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Procedures For Scientific Diving

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  1. Procedures ForScientific Diving

  2. Sources • American Academy of Underwater Sciences, Proc. of Scientific Diving Symposia, • Haddock, S.H.D., Heine J.N. 2005. Scientific Blue-Water Diving. California Sea Grant Publ. No. T-057. • Heine, J.N. 1999. Scientific Diving Techniques. Best Publishing Company, Flagstaff, AZ. • Joiner, J.T. (ed.). 2001. NOAA Diving Manual - Diving for Science and Technology, Fourth Edition. Best Publishing Company, Flagstaff, AZ.

  3. Objectives • Upon completion of this module, the participant will be able to: • Describe the general history of scientific diving • List ten environments in which scientific diving has been conducted • list the types and recommended design of diving slates • Describe three methods of locating a dive site • Describe methods to mark a site, both above and below the water • Describe ways for a diver to collect sediments • Describe ways for a diver to measure temperature, water motion, light and sound • Discuss mapping for archaeology studies, including horizontal and vertical offsets • Discuss the trilateration method of mapping • State how sediment is removed from archaeological sites

  4. Objectives (cont) • Upon completion of this module, the participant will be able to: • List the activities for biological research dives • List the major areas of biological research • Discuss quadrats and transect sampling • Describe the advantages of photography and videography in biological sampling • Describe the tools and methods used for assessing aquatic organisms

  5. History of Scientific Diving • Modern scientific diving began in the US in 1949 at the Scripps Institution of Oceanography • Scuba diving in support of science authorized at the University of California in 1953 • The first research published using scuba: • Aleem, Anwar Abdel. 1956. Quantitative underwater study of benthic communities inhabiting kelp beds off California. Science 123:183. • NOAA established the first National Undersea Laboratory at the West Indies lab • The American Academy of Underwater Sciences was formed in 1977 • Currently has more than 100 organizational members

  6. Coral reefs Mangroves Kelp forests Rocky shores Soft bottom habitats Polar environments Open ocean/blue water environments Offshore platforms Estuaries Hot springs Hypersaline environments Caves Lakes Rivers Scientific diving has been conducted in a wide variety of environments…

  7. …and been used in many different sciences • Chemical • Geological • Biological • Paleontological • Archaeological

  8. Chemistry • Diving has been used to support research such as determining the chemical ecology of invertebrates and collecting marine organisms for the extraction of chemical compounds

  9. Geology Divers may obtain core samples of rock and sediment or dig holes to examine depositional history Scuba is very useful for visual identification of sediments – and for collecting representative and relatively undisturbed samples

  10. Biology Divers may perform a wide variety of tasks such as measuring various community structural parameters like fish counts, algal counts, macroinvertebrate counts, percent cover of benthic algae and invertebrates, etc…, or measuring physiological responses of organisms in natural environments

  11. Paleontology Divers recover fossils from the underwater realm… Dinosaur fossils from the waters off the Isle of Wight

  12. Archaeology Diving is integral to the study of underwater archaeology Excavation of 4th – 6th century AD harbor site in Malta Serçe Liman1 excavation - 11th Century Byzantine Shipwreck - Diver hovers above grid used to mark locations of artifacts Serçe Limanl excavation – Diver raises fragile hull timber using a lifting box

  13. Scientific Diving - General • The diversity of disciplines involved in scientific diving, and the varied environments where this diving is performed, has necessitated the development of a wide variety of techniques for observing and sampling underwater

  14. Recording Information - Slates • Almost every scientific project requires that data be recorded underwater; slates are a simple tool for doing this • The best material for a slate is a white polycarbonate or acrylic • This material is strong, waterproof, and negatively buoyant • It will not corrode when exposed to salt water, and is available in sheets, which can be easily cut to the desired size

  15. Diver using slate to record organisms found in artificial reef

  16. Recording Information - Slates • Slate size and form may vary - large or small, single or multiple sheets, flat or curved to fit around the wrist

  17. Recording Information - Slates • For archaeology, it is recommended that the minimum dimensions of a slate should measure approximately 10 in x 12 in x ¼ in, to 12 in x 14 in x ¼ in • Much smaller and the diver has inadequate space for detailed recording • Larger slates are useful, but can be difficult to handle under certain conditions

