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Examples of data from two species, one showing a significant change, the other not. The bars show the actual data, while the curves show the fitted Poisson distribution. The LR test evaluates the similarity of the two distributions.
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Coral reef fish communities in the Seychelles are highly diverse and remain less affected by the direct impacts of human activities than those on many other coral reefs in the Indian Ocean. These factors make them highly suitable for a detailed survey of the impacts of the 1998 mass coral mortality, which devastated the coral faunas of the region....
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Citations
... A mix of granitic and carbonate islands, the coral reefs of the Seychelles were severely affected by temperatureinduced mass coral bleaching events in the past decades (Spencer et al. 2000;Engelhardt 2004;Graham et al. 2006). Coral reefs around these islands are mostly fringing and shallow patch reefs (Spalding and Jarvis 2002), which frequently exposes them to elevated sea temperatures, often caused by El Niño events and the Indian Ocean Dipole. In 1998, these two phenomena coincided, causing an extended positive sea-surface temperature anomaly, which lasted for several weeks. ...
... In 1998, these two phenomena coincided, causing an extended positive sea-surface temperature anomaly, which lasted for several weeks. The mass coral bleaching event, which ensued, caused over 90% coral mortality (Turner et al. 2000;Spalding and Jarvis 2002). Prior to the 1998 bleaching event, coral cover ranged from 35 to 80% and was dominated by branching Acropora corals (Turner et al. 2000). ...
Climate-induced mass bleaching events are one of the greatest threats to coral reefs, causing widespread loss of coral cover. Drivers of recovery and adaptation for coral reefs in the face of repeated large-scale disturbances are unclear, with marked differences across geographies. Using a monitoring dataset lasting from 2005 to 2018, we documented the response of coral reefs of northwest Mahé in the granitic Seychelles islands following the 1998 and 2016 mass bleaching events. We analysed trends in coral cover, coral community composition and key fish trophic group densities for 24 sites. Coral cover increased almost fourfold from 2005 to 2015 with 42.1% mean coral cover in 2015, highlighting a recovery from the 1998 bleaching event dominated by Acropora growth forms. Impacts of the 2016 bleaching event were less acute than the 1998 one. However, following the 2016 bleaching event, coral cover significantly decreased to 16.1% mean cover in 2017, marked by a sharp decrease of Acropora corals and branching growth forms. Corallivorous, herbivorous and piscivorous fish densities were positively correlated with coral cover from 2005 to 2016. These findings highlight the dominant role of Acropora in recovery from mass coral bleaching events. It also shows the importance of time-series datasets in understanding coral recovery dynamics and their use in an integrated management approach to building reef resilience.
... In addition to the corals themselves, research on the effects of marine heatwaves has also focused heavily on fishes [37][38][39][40][41][42][43][44][45][46][47][48], which are also typically included in coral reef monitoring efforts. However, studies have almost completely ignored the myriad of small, cryptic, species, which make up a disproportionate amount of coral reef biodiversity [49][50][51]. ...
... Large hosts, like many reef fishes, can also leave areas of warm water for cooler water, or leave habitat impacted by coral bleaching for other habitats [39,40,[43][44][45][46]147], depriving gnathiids and other similar ectoparasites, like natatory-stage cymothoid isopods of hosts [148]. The potentially impaired physiological and swimming ability of the parasite, combined with direct effects on mortality and host availability, could result in a decline in parasite populations. ...
