Christmas Island sits about as close to the middle of the Pacific as you can get. The main island of Kiribati, a small island nation, is 3,300 miles from San Francisco, 3,800 miles from Brisbane and just 140 miles north of the equator. Its closest neighbor of note is Hawaii, which is still 1,250 miles away.
Some might say it’s as close to the middle of nowhere as you can get. But it’s at the center of one of the biggest climate events in decades. A super El Niño has raised water temperatures to unprecedented levels and it’s causing a massive coral die off.
Researchers are racing to track the impacts the warming is having on coral as well as what happens to the reefs when the waters cool. The work has implications well beyond an island in the middle of nowhere. How coral respond to this year’s El Niño offers a preview of what the rest of the world’s coral will face as the world continues to warm.
Bivalve borings, bioclaustrations and symbiosis in corals from the Upper Cretaceous (Cenomanian) of southern Israel
Authors:
Wilson et al
Abstract:
Specimens of the small compound coral Aspidiscus cristatus (Lamarck, 1801) containing evidence of symbiosis with bivalves have been found in the En Yorqe'am Formation (Upper Cretaceous, early Cenomanian) of southern Israel. The corals have paired holes on their upper surfaces leading to a common chamber below, forming the trace fossil Gastrochaenolites ampullatus Kelly and Bromley, 1984. Apparently gastrochaenid bivalve larvae settled on living coral surfaces and began to bore into the underlying aragonitic skeletons. The corals added new skeleton around the paired siphonal tubes of the invading bivalves, eventually producing crypts that were borings at their bases and bioclaustrations at their openings. When a boring bivalve died its crypt was closed by the growing coral, entombing the bivalve shell in place. This is early evidence of a symbiotic relationship between scleractinian corals and boring bivalves (parasitism in this case), and the earliest record of bivalve infestation of a member of the Suborder Microsolenina. It is also the earliest occurrence of G. ampullatus.
Persistence and Change in Community Composition of Reef Corals through Present, Past, and Future Climates
Authors:
Edmunds et al
Abstract:
The reduction in coral cover on many contemporary tropical reefs suggests a different set of coral community assemblages will dominate future reefs. To evaluate the capacity of reef corals to persist over various time scales, we examined coral community dynamics in contemporary, fossil, and simulated future coral reef ecosystems. Based on studies between 1987 and 2012 at two locations in the Caribbean, and between 1981 and 2013 at five locations in the Indo-Pacific, we show that many coral genera declined in abundance, some showed no change in abundance, and a few coral genera increased in abundance. Whether the abundance of a genus declined, increased, or was conserved, was independent of coral family. An analysis of fossil-reef communities in the Caribbean revealed changes in numerical dominance and relative abundances of coral genera, and demonstrated that neither dominance nor taxon was associated with persistence. As coral family was a poor predictor of performance on contemporary reefs, a trait-based, dynamic, multi-patch model was developed to explore the phenotypic basis of ecological performance in a warmer future. Sensitivity analyses revealed that upon exposure to thermal stress, thermal tolerance, growth rate, and longevity were the most important predictors of coral persistence. Together, our results underscore the high variation in the rates and direction of change in coral abundances on contemporary and fossil reefs. Given this variation, it remains possible that coral reefs will be populated by a subset of the present coral fauna in a future that is warmer than the recent past.
Equatorial Pacific coral geochemical records show recent weakening of the Walker Circulation
Authors:
Carilli et al
Abstract:
Equatorial Pacific ocean-atmosphere interactions affect climate globally, and a key component of the coupled system is the Walker Circulation, which is driven by sea surface temperature (SST) gradients across the equatorial Pacific. There is conflicting evidence as to whether the SST gradient and Walker Circulation have strengthened or weakened over the late 20th century. We present new records of SST and sea surface salinity (SSS) spanning 1959-2010 based on paired measurements of Sr/Ca and δ18O in a massive Porites coral from Butaritari atoll in the Gilbert Islands, Republic of Kiribati, in the central-western equatorial Pacific. The records show 2-7 year variability correlated with the El Niño-Southern Oscillation (ENSO) and corresponding shifts in the extent of the Indo-Pacific Warm Pool, and decadal-scale signals related to the Pacific Decadal Oscillation. In addition, the Butaritari coral records reveal a small but significant increase in SST (0.39 °C) from 1959 to 2010 with no accompanying change in SSS, a trend that persists even when ENSO variability is removed. In contrast, larger increases in SST and SSS are evident in coral records from the equatorial Pacific Line Islands, located east of Butaritari. Taken together, the equatorial Pacific coral records suggest an overall reduction in the east-west SST and SSS gradient over the last several decades, and a recent weakening of the Walker Circulation.
