Ocean Acidification on the US Northeast Shelf:

Transcription

1 Ocean Acidification on the US Northeast Shelf: Present Status and Unknown Future NEFSCNarragansett, RI Nathan D. Rebuck 18 December 2014

2 Outline What is ocean acidification? What, and where, are the primary causes? What are the potential impacts on commercially available species? What does this mean for us; now and in years? Known Unkowns U.S. Department of Commerce National Oceanic and Atmospheric Administration NOAA Fisheries Page 2

3 What is Ocean Acidification? U.S. Department of Commerce National Oceanic and Atmospheric Administration NOAA Fisheries Page 3

4 Ocean Acidification: The Other CO 2 Problem The continuous trend of increasing acidity in marine waters resulting from increased carbon dioxide. Can be quantified with several parameters, such as ph, DIC, pco 2, Ω Primary focus on increasing atmospheric carbon dioxide (global) Also affected by NO x and SO x emissions from industrial activities (regional) Upstream eutrophication, followed by biological respiration (local)

5 U.S. EPA.gov 5

6 What, and where, are the primary causes of Ocean Acidification? U.S. Department of Commerce National Oceanic and Atmospheric Administration NOAA Fisheries Page 6

7 Atmospheric carbon dioxide: The dominant global component of OA Analytic Record: decrease in ph in last decade (0.002 yr -1 ) Isotopic Record: decrease since preindustrial ( yr -1, IPCC, among others) Data from Mauna Loa, Hawaii Figure from Feely 2008, BAMS (data from Tans et al., and Karl et al., updated online) decrease since last glacial maximum 15-20ky ( yr -1,Sanyal et al. 1995)

8 Future projections: CO 2 will increase, but how much? Estimates for global change over next 100 years: decrease in ph This is enough to affect much marine life. Figure 1. (a.)projected atmospheric carbon dioxide (CO 2 ) concentra=ons and (b.) the corresponding global average ocean ph under seven different modeled scenarios. The variability of atmospheric CO 2 is primarily dependent on the rate of fossil fuel emissions while ph variability is dependent on both atmospheric CO 2 and temperature. Figure adapted from Meehl et al. (2007).

9 Alkalinity: The antacid of the oceans Truth is, no one really knows what it is, but it s a really useful operational chemical measurement Essentially, it s a measure of the ability to resist increases in acidity with a similar amount of acid added (R-O-L-A-I-D-S) Household water softeners remove alkalinity (for basic tapwater and high calcium waters) Alkalinity is directly related to salinity, so fresh river water has low alkalinity, whereas offshore pure ocean water has relatively high alkalinity Gulf of Maine is relatively fresh compared to global oceans, and estuaries and nearshore areas are even more so. 9

10 Local hydrographic and Riverine inputs Rivers are local point sources of high dissolved carbon inputs. Freshwater has a low buffering capacity Estuaries and river mouths often are naturally occurring high acidity, low ph environments. Exacerbating naturally low ph environments can have outside impacts on native species Salisbury et al., 2001? 10

11 TIDE Toolbox: Geerts L, Maris T, Meire P (February 2013) 11

12 The magnitude of ocean acidification will be determined by both: Global increases in atmospheric carbon dioxide and local organic carbon inputs Local in situ alkalinity to buffer those inputs These changes will occur in addition to the natural background fluctuations of: Abiotic seasonal temperature and salinity cycles Phytoplankton bloom uptake and subsequent community respiration Regional scale hydrographic variability

13 Present Conditions Along the Northeast Shelf 13

14 Atmospheric carbon dioxide with global coverage: Descending like a blanket everywhere Increases aquatic carbon dioxide globally Effect moderated by alkalinity Primary disturbance to offshore and open oceans Localized eutrophication Small scale effects (1-10 miles) Can be severe in magnitude Less predictable than larger spatial scale changes Affects estuaries, coves, anywhere salinity varies with rivers 14

15 What are the potential biological impacts? U.S. Department of Commerce National Oceanic and Atmospheric Administration NOAA Fisheries Page 15

