Manuel Aranda, Michael K DeSalvo, Till Bayer, Monica Medina and Christian R Voolstra. BMC Genomics 2012, 13:501 doi:10.1186/1471-2164-13-501
Coral reefs belong to the most ecologically and economically important ecosystems on our planet. Yet, they are under steady decline worldwide due to rising sea surface temperatures, disease, and pollution. Understanding the molecular impact of these stressors on different coral species is imperative in order to predict how coral populations will respond to this continued disturbance. The use of molecular tools such as microarrays has provided deep insight into the molecular stress response of corals. Here, we have performed comparative genomic hybridizations (CGH) with different coral species to an Acropora palmatamicroarray platform containing 13,546 cDNA clones in order to identify potentially rapidly evolving genes and to determine the suitability of existing microarray platforms for use in gene expression studies (via heterologous hybridization).
Our results showed that the current microarray platform for A. palmata is able to provide biological relevant information for a wide variety of coral species covering both the complex clade as well the robust clade. Analysis of the fraction of highly diverged genes showed a significantly higher amount of genes without annotation corroborating previous findings that point towards a higher rate of divergence for taxonomically restricted genes. Among the genes with annotation, we found many mitochondrial genes to be highly diverged in M. faveolata when compared to A. palmata, while the majority of nuclear encoded genes maintained an average divergence rate.
The use of present microarray platforms for transcriptional analyses in different coral species will greatly enhance the understanding of the molecular basis of stress and health and highlight evolutionary differences between scleractinian coral species. On a genomic basis, we show that cDNA arrays can be used to identify patterns of divergence. Mitochondrion-encoded genes seem to have diverged faster than nuclear encoded genes in robust corals. Accordingly, this needs to be taken into account when using mitochondrial markers for scleractinian phylogenies.
Jörg Wiedenmann, Cecilia D’Angelo, Edward G. Smith, et al. Nature Climate Change (2012) doi:10.1038/nclimate1661
Mass coral bleaching, resulting from the breakdown of coral–algal symbiosis has been identified as the most severe threat to coral reef survival on a global scale1. Regionally, nutrient enrichment of reef waters is often associated with a significant loss of coral cover and diversity2. Recently, increased dissolved inorganic nitrogen concentrations have been linked to a reduction of the temperature threshold of coral bleaching3, a phenomenon for which no mechanistic explanation is available. Here we show that increased levels of dissolved inorganic nitrogen in combination with limited phosphate concentrations result in an increased susceptibility of corals to temperature- and light-induced bleaching. Mass spectrometric analyses of the algal lipidome revealed a marked accumulation of sulpholipids under these conditions. Together with increased phosphatase activities, this change indicates that the imbalanced supply of dissolved inorganic nitrogen results in phosphate starvation of the symbiotic algae. Based on these findings we introduce a conceptual model that links unfavourable ratios of dissolved inorganic nutrients in the water column with established mechanisms of coral bleaching. Notably, this model improves the understanding of the detrimental effects of coastal nutrient enrichment on coral reefs, which is urgently required to support knowledge-based management strategies to mitigate the effects of climate change. Read more
A recent report on coral loss from the Great Barrier Reef has pointed the finger at cyclones and Crown of Thorns starfish. The real culprit is human activity, and until we reduce port activity and pollution, coral will be unable to bounce back.
Last year, another report claimed the declines were more modest and the result of a natural cycle. But the latest report, from the Australian Institute of Marine Science, confirms earlier studies – the Great Barrier Reef is in trouble.
Corals are the backbone of the reef, providing habitat for many other species. Measuring coral cover on a reef is the simplest way to monitor its condition. But other metrics – like counts of sharks, dugongs and turtles – also show alarming downward trajectories. The decline in coral cover highlights UNESCO’s concerns about the dwindling Universal Heritage Values of the Barrier Reef. Read more
ScienceDaily (Sep. 28, 2012) — Soft horns and a tinkling piano form the backbone of “Fifty Degrees North, Four Degrees West,” a jazz number with two interesting twists: it has no composer and no actual musicians. Unless you count bacteria and other tiny microbes, that is.
The song is the brainchild of Peter Larsen, a biologist at the U.S. Department of Energy’s Argonne National Laboratory. Larsen, it turns out, has no musical training at all; his interests run less towards the blues and more towards blue-green algae.
When faced with an avalanche of microbial data collected from samples taken from the western English Channel, Larsen recognized he needed a way to make sense of it all. “Thinking of interesting ways to highlight interactions within data is part of my daily job,” he said. “I am always trying to find new ways to visualize those relationships in ways so that someone can make relevant biological conclusions.”
Listen to examples of microbial bebop: http://www.bio.anl.gov/microbialbebop.htm
In the case of the western English Channel data, however, Larsen decided that a visual representation of the data would not be as effective as one he could hear. Read more
ScienceDaily (Oct. 3, 2012) — Coral reefs — ecosystems of incredible environmental and economic value — are showing evidence of significant degradation, but do not have to be doomed. We can make a difference.
Once plentiful, coral reefs worldwide and locally have been ravaged by a number of stresses, including global threats like rising sea temperatures and ocean acidification, and local threats like pollution, overfishing and coastal development. An estimated 25-30 percent of the world’s coral reefs are already severely degraded or lost, and another very high percentage are in danger of greater impact or worse. Some even predict reefs could be essentially wiped out within a human generation unless action is taken.