Extreme warming events that contribute to mass coral bleaching are occurring with increasing regularity, raising questions about their effect on coral reef ecological interactions. However, the effects of such events on parasite-host interactions are largely ignored. Gnathiid isopods are common, highly mobile, external parasites of coral reef fishes, that feed on blood during the juvenile stage. They have direct and indirect impacts on their fish hosts, and are the major food source for cleaner fishes. However, how these interactions might be impacted by increased temperatures is unknown. We examined the effects of acute temperature increases, similar to those observed during mass bleaching events, on survivorship of gnathiid isopod juveniles. Laboratory experiments were conducted using individuals from one species (Gnathia aureamaculosa) from the Great Barrier Reef (GBR), and multiple unknown species from the central Philippines. Fed and unfed GBR gnathiids were held in temperature treatments of 29 • C to 32 • C and fed Philippines gnathiids were held at 28 • C to 36 • C. Gnathiids from both locations showed rapid mortality when held in temperatures 2 • C to 3 • C above average seasonal sea surface temperature (32 • C). This suggests environmental changes in temperature can influence gnathiid survival, which could have significant ecological consequences for host-parasite-cleaner fish interactions during increased temperature events.
... (7)(8)(9)(10), anthropogenic by use of destructive fishing gears (e.g. [5,[10][11]) or natural through, e.g., Crown-of-Thorns starfish infestations [12], storms and cyclones [13][14][15], or bleaching [16][17][18][19][20]). Several fish species are strongly associated with live coral cover (e.g. ...
Overfishing in the Spermonde Archipelago has resulted in long-term changes in fishery composition and structure, as well as in resource utilization patterns. Later on, the patterns of resource use are highly variable, with new activities and new target species, e.g., ornamental corals and intensive coral reef fishery being a relatively recent phenomenon in the area. This research aims at measuring the coral fishes abundance and assemblages in six islands (Kapoposang, Lanyukang, Lumu-Lumu, Badi, Ballang Lompo, and Karanrang), representing off-shore and in-shore of Spermonde Archipelago waters during the occurrence of the 2016 El Nino. Underwater Visual Census (UVC) method was done to measure coral fish abundance, once every seasonal interval, totaling four times for every island, on 70 meter transects covering an area of 350 m2 (2.5 m to the right and left and 5 m above). Fish species found were identified by following several coral fish identification books Data was analyzed for their total species abundance based on the family. Results showed that coral fish abundance by the family was found to be lowest (less than 10.000 individuals/hectare) all through the year in Karanrang Island. The most abundance was found in Lanyukang Island (84.600 individu/hectare) during the month of September, followed by Badi Island (59.971 individu/hectare). In February, fish abundance of 35. 743 and 46.886 individu/hectare were only found in Kapoposang and Badi islands. All in all, on average, Badi island showed for having relatively equal coral fish abundance in all four seasons. One hundred species were found in Lanyukang, while 78 species were found in Lumu-Lumu, totaling 136 species of coral fishes of 28 families. Coral fishes species always found in all trips were 20 species in Lanyukang and 11 species in Lumu-Lumu. Four species always found in both islands were Thalassoma hardwicke, Neoglyphidodon nigroris, Labroides dimidiatus, Cirrhilabrus ryukyuensis. Fishes found most abundance were from Labridae and Pomacentridae families, each of 31 and 30 species. The temporary conclusion was that Lanyukang has more species than Lumu-Lumu.
... Despite a slight reduction in effort in relation to the number of boats since 1991, the CPUE has not shown signs of recovery in the small-scale fisheries ( Figure 5A). The stable low CPUE since 1985 for small-scale sectors could be associated with shifting the targeted demersal species to those previously less exploited or an overall demersal stock depletion (Jennings et al., 1995;SFA, 1996;Nageon and de Lestang, 1998;Spalding and Jarvis, 2002). Since the mid-1980s, fishing effort has steadily increased while CPUE has declined. ...
