1. CLIMATE CHANGE IMPACTS ON PHYTOPLANKTON BIODIVERSITY & IMPACTS ON THE ECOSYSTEM OF THE ARABIAN SEA Joaquim I. Goes & Helga Gomes, Bigelow Lab. USA Prasad Thoppil, John Kindle & Sergio de Rada, NRL, USA Adnan Al Azri, Sultan Qaboos Univ., Oman Prabhu Matondkar & Sushma Parab NIO, India R. M. Dwivedi, Space Applications, Centre, India John Fasullo, NCAR, USA, Fei Chai, Univ. Maine, USA Richard Barber, Duke Univ., USA

2. UNIQUE FEATURES OF THE ARABIAN SEA Comes under the influence of the monsoon winds which reverse their direction seasonally driving one the most energetic current systems and the greatest seasonal variability of phytoplankton biomass Is a tropical sea and the northwestern landlocked arm of the Indian Ocean

3. Reversal of the winds and their intensity is strongly regulated by thermal gradient between land and sea

4. Schematic showing snow cover extent and wind direction superimposed on an ocean color chlorophyll image for the northeast monsoon season (Nov-Feb). LOW HIGH 0.10.51.02.05.010.020.0 WINTER MONSOON

5. Schematic showing the reversal in wind direction during the southwest monsoon (Jun-Sept), superimposed on satellite derived chlorophyll fields LOW HIGH 0.10.51.02.05.010.020.0 SUMMER MONSOON

6. LESS PHYTO COLDER LANDMASS SEA MORE SNOW WEAKER SW MONSOON WINDS WEAKER UPWELLING WEAKER LAND SEA PRESSURE GRADIENT HIGHER ALBEDO Schematic showing the SW Monsoon response of the Arabian Sea to snow cover over the Himalayan-Tibetan Plateau

7. Warming of SW Eurasia mirrors the global-land signal, but recent warming anomalies are >50% larger than global temperature trends. SW Eurasian-Land Warming

8. Trend line showing anomalies (departures from monthly means) of snow cover extent over Southwest Asia and Himalayas-Tibetan Plateau between 1967 and 2003.

9. 70 years of global warming?: Photograph of the Pindari glacier in the Himalayas taken on October 7, 1936, by then Deputy Conservator of Forests F W Champion. 70 years later at the exact spot, his grandson James Champion photographed the same glacier. (Source Sunday Indian Express, 29 th Dec. 2006).

10. Interannual changes in chlorophyll along coast of Somalia since 1997 (Goes et al., Science, 2005 )

11. SeaWiFS derived chlorophyll fields during the peak southwest monsoon growth season of 1997 and 2006 Sept. 1997 India Oman Sept. 2006 India Oman

12. The Arabian Sea’s permanent oxygen minimum zone 0.10.51.02.05.010.020.0 OMZ OMAN SOMALIA

13. FISH MORTALITY OMAN – NOV 2005

14. SEA LESS SNOW WARMER AND HUMID WINDS WARMER LANDMASS WEAKER CONVECTIVE MIXING LESS PHYTO STRONGER CONVECTIVE MIXING MORE PHYTO COLDER LANDMASS SEA MORE SNOW COLDER AND DRIER WINDS (E>P)_ NORTHEAST MONSOON

15. Air-temperature and Relative humidity for the northern Arabian Sea (60°E-70°E, 14°N-25°N).

16. Annual trends of net heat flux (NCEP-NCAR) (60-70°E, 14°N- 25°N) and Mixed Layer Depth (XBT, JEDAC, USA)

17. Observed and model-derived MLD for winter (Jan – Feb), and model derived Sea Surface Salinity (SSS, psu) during Jan – May for the 60°E-70°E, 14°N- 25°N. Model derived fields are obtained from the ECCO-JPL Kalman Filter Assimilation project.

18. Winter mean SeaWiFS Chl a averaged over the Eastern Arabian Sea (EAS, 66°E-70°E, 15°N-24°N) and in the western Arabian Sea (WAS, 55°E-62°E, 17.5°N-22.5°N). EAS WAS

19. High chlorophyll concentrations during the NEM are being caused by blooms of dinoflagellate Noctiluca miliaris

20. Its appearance in bloom proportions during the NEM is unprecedented as no reports of blooms of this organism during Int. Arabian Sea JGOFS 1992 to 1996 or from Int. Indian Ocean Expeditions of the 1960’s. It occurs in (cold) <22 o C, nutrient rich and oxygen poor waters Noctiluca is a heterotrophic dinoflagellate containing a green endosymbiont “Pedinomonas noctilucae” Noctiluca appears to have replaced diatoms as the major bloom forming phytoplankton of the NEM. CHARACTERISTICS OF ARABIAN SEA NOCTILUCA MILIARIS BLOOMS

21. PHYTOPLANKTON BLOOM OF 2003

22. Weekly SeaWiFS and MODIS/Aqua Level-3 merged Chl a images with Sea Surface Height anomalies and geostrophic velocity vectors from TOPEX/POSEIDON and ERS-2 Gomes et al. (2008) Deep-Sea Research

24. 20 th Feb 2008 OMAN

25. Precipitable water from SSM/I for June showing particularly strong postive and pervasive trends in the Arabian Sea (John Fasullo NCAR)

26. Is the appearance of N. miliaris blooms the result of climate change or natural variability? What are the long-term impact of this possible change in phytoplankton biodiversity and biological productivity on: OUTSTANDING QUESTIONS FOR THE ARABIAN SEA Carbon delivery to deeper layers of the Arabian Sea Bacterial processes Denitrification rates The Oxygen Minimum Zone and Increased storm activity Coastal Fisheries

27. 1/8-degree NCOM (Navy Coastal Ocean Model) 30S to 30N, 30.5 to 121.5E Mercator grid (~13km), 40 Levels σ/z Boundary and initial conditions from Global NCOM 0.5-degree NOGAPS Atmospheric forcing MODAS: Full 3D Temperature and Salinity relaxation Initial simulation for 2007 INDIAN OCEAN CIRCULATION MODEL ( John Kindle & Sergio deRada )

28. Physical Model Nitrate [NO 3 ] Advection & Mixing Small Phytoplankton [P1] NO 3 Uptake Micro- Zooplankton [Z1] Grazing Ammonium [NH 4 ] Excretion NH 4 Uptake Detritus-N [DN] Fecal Pellet Sinking Silicate [Si(OH) 4 ] Diatoms [P2] Si-Uptake N-Uptake Meso- zooplankton [Z2] Sinking Detritus-Si [DSi] Grazing Fecal Pellet Sinking Predation Lost Total CO 2 [TCO 2 ] Biological Uptake Air-Sea Exchange Dissolution Carbon, Silicate, Nitrogen Ecosystem Model (CoSiNE) Chai et al. 2002; Dugdale et al. 2002 Chai et al., 1996; 2003 Iron

29. SEAWIFSMODEL 30 th Sept 2006

30. “Nothing in the sea falls haphazard; if we cannot predict, it is because we do not know the cause, or how the cause works..." Henry Bryant Bigelow

31. ACKNOWLEDGEMENTS This work is being funded by NASA Oceans and Ice & NASA Biodiversity and Ecosystem Programs. We are thankful to the National Institute of Oceanography and the Indian Space Research Organization for supporting ship observations. Special thanks to Woody Turner and Paula Bontempi for their support