Archive Page 2

The role of natural variability in shaping the response of coral reef organisms to climate change

Purpose of Review

We investigate whether regimes of greater daily variability in temperature or pH result in greater tolerance to ocean warming and acidification in key reef-building taxa (corals, coralline algae).

Recent Findings

Temperature and pH histories will likely influence responses to future warming and acidification. Past exposure of corals to increased temperature variability generally leads to greater thermotolerance. However, the effects of past pH variability are unclear. Variability in pH or temperature will likely modify responses during exposure to stressors, independent of environmental history. In the laboratory, pH variability often limited the effects of ocean acidification, but the effects of temperature variability on responses to warming were equivocal.

Summary

Environmental variability could alter responses of coral reef organisms to climate change. Determining how both environmental history as well as the direct impacts of environmental variability will interact with the effects of anthropogenic climate change should now be high priority.

Continue reading ‘The role of natural variability in shaping the response of coral reef organisms to climate change’

Local habitat influences on feeding and respiration of the intertidal mussels Perumytilus purpuratus exposed to increased pCO2 levels

Coastal ecosystems are exposed to changes in physical-chemical properties, such as those occurring in upwelling and freshwater-influenced areas. In these areas, inorganic carbon can influence seawater properties that may affect organisms and populations inhabiting benthic habitats such as the intertidal mussel Perumytilus purpuratus. Feeding and metabolic responses were measured in adult mussels from two geographic regions (central and southern Chile) and two local habitats (river-influenced and non-river-influenced) and three pCO2 levels (380, 750, and 1200 μatm pCO2 in seawater). The feeding rates of mussels tend to increase at high pCO2 levels in seawater; however this response was variable across regions and local habitats. In contrast, there was no difference in the respiratory rate of mussels between geographic areas, but there was a significant reduction of oxygen consumption at intermediate and high levels of pCO2. The results indicate that river-influenced organisms compensate for reductions in metabolic cost at elevated pCO2 levels by having their energy demands met, in contrast with non-river-influenced organisms. The lack of regional-scale variability in the physiological performance of mussels may indicate physiological homogeneity across populations and thus potential for local adaptation. However, the local-scale influences of river- and non-river-influenced habitats may counterbalance this regional response promoting intra-population variability and phenotypic plasticity in P. purpuratus. The plasticity may be an important mechanism that allows mussels to confront the challenges of projected ocean acidification scenarios.

Continue reading ‘Local habitat influences on feeding and respiration of the intertidal mussels Perumytilus purpuratus exposed to increased pCO2 levels’

Multidecadal fCO2 increase along the United States southeast coastal margin

Coastal margins could be hotspots for acidification due to terrestrial-influenced CO2 sources. Currently there are no long-term (>20 years) records from biologically important coastal environments that could demonstrate sea surface CO2 fugacity (fCO2) and pH trends. Here, multi-decadal fCO2 trends are calculated from underway and moored time series observations along the United States southeast coastal margin, also referred to as the South Atlantic Bight (SAB). fCO2 trends across the SAB, derived from ∼26 years of cruises and ∼9.5 years from a moored time series, range from 3.0 to 4.5 µatm y−1, and are greater than the open ocean increases. The pH decline related to the fCO2 increases could be as much as -0.004 y−1; a rate greater than that expected from atmospheric-influenced pH alone. We provide evidence that fCO2 increases and pH decreases on an ocean margin can be faster than those predicted for the open ocean from atmospheric influence alone. We conclude that a substantial fCO2 increase across the marginal SAB is due to both increasing temperature on the middle and outer shelves, but to lateral land-ocean interactions in the coastal zone and on inner shelf.

Continue reading ‘Multidecadal fCO2 increase along the United States southeast coastal margin’

Associate Research Scientist, GOA-ON support – IAEA Environment Laboratories (NAEL), Monaco

Closing date: 3 December 2017. Position open for US citizens.

Note: This position is part of an IOC-UNESCO/IAEA- collaboration to support GOA-ON.

