Failure to confirm previous identification of two putative museum specimens of the Atlantic sturgeon, Acipenser sturio, as the Adriatic sturgeon, A. naccarii

MtDNA analyses were employed to examine the species identification of three preserved museum sturgeon specimens from the River Guadalquivir, two of which were originally described as Acipenser sturio L., 1758 by Hernando (1975; Doñana, Acta Vertd 2: 263–264). Later the same two specimens were identified as A. naccarii Bonaparte, 1836 by Garrido-Ramos et?al. (1997; Mar Biol 129: 33–39) on the basis of morphometric and nuclear DNA analyses. Three different laboratories using independent techniques were unsuccessful in extracting authentic DNA from tissue samples from the three specimens and in obtaining any verifiable PCR product. We cannot confirm the previous molecular identification of two of these specimens by Garrido-Ramos et?al. as A. naccarii. We suggest that these specimens are indeed A. sturio.     

Assessing Watershed-Scale, Long-Term Hydrologic Impacts of Land-Use Change Using a GIS-NPS Model

Land-use change, dominated by an increase in urban/impervious areas, has a significant impact on water resources. This includes impacts on nonpoint source (NPS) pollution, which is the leading cause of degraded water quality in the United States. Traditional hydrologic models focus on estimating peak discharges and NPS pollution from high-magnitude, episodic storms and successfully address short-term, local-scale surface water management issues. However, runoff from small, low-frequency storms dominates long-term hydrologic impacts, and existing hydrologic models are usually of limited use in assessing the long-term impacts of land-use change. A long-term hydrologic impact assessment (L-THIA) model has been developed using the curve number (CN) method. Long-term climatic records are used in combination with soils and land-use information to calculate average annual runoff and NPS pollution at a watershed scale. The model is linked to a geographic information system (GIS) for convenient generation and management of model input and output data, and advanced visualization of model results. The L-THIA/NPS GIS model was applied to the Little Eagle Creek (LEC) watershed near Indianapolis, Indiana, USA. Historical land-use scenarios for 1973, 1984, and 1991 were analyzed to track land-use change in the watershed and to assess impacts on annual average runoff and NPS pollution from the watershed and its five subbasins. For the entire watershed between 1973 and 1991, an 18% increase in urban or impervious areas resulted in an estimated 80% increase in annual average runoff volume and estimated increases of more than 50% in annual average loads for lead, copper, and zinc. Estimated nutrient (nitrogen and phosphorus) loads decreased by 15% mainly because of loss of agricultural areas. The L-THIA/NPS GIS model is a powerful tool for identifying environmentally sensitive areas in terms of NPS pollution potential and for evaluating alternative land use scenarios for NPS pollution management.     

Constructing Interpretable Environments from Multidimensional Data: GIS Suitability Overlays and Principal Component Analysis

In landscape planning applications, practitioners and governmental agencies are often faced with a broad array of clientele and constituents having particular land use requirements and needs, ranging from biological conservation to urban development, generating complex multidimensional regional planning goals and objectives. Under this often complex situation, investigators are searching for methods to intelligently simplify complicated spatial environments and render them into interpretable and practical settings. While numerous investigators have studied the generation of a single suitability map, we were interested in addressing the problem of coping with a set of many suitability maps. We applied a data reduction method, principal component analysis, across 15 suitability overlays representing diverse landscape requirements to search for simplified explanations indicating the latent structure of the landscape. The study area was located in a moraine landscape of southern Michigan. We discovered that the 15 suitability overlays could be reduced to seven dimensions, containing 65% of the original data structure and that the seven dimensions reflect a structure where a variety of land uses each have their own optimal spatial locations, indicating low to moderate competition between potentially conflicting land uses and rendering a more easily understood environment. This approach did not render a simple elegant solution but it did reduce the complexity associated with combining many suitability maps.     

对美洲热带湿润低地次生林管理的看法

在休闲农地上重新长出的次生林,尽管广被忽视,仍是美洲热带低地重要的景观单元.这些在私人占用土地中"新"的森林资源不是来源于境况较好农民的非持续性的大牧场就是来源于资源贫乏农民的耕种/休闲体系.