Purpose
To determine the nutritional state of the marine plants.
Materials
1.5 cm diameter PVC tubing
Jobbes fertilizer spikes (13-4-5, N:P:K)
Duct tape
cable ties
Labels
Overview
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.
Method
Preparation
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.
Deployment
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.
References
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.
