Ocean Acidification: What is it, why does it matter, and how can it be measured? Chris Hunt, Joe Salisbury, Doug Vandemark Special collaborators: William Mook and Meredith White (MSF), Dave Kuhn (VT), AJ Erskine (KCB), Kari Rapine (CAF), Michael Congrove (OSH) Northeast Aquaculture Conference and Exposition, Providence RI January 11-13

(More acidic!) (More alkaline) SLIDE 2. Ocean acidification is the term that has been given to the changes we are observing in the ocean’s chemistry as a result of humankind’s release of CO2 into the atmosphere. Here is a conceptual diagram that gives an overview of ocean chemistry over time and the potential biological impacts in a future high-CO2 world. Carbon dioxide reacts with seawater to form carbonic acid. The carbonic acid then dissociates to release a hydrogen ion that reacts with carbonate ion to form bicarbonate. The loss of carbonate ions slows the development of the CaCO3 shells and skeletons of many calcifying organisms including the pteropods shown here. The schematic indicates that below a certain carbonate ion concentration the shells of some calcifying organisms may begin to dissolve. The colors indicated the trend of acidification with higher CO2 levels to the right.

Why should you care about OA? pH change -0.3 units/century Based on 10 years of buoy data at Appledore Island, The Gulf of Maine is about -0.15 units/century

SLIDE 23. A wide variety of potential impacts have been identified for ocean acidification on marine organisms & ecosystems. The emphasis of most studies to date has been on negative impacts on calcifying organisms. Recent work as expanded the range of organisms and physiological processes being examined. Positive impacts are also possible, for example elevated growth by some types of algae and seagrasses. Good review articles include Fabry et al. ICES J. Mar. Sci., 2008 and Doney et al., Ann. Rev. Mar. Res., 2009).

But, OA is more than just CO2 5.5 inches of rainfall in 24 hours on 9/30 Freshwater inputs In-situ organic matter production and decomposition Upwelling of deep offshore water Other processes?

a a data from the ECOA cruise, summer 2015. Preliminary data from Cai’s U Delaware group

How do we examine ocean acidification? Geochemical/biochemical -Temperature, salinity -Dissolved oxygen -Carbonate System Measurements: pH Total Alkalinity (T-Alk) Dissolved Inorganic Carbon (DIC) Partial Pressure of Carbon Dioxide (pCO2) -Calcium (?) Biological Doney et al. 2009 Calcification

What is best to measure? pH Omega (Ω) Need 2 carbonate parameters plus temperature and salinity Bottle measurements for validation Ω > 1 animals can make shell Ω >>1 easier to make shell (Langdon & Atkinson, 2005) Ω < 1 shell dissolves

*Autonomous *Laboratory * CO2 DIC T-Alk pH * * * * * * * * * * * * *

Levels of accuracy and utility for measuring  - Collect water temperature, salinity, pH continuously - Model Ω using assumptions on how total alkalinity and salinity are related Level 2 – - Add continuous pCO2 measurements Level 3 – - Continuous, real time of pCO2 and dissolved inorganic carbon or total alkalinity *data must be validated with discrete measurements

UNH partnerships with aquaculturists MSF- Level 3 OSH- Level 2 CML- Level 3 BOC- Level 2 CAF- Level 2

 gives the most information for management and science Take Home on Cost  gives the most information for management and science Level 1- basic continuous Omega estimates ($6-7k) Level 2- intermediate, w/ pCO2 ($25-30k)* Level 3- deluxe w/pCO2 and TA or DIC (~$50k)* * Needs technical assistance

New options on the horizon- Level 2 on the cheap(er) + And salinity, water temperature

OK, so what do we do with the data? Put accurate, real-time information in the hands of growers and hatchery managers and make informed decisions to manage around highly variable water quality Threshold data for production water treatment Environmental data for seasonal, spatial predictions Inform the public on the the real state of today’s coastal oceans and enlist the help of the research community

Concluding Thoughts Ocean acidification has a real and increasing impact on coastal and marine systems We are just beginning to measure the impacts on specific species and regions Acidification in coastal systems may be more pronounced and derive from a number of different processes Aquaculturists stand to improve their operations through better analysis and control of the water they use Measuring acidification is expensive! But, promising new resources are coming Questions

But, how do we examine OCA? Ships Buoys Facilities

ECOA 2015 Cruise Data to be collected: Lead PI : CTD: Joe Salisbury - UNH Respiration, Filtration Total CO2 (DIC):                                    Leticia Barbero - AOML Dissolved Oxygen:                              Chris Langdon - RSMAS Total Alkalinity, pH:                                     Wei-Jun Cai - UDEL 13DIC, Oxygen, Argon:                                                    Bror Jonsson - Princeton 13C NPP, 15N NPP: Margaret Mulholland - ODU AOP, IOP: Veronica Lance - NESDIS Nutrients (Collected): Jia-Zhong Zhang - AOML

Gledhill et al. 2015

Why should you care about OA?

What is alkalinity, and why is it important? “the number of moles of hydrogen ion equivalent to the excess of proton acceptors over proton donors…” (Dickson 1981) The capacity of ocean water to neutralize acid OR The chemical buffering capacity of the ocean.