What will you be doing in lab this week?  Ocean Acidification lab  What is Ocean Acidification?  =Wo-bHt1bOsw =Wo-bHt1bOsw  Blowing bubbles  What are you exhaling with every breath?  Why does dissolving CO 2 in water result in a change of pH?  Dissolving shells  What are (most) shells made of?  Why do shells dissolve in low pH? 1

What role do the oceans play in climate?  Exchange and transfer of heat  Oceans carry heat from the tropics (equator) to the poles, to maintain Earth's temperature  Oceans are main reservoirs of readily available carbon dioxide (CO 2 )  The cold, deep water in the ocean is the main active reservoir of dissolved CO 2  Exchange and transfer of CO 2 (and O 2 )  Change in ocean pH 2

Status of Ocean Acidification  ~1/3 of fossil-fuel CO 2 dissolves in ocean  Between 1751 and 1994 surface ocean pH is estimated to have decreased from approximately 8.2 to 8.1  Logarithmic scale of pH; approximately a 25% increase in H +  Estimated that it will drop by a further 0.3 to 0.5 units by 2100

What is pH?  pH is a measure of the acidity or basicity of a solution  Defined based on the activity of dissolved hydrogen ions (H + )  Measured by pH scale  pH = -log [H + ]  higher [H+] = lower pH  0–6 = acid, 7 = neutral, 8–14 = alkaline  Each is a power of 10 difference in pH pH scale Low pH = lots of H + High pH = few H + 4

Oceans in a High CO 2 World  Oceans absorb and release CO 2  More CO 2 in the atmosphere, more CO 2 in the oceans  CO 2 reacts with water to form an acid  H + falls off into water  pH goes down 5

Oceans in a High CO 2 World  When CO 2 dissolves, it reacts with water to form a balance of chemical species: dissolved free carbon dioxide (CO 2 (aq)), carbonic acid (H 2 CO 3 ), bicarbonate (HCO 3 -1 ) and carbonate (CO 3 -2 )  The ratio of these species depends on temperature and pH and temperature  Dissolving CO 2 increases [H + ]  Lower pH 6

CO 2 chemistry in seawater  The equilibrium reaction for CO 2 chemistry in seawater that best captures its behavior is: CO 2 + H 2 O + CO HCO 3 -1 (carbon dioxide) (water) (carbonate) (bicarbonate)  Which direction does the reaction move given the decrease in pH observed since the Industrial Revolution?  CO 2 + H 2 O + CO 3 -2 _______ 2HCO 3 -1  What happened to the concentration of bicarbonate (HCO 3 -1 ) in the oceans?  What has happened to the concentration of carbonate (CO ) in the oceans? 7

Impacts of ocean acidification  Negative impacts on organisms that build shells, skeletons or exoskeletons of calcium carbonate (CaCO 3 )  Loss of biodiversity and ecosystem function  Extinction of marine organisms  WATCH:  Reduced survival of marine organisms  Larva or juveniles  Commercially important fish and shellfish  Decrease in fertilization and settling success  Changes in food web structure  Reduction or removal of important species  Reduction in photosynthetic potential?  Deafness in whales? 8

Why does increasing the dissolved CO 2 concentration in seawater affect shell building in marine organisms?  The calcification reaction that forms shells, exoskeletons, and the skeleton of coral reefs from CO 2 is: Ca 2+ + CO 3 2- CaCO 3 (calcium) (carbonate) (calcium carbonate)  At low pH, less carbonate (CO 3 2- )  “Harder” to form shells, exoskeletons and coral reef structures  In what direction will the dominant (or net) calcification reaction that forms coral reefs proceed at low ocean pH values? Ca 2+ + CO 3 2- ____________ CaCO 3  Dissolution of calcium carbonate hard parts 9

Impacts of Ocean Acidification  Impacts on organisms that build shells and plates out of calcium carbonate (CaCO 3 )  More acidic (lower pH) = less carbonate  Vulnerable organisms:  Bivalves (mussels, clams, oysters)  What’s happening to local shellfish industry?   Coccolithophorids (phytoplankton)  Pteropods, foraminifera (zooplankton)  Coral reefs Coccolithophore Pteropod Corals 10

Impacts of Ocean Acidification  Deformed coccoliths  Experimental corrosion of calcium shells  Pteropod (48 hrs) b = acid, c = normal seawater Healthy, swimming pteropod 11

What will happen to the Deadliest Catch? Coccolithophore bloom in the Bering Sea Benthic organisms Salmon Marine Mammals

How will ocean acidification impact marine foodwebs?  All organisms are linked to one another through a complex foodweb  Fish protein is an important component of the human diet 13

14 Pterpods can compose up to 50% of the diet of juvenile salmon

Will fish (and larvae) lose their way?  Use calcareous internal structures for:  Migration  Otolith: key sensory structure  Elevated CO 2 results in larger, misshapen structure  Settling  Statolith: granules in statocyst used to maintain equilibrium and orientation  Feeding  Gastrolith: stone in stomach to aid in digestion Misshapen otolith 15

Will whales go deaf?  Absorption of sound in seawater changes with the chemistry  pH  Sound causes groups of atoms to vibrate, absorbing sounds at specific frequencies  More acidic the seawater, the less low- and mid- frequency sound it absorbs  Sounds below about 3,000 cycles per second travel further  Low frequency sounds used by marine mammals CO 2 + H 2 O + CO HCO 3 -1 Increasing carbon dioxide in the atmosphere leads to an increase in the acidity of seawater, which in turn allows sounds (such as whale calls) to travel farther underwater 16

What role does THC play?  Downwelling (cold) waters carry carbon dioxide deep into the ocean, taking it away from the atmosphere  Deep and bottom water formation areas are sink for atmospheric CO 2  Flux of CO 2 from atmosphere into ocean  Upwelling waters bring deep water to the surface where it is in contact with the atmosphere  Flux of CO 2 from surface ocean to atmosphere

Why are WA waters so acidic? 18  During the summer months:  Ekman transport results in divergence along coast  Seasonal Upwelling  Deep water carried to surface  High CO 2 & nutrients  Low O 2  Coastal waters enter PS

120m Why are WA waters so acidic? Clams (mussels, oysters) made out of ? In-class Activity: Q1: FULL NAME Q2: Fill in the blanks Old water is ______ and ______ rich, ______ poor What’s happening to our local shellfish industry? Watch: ?v=x7MpI9dZIjk ?v=x7MpI9dZIjk

Understanding Ocean Acidification  Chemistry of oceans depends on chemistry of atmosphere  More CO 2 in atmosphere = more CO 2 in oceans  More CO 2 in oceans = more acidic oceans (lower pH)  More acidic oceans = negative impact (growth, reproduction, survival) on algae and animals with shells or skeletons made of calcium carbonate

Test your knowledge  Can you describe the role the oceans play in the global carbon cycle?  Can you identify the factors that determine how much O 2 or CO 2 dissolves in seawater?  Can you explain how increasing concentrations of CO 2 in the atmosphere results in a change of ocean pH?  Can you explain how a change in ocean pH affects marine organisms?  Can you explain thermohaline circulation and how the oceans transport and dissolved gases (O 2, CO 2 )? 21