Published 30 July 2014
Education , Meetings
EAST BOOTHBAY, Maine — Bigelow Laboratory for Ocean Sciences will open up to the public on Friday to allow science-minded residents a chance to tour the facility, meet experts and participate in hands-on activities.
The free event at the Maine laboratory will last from 10 a.m. to 3 p.m.. Dr. Graham Shimmield, executive director of the laboratory, says the event is a chance for the laboratory’s scientists to share what they are learning about the ocean.
Hands-on activities will include plankton tows from the dock, microscope viewing, and experiments about ocean acidification and fish DNA.
Continue reading ‘Maine’s Bigelow Laboratory for Ocean Sciences will open up to the public on Aug. 1.’
A natural pH gradient caused by marine CO2 seeps off Vulcano Island (Italy) was used to assess the effects of ocean acidification on coccolithophores, which are abundant planktonic unicellular calcifiers. Such seeps are used as natural laboratories to study the effects of ocean acidification on marine ecosystems, since they cause long-term changes in seawater carbonate chemistry and pH, exposing the organisms to elevated CO2 concentrations and therefore mimicking future scenarios. Previous work at CO2 seeps has focused exclusively on benthic organisms. Here we show progressive depletion of 27 coccolithophore species, in terms of cell concentrations and diversity, along a calcite saturation gradient from Ωcalcite 6.4 to <1. Water collected close to the main CO2 seeps had the highest concentrations of malformed Emiliania huxleyi. These observations add to a growing body of evidence that ocean acidification may benefit some algae but will likely cause marine biodiversity loss, especially by impacting calcifying species, which are affected as carbonate saturation falls.
Continue reading ‘Decline in coccolithophore diversity and impact on coccolith morphogenesis along a natural CO2 gradient’
We examined the combined impacts of future increases of CO2 and temperature on the growth of four marine diatoms (Skeletonema costatum, Chaetoceros debilis, Chaetoceros didymus, Thalassiosira nordenskioeldii). The four strains were incubated under four different conditions: present (pCO2: 400ppm, temperature: 20℃), acidification (pCO2: 1000ppm, temperature: 20℃), global warming (pCO2: 400ppm, temperature: 25℃), and greenhouse (pCO2: 1000ppm, temperature: 25℃) conditions. Under the condition of higher temperatures, growth of S. costatum was suppressed, while C. debilis showedenhanced growth. Both C. didymus and T. nodenskioldii showed similar growth rates under current and elevated temperature.None of the four species appeared affected in their cell growth by elevated CO2 concentrations. Chetoceros spp. showedincrease of pH per unit fluorescence under elevated CO2 concentrations, but no difference in pH from that under currentconditions was observed for either S. costatum or T. nodenskioeldii, implying that Chetoceros spp. can take up more CO2 per cell than the other two diatoms. Our results of cell growth and pH change per unit fluorescence suggest that both C. debilis and C. didymus are better adapted to future oceanic conditions of rising water temperature and CO2 than are S. costatum and T. nodenskioeldii.
Continue reading ‘Effects of increased CO2 and temperature on the growth of four diatom species (Chaetoceros debilis, Chaetoceros didymus, Skeletonema costatum and Thalassiosira nordenskioeldii) in laboratory experiments’
The influence of ocean acidification in deep-sea ecosystems is poorly understood, but is expected to be large owing to the presumed low tolerance of deep-sea taxa to environmental change. We used a newly developed deep-sea Free Ocean CO2 Enrichment (dp-FOCE) system1 to evaluate the potential consequences of future ocean acidification on the feeding behavior of a deep-sea echinoid, the sea urchin, Strongylocentrotus fragilis. The dp-FOCE system simulated future ocean acidification inside an experimental enclosure where observations of feeding behavior were performed. We measured the average movement (“speed”) of urchins as well as the time required (“foraging time”) for S. fragilis to approach its preferred food (giant kelp) in the dp-FOCE chamber (-0.46 pH units) and a Control chamber (ambient pH). Measurements were performed during each of 4 trials (days -2, 2, 24, 27 after CO2 injection) during the month-long period when groups of urchins were continuously exposed to low pH or Control conditions. Although urchin speed did not vary significant in relation to pH or time exposed, foraging time was significantly longer for urchins in the low-pH treatment. This first deep-sea FOCE experiment demonstrated the utility of the FOCE system approach and suggest that the chemosensory behavior of a deep-sea urchin may be impaired by ocean acidification.
Continue reading ‘Use of a Free Ocean CO2 Enrichment (FOCE) system to evaluate the effects of ocean acidification on the foraging behavior of a deep-sea urchin’
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.
Continue reading ‘Pacific-wide contrast highlights resistance of reef calcifiers to ocean acidification’
Published 29 July 2014
The Maine Ocean Acidification Committee will hold its first meeting on Aug. 1.
The committee is studying the impacts of ocean acidification on the state’s environment and its economy. It is slated to meet in Walpole.
The Maine state Legislature passed a law this spring establishing the commission to study and address the effects of ocean acidification on ecosystems and shellfisheries. State officials say the commission is the first of its kind in the eastern United States.
State officials say the 16-member council will meet at least four times before completing its work by Dec. 5. It will then report findings to the state legislature’s Marine Resources Committee.
Continue reading ‘Maine ocean acidification committee to hold its first meeting on Aug. 1′
Ocean acidification is anticipated to decrease calcification and increase dissolution of shelled molluscs. Molluscs with thinner and weaker shells may be more susceptible to predation, but not all studies have measured negative responses of molluscs to elevated pCO2. Recent studies measuring the response of molluscs have found greater variability at the population level than first expected. Here we investigate the impact of acidification on the predatory whelk Morula marginalba and genetically distinct subpopulations of the Pacific oyster Crassostrea gigas. Whelks and eight family lines of C. gigas were separately exposed to ambient (385 ppm) and elevated (1000 ppm) pCO2 for 6 weeks. Following this period, individuals of M. marginalba were transferred into tanks with oysters at ambient and elevated pCO2 for 17 days. The increase in shell height of the oysters was on average 63% less at elevated compared to ambient pCO2. There were differences in shell compression strength, thickness, and mass among family lines of C. gigas, with sometimes an interaction between pCO2 and family line. Against expectations, this study found increased shell strength in the prey and reduced shell strength in the predator at elevated compared to ambient pCO2. After 10 days, the whelks consumed significantly more oysters regardless of whether C. gigas had been exposed to ambient or elevated CO2, but this was not dependent on the family line and the effect was not significant after 17 days. Our study found an increase in predation after exposure of the predator to predicted near-future levels of estuarine pCO2.
Continue reading ‘Populations of Pacific oysters Crassostrea gigas respond variably to elevated CO2 and predation by Morula marginalba’