16 Ocean Acidification Biological Consequences: Demonstrated, but inconsistent and variable effects on: Corals Pteropods and Coccolithophores Bivalves and other Crustaceans (some positive!) Some Ichthyplankton Elemental BGC cycling Mechanisms low ph generates stress on acid/base reactions and ion transport in finfish NASA low Ω decreases growth of some shellfish NMFS high pco 2 increases photosynthetic uptake Wes Pratt, NMFS

17 What is the expected acidification in 5, 10, 50, 100 years? U.S. Department of Commerce National Oceanic and Atmospheric Administration NOAA Fisheries Page 17

18 Decadal-scale trends Average ph change over 29 years, /yr

19 NASA s best model in 2010 (ESM2M, since upgraded, ask Vince ) 50 year change in ph = year change in ph = Drastically different ph environment than today Cannot account for local environmental changes!!!! 19

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21 Algal blooms Magnitude of ph variability in marine systems Open ocean (~8.1) 2010 Average NE Shelf (~8.05) Lower salinity estuaries, heterotrophic productive waters

22 Algal blooms Magnitude of ph variability on the NE Shelf Average Diurnal (~0.05) PMEL Carbon Group and UNH Coastal Carbon Group GOM 7.8 Estuaries, Night

23 Algal blooms Magnitude of ph variability on the NE Shelf Average 8.0 Diurnal (~0.05) Estuaries, Night Seasonal ( ) Data shown here; extremes from PMEL Carbon Group and UNH Coastal Carbon Group GOM

24 Algal blooms Seasonal (0.25) Magnitude of ph variability on the NE Shelf 8.1 Average Diurnal (~0.05) Since pre-industrial ~200 years (0.11) Meehl et al Estuaries, Night

25 Algal blooms Seasonal (0.25) Pre-industrial (0.11) Magnitude of ph variability on the NE Shelf 8.1 Average Diurnal (~0.05) Measured regional change since 1980 (~0.03 since 1980) 7.8 Estuaries, Night

26 Algal blooms Diurnal (~0.05) Seasonal (0.25) Pre-industrial (0.11) (~0.03) Magnitude of ph variability on the NE Shelf Average Estuaries, Night Modeled (0.12) Orr et al. 2005, GFDL ESM2M CMIP5 RCP8.5

27 Algal blooms Seasonal (0.25) Pre-industrial (0.11) Magnitude of ph variability on the NE Shelf 8.1 Average 8.0 Diurnal (~0.05) (~0.03) (0.12) Estuaries, Night Modeled (0.31) GFDL ESM2M CMIP5 RCP8.5

28 Algal blooms Average 8.0 Diurnal (~0.05) Seasonal (0.25) Pre-industrial (-0.11) (-0.03) Magnitude of ph variability on the NE Shelf (-0.12) (-0.31) Estuaries, Night

29 What do we know that we don t know? And take home messages. U.S. Department of Commerce National Oceanic and Atmospheric Administration NOAA Fisheries Page 29

30 Genetic variability exists within species that might adapt to acidified conditions, but at what time scales? Implication that current eutrophication in many estuaries has acidified many places similar to 50 year projections of offshore waters Are coastal spawners in variable acidity environments may be more resilient to OA than offshore species? Some species grow better in high carbon dioxide environments, most notably phytoplankton and primary producers. Are there other commercially important winners in this scenario? Shellfish farms at the mouth of rivers in New England are likely to remain unaffected by global trends in carbon dioxide on the 5-25 year timeframe Areas of high organic inputs, which unfortunately make for the optimum shellfish growth conditions, are especially susceptible to increases in acidity Approaching the 2050 time period, atmospheric carbon makes aquaculture with present methods a risky proposition. Local upstream land usage and nutrient inputs will continue to be the primary determinants of acidification for nearshore coastal regions 30

31 Acknowledgements: NOAA s Ocean Acidification Program National Research Council Chris Taylor NOAA Fisheries Narragansett Rick Wannikhof at AOML (Miami) Joe Salisbury & Doug Vandemark University of New Hampshire Alex Wang Woods Hole Oceanographic Institute Margaret Mulholland at Old Dominion University.