  18. Recording Information - Slates • A wooden or mechanical pencil is attached to the slate by a string, cord, or rubber tubing • Bic brand mechanical pencils have been found to work the best due to the hardness of the lead, but the mechanics of the pencil are not always reliable when repeatedly exposed to water • Regardless of the pencil chosen, always carry at least one spare • A pencil may be used to write directly on the plastic of a slate, or to write on material attached to a slate

  19. Recording Information - Slates • Underwater paper is available for use on slates (e.g., Xerox “Never-Tear”) • Can be used in copiers and printers to duplicate data sheets • Sheets can be secured to slate with binder clips, surgical tubing, or a wing-nut bar

  20. Locating, Relocating, and Marking Sites • Locating, relocating, and adequately marking a study site are critical • Many methods may be employed • Compass bearings • Use compass bearings towards readily identifiable objects on land • For greater accuracy, use shore lineups, where pairs of objects that are in a straight line can be used to triangulate a position • Disadvantage – shore markers may not always be visible

  21. Locating, Relocating, and Marking Sites • Global Positioning Units (GPS) • Relatively inexpensive, portable, and accurate • Can store multiple points (waypoints), give the heading, distance, time to each waypoint from your present position and store multiple routes with many legs on each route • Sonar (depth finders) • Tell water depth, or distance underwater to structures

  22. Locating, Relocating, and Marking Sites • Buoys • Perhaps the best and easiest method for relocating a site from the surface • May be inexpensively made from plastic bottles • Torpedo shaped buoys minimize chances of entanglement with kelp • May be connected to the bottom with chain, cable, or lines • May be tied to structure on bottom – length of garden hose may help to avoid chafing – or weighted on bottom • In sandy or soft-bottom areas, sand, earth, or fence anchors can be screwed into the bottom • Disadvantages – take time to install correctly, and are subject to loss from storms, theft, entanglement in boat propellers, or mauling by marine animals • May also require a permit from a management agency

  23. Locating, Relocating, and Marking Sites • Underwater marking – may be necessary once the surface location of a site is established • May also require a permit from a management agency • Variety of items may be driven into the substrate • Nails • Tent stakes • Rebar • Railroad spikes • Pitons • Marking tags may be placed on these • Cable ties • Vinyl roll flagging tape • Pieces of PVC

  24. Locating, Relocating, and Marking Sites • To properly mark an area, it may be necessary to drill holes • Star Drill – hammered in by hand • The drill is held with pliers and is rotated slightly with each blow of the hammer • Time consuming and tiring; not practical if large number of holes must be drilled

  25. Locating, Relocating, and Marking Sites • Pneumatic drill or hammer – good for making numerous holes, especially in hard rock - or for more permanent fastening • May be fitted to work off a scuba tank • Disadvantages: • May use a great deal of air • Very loud • Require considerable maintenance after use • Hydraulic systems • Advantages - Quieter and more efficient than pneumatic tools • Disadvantages – More expensive – requires a link with control station on surface

  26. Locating, Relocating, and Marking Sites • Cement and epoxy may also be used to adhere items to the substrate • Generally work best on a clean substrate • May be packed into cracks, crevasses, or drilled holes • Marine putties or underwater patching compounds have been used • A mixture of four parts Type II Portland cement and one part molding plaster combined with seawater may be carried underwater in plastic bags • This mixture can be packed into holes before placement of eyebolts or stakes

  27. Geological Measurements and Collections • Collection of sediments - Coring devices – useful for stratigraphy determination or grain size analysis • A wide variety of corers are available: • Coffee can with plastic lid • Remove bottom and replace with fine mesh screen • Insert corer into substrate and push lid under lip of corer to seal it before removing • Very inexpensive • Piston corer • May be constructed from PVC, designed to collect a complete and undisturbed sample

  28. Geological Measurements and Collections • Small Ekman grabs and box corers May be manually inserted and tripped by divers, insuring proper and complete samples are collected

  29. Geological Measurements and Collections • Box corers may be fitted with a slide hammer for driving into the sediment • Some corers also have sliding doors – grooves along the open side of the corer guide the removable door down the open face once the corer is in place in the sediment • This eliminates the need to excavate and expose the lower surface of the corer to install a lower plate before removing a sample from the sediment Sliding door Slide hammer Box corer filled with sediment

  30. Geological Measurements and Collections • Vibrocoring (vibracoring) – collecting cores of unconsolidated material by driving a tube with a vibrating device (vibrohead) • Three types of vibrators: • Pneumatic • Hydraulic • Electric

  31. Pneumatic vibrocorers – can be made to work underwater with very few adjustments and don’t involve the use of electrical current. They work best in relatively shallow water because of increased air consumption at depth. They also require a cumbersome compressor, and the hose becomes an impediment in swift or choppy waters. Hydraulic vibrocorers – Do not share depth limitations with pneumatic corers, but do require a hydraulic power plant and an umbilical hose. Hydraulic corer Electric vibracorers – are more efficient (have a better force/weight ratio) than other types, and do not require umbilical hoses or large compressors or power plants.