Late-summer water temperatures near the Florida Keys were warmer by nearly 2 degrees Fahrenheit in the last several decades compared to a century earlier, according to a new study by the U.S. Geological Survey.
Researchers indicate that the warmer water temperatures are stressing corals and increasing the number of bleaching events, where corals become white resulting from a loss of their symbiotic algae. The corals can starve to death if the condition is prolonged.
"Our analysis shows that corals in the study areas are now regularly experiencing temperatures above 84 F during July, August and September; average temperatures that were seldom reached 120 years ago," said Ilsa Kuffner, a USGS research marine biologist and the study's lead author. "When corals are exposed to water temperatures above 84 F they grow more slowly and, during extended exposure periods, can stop growing altogether or die."
The new analysis compares water temperatures during two time periods a century apart at two of Florida's historic offshore lighthouses – Fowey Rocks Lighthouse, off Miami, and Carysfort Reef Lighthouse, off Key Largo, Florida. The first period included data from 1879 to 1912, while the second period spanned from 1991 to 2012. Temperatures at a third area, a reef off Islamorada, Florida, were also monitored from 1975 to 2007.
"What's interesting is that the temperature increase observed during this recent 32-year period was as large as that measured at the lighthouses spanning 120 years," said Kuffner. "This makes it likely the warming observed at the lighthouses has actually occurred since the 1970s."
The study indicates that August is consistently the month when Florida's ocean temperatures peak. In the analysis of recent decades, average temperatures for August have been at or very close to 86 F. At Fowey Lighthouse from 1879 to 1912, the average August temperature was just 84.2 F. Temperatures this August at the same location, though not included in the study, averaged 87 F.
As the minibus wobbles over the dusty, pothole-filled road that runs the length of South Tarawa island, a song blasting over Kiribati's state radio envisions an apocalypse for this fishhook-shaped atoll halfway between Honolulu and Fiji: “The angry sea will kill us all.”
The song, which won a competition organized by Kiribati's government, reflects the views of President Anote Tong, who has been warning for years of a knockout punch from climate change. In an interview with CNN in June, Tong insisted that rising sea levels due to global warming will mean “total annihilation” for this nation of 33 coral islands spread over a swath of the Central Pacific the size of India, and for other atoll island nations like Tuvalu and the Maldives. In May, Tong announced that Kiribati had spent $8.7 million to buy 22 square kilometers of land on Vanua Levu in Fiji as a haven for displaced citizens, cementing his nation's global reputation as an early victim of climate change.
Many scientists quietly demur.
No doubt, the sea is coming: In a 2013 report, the U.N. Intergovernmental Panel on Climate Change predicted that global sea levels will rise up to 1 meter by 2100. But recent geologic studies suggest that the coral reefs supporting sandy atoll islands will grow and rise in tandem with the sea. The only islanders who will have to move must do so for the same reason as millions of people on the continents: because they live too close to shore.
Pacific-wide contrast highlights resistance of reef calcifiers to ocean acidification
Authors:
Comeau et al
Abstract:
Ocean acidification (OA) and its associated decline in calcium carbonate saturation states is one of the major threats that tropical coral reefs face this century. Previous studies of the effect of OA on coral reef calcifiers have described a wide variety of outcomes for studies using comparable partial pressure of CO2 (pCO2) ranges, suggesting that key questions remain unresolved. One unresolved hypothesis posits that heterogeneity in the response of reef calcifiers to high pCO2 is a result of regional-scale variation in the responses to OA. To test this hypothesis, we incubated two coral taxa (Pocillopora damicornis and massive Porites) and two calcified algae (Porolithon onkodes and Halimeda macroloba) under 400, 700 and 1000 μatm pCO2 levels in experiments in Moorea (French Polynesia), Hawaii (USA) and Okinawa (Japan), where environmental conditions differ. Both corals and H. macroloba were insensitive to OA at all three locations, while the effects of OA on P. onkodes were location-specific. In Moorea and Hawaii, calcification of P. onkodes was depressed by high pCO2, but for specimens in Okinawa, there was no effect of OA. Using a study of large geographical scale, we show that resistance to OA of some reef species is a constitutive character expressed across the Pacific.
