49 



Discussion 



Based on the estimated sedimentation rates and seed densities, 

 seed deposition rates were as high as 2000-6000 m ^ y -^ m Waquoit Bay, 

 which is somewhat higher than the mean deposition of new seeds measured 

 at the mouth of that Bay (slOOO seeds m ■^ y •^) . This difference may not 

 be significant because there considerable variability in the density of 

 recently produced seeds in surface cores within beds. Similarly, cores 

 from the other bays suggest that the seed deposition rates generally 

 peak between 1500-2500 seeds my. These rates of seed deposition 

 are consistent with seed production rates measured elsewhere (Thayer et 

 al., 1984), and with rates that I have measured locally (up to 15,000 



— 7 —1 



seeds m ^ y ■^) . 



Other factors may contribute to different seed deposition rates in 

 eelgrass beds. Environmental conditions have a strong effect on the 

 expression of flower abundance in eelgrass, and therefore seed 

 production (Phillips et al., 1983). Some eelgrass beds produce mostly 

 reproductive shoots and others produce mostly vegetative shoots, and 

 there is a high degree of consistency for beds in a particular habitat 

 (Phillips et al.,1983; Keddy, 1987). For example, Allee (1923b) noted 

 that eelgrass beds in the Northwest gutter of Uncatena Island in the 

 Elizabeth Islands always have high flower densities. These beds 

 continue to have high flower densities today (pers. obser) . 



Thus, eelgrass seed coat abundance is a good indicator of local, 

 relative eelgrass abundance, but not necessarily an absolute indicator 

 of biomass or production. Undoubtedly there are yearly differences in 

 seed production, but because these core sections equal 2.5-8 years of 



