44 



enlargement of the flood delta of a small lagoon nearby (Quahog Pond) . 

 On recent photographs, this delta is more prominent because of loss of 

 eelgrass cover, and may have expanded during the last 40 years. Boat 

 activity in the Bay has increased appreciably in recent decades and the 

 resulting sediment resuspension may have contributed to increases in 

 sedimentation there. 



The loss of resolution in the seed peaks in core WB4 may be due to 

 the slower deposition rates, increased disturbance from wave action 

 nearshore, or greater contribution from shallow annual beds that 

 persisted between declines. 



The highest rates of sedimentation occurred at the station nearest 

 to the Quashnet River (WB3) during the period 1932-1954 (8.8 mm y"-^) 

 which was higher than stations further offshore (5.5) during the same 

 period, and higher than observed later at the same station (1954-1987, 

 6.4 cm y~ ) . The higher rates may have been associated with cranberry 

 bog construction and use along the Quashnet River during the earlier 

 period. 



Using the biogenic markers and rates of sedimentation, the date of 

 recent and earlier declines can be calculated. If the most recent 

 scallop mortality is used as a marker, the date of the decline in peak B 

 can be calculated for each core. At the deepest mid-Bay station (WBl) , 

 eelgrass disappeared first -1961, then at the shallow mid-bay stations 

 in -1971 (core WB2) , -1973 (WB3, Fig. 4). In the north end of the Bay, 

 eelgrass disappeared -1965. The loss of eelgrass in deeper and upper 

 bay stations first, supports the hypothesis that these declines were 

 associated with declining light availability, because this pattern has 



