Missing the boat: Critical threats to coral reefs are neglected at global scale

Coral reefs have experienced a global decline due to overfishing, pollution, and warming oceans that are becoming increasingly acidic. To help halt and reverse this decline, interventions should be aimed at those threats reef experts and managers identify as most severe. The survey included responses from 170 managers, representing organizations from 50 countries and territories, and found that respondents generally agreed on the two major threats: overfishing and coastal development. However, resource allocation did not match this consensus on major threats. In particular, while overfishing receives much attention, coastal development and its attendant pollution are largely neglected and underfunded. These results call for a re-examination of how resources are allocated in coral reef conservation, with more attention given to aligning how money is spent with what are perceived to be the primary threats.

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A first look at factors affecting aragonite compensation depth in the eastern Arabian Sea

Water column measurements suggest shoaling of aragonite saturation depths (ASD) throughout the world oceans, due to increase in greenhouse gas concentration. Past records of aragonite saturation state under different climatic conditions are required to assess the impact of climatic changes on shoaling/deepening of ASD. The preservation state of organisms having aragonite skeletons, is used to assess the past changes in aragonite saturation depths, with respect to the modern ASD. Here for the first time, we delineate and discuss the factors that affect the modern aragonite compensation depth (ACD) in the eastern Arabian Sea by using pteropod abundance in the surface sediments. A total of 78 spade core-top samples collected along seven latitudinal transects, covering the continental shelf, slope and abyssal region of the eastern Arabian Sea were used. Pteropods were picked from coarse fraction (≥ 63 μm). Based on the pteropod preservation, we report that in the eastern Arabian Sea, ACD lies at a water depth of ≤ 525 m, which matches with the chemically defined aragonite saturation depth. We further report that the ACD shoals from north to south. The zone of high pteropod abundance coincides with low %Corg. The increase in pteropod abundance in the outer shelf region coincides with the drop in dissolved oxygen concentration. The deeper limit of pteropod abundance lies in the center of the oxygen minimum zone with higher %Corg. Therefore, we suggest that the pteropod abundance in the eastern Arabian Sea is not always related with the lower dissolved oxygen, but is strongly influenced by %Corg. This first report of the pteropod based aragonite compensation depth estimates from the eastern Arabian Sea will help in assessing future changes in ACD under the influence of anthropogenic green-house gas emissions.

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Increased activity of lysozyme and complement system in Atlantic halibut exposed to elevated CO2 at six different temperatures

Ocean acidification and rising seawater temperature are environmental stressors resulting from the continuous increase of the atmospheric CO2 concentration due to anthropogenic activities. As a consequence, marine fish are expected to undergo conditions outside of their tolerance range, leading to physiological challenges with possible detrimental implications. Our research group has previously shown that exposure to elevated CO2 modulated the immune system of the Atlantic halibut. To further investigate this finding, we analysed non-specific immune components in blood plasma of Atlantic halibut (Hippoglossus hippoglossus) juveniles acclimated to six different temperatures (5, 10, 12, 14, 16 and 18 °C), and to water pH of 8.0 (control) or 7.6 (predicted for year 2100) for three months. Plasma ions (K+, Na+, Ca++, Cl−) and lactate concentrations were also measured. The analysis of plasma ions did not show any trends related to temperature or CO2 exposure, and the majority of the experimental fish were able to maintain ionic balance. The results show that both innate immune components (lysozyme and alternative complement system) had increased activities in response to elevated CO2, representing a CO2-related impact on the halibut’s immune system. The increased activity of lysozyme and complement system is possibly part of the acclimatization process, and might be protective.

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The 3rd Xiamen Symposium on Marine Environmental Sciences (XMAS), 9-11 January 2017, Xiamen, China

The ocean system is undergoing rapid and dramatic changes in response to global climatic and regional anthropogenic forcings. These drivers, including primarily temperature rise, intensified stratification, ocean acidification, eutrophication, and ocean deoxygenation, may, or already has, lead to fundamental changes in marine biogeochemistry, such as the carbon, nitrogen, phosphorus, and iron cycles, productivity and community shifts of marine microbes, and further impacts to fishery resources. These changes are affecting a broad range of goods and services provided to humans by marine ecosystems and are causing a number of marine environmental problems, particularly in coastal regions.

