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Can kelp extract (KELPAK) be useful in seaweed mariculture?
 

Can kelp extract (KELPAK) be useful in seaweed mariculture?

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This presentation was given at the 2003 Phycological Society of Southern Africa meeting in 2003. The presentation asks whether a seaweed extract (normally used on land plants) can also be used to ...

This presentation was given at the 2003 Phycological Society of Southern Africa meeting in 2003. The presentation asks whether a seaweed extract (normally used on land plants) can also be used to increase seaweed produciton.

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    Can kelp extract (KELPAK) be useful in seaweed mariculture? Can kelp extract (KELPAK) be useful in seaweed mariculture? Presentation Transcript

    • Can kelp extract (K ELPAK  ) be useful in seaweed mariculture?   Bolton JJ 1 , Robertson-Andersson D, Njobeni A 1 , Leitao D 1 , Anderson RJ 2 and Ruck, K 3 1 Botany Department, U CT 2 Seaweed Unit, M&CM 3 Jacobsbaai Sea Products
    •  
    • Honours project (2002, UCT). Daniela Leitao
      • Growth of 15mm excised tips of Gracilaria for 14 days (n = 15)
      • 200ml glass culture dishes in laboratory @ 15  C
      • Seawater or Provasoli ES medium (changed every 3 days)
      • Range of 1:25 to 1:25 000
      • industrial-strength KELPAK added (6 concentrations)
    • Gracilaria tip experiment
      • 1:25 and 1:125 seawater/ES:KELPAK
      • Tips died after 2 days
      • All others grew well (1:500, 1:2500, 1:5000, 1:25000)
    • Gracilaria : weight of tips after 14 days a a b b c
    • Gracilaria : weight of tips after 14 days a a ac b c d
    • Gracilaria : number of branches after 14 days
    • Gracilaria : number of branches after 14 days
    • Larger scale aquaculture of Gracilaria and Ulva at a commercial abalone farm
      • Jacobsbaai Sea Products (JSP)
      • Run as a experimental operation
      • 20 volume exchanges per day
      • Small Gracilaria and Ulva tanks (0.6 X 0.38 X 0.36 m) for experiments
        • fresh seawater tanks
        • turbot/abalone effluent tanks
        • abalone effluent tanks
    •  
    •  
    • Methods
      • Harvesting
      • Two-weekly intervals
      • Tanks are scrubbed to remove fouling epiphytic algae
      • Samples were taken to record dry to wet weight ratios and for biochemical analysis
      • Growth rate experiments
      • Relative Growth rate (RGR = % d-1)
      • RGR = [ln(Wt / W0)] / (tt – t0)
    • JSP Kelpak experiments 3 replicates of each treatment EXPT 1: Concentrations of Kelpak (1:5000, 1:2500, 1:500) added to turbot/abalone effluent EXPT 2: Chosen concentration of Kelpak in two types of effluent, with and without fertiliser supplement
    • Gracilaria at JSP: RGR in different Kelpak concns. (Run 1)
    • Temperature in JSP tanks: June/July 2002 (SD, maximum and minimum)
    • CONTROL (no KELPAK)
    • KELPAK @ 1:5000
    • KELPAK @ 1: 2500
    • KELPAK @ 1: 500
    • Gracilaria : Number of branches per 10cm apex (Runs 1 & 2)
    •  
    • E ffect s of various K elpak dilutions in turbot effluent on R GR (% d -1 ) o f Ulva at JSP
    • Effects of K elpak in turbot effluent on tissue N of Ulva at JSP
    • Fertiliser treatment As used on I&J farm at Gansbaai 6 parts Maxiphos to 1 part ammonium sul ph ate Added weekly, for 8 hours in non-flowing water in the day (08:30 to 16:30) Concentration in water after fertilization: 575  M ammonium/ 280  M phosphate
    • Effect of 1:2500 Kelpak and fertilizer (separately or combined) in turbot effluent on RGR (% d -1 ) of Ulva lactuca at JSP .
    • Effects of Kelpak (1:2500) and fertilizer in turbot effluent on tissue N (mg N per g) Ulva at JSP.
    • Abalone effluent: RGR’s
    • Abalone effluent: tissue N
    • Conclusions:
      • First demonstration of effects of seaweed extract on seaweed growth?
      • Tips of Gracilaria (lab.) – most growth with Kelpak at 1:5000 - suggestion of increased branching at Kelpak 1:25 000
      • Suggestion of increased Gracilaria branching with Kelpak treatments at JSP (turbot/abalone effluent)
      • Kelpak causes increase in Ulva growth at JSP
      • Best growth of Ulva with fertiliser plus Kelpak at 1:2500 (high N content)
      • Beneficial concentrations of Kelpak similar to those in agriculture