Potential Ecological and Foodweb Impacts of Ocean Acidification

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1 Potential Ecological and Foodweb Impacts of Ocean Acidification Dr Carol Turley United Nations Open-ended Informal Consultative Process on Oceans and the Law of the Sea Fourteenth meeting, New York June 2013

2 Major Ocean Acidification Research Efforts Across the World since Keizer and Turley

3 Rapid Changes to Ocean Chemistry are Underway Result of a series of chemical reactions is: Increase in hydrogen ions (H+), i.e. ph decreases Carbonate ions decreases

4 Speed and Scale of Change is Significant It is happening now, at a speed and to a level not experienced by marine organisms for about 60 million years possibly 300 million years Mass extinctions linked to previous ocean acidification events Courtesy A. Ridgeway

5 Today is a rare event in the history of the World Learning from Earth s Deep Past from sediment cores: Sediment core Paleo OA event 55 million years ago Start of PETM event 55 million years ago CaCO3 Clay Similar amount of carbon to today s event But much slower (~x10) Deep Sea extinction amongst foraminifers 10,000 s of years for sediment carbonate to recover Foster et al. (2013)

6 Model Projection of Future Surface Water ph Courtesy A Yool

7 Model Projection of Future Aragonite Saturation Simulated Ωarag: CMIP5 model mean under RCP8.5 Courtesy J. Orr

8 Early Vulnerabilities upwellings, estuaries, polar waters and tropical and cold water corals Steinacher et al. 2008, Orr et al Feely et al. Science (2008) Guinotte et al 2006

9 Mounting Concern for Survival of Many Marine Organisms, Food Webs & Ecosystems... What will ocean ecosystems and foodwebs look like in a future high CO2 world? Meta-analysis of 139 experiments show that acidification significantly reduce survival, calcification, growth and reproduction in very many species But processes are not well-understood, variability is high and ecosystem and foodweb effects are uncertain Kroeker et al. (2010)

10 Key links in the food chain show vulnerability. Krill embryo development Pteropods shell growth ph 8.09 ph ppm 2000 ppm ph 7.8 Arctic Limacina helicina stained with calcein. 30% reduction of the calcification rate at ph 7.8. Comeau et al Kawaguchi et al Brittlestar larval - 100% mortality in 7 days with a -0.2 ph. Dupont et al. 2010

11 Benthic Ecosystems and Foodwebs..

12 Some Species may become Extinct (Dupont et al. 2008)

13 Within one Ecosystem, there could be Winners and Losers. Losers (e.g. Green sea urchin, Dupont & Thorndyke 2009) Winners (e.g. Seastar Crossaster papposus, Dupont et al 2010) But both can have negative effect on marine ecosystems

14 CO2 Vents: Windows into a Future High CO2 Ocean may Help Assess Ecosystem Impacts Courtesy: J. Hall- Spencer

15 Future Seagrass Beds: Winners. or are they? CO2 enrichment increases productivity Loss of protective phenolics in seagrasses with high CO2 They may be less able to defend against grazing fish Russell BD et al. (2013); Arnold et al. (2012) Ecosystems are complex!

16 Shift in Ecosystems as ph Decreases Near Vents Total loss of some calcareous species The habitat is less biodiverse Some species benefit but so do invasive species e.g. seaweed production increases and sea anemones may thrive but other grazers decrease Regime shifts to totally different ecosystems are clearly visible Hall-Spencer et al. (2008); Johnson et al. (2012); Suggett et al. (2012)

17 Papua New Guinea: Similar Findings at CO 2 Seeps in Coral Reefs Ocean acidification leads to loss in diversity, structural complexity. No reef development at <7.8 ph. Today: ph 8.1 ph 7.9 (RCP=4.5) ph 7.8 (RCP=6.0) A vision of the future of coral reefs in a high CO 2 world? Fabricius et al. (2011)

18 Pelagic Ecosystems and Foodwebs.

19 Svalbard 2010: CO2 Enriched Mesocosms pco2 (ppm) participants from 12 partner institutes 180

20 Time schedule Major Changes at the Base of the Pelagic Foodweb... with likely consequences for higher trophic levels and foodwebs outcompeted at high CO 2 moderately stimulated at high CO 2 strongly stimulated at high CO 2 (unpublished data coutesy Ulf Reibesell, BIOACID and EPOCA)

21 Pteropod (Sea Butterfly) Vulnerability key links in foodwebs Live pteropods were dissolved within their natural environment as a result of exposure to waters where ΩA 1 Ocean acidification is already impacting living populations Pteropods are an important link in the foodweb Smith et al. (2007) Bednarsek et al. 2012

22 Key components of food for fish such as salmon and herring Pacific Salmon Pteropods Aydin et al. (2005) Courtesy: R Feely

23 Adverse Effects of Ocean Acidification on Early Development of Squid SEM images of paralarval statoliths Reduced mantle length, hatching time and statolith surface area statolith malformation Important link in food chain both predators and prey Squid are a key food source for many commercially important fish, including tuna and hake U.S. harvest of squid with a value of more than $100 million Kaplan et al. (2013) n MB, et al. (2013) Global squid catches are near 3 million ton per yr

24 Ocean Acidification: how certain can we be? Note: Ocean acidification, warming and deoxygenation can act together ( stress.com) Turley and Gattuso (2012)

25 Ocean Acidification and Certainty: expert assessment Gattuso et al. (2012)

26 Ocean Acidification and Certainty: expert assessment Gattuso et al. (2012)

27 Ocean Acidification and Certainty: expert assessment Gattuso et al. (2012)

28 Ocean Acidification and Certainty: expert assessment Gattuso et al. (2012)

29 Ocean Acidification and Certainty: expert assessment

30 Ocean Acidification and Certainty: expert assessment Gattuso et al. (2012)

31 Conclusion Global ocean acidification is caused by CO2 and is occurring rapidly It is likely that some organisms will be effected positively and others negatively Courtesy: J Orr projected aragonite saturation Some communities, foodwebs and ecosystems are likely to change Future ocean foodwebs and ecosystems depend on CO2 emissions to the atmosphere Thank you It is difficult to predict what future ocean foodwebs and ecosystems will look like and what goods and services they will be able to provide Humankind