Biogeochemical and redox record of mid-late Triassic reef evolution in the Italian Dolomites
Authors:
Tosti et al
Abstract:
Geochemical signatures and carbonate microfacies highlight contrasts between two distinctive mid-late Triassic reef communities in the Dolomite Alps, Italy. In the first community, sponges, bryozoans, calcified cyanobacteria and problematic organisms (Archaeolithoporella, Shamovella), together with a variety of micritic fabrics, formed compact reefs in high energy shallow-water at the margins of high-rise Ladinian-Carnian carbonate platforms. Debris from these margins created steep foreslopes, and some large blocks of the allochthonous material (Wengen-Cassian formations, Cipit Boulders) were buried in basinal shales that protected them from subsequent alteration and regional dolomitization. In the second and slightly younger community, small Carnian patch reefs (Heiligkreuz Formation, Alpe di Specie) developed in quieter shallow water, where they too were protected against alteration by enclosing shales. They were constructed mainly by scleractinian corals, sponges and red algae, and contain relatively large framework cavities with clotted-peloidal micrite. These early examples of coralgal reefs have broad similarities to present-day examples, whereas the community represented by the Cipit Boulders has more in common with Late Permian reefs.
Both bioconstructions preserve primary microfabrics and biomarkers. The Cipit Boulder samples contain bacterial, mainly cyanobacterial biomarkers, lack specific molecules typical of sulfate-reducing bacteria (SRB), and have Rare Earth Element (REE) values indicative of oxic conditions. These signatures are consistent with their original high-energy platform margin location, compact structure, and presence of calcified cyanobacteria such as Cladogirvanella and Girvanella. In contrast, the coralgal patch reefs contain SRB biomarkers, lack specific molecules typical of cyanobacteria, and have REE values indicative of sub-oxic conditions. These signatures are consistent with their lower energy depositional conditions and well-developed skeletal framework that created protected low-oxygen micro-habitats. The SRB biomarkers can be linked to the associated clotted-peloidal fabrics which resemble those commonly present in younger coral-reef frameworks. These details of redox conditions and bacterial processes underscore the important biotic, structural and environmental changes that affected shallow marine reefs during the Triassic.
Cryptic coral-crinoid "hanging gardens" from the Middle Devonian of southern Morocco
Authors:
Jakubowicz et al
Abstract:
An unusual and exceptionally well preserved cryptic community of cnidarians, crinoids, sponges, and microbes developed in a submarine cavity of Middle Devonian age in the Hamar Laghdad area (Morocco). The biota encrusted the cavity roof and grew predominantly in an upside-down position, forming spectacular "hanging gardens." The investigated assemblage differs strikingly from both its Paleozoic and modern analogues; it constitutes one of a very few known examples of fossil cryptic assemblages developed in relatively deep water settings, and is the first report of a cryptic paleoecosystem dominated by rugose corals. The results support the view that during the middle Paleozoic there was no distinct polarization between open-surface and cryptic faunas in deep-water environments, but keen competition for space already existed in Devonian cryptic assemblages. The regional species pool seems to have been the main determinant of the ecological succession and structure of this cryptic community.
The Rugosa-Scleractinia gap re-examined through microstructural and biochemical evidence: a tribute to H.C. Wang
Author:
Jean-Pierre Cuif
Abstract:
More than sixty years ago, H.C. Wang carried out an extensive study of skeletal microstructures of the Paleozoic corals and concluded that a “direct descent” may have existed between the two coral suborders: the Paleozoic Rugosa and the younger Scleractinia that had been established as distinct phyla by Haeckel (1896). Skeletal microstructures and three-dimensional reconstructions of walls and septa have revealed remarkable similarities between some Permian and Triassic corals, but it is only during the recent years that significant relationships were established between the structural properties of coral skeletons and their control by the biological process. Supported by recent genetic studies of calcareous biomineralization among various invertebrate phyla, the Wang's opinion now appears a reasonable working hypothesis.
Many ancient crustaceans went extinct following a massive collapse of reefs across the planet, and new University of Florida research suggests modern species living in rapidly declining reef habitats may now be at risk.
Available online and scheduled to appear in the November issue of Geology, the study shows a direct correlation between the amount of prehistoric reefs and the number of decapod crustaceans, a group that includes shrimp, crab and lobster. The decline of modern reefs due to natural and human-influenced changes also could be detrimental, causing a probable decrease in the biodiversity of crustaceans, which serve as a vital food source for humans and marine animals such as fish, said lead author Adiël Klompmaker, a postdoctoral researcher at the Florida Museum of Natural History on the UF campus who started the study at Kent State University.