The adoption of sovereign blue bonds by the Republic of Seychelles, hereafter referred to as Seychelles, focuses on resource sustainability and illustrates options for island countries to use their ocean resources for years into the future. The fishing industry is one of the main pillars of Seychelles’ economy and is of crucial importance for domestic food- and employment-security. In order to promote long-term ecological sustainability and economic viability of domestic fisheries, accurate and long-term baseline information is required. Such baseline data were derived here with a reconstruction of the Seychelles’ domestic fisheries catches and fishing effort within its Exclusive Economic Zone (EEZ) from 1950 to 2017, coupled with resulting Catch Per Unit Effort data (CPUE). The total reconstructed domestic catch was approximately 1.5 times larger than the baseline as reported by the United Nations Food and Agriculture Organization (FAO) on behalf of Seychelles from 1950 to 2017 after adjustment for fully domestic catches within the EEZ. Domestic catches (i.e., excluding the large-scale industrial pelagic catches) increased by over 500% throughout the time period, growing from 1,900 t⋅year⁻¹ in the 1950s to around 11,200 t in 2017. The major targeted taxa were jacks (Carangidae), tuna-like fishes (Scombridae) and snappers (Lutjanidae). Total fishing effort in the form of fishing capacity grew from 21,500 kWdays in 1950 to over 3.4 million kWdays in 2017. The resultant artisanal CPUE displayed a declining trend over time, suggesting a potential decline in relative abundance of fish populations within the Seychelles EEZ or targeted fishing areas.
... Our analysis revealed that the decrease in the density of corallivores and herbivores matched with the decrease in coral cover following mass bleaching, while changes in species richness were not correlated with a coral cover change. Such a short-term decline in corallivores was common in the Great Barrier Reef following the 2016 mass bleaching (Stuart-Smith et al. 2018) and at Ishigaki Island and other sites during the 1998 bleaching event (Kokita and Nakazono 2001;Sano 2004;Shibuno et al. 1999;Spalding and Jarvis 1998), while response of herbivores varied from place to place. As described above, all of the potential stocks (fisheries production, aquarium fish production, recreational diving, and seaweed control by herbivores) decreased following the bleaching. ...
Climate change is projected to have large impacts on natural capital and ecosystem services under scenarios of the IPCC. In the summer of 2016, elevated seawater temperatures triggered mass coral bleaching in Sekisei Lagoon, southern Japan. Based on data from field surveys and relevant websites, we mapped potential stocks of four major ecosystem services (fisheries production, aquarium fish production, recreational diving, and seaweed control) supplied by coral reef fishes before and after the bleaching event and predicted the possible future state of socio-ecological systems in the lagoon under climate change. We also evaluated whether current management options had mitigated the negative effects of extreme heating and coral bleaching on the potential stocks. Before the coral bleaching, the potential stock of recreational diving was estimated as 41.44 billion Japanese yen per year for the entire lagoon, while those of fisheries and aquarium fish productions were 2.10 billion and 15.03 billion yen, respectively. After bleaching, the four potential stocks including seaweed control decreased. The marine park zone and the extermination area of crown of thorns starfish mitigated changes in fish species richness and the value of recreational diving following coral bleaching. Extreme heating and coral bleaching are considered to be representative of a possible future state under global warming, and the results suggest that even management for local disturbances can mitigate the interactive effect of climate change on the potential stocks. Additional integrative management accounting for climate change and local stressors would be necessary for protecting ecosystem services in Sekisei Lagoon.
... Coral cover and species richness are expected to be particularly important in explaining the diversity and abundance of obligate coral-dwelling species (Munday et al. 1997;Munday 2002;Gardiner and Jones 2005) and corallivorous fishes (Bell and Galzin 1984;Kokita and Nakazono 2001;Spalding and Jarvis 2002;Pratchett et al. 2006). In the recent years there have been extensive declines in coral cover on many tropical reefs around the world due to various extreme events, such as frequent severe cyclones, coral bleaching and crown-ofthorns outbreaks (Pandolfi et al. 2005;De'ath et al. 2012;Cheal et al. 2017;Hughes et al. 2017). ...
