1 / 14

Ocean acidification and New Zealand coastal waters

Ocean acidification and New Zealand coastal waters. Catriona Hurd, Department of Botany, University of Otago. NZ’s coastal ecosystems. Temperate reefs Primary producers: seaweeds and phytoplankton Secondary producers Filter feeders: mussels, oysters, barnacles

alyson
Download Presentation

Ocean acidification and New Zealand coastal waters

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Ocean acidification and New Zealand coastal waters Catriona Hurd, Department of Botany, University of Otago

  2. NZ’s coastal ecosystems • Temperate reefs • Primary producers: • seaweeds and phytoplankton • Secondary producers • Filter feeders: mussels, oysters, barnacles • Grazers: kina, paua, limpets • Predators • Starfish • Fish

  3. Which species will OA affect directly? • All algae – fleshy and calcifying • Calcifying invertebrates: • Mollusks: paua (abalone), oysters, mussels • Crustaceans: barnacles, crabs, crayfish • Echinoderms: kina, (urchins), starfish • Sponges • Corals • Bryozoans • Serpulid worms Stanley (2008) Chem. Rev. 108; Hurd et al. J. Phycol. (2009 in press)

  4. Seaweed-based ecosystems • Ecosystem engineers • Provide habitat complexity and shelter for animals • Supply 50% of energy to coastal food webs • Some seaweeds are grazed • Most provide food particles - ‘kelp flakes’ • Globally unique ~800 seaweed species ~30% found only in NZ • Hurd et al. (2004) Phycol. Res. 52

  5. Predictions on how seaweed productivity will be affected • Increase in growth and productivity of fleshy seaweeds • Seaweeds reliant on only CO2 will have greatest increase • Decline in growth of calcifying (coralline) seaweeds • 80% cover of subtidal habitats around Otago Hurd et al. (2009) J. Phycol. In press

  6. Coralline seaweeds Paua larva • Global distribution • Invertebrate recruitment and settlement • Release chemicals that induce attachment and metamorphosis in e.g. paua • Vulnerable • Canaries in the coal mine? Paua larva newly settled on coralline seaweed Nelson (2009) Mar. Fresh. Res. 60

  7. Calcifying invertebrates • A substantial proportion of marine invertebrates calcify • Keystone species • kina (sea urchins) • Commercial species • Mussels, oysters, paua (abalone) • Predators • starfish

  8. Impacts of high CO2 (low pH) - Echinoderms • Keystone species controlling kelp distributions • Fished extensively worldwide • Production of outer test • affected during larval settlement stage at high pCO2

  9. Molluscs – reduced Calcification at low pH Ecosystem function – Bioturbators, Food source & Habitat modifiers C. gigas Net calcification rate umol CaCO3 g FW-1 h-1 M. edulis Gazeau et al. 2007

  10. Bivalves – reduced Calcification at low pH Incubations at pH 7.3 (max pH decrease in business-as-usual climate change scenario by year 2300) (Caldeira and Wickett, 2003) control 55 % growth reduction & 65% metabolic depressionDiversion of energy to shell maintenance from growth & reproduction Michailidis et al. (2004)

  11. Economic importance How will lower pH affect Greenlip Mussels, Paua and other NZ commercial species? Mussel farms • green lipped mussels • 898 farms, approx. 6535 ha • total revenue $181,400,000 Oyster farms • pacific oysters, North Island • 236 farms, approx. 928 ha • total revenue $26,000,000 Photos and data from www.fish.govt.nz

  12. Ecosystemresponses pH • Volcanic CO2-vents • Coralline seaweeds replaced by fleshy species at low pH • Decline in all calcareous invertebrates at low pH Hall-Spencer et al. (2008) Nature 454

  13. Seaweeds engineer their own environment • Photosynthesis raises the pH of seawater • Calcification rates of coralline seaweeds enhanced in this seagrass meadow Semesi et al. (2009) Mar. Ecol. Prog. Ser. 382

  14. New Zealand coastal waters:What do we need to know? • Species-specific responses to OA • Select ‘model’ seaweed and animal species • Controlled laboratory experiments • Acclimation and adaptation • Ecosystem responses • What knowledge do we have of NZ coastal ecosystems? • Near-shore observatories • Food-web studies

More Related