Table 4.2. Conceptual model of algal dynamics (modified from Rudnicki 1986 and Fong 1986). 



Environmental condition 



Phytoplankton response 



Macroalgal response 



Marine tides dominate 

 Nutrient addition 

 Warm temperatures 

 Salinity reduction 



Sluggish currents 



No currents 



Optimal conditions 



Initial low biomass 



Increase 



Dinoflagellates bloom 



Bluegreen monads bloom 

 at 10 ppt 



Dilution and export 

 Blooms develop 



High nutrients 

 No tidal flushing 

 Warm temperatures 

 Any salinity 



Initial low biomass 



Increase 



Decrease 



General decrease unless 

 high nutrient cone. 



Biomass accumulates; 

 bloom develops 



Water temperature rises, 

 limits macroalgal bloom 



High nutrients 

 Reduced currents 

 Cool temperatures 

 Saline water 



Table 4.3. Productivity of benthic algal mats and vascular plants (from Zedler 1980). 



Algal productivity estimates by habitat: 



cordgrass Jaumea saltwort shore grass 



Gross primary productivity (1977) 

 (mean hourly, mg 02/m 2 /hr) 

 Coefficient of variability (%) 

 (mean daily, g 02/m 2 /day) 

 (annual, g 02/m 2 /yr) 



Gross primary productivity (1978) 

 (mg 02/m 2 /hr) 

 Coefficient of variability (%) 



Net primary productivity 



Vascular plants (g C/m 2 /yr 



Algae 3 (g C/m 2 /yr) 

 Ratio of algae:vascular plants 



a Net pri. prod, estimate = 0.85 Gross pri. prod.; PQ = 1.2. 



b Middle marsh datum. 



84 