Habitat characteristics play an important role
in determining the structure of fish communities. The
decline in fish diversity and abundance with the decline
in coral diversity and cover may be explained by habitat
specialisation and partitioning among reef fishes and/or
preferences for particular corals that are susceptible to
disturbance. These preferences may develop at different
life history stages. Here, we investigated patterns of
habitat specialisation and ontogenetic shifts in habitat
preference among 14 co-existing damselfish species at
Lizard Island lagoon on the Great Barrier Reef. Although
live coral cover contributed only 26% of the
substratum, 28% of adults and 57% of new settlers were
mostly found on live coral, indicating a strong preference
for live coral habitat by new settlers. Only a few
species exhibited a high degree of habitat specialisation
and low overlap in habitat use with other species. Specialisation
differed among species and life stages. New
settlers were more commonly associated with finely
branched corymbose corals and using those habitats
with higher frequency than expected based on habitat
availability alone. Adults were more commonly linked
to more open branching morphologies or non-coral
substrata. Our results suggest that habitat loss may not
uniformly impact on all life stages. While adult individuals
may not be as reliant as juveniles on corals, detrimental
effects of habitat loss on juvenile survival may
have longer-term impacts on adult populations. As juveniles
show preferential associations with particular
coral species, such as corymbose corals, the loss of these
growth forms is likely to have the most significant
negative impacts on this critical life history stage.
... Butterflyfishes are highly associated with live coral reefs, as the latter provide food for both, obligate and facultative corallivorous species (Pratchett et al., 2015). Some studies have demonstrated that coral-dependent species are affected early by habitat loss, as many of them migrate or die during and after events that cause reductions in LCC (Russ & Leahy, 2017;Spalding & Jarvis, 2002). For this reason, the reduction of chaetodontids in response to LCC decline has been highlighted as one of the first symptoms of coral reef degradation (Flower et al., 2017). ...
Benthic structure of coral reefs determines the availability of refuges and food sources. Therefore, structural changes caused by natural and anthropogenic disturbances can have negative impacts on reef‐associated communities. During the 1990s, coral reefs from Bahía Culebra were considered among the most diverse ecosystems along the Pacific coast of Costa Rica; however, recently they have undergone severe deterioration as consequence of chronic stressors such as El Niño‐Southern Oscillation and harmful algal blooms. Reef fish populations in this area have also been intensely exploited. This study compared reef fish assemblages during two periods (1995–1996 and 2014–2016), to determine whether they have experienced changes as a result of natural and anthropogenic disturbances. For both periods, benthic composition and reef fish abundance were recorded using underwater visual censuses. Live coral cover (LCC) decreased from 43.09 ± 18.65% in 1995–1996 to 1.25 ± 2.42% in 2014–2016 (U = 36, p < 0.05). Macroalgal cover (%) in 2014–2016 was sixfold higher than mean values reported for the Eastern Tropical Pacific region. Mean (±SD) fish species richness in 1995–1996 (36.67 ± 14.20) was higher than in 2014–2016 (23.00 ± 9.14; U = 20, p < 0.05). Over 40% of reef fish orders observed in 1995–1996 were not detected in the 2014–2016 surveys, including large‐bodied predators. Reduction in abundance of fish predators such as sharks, grunts, and snappers is likely attributed to changes in habitat structure. Herbivorous such as parrotfishes and pufferfishes increased their abundance at sites with low LCC, probably in response to predators decline and increased algal cover. These findings revealed significant degradation and drastic loss of structural complexity in coral reefs from Bahía Culebra, which now are dominated by macroalgae. The large reduction in structural complexity of coral reefs has resulted in the loss of diversity and key ecological roles (e.g., predation and herbivory), thus potentially reducing the resilience of the entire ecosystem.
... In 1998 an El-Nino event coupled with the Indian Ocean Dipole (a similar phenomenon to El Nino but which occurs ahead of El Nino events (Graham et al., 2006), resulted in both the highest seawater temperature anomaly recorded in 50 years and widespread coral mortality worldwide; affecting most severely the reefs of the Indian Ocean (Sheppard et al., 2005). At a regional level, mortality was recorded at 30% (Obura, 2005), with a reduction of live coral cover as much as 80-95% at the most heavily impacted reefs, of which those were amongst the Seychelles (Spencer et al., 2000;Spalding and Jarvis, 2002). Within the inner granitic islands of Seychelles, the 1998 bleaching catastrophe decreased the coral cover to less than 3% in some areas, leaving no depth refuge from coral mortality (Graham et al., 2006. ...
