Sampling The Benthos

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Sampling The Benthos

  1. 1. SAMPLING THE BENTHOS
  2. 2. Sampling the Benthos <ul><li>Used to determine: </li></ul><ul><ul><li>diversity </li></ul></ul><ul><ul><li>biomass </li></ul></ul><ul><ul><li>distribution of life </li></ul></ul><ul><ul><li>historical data </li></ul></ul>
  3. 3. Sampling the Benthos <ul><li>Must assume that a small amount of material is representative of the larger area </li></ul><ul><li>Therefore, must take as many samples as time and money allow </li></ul>
  4. 4. Grab Like a crane with jaws to grab sediment & organisms
  5. 5. Grab
  6. 6. Grab <ul><li>works differently in </li></ul><ul><li>different seds </li></ul><ul><li>soft seds – sinks </li></ul><ul><li>deeper </li></ul><ul><li>hard seds – does </li></ul><ul><li>not grab as much </li></ul>
  7. 7. Dredge <ul><li>- Collects materials from </li></ul><ul><li>benthic zone </li></ul><ul><li>Often used to clear channels </li></ul><ul><li>for navigation </li></ul><ul><li>- Sometimes to collect organisms </li></ul>
  8. 8. Types of dredges: Dredge clam shell dredge
  9. 9. Types of dredges: Dredge suction dredge
  10. 10. scallop dredge backhoe dredge Types of dredges: Dredge
  11. 11. Trawl <ul><li>net dragged behind boat </li></ul><ul><li>at various depths or </li></ul><ul><li>along bottom </li></ul>
  12. 12. Trawl
  13. 13. trawl tracks can damage benthic habitat Trawl
  14. 14. Epibenthic Sled <ul><li>drag along bottom – </li></ul><ul><li>like dredge </li></ul><ul><li>can collect samples </li></ul><ul><li>can house equipment </li></ul>
  15. 15. Core drill to collect a long tube of sediment
  16. 16. Core good for analyzing historic changes over long periods of time
  17. 17. SCUBA <ul><li>s elf- c ontained u nderwater b reathing </li></ul><ul><li>a pparatus </li></ul><ul><li>allows person to see and sample </li></ul><ul><li>limited time on bottom </li></ul><ul><li>limited depth – about 100 feet </li></ul>
  18. 18. Submersible Alvin small research submarine
  19. 19. Submersible Johnson Sea Link can go as deep as 4,000 meters
  20. 20. R.O.V. r emotely o perated v ehicle <ul><li>small robot operated from boat </li></ul><ul><li>cables to boat </li></ul><ul><li>safer and cheaper </li></ul>
  21. 21. A.U.V. <ul><li>autonomous underwater vehicle </li></ul><ul><li>small robot </li></ul><ul><li>no cables to surface </li></ul>
  22. 22. Satellites <ul><li>used for navigation </li></ul><ul><li>and to map ocean </li></ul><ul><li>bottom </li></ul>
  23. 23. Satellites <ul><li>Global map of ocean floor gravity </li></ul><ul><li>from Geosat and ERS-1 satellite altimetry </li></ul>
  24. 24. Side scan sonar <ul><li>uses sound waves and computer </li></ul><ul><li>imaging to get an image of the </li></ul><ul><li>ocean bottom </li></ul><ul><li>towed behind ship </li></ul><ul><li>can determine benthic habitats </li></ul>
  25. 25. Side scan sonar

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