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1. Quahog Parasite Unknown (Qpx) And Its Growing Impact On The Hard Clam.

Author

Chew, Kenneth K.

Subjects
*ANNUAL meetings, *SHELLFISH fisheries, *ASSOCIATIONS, institutions, etc., *NORTHERN quahog, *THRAUSTOCHYTRIALES, *MARINE resources
Abstract

This article presents information on the 97th Annual Meeting of the National Shellfisheries Association held in Philadelphia, Pennsylvania from April 10-14, 2005. The first presentation was provided by Soren F. Dahl, who coauthored a paper with colleagues from Marine Sciences Research Center titled Transmission of Quahog Parasite Unknown In Hard Clams: Interactions Between Different Host Strains And Pathogen Isolates. Dahl noted this pathogen caused a major hard clam mortality event in the summer of 2002 in Raritan Bay, a source area for the state's hard clam relay fishery, necessitating the suspension of this transplant program. The second presentation was given by M. Maille Lyons, who coauthored the paper titled Quahog Parasite Unknown (QPX) and Marine Aggregates: Are Macrophytes The Link? They investigated the role of marine aggregates as an environmental reservoir for the thraustochytrid pathogenic QPX parasite of the northern quahog. The third presentation was by Bassem Allam, who coauthored the paper titled Monitoring QPX Disease In Rartan-Sandy Hook Bays: Results of A 3-year Survey Program. The quahog populations in this area represents an important marine resource for the states of New York and New Jersey, which use this population as a source for their hard clam relay fisheries. The presence of QPX in this area was confirmed during the summer of 2002, resulting in the suspension of transplant fisheries.

Published
2005

2. An object-oriented approach to automated landform mapping: A case study of drumlins

Author

Saha, Kakoli, Wells, Neil A., and Munro-Stasiuk, Mandy

Subjects
*LANDFORMS, *DRUMLINS, *GEOGRAPHY, *THREE-dimensional imaging, *POLYGONS, *PIXELS, *DIGITIZATION, *GEOMORPHOLOGICAL mapping
Abstract

Abstract: This paper details an automated object-oriented approach to mapping landforms from digital elevation models (DEMs), using the example of drumlins in the Chautauqua drumlin field in NW Pennsylvania and upstate New York. Object-oriented classification is highly desirable as it can identify specific shapes in datasets based on both the pixel values in a raster dataset and the contextual information between pixels and extracted objects. The methodology is built specifically for application to the USGS 30m resolution DEM data, which are freely available to the public and of sufficient resolution to map medium scale landforms. Using the raw DEM data, as well as derived aspect and slope, Definiens Developer (v.7) was used to perform multiresolution segmentation, followed by rule-based classification in order to extract individual polygons that represent drumlins. Drumlins obtained by automated extraction were visually and statistically compared to those identified via manual digitization. Detailed morphometric descriptive statistics such as means, ranges, and standard deviations were inspected and compared for length, width, elongation ratio, area, and perimeter. Although the manual and automated results were not always statistically identical, a more detailed comparison of just the drumlins identified by both procedures showed that the automated methods easily matched the manual digitization. Differences in the two methods related to mapping compound drumlins, and smaller and larger drumlins. The automated method generally identified more features in these categories than the manual method and thus outperformed the manual method. [Copyright &y& Elsevier]

Published
2011
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