  32. Geological Measurements and Collections • Heavy cores may be brought to the surface with lift bags

  33. Measuring Temperature • Hand-held thermometer • Generally encased in stainless steel or plastic • Temperature data loggers • Long term • May be downloaded to computer after retrieval or in situ • Fouling organisms may be issue – users often wrap download connection points with tape or encase thermometer in PVC

  34. Multiparameter Instruments • Conductivity, Temperature, and Depth units (CTDs) • May measure other parameters such as salinity, fluorescence, pH, turbidity and oxygen and may take water samples from different depths • May be small enough for divers to swim with them underwater to collect discreet data from precise locations

  35. Niskin Bottles for water sample collection CTD instrument underneath

  36. Measuring Water Motion • May be difficult and complex to measure • Plaster • Blocks of plaster are weighed, affixed to some sort of framework and deployed • The plaster dissolves in water – faster or slower depending on water velocity • After recovery, the plaster is dried and weighed again; differences in weight give a relative measure of water motion Plaster attached to cards (referred to as “Clod cards”). The one on the left has not been deployed – the other two have. Note the size difference

  37. Measuring Water Motion • Fluorescent dye • useful for determining current direction and velocity - may be released and visually tracked and timed, or recorded on a video camera with a timer

  38. Measuring Water Motion • Current meters • Small hand-held flow meters • Different rotor size for different water velocity ranges

  39. Measuring Water Motion • Current meters may also be attached: • Taut- line mooring – current meter is attached to a line that is weighted, anchored, or fixed to a sand anchor in soft sediment • Under a strong current, however, the meter will be deflected • Rigid mooring – will prevent deflection of current meter • Inexpensive option: concrete block with four out-riggers for stability, and a vertical pole with a swivel on top for the current meter

  40. Rigidly moored current meter on tripod

  41. Measuring Light • A variety of light meters are available • Divers may use hand held light meters for measuring light in precise locations • Light meters may also be deployed for long periods of time in specific locations Light meter collector

  42. Diver uses handheld light meter to determine level of light reflected from coral

  43. Sound • Measuring sound underwater often requires the deployment of transducers (for transmitting sound) and hydrophones (for listening to sound emitted from both biological and physical sources) – these are sometimes quite large

  44. Diver deploying transducer Biologist using video and hydrophone to record fish sounds

  45. Chemical Measurements • May range from simply collecting water in a plastic container to using sophisticated collection techniques and analyzing devices

  46. Van Dorn Bottle –May be mounted on scuba cylinders and tripped by diver at precise time and location to collect discrete water sample for analysis Sediment oxygen demand chamber – may be positioned by divers at specific locations – used to measure sediment oxygen demand

  47. Underwater Archaeology • Underwater archeologists locate, draw, excavate, and recover material objects in order to better understand history and culture • Divers are integral to this process

  48. Archaeologyand Low Visibility • Because many sites of archeological interest are located in coastal environments, estuaries, or rivers, a great deal of underwater archaeology takes place in locations with poor water visibility Dredging during 1992 Maple Leaf expedition

  49. Low Visibility - Measuring • Clear ziplock plastic bags (“Brody Bags”) filled with water may be used to view measuring tapes in low visibility situations • The bag is placed on the tape and a flashlight is used for illumination • The bag may be made more secure by applying duct tape to the sealed portion of the bag • Before recording measurements, it is always a good idea to have a diver swim the tape to ensure it is not snagged somewhere

  50. Archaeology – Mapping • Mapping is the process of representing the arrangement of objects in two- or three-dimensional space - this is done by taking measurements • Site maps are two dimensional plan views looking down from above, using an X and Y coordinate system • The third dimension, or Z coordinate, provides depth or elevation data (profile views use the Z coordinate to record cross sections that show the vertical components of a site) A 2-dimensional and 3-dimensional coordinate system