CHAPTER 2 

 METHODS 



, Collection of Sediment Samples 

 Sediment samples were collected from the sediment-water 

 interface of 30 Florida lakes. Lakes chosen for study were those 

 named in data sets (Canfield and Duarte 1988, Canfield unpub. data) 

 that contained data on macrophyte abundance. Lakes were selected 

 to cover the range of macrophyte presence as uniformly as possible. 

 Sediment samples were collected in two sets of field surveys. Survey 

 Set 1 consisted of samples from 10 lakes collected in the Spring of 

 1982. Samples were collected at a mid-lake station using an Ekman 

 dredge. Volumetric portions were removed with a pipette and 

 transferred to 125-ml Nalgene bottles. Sediment samples in Survey 

 Set 2 were collected between November 1987 and May 1988 from 

 20 additional Florida lakes. These samples were collected with a 77- 

 cm long, 8.8-cm diameter acrylic piston corer that was driven into 

 the sediment with 1 m long sections of magnesium-zirconium coring 

 rods. Water above the sediment-water interface was removed by 

 aspiration. The top 2 cm of sediment was collected with a syringe 

 and transferred to 125 ml Nalgene bottles. 



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