► Prevalence of Symbiodinium clade C3 in heat stress tolerant corals from Abu Dhabi. ► Heat stress regulation of green fluorescent protein (GFP)-like coral pigments. ► Stability of coral-algal ...symbiosis in Porites lobata. ► Thorough characterisation of P. lobata from the Arabian/Persian Gulf. ► Natural growth rates of Gulf corals in successful laboratory cultures.
Corals in the Arabian/Persian Gulf endure summer temperatures of up to 36°C, making them ideal subjects to study the mechanisms underlying thermal tolerance. Unexpectedly, we found the “generalist” Symbiodinium clade C3 to be the prevalent symbiont among seven coral species from Abu Dhabi (UAE) waters. Moreover, C3 represented the only dominant symbiont type in Porites spp. from this region. The “thermotolerant” symbionts D1a and C15 were not encountered, indicating that the association with these symbionts cannot be the sole reason for the heat tolerance of Gulf corals. The association of Porites lobata with specific symbiont types (C3 vs. C15) in samples from habitats with very different temperature regimes (Abu Dhabi vs. Fiji) remained unaffected by laboratory culture. During temperature stress experiments specimens from both locations strongly downregulated green fluorescent protein (GFP)-like pigments. However, the Abu Dhabi samples were less prone to bleaching and showed lower mortality.
Coral reefs are one of the most biodiverse and economically important ecosystems in the world, but they are rapidly degrading due to the effects of global climate change and local anthropogenic ...stressors. Reef scientists are increasingly studying coral reefs that occur in marginal and extreme environments to understand how organisms respond to, and cope with, environmental stress, and to gain insight into how reef organisms may acclimate or adapt to future environmental change. To date, there have been more than 860 publications describing the biology and/or abiotic conditions of marginal and extreme reef environments, most of which were published within the past decade. These include systems characterized by unusually high, low, and/or variable temperatures (intertidal, lagoonal, high-latitude areas, and shallow seas), turbid or urban environments, acidified habitats, and mesophotic depth, and focus on reefs geographically spread throughout most of the tropics. The papers in this special issue of Coral Reefs, entitled
Coral Reefs in a Changing World: Insights from Extremes
, build on the growing body of literature on these unique and important ecosystems, providing a deeper understanding of the patterns and processes governing life in marginal reef systems, and the implications that these insights may have for the future of tropical coral reefs in our rapidly changing world.
The findings in this paper show that Arabian Gulf (Abu Dhabi, Dubai, Sharjah) corals have already been measurably affected by climate change and further negative impacts are expected. Corals in South ...Africa have been only weakly impacted and are expected to persist in this likely refuge. The Arabian Gulf has recently experienced high-frequency recurrences of temperature-related bleaching (1996, 1998, 2002). First evidence may suggest that bleaching patterns in corals changed due to phenotypic adaptation after two strong bleaching events in rapid succession, because Acropora, which during the 1996 and 1998 events always bleached first and suffered heaviest mortality, bleached less than all other corals in 2002 at Sir Abu Nuair and recovered at Jebel Ali and Ras Hasyan. In South Africa, reef corals largely escaped the mass mortalities observed across the tropics in the late 1990s, although bleaching has also increased since 1999. These reefs are protected by local small-scale upwelling events in summer that, if they occur at the right time, keep temperatures below bleaching levels. Both areas, the Arabian Gulf and South Africa, have rich coral faunas but little to no recent reef-framework production. It is possible that many reefs worldwide may have similar dynamics in the future, if the changed climate (recurrence of temperature anomalies, changes in aragonite saturation state, etc.) suppresses sustained reef building at least temporarily. Global climate models predict the possibility of significant environmental changes, including increases in atmospheric temperature, sea-surface temperature (SST), and sea level. Monsoon and El Niño Southeastern Oscillation (ENSO) patterns might change, but climate models are not conclusive. Sea-level rise by up to 0.88 m is expected to be a problem in some low-lying areas, like the southern Arabian Gulf. Ocean aragonite saturation state is predicted to fall throughout the ocean but may not change reef dynamics in the two study areas.PUBLICATION ABSTRACT
Between May and August 1996 and 1998, sea-surface temperatures in the southern Arabian Gulf were elevated by 2 degrees C above average. It appears that even though much of the coral was dead, the ...maintenance of structural complexity allowed the fish assemblage to avoid a similar catastrophic change to that experienced by the coral assemblage.
High-elevation neotropical environments of the Andes include the Páramo, a biodiversity hotspot with fast speciation rates. The genus
Espeletia
is distinctive of this ecosystem in the northern Andes. ...Its southern distribution limit lies in Ecuador, with the endemic
E
.
pycnophylla
subsp.
llanganatensis
being the only known representative south of the equator. This study presents the distribution, population structure and co-occurring flora of the subspecies
llanganatensi
s in the Valle de los Frailejones (VFL), Cordillera de los Llanganates. Four clusters totalling ~ 20 ha could be identified at elevations of 3400–3550 m above sea level.
