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          Marine Algae of Hawai`i


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Methods Manual for Managers: 

   Field Techniques for Algal Research


These methods were developed for research with the Hawaii Coral Reef Initiative Program and are being compiled for a Methods Manual to be distributed by HCRI.  The manual was written by Linda Preskitt and edited by Celia M. Smith and I.A. Abbott of the University of Hawaii, Botany Department, Honolulu, Hawaii.

More Pages:

Algal Collection


     Handling and Pressing

Photoquadrat Survey

     Photoquadrat Framer

Sediment Trap

Light Measurement

Alizarin Stain

Nutrient Enrichment


To determine the nutritional state of the marine plants.



1.5 cm diameter PVC tubing

Jobbes fertilizer spikes (13-4-5, N:P:K)

Duct tape

cable ties




This nutrient enrichment method is used in conjunction with the Alizarin Stain method to determine if environmental nutrient levels may be influencing the growth rate of the plants. If the treated plant exhibits greater growth than the untreated plants (controls), the population is very likely nutrient limited.





Construct fertilizer holders by cutting PVC tubing into 6 cm long pieces. Drill 15 holes into each piece with 5 mm drill bit, distributing holes evenly to allow for fertilizer diffusion. Insert a fertilizer spike into each drilled fertilizer holder and tape the open ends with duct tape. Put a cable tie through the middle of the holder for later attachment to the plants in the field. Attach an identification tag with a unique number to each one and prepare additional tags to be attached to the control plants in the field. 30 plants are to be fertilized, 30 to act as controls. When selecting random numbers for the Alizarin stain method, select random numbers for transect placement that allows for plants to be 1 meter apart.



After the plants have been treated with the Alizarin Stain and left for 24 hours, remove the plastic bags. If the plant is to be a control, mark the plant with a control ID tag or, if to be treated, tie the fertilizer holder onto the base of the plant with the cable tie. Follow the Alizarin Stain method for collection and processing. When processing, be sure to note which plants are treated and which are control.



Smith, J.E., C.M. Smith, P.S. Vroom, K.S. Beach and S. Miller. Nutrient dynamics of Halimeda tuna along a depth gradient in the Florida Keys: possible influence of internal tides? Submitted to Limnology and Oceanography.

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