“We estimate that earth’s decapod crustacean species biodiversity plummeted by more than 50 percent during a sharp decline of reefs nearly 150 million years ago, which was marked by the extinction of 80 percent of crabs,” Klompmaker said. “If reefs continue to decline at the current rate during this century, then a few thousand species of decapods are in real danger. They may adapt to a new environment without reefs, migrate to entirely new environments or, more likely, go extinct.”
Some scientists predict as much as 20 percent of the world’s reefs may collapse within 40 years, with a much higher percentage affected by the end of the century due to natural and human-influenced changes such as ocean acidification, diseases and coral bleaching.
The study is the first comprehensive examination of the rise of decapod crustaceans in the fossil record. Researchers created a database of fossils from the Mesozoic Era, 252 million to 66 million years ago, from literature records based on museum specimens worldwide. The data included 110 families, 378 genera and 1,298 species. They examined the patterns of diversity and found an increase in the number of decapod species was influenced by the abundance of reefs, largely due to the role of reefs as a provider of shelter and foraging. Researchers call this period the “Mesozoic decapod revolution” because of the 300-fold increase in species diversity compared with the previous period and the appearance and rapid evolution of crabs.
Compiling information about crustaceans on this scale has historically been a challenge for researchers because most decapods possess a fragile and weakly calcified exoskeleton that does not fossilize well.
“Only a scant fraction of decapod crustaceans is preserved in rocks, so their fossil record is limited,” said study co-author Michal Kowalewski, curator of invertebrate paleontology at the Florida Museum. “But, thanks to efforts of paleontologists many of those rare fossils have been documented all around the world, finally giving us a chance to look at their evolutionary history in a more rigorous, quantitative way.”
“This new work builds a good case for the role of reefs in promoting the evolutionary diversification of crustaceans,” said David Jablonski, a paleontologist in the department of geophysical sciences at the University of Chicago who was not involved in the study. “We have to take their argument for the flipside of that story very seriously. The positive relation between reefs and crustaceans implies that the damage caused to reefs by human activities — from overfishing to ocean acidification — is likely to have cascading consequences for associated groups, including crustaceans.”
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Upper Triassic Corals from Nevada, Western North America, and the Implications for Paleoecology and Paleogeography
Authors:
1. Ewa Roniewicz (a)
2. George D. Stanley, Jr. (b)
Affiliations:
a. Institute of Paleobiology, Polish Academy of Sciences, Twarda 51/55, 00–818 Warszawa, Poland, < eron.twarda@pan.pl>
b. The University of Montana Paleontology Center, Missoula MT 59812, USA, < george.stanley@umontana.edu>
Abstract:
Late Carnian–early Norian corals from the Luning and Osobb formations in west-central Nevada represent an important Late Triassic fauna for understanding the paleoecology and the paleogeography of the eastern Panthalassa region during Late Triassic time. The corals occur in bedded limestone representing biostromes and patch reefs and their composition presages the important global changeover of faunas of the intra-Norian interval. A taxonomic analysis of over 60 specimens reveals a majority of colonial corals ranging from cerioid, astreoid (i.e., cerioid-plocoid lacking walls), meandroid and thamnasterioid types. Surprisingly, remnants of the original aragonite microstructure remain in some specimens, allowing a better comparison with more remote Tethyan corals. In total, 14 genera have been identified from Nevada while two genera remain undetermined. The fauna is composed of species considered typical of both the North American Cordillera and cratonal South America. The following genera and species are new and endemic to the Americas: Khytrastrea silberlingi and K. cuifiamorpha, Flexastrea serialis, Nevadoseris punctata, Areaseris nevadaensis and a new genus Minasteria (with Astrocoenia shastensis Smith, 1927 as type species). Likewise are the new species: Margarogyra silberlingi and Curtoseris dunlapcanyonae. Genera Meandrovolzeia, Margarogyra, Ceriostella, Ampakabastraea, Retiophyllia, Distichomeandra, Curtoseris, Thamnasteria and Astraeomorpha provide important links to the former Tethys province. The revised coral fauna changes previous views of the close taxonomic similarity with the Tethys, instead producing a paleogeographic pattern emphasizing a much greater degree of endemism. This pattern emphasizes the isolation of Nevada from the Tethys and the similarities with some outboard terranes of the Cordillera.