... Within the inner granitic islands of Seychelles, the 1998 bleaching catastrophe decreased the coral cover to less than 3% in some areas, leaving no depth refuge from coral mortality (Graham et al., 2006. Shortly thereafter, a rapid algal-colonization was observed (Spalding and Jarvis, 2002), along with a gradual transformation of the impacted reefs into rubble and algaldominated communities, accompanied by a collapse in the structural complexity (Baker et al., 2008). During the following decade, recovery has been extremely slow in the inner granitic islands of Seychelles (Graham et al., 2006. ...
Coral reef restoration is a subfield within the larger scientific discipline of ecological restoration (also known as
restoration ecology). Ecological restoration is the process of assisting the recovery of an ecosystem that has been
degraded, damaged, or destroyed (SER, 2018).
Coral reef restoration must follow the four basic principles of planning and implementation of ecological restoration
in order to increase sustainable and valuable outcomes (Suding et al. 2015):
1. Restoration increases ecological integrity. Restoration initiates or accelerates recovery of degraded areas
by prioritizing the complexity of biological assemblages, including species composition and representation of all
functional groups, as well as the features and processes needed to sustain these biota and to support ecosystem
function;
2. Restoration is sustainable in the long term. Restoration aims to establish systems that are self-sustaining and
resilient; thus, they must be consistent with their environmental context and landscape setting. Once a restoration
project is complete, the goal should be to minimize human intervention over the long term. When intervention is
required, it should be to simulate natural processes that the landscape no longer provides or to support traditional
practices of local communities;
3. Restoration is informed by the past and future. Historical knowledge, in its many forms, can indicate how
ecosystems functioned in the past and can provide references for identifying potential future trajectories and
measuring functional and compositional success of projects. However, the unprecedented pace and spatial extent
of anthropogenic changes in the present era can create conditions that depart strongly from historical trends. Often,
then, history serves less as a template and more as a guide for determining appropriate restoration goals.
4. Restoration benefits and engages society. Restoration focuses on recovering biodiversity and supporting the
intrinsic value of nature. It also provides a suite of ecosystem services (e.g., improved water quality, fertile and stable
soils, drought and flood buffering, genetic diversity, and carbon sequestration) that enhance human quality of life
(e.g., clean water, food security, enhanced health, and effective governance). Restoration engages people through
direct participation and, thus, increases understanding of ecosystems and their benefits and strengthens human
communities.
We followed the four basic principles of ecological restoration when implementing our coral reef restoration project.
These principles are summarized in a practical decision tool in the next section (Figure 1).
We encourage readers of our Coral Reef Restoration Toolkit to follow the basic principles of ecological restoration
in their own projects. As coral reef restoration scientists and practitioners, we were rewarded with the experience of
bringing back life to a dead coral reef. We hope newcomers to the field of coral reef restoration and those already
with some experience will benefit from reading and implementing our Toolkit, so they are also rewarded with
successful outcomes.
The Reef Rescuers Team
Nature Seychelles, Mahe, Republic of Seychelles
August 2018
... Diversos autores mencionan que posterior a un evento de mortalidad coralina, aproximadamente más del 30 % especies de peces exhiben cambios significativos en su abundancia con un rango de respuesta desde extinciones locales hasta decrementos e incrementos en la abundancia (Booth & Beretta, 2002;Spalding & Jarvis, 2002;Munday, 2004). Correspondiendo con lo anterior, el análisis empleado reveló que más del 46 % de especies en Maguey presentaron decrementos en la abundancia promedio posterior a la perturbación, destacando la ausencia de P. laticlavius, así como el decremento en la abundancia de 11 especies. ...
