91. KYTE, M.H., AVERILL, P., and HENDERSHOTT, T., "The Impact of the Hydraulic 

 Escalator Shellfish Harvester on an Intertidal Soft-Shell Clam Flat in 

 the Harruseeket River, Maine," Project NOAA - NMFS-3-170-R, Main State 

 Department of Marine Resources, Augusta, Me., Mar. 1975. 



A hydraulic escalator shellfish harvester originally developed by Fletcher 

 Banks in Maryland has been the basis of a significant fishery on Mya areruxria, 

 the soft-shell clam, for the last 20 years in the Chesapeake Bay. The similar- 

 ity to actual dredging has caused much concern to be expressed over the impact 

 of the harvester on the stocks of clams and on the associated biota and environ- 

 ment. An attempt was made to establish an escalator harvester fishery in Maine. 

 The rather alarming appearance of a turbidity plume and the harvesting scars 

 prompted the initiation of an impact study. The report details that study. 

 The development, impact study, and fishery history are briefly reviewed. The 

 impact study performed in Maine was specifically located in an area character- 

 ized by a silt-clay mudflat. 



92. LEATHEM, W., "Effect on Spoil Disposal or Benthic Communities Near the 

 Mouth of Delaware Bay," Marine Pollution Bulletin^ Vol. 4, No. 8, Aug. 

 1973, pp. 122-125. 



Hydrualic dredging and spoil disposal behind the inner breakwater in 

 Delaware Bay had an impact at distances over several kilometers from the site 

 of operations. While the dissolved oxygen and the density of animals fell in 

 the areas immediately affected, the total impact of this operation appears to 

 have been small. There might have been some recruitment of animals to the 

 spoil areas after the operations. The greatest damage to benthic macroinver- 

 tebrates occurred in the dredging and dump sites, which demonstrated signifi- 

 cant changes in community structure due to reduced numbers. However, oxygen 

 saturation returned to predredging values within 3 months, indicating that 

 potential damage to the benthos was probably negligible. 



93. LEHMAN, E.J., "Dredging: Biological Effects," Citation, National Technical 

 Information Service, Springfield, Va., Dec. 1979. 



This is a citation of federally funded research covering the relationship 

 of dredging to biology in estuaries, marshes, harbors, channels, and waterways. 

 Some of the topics include the wildlife habitat of dredge spoil sites, eco- 

 system studies, and the detrimental effects of dredge material. 



94. LEVINGS, CD., "Consequences of Training Walls and Jetties for Aquatic 

 Habitats at Two British Columbia Estuaries," Coastal Engineering, Vol. 4, 

 Elsevier Scientific Publishing Company, Amsterdam, 1980, pp. 111-136. 



The effects of training walls and river channelization on macroinverte- 

 brates and their habitats were studied at the Squamish and Fraser River estu- 

 aries in southwestern British Columbia. A similar, but undisturbed estuary, 

 the Homathko, was also examined. Training walls deflected freshwater from 

 sectors of the Fraser and Squamish estuaries, whereas the Homathko salinity 

 distributions were uniform across the delta front. At the Squamish estuary, 

 the training wall has allowed penetration of a salt wedge into a former river 

 channel; the flow of water in culverts through the wall has only a local miti- 

 gative effect. Erosion is continuing in the trained part of the Squamish River, 

 but important intertidal habitats behind the wall have remained unchanged for 

 6 to 7 years. Sediments stabilized or redistributed by river channelization 



33 



