagos Archipelago was more highly impacted than Aldabra with a hard-coral cover dropping from 50-75% to 12% following 1998 (Sheppard 1999) and from 40-50% to \ 10% following the 2014event (Sheppard et al. 2017, during which DHW peaked at 7.5 °C-weeks in 2015and 17.6 °C-weeks in 2016(Head et al. 2019). ...
The third global bleaching event caused prolonged elevated sea surface temperatures from 2014 to 2017 that heavily impacted coral reefs worldwide. This study determines changes in benthic community following this bleaching event at a remote UNESCO World Heritage Site in the Western Indian Ocean. Aldabra Atoll offers a rare opportunity to study global impacts in the absence of local anthropogenic stressors. Analysis of satellite-derived temperature data indicated that Aldabra was exposed to the highest bleaching-risk intensity of the past 20 years during this bleaching event. Bleaching-risk conditions lasted from December 2015 to June 2016 close to the 4 °C-week threshold, when bleaching is expected. Benthic cover was established pre- and post-bleaching from 21 transects across two reef locations (lagoonal reef, 2 m depth; seaward reef, 5 and 15 m depth). From a pre-bleaching benthic community in which living corals and epilithic algal matrix (EAM) predominated, Aldabra’s reefs switched to an EAM-dominated community 8 months after bleaching. Soft corals declined by 93% of their overall pre-bleaching cover to < 1%. Although overall hard-coral cover was also reduced, the decline varied among depths and might indicate local adaptations of the lagoonal reef, due to greater variability in sea surface temperature compared to the seaward reef. With the exception of Isopora palifera, all taxomorphic coral groups experienced a decline following bleaching. Overall, Rhytisma experienced a near-complete extirpation, Acroporids (excluding I. palifera) and branching Poritids declined by more than 80%, Merulinidae lost ca. 60% of their pre-bleaching cover, while massive Poritids cover slightly decreased. Aldabra’s benthic community therefore underwent substantial changes following the 2014–2017 bleaching event and showed that live coral cover declines significantly even in protected areas isolated from local anthropogenic pressures.
... During this period, the Western Indian Ocean (WIO) experienced region-wide high temperatures in 2016. In the WIO, temperatures in the south (South Africa, southern Madagascar) peaked in January and then as the sun moved northwards, temperatures in Kenya and Seychelles peaked in April (Gudka et al. 2018). Previous bleaching events in the WIO include the first global event in 1998 (Wilkinson et al. 1999;Goreau et al. 2000) as well as lesser events such as in 1983,2005,2007 and 2010 (Faure et al. 1984;McClanahan et al. 2014;Obura et al. 2018), and more localised events, e.g. ...
... Historically, monitoring and reporting of coral bleaching in the WIO has been undertaken through individual studies, e.g. South Africa (Floros et al. 2004), Seychelles (Spencer et al. 2000), Kenya (McClanahan et al. 2001), as well as syntheses led by research programmes (McClanahan et al. 2014) and the Global Coral Reef Monitoring Network (Wilkinson 2001;Obura et al. 2017;Gudka et al. 2018). This reporting is also included in global syntheses (Donner et al. 2017;Hughes et al. 2018). ...
A full-text view-only version of the paper is available here https://rdcu.be/bQUYS. Climate change, coupled with an El Niño, caused a devastating bleaching event in the Western Indian Ocean (WIO) in 1998. Similar extreme conditions at the end of 2015 meant that there was a very high risk of widespread bleaching in the WIO at the start of 2016. In anticipation of a regional bleaching event, a citizen-science online reporting tool was developed to collect data in broad categories of bleaching and mortality from various stakeholders across the region, e.g. general public, scientists, reef managers, divers. The main objectives were to (i) document in real-time the impacts of the 2016 coral bleaching event at a regional scale and (ii) demonstrate the value of basic data to illustrate and understand important trends. A total of 698 records from 55 organisations and over 80 observers were collected through the online reporting form and via email. Thermal stress across the WIO during the bleaching season (January–May) was high enough to cause widespread bleaching and significant mortality, with reef sites on average, experiencing a maximum of 5.4 Degree-Heating-Weeks (DHW), with some sites experiencing up to 15 DHW. During the peak-bleaching months, 37% of sites were affected by high or extreme bleaching, while 8.5% of sites showed no evidence of bleaching. Seychelles was the most affected by bleaching with 90% of reported sites showing high or extreme bleaching, followed by Tanzania, Comoros, Reunion and Mauritius. Sites in the Mozambique Channel (south and north) were the least affected by bleaching. Over 60% of sites experienced some level of bleaching-induced coral mortality from April onwards, but the impact was heterogeneous, with reefs in some areas showing substantial recovery from bleaching and others showing almost no recovery. As the first effort in the WIO to gather bleaching data at this scale during a major bleaching event, this study has shown that participatory data collection from various stakeholders, even at a basic level, can reveal important regional-scale, real-time trends and information about coral bleaching.