Coastal development and urbanization have increased the sediments that are washed from the land surface, producing adverse effects on the structure and functioning of coral reefs. The objective of this study was to identify the degree to which excessive sediments have disturbed the fish community in the coral reefs in the Maguey and Violin bays, located in the Huatulco National Park (Mexico). Fish samples were collected before and after disturbances produced by sediments associated with coastal development projects. Indicators of changes in the fish communities included the number and diversity of species as well as equity and dominance before and after the disturbances. The analysis was performed through means comparison tests, similarity analysis (ANOSIM) and similarity percentage analysis (SIMPER). In both locations, it was observed that the diversity, evenness, abundance and number of species were higher prior to the disturbance, but not for dominance, which shows an inverse pattern. In Maguey, significant differences in evenness and dominance were observed (U = 28, p = 0.0401; U = 24, p = 0.0472), as well as in species composition and abundance (ANOSIM = 0.35, p = 0.009). The similarity percentage analysis (SIMPER) indicated that after the disturbance, more than 46 % of the species showed decreases in average abundance, highlighting the absence of Prionurus laticlavius, as well as the decrease in abundance of: P. punctatus, Cirrhitichthys oxycephalus, Microspathodon dorsalis, Lutjanus novemfaciatus and Stegates acapulcoensis. Inadequate planning and implementation of coastal development projects that contribute to the discharge of excessive sediments into the sea were determinants of negative changes in the coral communities in Maguey and Violin, whose effects could be seen in the composition of the species and the abundance, equity, and dominance of the fish community in Maguey.
... damselfishes, often exhibit pro- nounced decreases in abundance in response to bleaching and or habitat loss, a phenomenon that has been repeatedly documented across multiple spatial scales (e.g. Bellwood et al., 2006;Booth and Beretta, 2002;Ceccarelli et al., 2016;Halford et al., 2004;Jones et al., 2004;Pratchett et al., 2008a;Spalding and Jarvis, 2002;Wilson et al., 2008). Our results support this general pattern, yet they raise questions about our assumptions regarding the basis of this decline. ...
... Hence, short-term post-bleaching changes in the assemblages of reef fishes are often restricted to coral-dependent species (e.g. Riegl, 2002;Shibuno et al., 1999;Spalding and Jarvis, 2002). However, over time, dead coral skeletons are eroded by biological and physical agents. ...
Record-breaking temperatures between 2015 and 2016 led to unprecedented pan-tropical bleaching of scleractinian corals. On the Great Barrier Reef (GBR), the effects were most pronounced in the remote, northern region, where over 90% of reefs exhibited bleaching. Mass bleaching that results in widespread coral mortality represents a major disturbance event for reef organisms, including reef fishes. Using 133 replicate 1 m2 quadrats, we quantified short-term changes in coral communities and spatially associated reef fish assemblages, at Lizard Island, Australia, in response to the 2016 mass bleaching event. Quadrats were spatially matched, permitting repeated sampling of fish and corals in the same areas: before, during and 6 months after mass bleaching. As expected, we documented a significant decrease in live coral cover. Subsequent decreases in fish abundance were primarily driven by coral-associated damselfishes. However, these losses, were relatively minor (37% decrease), especially compared to the magnitude of Acropora loss (>95% relative decrease). Furthermore, at a local, 1 m2 scale, we documented a strong spatial mismatch between fish and coral loss. Post-bleaching fish losses were not highest in quadrats that experienced the greatest loss of live coral. Nor were fish losses associated with a proliferation of cyanobacteria. Several sites did, however, exhibit increases in fish abundance suggesting substantial spatial movements. These results challenge common assumptions and emphasize the need for caution when ascribing causality to observed patterns of fish loss at larger spatial scales. Our results highlight the potential for short-term resilience to climate change, in fishes, through local migration and habitat plasticity.