Organizational Setting

The Department of Nuclear Sciences and Applications implements the IAEA’s Major Programme 2, “Nuclear Techniques for Development and Environmental Protection”. This Major Programme comprises individual programmes on food and agriculture, human health, water resources, environment and radiation technologies. These programmes are supported by laboratories in Seibersdorf, Monaco and Vienna. The Major Programme’s objective is to enhance the capacity of Member States to meet basic human needs and to assess and manage the marine and terrestrial environments through the use of nuclear and isotopic techniques in sustainable development programmes. The IAEA Environment Laboratories consists of four laboratories, three of which are located in Monaco and one in Seibersdorf. The Division implements the IAEA Environment Programme and operates in a complex matrix environment with inputs from many parts of the organization, such as the Department of Technical Cooperation for the implementation of projects, and collaborates with other Departments.

Continue reading ‘Associate Research Scientist, GOA-ON support – IAEA Environment Laboratories (NAEL), Monaco’

Alaska Ocean Acidification Network Survey

The Alaska Ocean Acidification Network is interested in your opinion and priorities.  Researchers and resources managers are monitoring ocean acidification in Alaska, and need your input to develop a build-out plan for the monitoring network. Your help will make sure the plan addresses questions that are important to Alaskans. This survey should take less than 10 minutes. The AK Ocean Acidification Network appreciates your participation.

Continue reading ‘Alaska Ocean Acidification Network Survey’

Southern Ocean pteropods at risk from ocean warming and acidification

Early life stages of marine calcifiers are particularly vulnerable to climate change. In the Southern Ocean aragonite undersaturation events and areas of rapid warming already occur and are predicted to increase in extent. Here, we present the first study to successfully hatch the polar pteropod Limacina helicina antarctica and observe the potential impact of exposure to increased temperature and aragonite undersaturation resulting from ocean acidification (OA) on the early life stage survival and shell morphology. High larval mortality (up to 39%) was observed in individuals exposed to perturbed conditions. Warming and OA induced extensive shell malformation and dissolution, respectively, increasing shell fragility. Furthermore, shell growth decreased, with variation between treatments and exposure time. Our results demonstrate that short-term exposure through passing through hotspots of OA and warming poses a serious threat to pteropod recruitment and long-term population viability.

Continue reading ‘Southern Ocean pteropods at risk from ocean warming and acidification’

Competitive interactions moderate the effects of elevated temperature and atmospheric CO2 on the health and functioning of oysters

Global increases in sea temperatures and atmospheric concentrations of CO2 may affect the health of calcifying shellfish. Little is known, however, about how competitive interactions within and between species may influence how species respond to multiple stressors. We experimentally assessed separate and combined effects of temperature (12 or 16°C) and atmospheric CO2 concentrations (400 and 1000 ppm) on the health and biological functioning of native (Ostrea edulis) and invasive (Crassostrea gigas) oysters held alone and in intraspecific or interspecific mixtures. We found evidence of reduced phagocytosis under elevated CO2 and, when combined with increased temperature, a reduction in the number of circulating haemocytes. Generally, C. gigas showed lower respiration rates relative to O. edulis when the species were in intraspecific or interspecific mixtures. In contrast, O. edulis showed a higher respiration rate relative to C. gigas when held in an interspecific mixture and exhibited lower clearance rates when held in intraspecific or interspecific mixtures. Overall, clearance rates of C. gigas were consistently greater than those of O. edulis. Collectively, our findings indicate that a species’ ability to adapt metabolic processes to environmental conditions can be modified by biotic context and may make some species (here, C. gigas) competitively superior and less vulnerable to future climatic scenarios at local scales. If these conclusions are generic, the relative role of species interactions, and other biotic parameters, in altering the outcomes of climate change will require much greater research emphasis.

Continue reading ‘Competitive interactions moderate the effects of elevated temperature and atmospheric CO2 on the health and functioning of oysters’


Subscribe to the RSS feed

Powered by FeedBurner

Follow AnneMarin on Twitter

Blog Stats

  • 1,040,307 hits

OA-ICC HIGHLIGHTS

Ocean acidification in the IPCC AR5 WG II

OUP book