Oysters and Ocean Acidification (OA)

Transcription

1 Oysters and Ocean Acidification (OA) Iria Gimenez, on behalf of Dr. George G. Waldbusser Gulf States Marine Fisheries Commission "Gulf of Mexico Oysters, the Industry, and the Future October 13, 2016 WRAC

2 What is Ocean Acidification (OA)? The balance of these two processes controls the C chemistry of the ocean: 1) CO 2 emissions into the atmosphere and oceans 2) Weathering of terrestrial sediments into the ocean that buffer the addition of CO 2 Now we are increasing CO 2 emissions faster (10s of years) than weathering can keep up with (10,000 years) NOAA (2016) The release of CO 2 was 10x slower during our closest analog on the geological record (PETM) (Zeebe et al. 2016)

3 How does OA change the chemistry of the ocean? The increase of dissolved CO 2 (P CO2 ) in the ocean has already decreased ph and saturation state (Ω) Ω is a measure of how corrosive the water is for calcium carbonate (shells) Mauna Loa observatory; HOTS PMEL (2016) Ω = 1 : Thermodynamic stability

4 What does OA mean for shellfish? ~80% of bivalves studied to date show how negative responses to increasing CO 2 Windows of vulnerability across and within lifestages Carry-over effects across life stages

5 PNW Pacific oysters: Canary in the Coal Mine Starting in 2007, WCSH located in Netarts Bay, OR experienced Pacific Oyster larval production failures. In 2009, Dr. Burke Hales (OSU) installed carbonate chemistry high-frequency monitoring equipment Barton et al.(2015) Hourly, daily and weekly timescales of variability are physiologically relevant for larvae Whiskey Creek Shellfish Hatchery (WCSH)

6 PNW Pacific oysters: A partnership between Industry and research 10s of cohorts of larvae raised in hatchery analyzed 50% of the variability in larval cohort hatchery production explained by Ω Ar in first 48 hours (first 48 hours) Barton et al Barton et al. (2012)

7 Ω controls early calcification on C. gigas larvae C. gigas Laboratory experiments identify Ω (not ph or PCO2) as the parameter controlling development and growth on early bivalve larvae Proportion normal Shell length (µm) Waldbusser et al. 2015

8 Pacific oysters: early larval stage very sensitive. Why? PDI Shell Formation (First hours) 1. High rate of calcification 2. Calcification exposed 3. Limited energy 14 Hrs. 10 Hrs. 16 Hrs. Waldbusser et al. 2015

9 What about the West Coast native oyster? Proportion Normal Shell Length (µm) 96 Hrs 108 Hrs O. lurida : no acute negative response to increasing P CO2 or decreasing Ω ar and ph PDI Shell (First hours) Waldbusser et al Hrs 1. Slow calcification 2. High energy supply 3. Low energy consumption

10 Does this mean that native species are adapted? Waldbusser et al PNW native mussels show the same response to saturation state than the non native species.

11 What does OA mean for Eastern Oyster larvae? % Survival ~1,500 ppm PCO 2 ~660 ppm PCO 2 ~350 ppm PCO 2 Larvae length (μm) ~350 ~660 ~1,500 PCO 2 treatment (ppm) Modified after Talmage and Gobler 2009 Increased mortality, delayed development and reduced growth under increased P CO2 Delayed development and metamorphosis increase vulnerability to predation No experimental data that includes exposure to OA during early shell development!

12 What does OA mean for Eastern Oyster larvae? ~390 ppm P CO2 Harmful Algal Blooms (HABs) are already prevalent in the Gulf of Mexico and are predicted to intensify ~850 ppm P CO2 Exposure to OA and even low density HABs: Synergistic effects Modified after Talmage and Gobler 2012 Further reduced survival and delayed development

13 What does OA mean for Eastern Oyster juveniles? Juvenile calcification rate (proxy for growth) correlated with Ω ca Different sensitivity thresholds across lifestages Waldbusser et al Potential for carry-over effects from early exposures, already demonstrated in other oyster species.

14 Gulf of Mexico and OA Multiple drivers of coastal carbonate chemistry can interact and decouple the carbonate system: Cai et al Carbonate chemistry in the GOM : freshwater input nutrient run-off upwelling 1. high Ω ar in surface shallow waters 2. seasonal low Ω ar in coastal subsurface waters 3. Projections of lower Ω ar by the end of the century

15 Gulf of Mexico signaled as vulnerable to OA Why? Local amplifiers of OA: Coastal eutrophication and large freshwater inputs Social vulnerability: Great importance of shellfish industry for local economy Modified after Ekstrom et al. 2015

16 Gulf of Mexico and OA What next? Global Ocean Acidification Network (GOA-ON) on 10/10/2016 Only 2 high frequency monitoring carbonate chemistry data in the Gulf of Mexico and limited research cruises High temporal resolution data close to oyster recruitment areas are key to: 1. Understand environmental variability 2. Identify sensitivity thresholds 3. Improve forecast models 4. Design effective mitigation strategies if needed

17 Gulf of Mexico and OA Building resiliency Monitoring stations to assess carbonate chemistry conditions relevant to oyster larvae, juveniles and adults Conduct research in OA effects on C. virginica across lifestages (particular emphasis on windows of sensitivity Support efforts to restore and manage oyster reefs and seagrass beds Support actions to manage nutrient inputs into estuaries Kelly et al Partnerships with local, regional and state stakeholders to facilitate action

18 Conclusions 1) Higher CO 2, and lower ph and Ω result from the addition of CO 2 to the ocean faster than alkalinity 2) Ω matters most for rapidly developing bivalve embryos- native and non-native. Probably the case for Eastern oysters. 3) Slow PDI shell formation may be a trait for resiliency to acute OA stress (O. lurida) (Kinetics!) 4) Eastern oyster larvae show decreased survival and growth and delayed development with high CO 2, exacerbated during HABs. 5) Eastern oyster juveniles calcification rates also higher with increasing Ω 6) GOM vulnerable to OA due to local amplifiers of OA, but more monitoring and research needed to avoid a tipping point scenario for the shellfish industry.

19 Thank you Questions? Iria Gimenez

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21 Methods: Decoupling carbonate variables Stripping DIC and adding different DIC:Total Alkalinity ratios 4x4 factorial design: 16 treatments Independent: 4 PCO 2 levels and 4 Aragonite saturation states (Ω Ar ) Pseudo-independent: ph C. gigas M. galloprovincialis Waldbusser et al. 2015

22 Results: Development to PDI C. gigas M. galloprovincialis Normal Proportion normal Abnorm al Saturation State explained more than 85% of the variance in shell development. Waldbusser et al. 2015

23 Results: Shell length of normally developed larvae C. gigas M. galloprovincialis Shell length (µm) Saturation State explained more than 80% of the variance in shell length of normally developed larvae. Waldbusser et al. 2015

24 Calcification Rates and Energy C. gigas vs O. lurida C. gigas O. lurida O. lurida calcification rate is > 7x slower than C. gigas during the PDI stage. The TAG:ST ratio (~energy : structural lipids) declines 50x faster in C. gigas than O. lurida. Waldbusser et al. 2016

25 Calcification exposed Waldbusser et al. 2013