Studies of the influence of parasites on host fitness generally conclude that parasites have a strong negative effect on their hosts. In this study, we have investigated experimentally the role of Polymorphus minutus, an acanthocephalan parasite, on the salinity tolerance of the freshwater amphipod Gammarus roeseli, one of its intermediate hosts. Unexpectedly, P. minutus-infected gammarids were more tolerant to salinity stress than uninfected ones. The mean lethal salt concentrations for 50% mortality of hosts tested were 17.3 (infected) and 9.7 g/L (uninfected). The parasitic load (one or two parasites per host) did not affect the result. The size of hosts had no significant influence on the salinity tolerance of either infected or uninfected gammarids. The mobility of all types of gammarid decreased when the salinity exceeded 9.0 g/L, but there was no significant difference between infected and uninfected gammarids. We discuss the higher salinity tolerance of infected amphipods in relation to O(2) consumption and osmoregulation. Finally, we demonstrate that the salinity tolerance is enhanced in the parasitized amphipod but without a significant change in behavior or an osmoregulatory adjustment.

No abstract

In 2016, the U.S. Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory (CHL), Ship-Tow Simulator (STS) was used to perform a navigation study assisting the Charleston District in evaluating different channel widening alternatives for larger containerships calling at the Port of Charleston. The widening proposals were associated with the proposed Charleston Harbor Deepening and Widening Project, known as Post 45. The Feasibility Study for the Post 45 project has already been completed. This study was done at the CHL STS real-time simulator. Real-time refers to the fact that model time uses a 1:1 ratio to prototype time. Also, realworld environmental forces were simulated and acted upon the modeled ships during the study. These forces included currents, wind, waves, bathymetry, bank effects, and ship-to-ship interaction. Simulations for the project's alternatives were conducted at CHL over a 6-week period from March through May 2016. More than 20 mariners including harbor pilots, docking pilots, and tractor tug captains participated in the testing and validation exercises. Most of the simulations involved containerships of either Post Panamax Generation 3 class or Post Panamax Generation 2 class. Results, in the form of track plots and pilot questionnaires, were reviewed to develop final conclusions and recommendations.

In 2018, the U.S. Army Engineer Research and Development Center (ERDC), Coastal and Hydraulics Laboratory, participated in a navigation study to assist the Virginia Port Authority evaluation of a proposed channel widening alternative for the Port of Norfolk, Virginia. The proposal will allow large coal colliers and containerships to load to a deeper draft. The proposals also included deepening portions of Norfolk Harbor and providing additional widening in one section for two-way traffic. The simulations were conducted at the Maritime Institute of Technical and Graduate Studies (MITAGS) facility in Linthicum, MD. Moffatt & Nichol directed the simulation and modeling efforts, with assistance from Webb Simulation Consulting. The U.S. Army Engineer District, Norfolk, and ERDC provided oversight to ensure that all U.S. Army Corps of Engineers simulator study requirements were met. The MITAGS simulator includes a variety of environmental forces act upon the ship during the simulation transit. These include currents, wind, waves, bathymetry, and ship-to-ship interaction. Online simulations of the project were conducted at MITAGS. Seven mariners including harbor pilots and a master mariner participated in the testing and validation exercises. Results in the form of track plots and pilot questionnaires were reviewed to develop final conclusions. DISCLAIMER: The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents.

Boston Harbor is located on the eastern shore of the Commonwealth of Massachusetts, on Massachusetts Bay. The Corps of Engineers and the Massachusetts Port Authority (Massport) are evaluating a number of improvements to Boston Harbor. These improvements include deepening and widening portions of the Broad Sound North Entrance Channel, Main Ship Channel, and lower Reserved Channel and its turning area for the benefit of larger container vessels calling on Massport's Conley Terminal. To assist in evaluating these improvements, the U.S. Army Engineer Research and Development Center (ERDC) conducted a ship-simulatorbased navigation study. Data for the simulation models were obtained during a site visit to ride ships in the project area. Currents for both the existing and proposed channels were calculated using the ADCIRC computer model in a joint effort between ERDC and the U.S. Army Engineer District, New England. Harbor pilots traveled from Boston to validate and operate the simulations in September 2005.