The coral reef issue is not only an environmental problem, but an economic one. The United Nations estimates globally, coral reefs generate over $172 billion per year from the services they provide including tourism, recreation and fisheries. In South Florida alone, where 84 percent of the nation’s reefs are located, reef ecosystems have been shown to generate over $6 billion in annual economic contributions and more than 71,000 jobs.
In July, hundreds of scientists joined in a consensus statement written at the recently held 12th International Coral Reef Symposium in Cairns Australia, stating: “Across the globe, these problems cause a loss of reef resources of enormous economic and cultural value. A concerted effort to preserve reefs for the future demands action at global levels, but also will benefit hugely from continued local protection.”
By Juliet Eilperin, Published: October 1, 2012. Washington Post
The sobering findings highlighted how even the world’s most protected marine areas are under assault from natural forces and causes linked to the human activity that is resulting in climate change. The Great Barrier Reef is the world’s largest coral reef ecosystem, featuring nearly 3,000 individual reefs within 133,205 square miles. A third of the Great Barrier Reef Marine Park is off-limits to fishing and collecting.
“We are basically losing an ecosystem that is so iconic for Australia and the rest of the world,” said institute scientist Katharina E. Fabricius, one of the paper’s authors.
Storm damage accounted for 48 percent of the decline, scientists said, while crown-of-horns starfish contributed 42 percent. Coral bleaching, caused by warmer water, accounted for 10 percent of coral loss. Read more
A new report from the Federal University of Pernambuco and Environment Ministry says Brazil has lost 80 percent of its coral reef over the past 50 years.
SÃO PAULO, Brazil — A new report from the Federal University of Pernambuco and Brazil’s Environment Ministry says the South American country has lost 80 percent of its coral reef in just the past 50 years.
According to EFE, the report blames abusive extraction and pollution from urban and industrial resources, as well as excessive fishing, for the destruction of the reef.
“Until the 1980s, there was much extraction to make lime in the country,” said Professor Beatrice Padovani, who collected data since 2002 with her research group, EFE reported.
More from GlobalPost: Caribbean coral reefs: “time is running out” to save them, says IUCN report
Padovani also noted that domestic, industrial and farm pollution were factors in creating sediment accumulation that has destroyed the reef systems, according to The Economic Times.
EFE went on to report that rising temperatures in the ocean because of climate change and frequent weather phenomena, like El Niño, have impacted the reef.
“In 2012, it is likely that there will be a new El Niño,” Padovani explained to the news outlet. “The reefs that will suffer most are the ones in the worst environmental condition.”
Brazil’s coral reef was once present along 1864 miles of its northeastern coast, in places like Recife, Fortaleza and Natal, reported Agence France-Presse. Its reef ecosystems have 18 species of coral, algae and at least three types of fish.
The report will be presented at an environmental conference on Monday, the Economic Times said.
ScienceDaily (Sep. 30, 2012) — Changes in ocean and climate systems could lead to smaller fish, according to a new study led by fisheries scientists at the University of British Columbia.
The study, published September 30 in the journal Nature Climate Change, provides the first-ever global projection of the potential reduction in the maximum size of fish in a warmer and less-oxygenated ocean.
The researchers used computer modeling to study more than 600 species of fish from oceans around the world and found that the maximum body weight they can reach could decline by 14-20 per cent between years 2000 and 2050, with the tropics being one of the most impacted regions.
“We were surprised to see such a large decrease in fish size,” says the study’s lead author William Cheung, an assistant professor at the UBC Fisheries Centre. “Marine fish are generally known to respond to climate change through changing distribution and seasonality. But the unexpectedly big effect that climate change could have on body size suggests that we may be missing a big piece of the puzzle of understanding climate change effects in the ocean.” Read more
27 September 2012, by Tom Marshall
Too many nutrients can put corals at risk, a new study shows. Excessive nitrogen in the water affects their ability to cope with rising water temperatures and other environmental pressures, making them vulnerable to harmful bleaching.
That is, an excessive supply of nutrients can paradoxically lead to nutrient starvation. It does this by over-fertilizing the symbiotic algae on which corals depend, making them grow more quickly than the more limited supply of phosphorus can support. This unbalanced growth makes them more susceptible to stress.
The discovery may point towards ways we can help protect coral reefs, safeguarding these uniquely rich habitats as well as the livelihoods of the millions of people who depend on them. It’s the latest in a long list of reasons to control nitrogen pollution, which has also catastrophic effects on river ecosystems and causes harmful algal blooms in coastal waters.
Published 26 September 2012. ABCScience
Dr Ashley Ward is a fish biologist at the University of Sydney. He was interviewed by Rachel Sullivan.
Almost 80 per cent of the more than 20,000 known fish species school at some point in the life cycle.
Schooling helps reduce the risk of being attacked by predators, and also makes swimming easier because the fish position themselves so they are able to slipstream in their neighbours’ wake.
Some species school only when they are vulnerable juveniles, others when they are older. They begin by swimming in pairs and then in larger and larger groups of the same species.
While fish have big eyes to help them find prey and keep track of each other up close, they rely on their chemosensory system to track other fish of the same species in the vastness of the ocean, says Dr Ashley Ward, a fish biologist at the University of Sydney.
“A fish can smell itself, and recognises others with the same smell,” says Ward, who studies the social behaviour of fish.”