ECOLOGY OF BUZZARDS BAY: An Estuarine Profile 1 1 9 



The effect of the wind has greater consequences 

 than direct damage and producing larger waves; in 

 the Buzzards Bay system winds can also have a 

 major effect on storm surge. Surge is the increase 

 in bay water levels associated with meteorologic as 

 opposed to lunar (tidal) events. Buzzards Bay is a 

 funnel-shaped estuary with the mouth facing to the 

 south-southwest, a situation enhancing the build-up 

 of wind-driven water (surge) most dramatically at 

 the head of the bay as a storm moves northward 

 (the normal path) and passes to the west. Surge is 

 also created by the low barometric pressures of 

 storm systems, especially hurricanes. The waves 

 built up by storm winds ride on top of the surge, 

 allowing them to strike the coast with greater force 

 and penetrate farther inland. 



Given the positioning and structure of Buzzards 

 Bay. the ingredients for a maximum strength coastal 

 storm are a major storm (e.g., hurricane) passing 

 near the west of the bay. maximizing winds via the 

 dangerous semicircle effect, and maximum water 

 levels from surge coinciding with the lunar high tide. 

 These were just the conditions for the largest storm 

 to hit the bay in recorded history, the "Great Long 

 Island-New England Hurricane of September 2 1 . 

 1938"(cf. Potter and Steward 1991). The forward 

 motion of the hurricane was 97-113 km/h with sus- 

 tained winds of 121-145 km/h and gusts to 161 

 km/h when it reached Buzzards Bay. In the upper 

 bay, the storm surge raised levels 4 m above the 

 coincident high tide, with waters 4.9 and 5.8 m 

 above mean low water in the bay's mid and head 

 regions, respectively. The combined high waters and 

 2.4 m wind-driven waves tossed rocks through 

 windows 8.8 m above mean low water at a site 

 near the entrance to the Cape Cod Canal (Oldale 

 1992). The 1938 hurricane was extreme but not 

 unique. In 1 954 Hurricane Carol followed the 1 938 

 track and produced an even higher surge (4.9 m) 

 because the eye passed closer to the bay. It is clear 

 that other similar storms have taken place and will 

 continue to occur. 



Storm effects on the Buzzards Bay system are 

 related to sea-level rise although they differ in sev- 

 eral aspects. One way to envision the relationship 

 is that storm effects can be increased incrementally; 



i.e.. wave height on a surge on a high tide on a rising 

 bay level. The impact of sea-level rise, on the other 

 hand, is more constant and can be predicted with 

 some confidence. An important difference is that 

 while flooding by bay incursions during storms may 

 produce "short-term" effects, an area flooded due 

 to relative sea-level rise persists. Both of these short- 

 and long-term processes result in coastal erosion 

 and the retreat of the shoreline. 



Storms do have some unique physical and eco- 

 logical effects on the bay system. Overwash of sand 

 from barrier dunes onto salt marshes (Fig. 6. 1 1 A) 

 not only restructures the dune systems and some- 

 times tidal inlet dynamics, but also can produce 

 changes in plant communities. If overwash deposits 

 cover salt marsh to a level above all but the highest 

 tides, they will not be recolonized by the marsh 

 grasses or by dune plants but sometimes will per- 

 sist for many years with a cover of opportunistic 

 colonizers (e.g., Salicornia). Storms can affect in- 

 land plant communities as well, not only through the 

 obvious effects of uprooting trees but also often 

 through greater effects of desiccation and salt sprays 

 as almost all inland plants are not salt tolerant. These 

 latter processes were responsible for major impacts 

 to the terrestrial ecosystems within the Buzzards Bay 

 watershed during the passage of Hurricane Bob. 

 1 9 August 1 991 . The eastern shore of the bay re- 

 ceived almost no rain during the hurricane, but in- 

 stead a spray of salt water was delivered kilome- 

 ters inland. The result was that many deciduous 

 trees browned and lost their leaves, and a few died. 

 However, among the affected conifers, particularly 

 the relatively salt-sensitive white pine trees, a mor- 

 tality of 50% was predicted (Potter 1 99 1 ). The ef- 

 fects of salt spray are compounded by the simulta- 

 neous high winds, which increase the rate of 

 evaporation from the leaves and hence enhance 

 their desiccation. 



Storms that deposit significant fresh water can 

 also have important ecological impacts, primarily 

 on aquatic systems. The increased freshwater flow 

 into coastal salt ponds and embayments carries with 

 it sediments and nutrients and frequently results in a 

 temporary stratification of water columns. 