To foster knowledge and ideas exchange within the marine environmental science community and, in particular, to promote interdisciplinary studies, the State Key Laboratory of Marine Environmental Science (MEL, http://mel.xmu.edu.cn/en) of Xiamen University initiated the Xiamen Symposium on Marine Environmental Sciences (XMAS), with the overarching theme of The Changing Ocean Environment: From a Multidisciplinary Perspective. The first two symposia (http://mel.xmu.edu.cn/conference/1xmas, http://mel.xmu.edu.cn/conference/2xmas) were held in Jan 2014 and Jan 2015, attracting over 800 participants from more than 100 institutions across 14 countries.

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Increased levels of carbon dioxide could drive fish crazy, study finds

High levels of carbon dioxide could impair the brain chemistry of fish, scientists found.

Researchers from the University of Miami Rosenstiel School of Marine and Atmospheric Science and the ARC Center of Excellence for Coral Reef Studies at James Cook University found that increased concentrations of carbon dioxide in the ocean alters the brain chemistry of fish that may lead to neurological impairment.

“Coral reef fish, which play a vital role in coral reef ecosystem, are already under threat from multiple human and natural stressors,” Rachael Heuer, lead author of the study, said in a news release. “By specifically understanding how brain and blood chemistry are linked to behavioral disruptions during CO2 exposure, we can better understand not only ‘what’ may happen during future ocean acidification scenarios, but ‘why’ it happens.”

In the study published in the journal Scientific Reports, researchers collected spiny damselfish from the reefs off Lizard Island in Australia’s Great Barrier Reef. The fish were separated into two groups: one is exposed to ordinary CO2 “control conditions and the other exposed to elevated CO2 levels expected to occur by the year 2300. After the exposure, the two fish groups were subjected to a behavioral test, and brain and blood chemistry were measured.

Continue reading ‘Increased levels of carbon dioxide could drive fish crazy, study finds’

Tropical coral reefs lose their zooplankton through ocean acidification

Tropical coral reefs lose up to two thirds of their zooplankton through ocean acidification. This is the conclusion reached by a German-Australian research team that examined two reefs with so-called carbon dioxide seeps off the coast of Papua New Guinea. At these locations volcanic carbon dioxide escapes from the seabed, lowering the water’s acidity to a level, which scientists predict for the future of the oceans. The researchers believe that the decline in zooplankton is due to the loss of suitable hiding places. It results from the changes in the coral reef community due to increasing acidification.

Instead of densely branched branching corals, robust mounding species of hard coral grow, offering the zooplankton little shelter. In a study published on 19 September 2016 at the online portal of the journal Nature Climate Change, the researchers report that the impact on the food web of the coral reefs is far-reaching, since these micro-organisms are an important food source for fish and coral.

The volcanic carbon dioxide sources off the coast of Papua New Guinea are a unique natural laboratory. “Here, we can already observe under natural conditions how the reefs may change when the world’s oceans absorb more and more carbon dioxide from the atmosphere and the acidity of their water rises due to climate change,” says coral expert and study co-author Prof Claudio Richter of the Alfred Wegener Institute, the Helmholtz Centre for Polar and Marine Research.

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New York needs to act on ocean acidification

“The ocean acts like a sponge, absorbing most of the extra heat caused by our greenhouse gases. And it’s been growing warmer and more acidic for decades now. In other words, the very chemistry of our oceans is changing, which is risking marine life and rippling all the way up the food chain … This is not a far-off problem; it’s happening as we speak. It’s happening here in America.” – President Obama, at last week’s Our Ocean Conference

New York State needs Governor Cuomo to help prepare our state for the coming onslaught of a little known problem caused by more than a century of burning fossil fuels: ocean acidification.

It’s hard to imagine how we missed the connection for so long. Oceans naturally absorb carbon dioxide and, as we’ve increased the amount of carbon dioxide in the atmosphere by burning coal and oil, the basic chemistry of our oceans has become more acidic. Awareness of the impacts of ocean acidification – the so-called evil twin of global warming – is just beginning, but we know that acidic water makes it harder for many species of shell-building organisms, like clams, oysters, and scallops, to grow their protective coverings and survive.

Continue reading ‘New York needs to act on ocean acidification’

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Ocean acidification in the IPCC AR5 WG II

OUP book