Espelatia
pycnophylla
subsp.
llanganatensis
occurred amidst the sub-Páramo upper elevational limits of montane forests and within transitional areas between forest margins and waterlogged terrains. This habitat preference was a distinguishing ecological difference to the nearest (200 km) congener,
E. pycnophylla
subsp.
angelensis
. Plants (
N
= 781 measured) were skewed towards the smallest size classes ≤ 20 cm (28% of the population, including 17% recruits ≤ 10 cm) and reaching a total plant height of 900 cm. Synflorescences were observed in specimens ≥ 110 cm and in 51% of the mature population. The oldest specimens grew on terrains with higher edaphic stability. While local recruitment appears healthy, geographic distribution is limited suggesting vulnerability to local extinction. Co-occurring vegetation encompassed ~ 70 species, with grasses (Poaceae) and mosses (Bryophyta) dominating the ground cover, resulting in homogenous vegetation. Although
E. pycnophylla
subsp.
llanganatensis
is currently not exposed to direct human disturbance, clandestine mining activities intruding the region pose a potential threat to the survival of this Ecuadorian endemic.
The sedimentary footprint of the 1982/83 ENSO event in the Galapagos was investigated. While coral biomass has been greatly reduced, and so far not recovered, carbonate mass has been transferred from ...a coral framework to a rubble bed, which has allowed a great increase in coralline algal biomass due to new substratum availability. Hence, environmentally triggered attening of coral frameworks has lead to the formation of rhodolith beds within a short time frame emphasizing the high temporal variability in carbonate budgets of shallow marine systems
Predicted increases in seawater temperatures accelerate coral reef decline due to mortality by heat-driven coral bleaching. Alteration of the natural nutrient environment of reef corals reduces ...tolerance of corals to heat and light stress and thus will exacerbate impacts of global warming on reefs. Still, many reefs demonstrate remarkable regeneration from past stress events. This paper investigates the effects of sea surface temperature (SST) and water column productivity on recovery of coral reefs. In 71 Indo-Pacific sites, coral cover changes over the past 1-3 decades correlated negative-exponentially with mean SST, chlorophyll a, and SST rise. At six monitoring sites (Persian/Arabian Gulf, Red Sea, northern and southern Galápagos, Easter Island, Panama), over half of all corals were <31 years, implying that measured environmental variables indeed shaped populations and community. An Indo-Pacific-wide model suggests reefs in the northwest and central Indian Ocean, as well as the central west Pacific, are at highest risk of degradation, and those at high latitudes the least. The model pinpoints regions where coral reefs presently have the best chances for survival. However, reefs best buffered against temperature and nutrient effects are those that current studies suggest to be most at peril from future ocean acidification.
Discovery of a late Pleistocene (∼13,300 cal BP) reef-building coral species (Pocillopora damicornis) at the prehistoric Huaca Prieta settlement in Peru raises the question of its origin. Did it ...arrive in northern Peru from tropical Ecuador via larval dispersal in south-flowing El Niño currents or over land by human trading? The Holocene distribution of Pocillopora in the eastern Pacific extends as far south as southern Ecuador and possibly northern Peru. The marine climate during the late Pleistocene was cooler and likely limited the occurrence of corals at today’s latitudinal range. This suggests that overland or onshore transport was the most likely means of a southerly introduction, thus supporting interpretative models of early human movement along the Pacific coast of South America.
This paper investigates the refuge potential of (1) upwelling areas, (2) coral areas at medium depth, and (3) offshore bank and island reefs in a scenario of increased global warming, and thus ...increased sea surface temperature (SST) and increased solar UV radiation. (1) Observations on coral health and water temperature in the subtropical Atlantic (Eleuthera and Cat Island, Bahamas) and Indian Ocean (Sodwana Bay, South Africa) suggest a link between cool water delivered by upwelling and coral health. After the 1998 bleaching event, caused by strong SST anomalies, coral health and recovery from the previous year's bleaching was significantly better on the narrow southern Cat Island shelf (70% of corals healthy) where the presence of cold water was observed, which was attributed to small-scale upwelling, than on the wide northern Eleuthera shelf (44% of corals healthy), where downwelling of hot bank waters was believed to have damaged corals. In South Africa, regular, short-term upwelling events in five summers reduced SST to well below bleaching level. (2) In the northern Red Sea (Safaga Bay) and in South Africa (Sodwana Bay), wide areas with either coral frameworks or non-framework communities exist. Calculations show that if the top 10 m (20 m) of the ocean became inhospitable to corals, still 50.4% (17.5%) of the coral area would remain intact in the Red Sea and 99% (40%) in South Africa. (3) Offshore bank and island reefs investigated in the Turks, Caicos, and Mouchoir Banks and Grand and Little Cayman showed high rates of mortality and coral diseases. The most remote sites (Mouchoir Bank) were not the healthiest. Refuge areas appear to exist in (1) and (2), but in (3) only if vigorous water-circulation is encountered.PUBLICATION ABSTRACT
In an eastern-Pacific coral assemblage at Devil’s Crown, Galápagos Islands, Ecuador, two coral species,
Psammocora stellata
and
Cycloseris
(
Diaseris
)
distorta
, form dense populations of unattached ...colonies on sand and rubble substrata. In the Galápagos, living
C
. (
D
.)
distorta
is found only at this single site, whereas populations of
P. stellata
are found throughout the Archipelago. Six cores dating to ~ 7700 yBP showed
P. stellata
to be dominant throughout the history of this isolated community, but
C
. (
D
.)
distorta
increased in abundance from ~ 2200 yBP and reached peak abundance between 1471 yBP and the present. The relative frequency of the two coral species may be linked to millennial-scale climatic variability, and this site may represent a refuge for
C.
(
D
.)
distorta
from unfavorable climatic fluctuations on millennial timescales. Our results demonstrate that some corals can persist in isolated populations for millennia.
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