Published 10 September 2012
SEATTLE – September 7 – A new report has found that ocean acidification continues to threaten water quality and wildlife in the Puget Sound. According to the report, surveys revealed the waters from the Strait of Juan de Fuca to the Great Bend of the Hood Canal are corrosive during part of the year — a troubling sign for animals that may be unable to build the shells they need to survive when seawater becomes increasingly acidic.
Authored by the Puget Sound Ecosystem Monitoring Program, a scientific partnership among universities and government agencies, the report also noted the presence of unusual, harmful algae that can contaminate shellfish, as well as nutrients from human activities, both of which are potential water-quality problems.
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Rising atmospheric carbon dioxide concentration is causing global warming, which affects oceans by elevating water temperature and reducing pH. Crustaceans have been considered tolerant to ocean acidification because of their retained capacity to calcify during subnormal pH. However, we report here that significant immune suppression of the Norway lobster, Nephrops norvegicus, occurs after a 4-month exposure to ocean acidification (OA) at a level predicted for the year 2100 (hypercapnic seawater with a pH lowered by 0.4 units). Experiments carried out at different temperatures (5, 10, 12, 14, 16, and 18 °C) demonstrated that the temperature within this range alone did not affect lobster immune responses. In the OA-treatment, hemocyte numbers were reduced by almost 50% and the phagocytic capacity of the remaining hemocytes was inhibited by 60%. The reduction in hemocyte numbers was not due to increased apoptosis in hematopoetic tissue. Cellular responses to stress were investigated through evaluating protein carbonyls and lipid oxidation in lobster hepatopancreata, and OA-treatment was shown to significantly increase protein carbonyls, indicating stress-induced protein alterations. Furthermore, the extracellular pH of lobster hemolymph was reduced by approximately 0.2 units in the OA-treatment group, indicating either limited pH compensation or buffering capacity. The negative effects of OA-treatment on the nephropidae immune response and tissue homeostasis were more pronounced at higher temperatures (12–18 °C versus 5 °C), which may potentially affect disease severity and spread. Our results signify that ocean acidification may have adverse effects on the physiology of lobsters, which previously had been overlooked in studies of basic parameters such as lobster growth or calcification.
Continue reading ‘Simulated climate change causes immune suppression and protein damage in the crustacean Nephrops norvegicus’
Anthropogenic CO2 emissions have exacerbated two environmental stressors, global climate warming and ocean acidification (OA), that have serious implications for marine ecosystems. Coral reefs are vulnerable to climate change yet few studies have explored the potential for interactive effects of warming temperature and OA on an important coral reef calcifier, crustose coralline algae (CCA). Coralline algae serve many important ecosystem functions on coral reefs and are one of the most sensitive organisms to ocean acidification. We investigated the effects of elevated pCO2 and temperature on calcification of Hydrolithon onkodes, an important species of reef-building coralline algae, and the subsequent effects on susceptibility to grazing by sea urchins. H. onkodes was exposed to a fully factorial combination of pCO2 (420, 530, 830 μatm) and temperature (26, 29 °C) treatments, and calcification was measured by the change in buoyant weight after 21 days of treatment exposure. Temperature and pCO2 had a significant interactive effect on net calcification of H. onkodes that was driven by the increased calcification response to moderately elevated pCO2. We demonstrate that the CCA calcification response was variable and non-linear, and that there was a trend for highest calcification at ambient temperature. H. onkodes then was exposed to grazing by the sea urchin Echinothrix diadema, and grazing was quantified by the change in CCA buoyant weight from grazing trials. E. diadema removed 60% more CaCO3 from H. onkodes grown at high temperature and high pCO2 than at ambient temperature and low pCO2. The increased susceptibility to grazing in the high pCO2 treatment is among the first evidence indicating the potential for cascading effects of OA and temperature on coral reef organisms and their ecological interactions.
Continue reading ‘Ocean acidification and warming decrease calcification in the crustose coralline alga Hydrolithon onkodes and increase susceptibility to grazing’
Published 10 September 2012
Jobs , Science
Reference number: 80/G/Bio Deadline: 14.Sep.2012
The Alfred Wegener Institute for Polar and Marine Research (AWI), division of „Biosciences“, sections “Integrative Ecophysiology” & “Functional Ecology“, is seeking to appoint within the framework of the BMBF funded ‘Verbundprojekt’ BIOACID phase II, consortium 4
a Scientist (Postdoc) (f/m)
(with focus on transcriptomics/genomics /bioinformatics)
Continue reading ‘Scientist (Postdoc) (f/m) (with focus on transcriptomics/genomics /bioinformatics)’