6 

 u 



Q. 

 LlJ 

 O 



ROOTS 



0-2 

 2-5 



5-10 |~ 

 10-15 J 

 I5-20J 



100 



500 



_L_1_L 



900 



BIOMASS , g/m' 

 RHIZOMES 



100 



_| L 



500 

 I I 1 I 



r 



IT 



900 



DEAD 







MATTER 



20 



40 



i_ 



60 



__i 



Figure 18. Vertical distribution of roots, rhizones, and dead matter on the 



high marsh at Great Sippewissett Marsh on Cape Cod (Valiela et al. 1976). 



Most of the living material is found within 5 cm (2 inches) of the marsh 

 surface. 



difficult to measure than that shown 

 above ground by grasses, and Great 

 Sippewissett Marsh is the only site in 

 New England that has been studied for 

 this aspect (Van Raalte et al. 1976). 

 There is some uncertainty in the 

 results, but it appeared that algal 

 production was greatest in spring, 

 before the grass canopy shaded the 

 sediment, with a secondary peak in 

 fall. When integrated over the year, 

 algal production airiounted to some 

 IOC gdw/m^or about 20% of the average 

 aboveground S^. al terniflora produc- 

 tion. A similar value for epibenthic 

 and epiphytic algae was also found in 

 a Long Island marsh (Woodwell et al. 

 1979). 



There is also some production in 

 marsh pools by phytoplankton, 

 macroalgae, and, in some cases, rooted 

 macrophytes such as widgeongrass. 



Ruppia 



ecology 



studied 



phytopl 



pools 



marsh 



550 gdw 



Because 



portion 



contrib 



will be 



maritima. This aspect of rr;arsh 



not been adequately 



recent measurements of 



Cladophora mats in 



northern Massachusetts 



production of about 



(Ruber et al. 1981). 



usually cover a small 



m.arsh, however, their 



production 



has 



though 

 ankton and 

 on a 

 showed 

 /m^/yr 

 pools 

 of the 

 ution to total miarsh 

 considerably lower. 



All these production figures are 

 rough approximations that vary 

 considerably according to the method 

 used for measurement (Linthurst and 

 Reimold 1978) as well as from year to 

 year and from place to palce, even 

 within a restricted area. For 

 example, in three consecutive years at 

 the Great Sippewissett Marsh, Valiela 

 et al. (1975) calculated the following 

 values for the high marsh: 



39 



