View of Paraiso Yard showing dredging equipment, Panama Canal. (ca. 1914)

Leonard Carpenter Panama Canal Collection. Photographs: Dredging, Soldiers, and Ships. [Box 1] from the Special Collections & Area Studies Department, George A. Smathers Libraries, University of Florida.

A short survey of the environment at the dumping site for Santa Cruz Harbor dredging and A study of seaward dipping internal structures in marine ripple marks at Whaler's Cove, California. Annual report, Part 4, August 1972

(PDF contains 76 pages)

Environmental impact of hydraulic escalator dredging on oyster communities

A study to assess the effects of hydraulic escalator dredging on an oyster community was initiated at the request of the Department of Natural Resources, Mary1and Tidewater Fisheries Administration. The purpose of the work was to reevaluate a study done by Manning (1957). A site in the Patuxent River north of Broome Island classified as oyster bottom was selected to conduct an in - situ intensive experiment using the Manning study as a framework for project design. Clams and oysters were present in the study area,although oyster populations were limited in number. (PDFs consists of pp 1-97 and additional Sect II: Middle Bay proposed reclassification sites)

Patterns of succession in benthic infaunal communities following dredging and dredged material disposal in Monterey Bay

This report is the final product of a two-year study conducted for the Office, Chief of Engineers, by the Moss Landing Marine Laboratories, Moss Landing, California, under Contract No. DACW39-74-C-OI51 with the Environmental Effects Laboratory (EEL), U. S. Army Engineer Waterways Experiment Station (WES), Yicksburg, Mississippi. (PDF contains 192 pages)

Effects of harvesting methods on sustainability of a bay scallop fishery: dredging uproots seagrass and displaces recruits

Fishing is widely recognized to have profound effects on estuarine and marine ecosystems (Hammer and Jansson, 1993; Dayton et al., 1995). Intense commercial and recreational harvest of valuable species can result in population collapses of target and nontarget species (Botsford et al., 1997; Pauly et al., 1998; Collie et al. 2000; Jackson et al., 2001). Fishing gear, such as trawls and dredges, that are dragged over the seafloor inflict damage to the benthic habitat (Dayton et al., 1995; Engel and Kvitek, 1995; Jennings and Kaiser, 1998; Watling and Norse, 1998). As the growing human population, over-capitalization, and increasing government subsidies of fishing place increasing pressures on marine resources (Myers, 1997), a clear understanding of the mechanisms by which fishing affects coastal systems is required to craft sustainable fisheries management.

Distribution and abundance of Dungeness crab and crangon shrimp, and dredging-related mortality of invertebrates and fish in Grays Harbor, Washington

The impacts of widening and deepening the existing navigation channel in Grays Harbor on Dungeness crab, crangon shrimp and fish was investigated. The spatial and temporal distribution of these organisms was studied using an otter trawl and ring nets, and the uptake of organisms by dredges was estimated from samples collected on working hopper and pipeline dredges. ... Impacts of the dredging project on crabs, shrimp and fish could be associated with entrainment, food loss and toxicants released from sediments. Scenarios are presented that predict impacts. Suggestions for reducing impacts are given.

Conserving oyster reef habitat by switching from dredging and tonging to diver-harvesting

A major cause of the steep declines of American oyster (Crassostrea virginica) fisheries is the loss of oyster habitat through the use of dredges that have mined the reef substrata during a century of intense harvest. Experiments comparing the efficiency and habitat impacts of three alternative gears for harvesting oysters revealed differences among gear types that might be used to help improve the sustainability of commercial oyster fisheries. Hand harvesting by divers produced 25−32% more oysters per unit of time of fishing than traditional dredging and tonging, although the dive operation required two fishermen, rather than one. Per capita returns for dive operations may nonetheless be competitive with returns for other gears even in the short term if one person culling on deck can serve two or three divers. Dredging reduced the height of reef habitat by 34%, significantly more than the 23% reduction caused by tonging, both of which were greater than the 6% reduction induced by diver hand-harvesting. Thus, conservation of the essential habitat and sustainability of the subtidal oyster fishery can be enhanced by switching to diver hand-harvesting. Management schemes must intervene to drive the change in harvest methods because fishermen will face relatively high costs in making the switch and will not necessarily realize the long-term ecological benefits.

The Corogal: one of the big dredges in Culebra Cut, Panama Canal (ca. 1914)

Leonard Carpenter Panama Canal Collection. Photographs: Dredging, Soldiers, and Ships. [Box 1] from the Special Collections & Area Studies Department, George A. Smathers Libraries, University of Florida.

First U.S. battleships through Panama Canal: Missouri, Ohio, Wisconsin (postcard ca 1914)

Leonard Carpenter Panama Canal Collection. Photographs: Dredging, Soldiers, and Ships. [Box 1] from the Special Collections & Area Studies Department, George A. Smathers Libraries, University of Florida.

Tow boat fleet at Paraiso, Panama Canal (ca. 1914)

Leonard Carpenter Panama Canal Collection. Photographs: Dredging, Soldiers, and Ships. [Box 1] from the Special Collections & Area Studies Department, George A. Smathers Libraries, University of Florida.

Panama Beach

Leonard Carpenter Panama Canal Collection. Photographs: Dredging, Soldiers, and Ships. [Box 1] from the Special Collections & Area Studies Department, George A. Smathers Libraries, University of Florida. Photo caption: The tide rises 20 feet at high tide; at low tide the boats are used as stores to market goods.

Emergency dam at Pedro Miguel, Panama Canal (ca. 1914)

Leonard Carpenter Panama Canal Collection. Photographs: Dredging, Soldiers, and Ships. [Box 1] from the Special Collections & Area Studies Department, George A. Smathers Libraries, University of Florida.

Berm cranes at Miraflores Locks

Leonard Carpenter Panama Canal Collection. Photographs: Dredging, Soldiers, and Ships. [Box 1] from the Special Collections & Area Studies Department, George A. Smathers Libraries, University of Florida. Photo notation: These are most economical in handling concrete but not so elastic as the cable way method (ca. 1914)

Lantern spillway and hydroelectric plant, Panama Canal (ca. 1914)

Leonard Carpenter Panama Canal Collection. Photographs: Dredging, Soldiers, and Ships. [Box 1] from the Special Collections & Area Studies Department, George A. Smathers Libraries, University of Florida.