Massive Porites sp. corals as indicators of historical changes in river runoff:

1. Massive Porites sp. corals as indicators of historical changes in river runoff: A case study for Antongil Bay (Masoala National Park, NE Madagascar) J. Zinke1, C. Grove2, G. J. Brummer2 1Vrije Universiteit Amsterdam, The Netherlands 2Royal NIOZ, The Netherlands in cooperation with WCS Madagascar

2. GLOBAL • Climate Change • Global Warming (coral bleaching) • Increased pCO2 (ocean acidification) • Sea Level Rise Healthy Reef Ecological Response of Reefs:global & local impacts • LOCAL IMPACTS • CORAL PREDATORS – Crown of Thorns (COTS) • FISHING/TRAWLING – Reef ecology • RIVER RUNOFF - Sediments, Nutrients, Freshwater input HERBIVORES Fish, Invertebrates CORALS Adults Juveniles reproduction ALGAE CROWN OF THORNS competition for space Algal Reef

3. Study area: NE Madagascar, Antongil Bay, St. Marie, Ifaty

4. Main climatic variables in the region: Rainfall and SST • Rainfall (cyclonic) impacts on: • Freshwater runoff and sedimentation of river systems • Ocean chemistry and physical conditions • Nutrient and pollutant export rates Sea surface temperature patterns affect rainfall variability • Climate change impacts on reefal ecosystem: • Multiple stress factors: SST, salinity, sediments, pollutants, nutrients • Impact on livelihoods: • large-scale flooding of villages • Erosion of agricultural land, loss of fertile soil • Sewage export impacts on fisheries

5. Objectives Madagascar Recontruction of surface ocean chemistry, temperature and salinity related to global and local factors: To provide baseline of natural variability against which anthropogenic impacts can be assessed Learn about spatial and temporal changes in climate Study sedimentation, pollutant and nutrient export and how it relates to climate variability Quantify the impacts of climatic and environmental changes on coastal ecosystems

6. Our monitoring tool: • Massive corals Porites sp. • Life span: up to 400 years • Geochemical proxies in corals: • Sr/Ca for SST • Oxygen isotopes for salinity • Combination Sr/Ca and d18O for hydrology • Ba/Ca, Y, Mn for river runoff • Cu, Zn etc. for biological activity • Luminescence for runoff • Density and Calcification for status of coral health

7. Zinke et al., 2004

8. Ifaty and Reunion corals record link to Pacific Decadal Oscillation (18-25 years)

9. Ba/Ca as a proxy for sediment river discharge Ba is highly abundant in river sediment load Ba is released when river water flows into seawater (salinity, pH gradient) Freshwater plumes into the coastal ocean are correlated with higher Ba/Ca ratios in corals Floods after drought years contain more Ba than in normal years McCulloch et al., 2003, Nature 421

10. Increase in temperature and sedimentation over 20th century: Antongil Bay

11. Seasonal timing of runoff Ba/Ca: late summer/winter max Mn: summer max

12. Luminescence banding related to river runoff: Quantification of runoff intensity in single years

13. XRF-scanning luminesecence (Royal NIOZ Netherlands): subweekly resolution

14. Calcification rate and density decrease over the 20th century: Ocean Acidification? MAS1 coral, Masoala Park

15. Gaps in monitoring and research: • monitoring natural variability of sedimentation, nutrient and pollutant export to provide natural levels • combine environmental monitoring with ecosystem studies (reef monitoring) • monitor SST and salinity to evaluate choice of MPA’s • climatological monitoring land and ocean (isotopes in precipitation, isotopes in groundwater/seawater) • combine terrestrial (tree rings, stalagmites, lakes) and marine studies (corals, bivalves) to investigate land-ocean interaction (gradients) • hydrological modelling of climate and land-use impacts