THE IMPACT OF DIATOMS Dia=two Tom=cut Clinton Wilkinson SASQAP

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1 THE IMPACT OF DIATOMS Dia=two Tom=cut Clinton Wilkinson SASQAP

2 Diatoms HISTORY

3 Discovery 1703 English gentleman reported to Royal Society of London adhering to pondweed many pretty branches, composed of rectangular oblongs and exact squares between 1844 and 1900 golden age of expeditions Cleve, Grunow, Gran, Karsten, Castracane, Peragallo permanent slide collections (objects of scientific fashion) 5,000 living species, 10,000 fossil species

4 Diatoms Diatoms are photosynthetic algae. Have a silicate skeleton (frustule). Found in almost every aquatic environment. SW, FW and soils. Mainly non motile, capable of limited movement along a substrate.

5 Diatoms are the Grasses of the Sea Basis of life

6 Diatomaceous earth is used as an abrasive in toothpaste and metal polishes, absorbent for liquid nitroglycerin to make dynamite, filtration of liquids (especially sugar refineries), insulation of boilers, filler for paint and used in cosmetics.

7 Diatoms have inspired Architects How to build the strongest possible structure, using the least amount of material? Montreal Expo, 1967 Geodesic dome

8 Diatoms Audience quiz

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10 Diatoms Estimated that 20%-25% of all organic carbon fixation on the planet is carried out by diatoms. They contribute to about 45% of the total oceanic primary production.

11 Diatoms Unicellular Single cells

12 Diatoms Colonies

13 Fouling Diatoms

14 Liawenee Canal (Central Tasmania) Biofouling

15 Chaetoceros socialis Mucus colony

16 Spiny diatoms can damage fishes gills Chaetoceros concavicorne

17 Chain Formation Thalassiosira rotula Chitan threads exuded from Strutted Processes

18 Chain Formation Strutted processes Detonula Lauderia Occluded processes

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20 Achnanthes Amphora Cyclotella Cocconeis Coscinodiscus Cymbella

21 Amnesic Shellfish Poisoning Prince Edward Island, Canada, deaths, 105 cases of permanent brain damage Amino acid Domoic acid Chainforming pennate diatom Pseudo-nitzschia multiseries

22 Californian Bird & Sea lion Poisonings 1991 Pseudo-nitzschia australis

23 Rhizosolenia amaralis bitter taste 2010

24 Diatoms Leptocylindrus danicus 2011

25 Leptocylindrus danicus 2003

26 L. danicus 860 um long 2011

27 Skeletonema group. 2011

28 Diatoms Occurrence of diatoms in SA waters seasonal Summer, autumn up-welling events move diatoms into coastal areas (shellfish growing areas) Environmental factors play an important role (tides, wind and sun)

29 Diatoms UPWELLING Upwelling is an oceanographic phenomenon that involves wind-driven motion of dense, cooler, and usually nutrient-rich water towards the ocean surface. This replaces the warmer, usually nutrientdepleted surface water.

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33 Diatoms 10/02/2008 Denial Bay (1,829,000 cells/l) St Peters (918,666 cells/l) 17/02/2008 Port Douglas(3,320,000 cells/l) 18/02/2008 Smoky Bay (1,354,666 cells/l) Streaky Bay(3,630,000 cells/l)

34 Diatoms Result of upwelling in SA; seasonal distribution of phytoplankton into harvesting areas. Influenced by wind, tide and current but can be hit and miss.

35 Denial Bay Est. Total Phytoplankton Est. Total Diatom

36 St Peters Island Total Est. Diatom Total Est. Phyto

37 Smoky Bay Est. Total Phytoplankton Est. Total Diatom

38 Port Douglas Est. Total Phytoplankton Est. Total Diatom

39 Franklin Harbour Est. Total Phytoplankton est. Total Diatoms

40 Stansbury Est. Total Phytoplankton Est. Total Diatom

41 Denial Bay St Peters

42 Smoky Bay Streaky Bay

43 Port Douglas Port Douglas

44 Franklin Franklin

45 Stansbury Port Vincent

46 Oyster Deaths Outside of the scope of SASQAP

47 Diatoms Diatoms don t kill oysters; dinoflagellates can. An oyster can survive for up to two months without an adequate food supply. Bacteria in the water good food source Stress of the oyster plays an important role in their survival. No food + stress + bad EF = DEATH

48 Diatoms Management on the farm plays an important role in the survival of the oyster. Have gone from summer mortalities to winter mortalities. From my basic survey and phone conversations. 10 yrs ago 10-15% mortalities Present 20-25% mortalities

49 Diatoms May July 2011 some growers lost up to 45% of stock, average lost 25% Not confined to one harvesting area, or hatchery, or lines Size of oysters 10 70mm Majority of deaths occurred after handling, (Douglas event great example) some found dead with meats still in on next grading.

50 Diatoms Every need to know what the microalgae counts are Office: Mobile:

51 $30 In the process of revision See me to place an order

52 Acknowledgements Gustaaf Hallegraeff UTAS for his amazing SEM images and for being a great mentor over the past ten years THANK YOU

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