Comparing quality of estuarine and nearshore intertidal habitats for Carcinus maenas     

Valter Amaral  Henrique N. Cabral  Stuart Jenkins  Stephen Hawkins  José Paula 《Estuarine, Coastal and Shelf Science》2009

Estuarine and nearshore marine areas are vital habitats for several fish and benthic invertebrates. The shore crab Carcinus maenas (Crustacea: Brachyura: Portunidae) inhabits a variety of coastal, estuarine and lagoon habitats. At low tide, habitat structural complexity may be most important for crabs in the intertidal, providing refuge from predation and desiccation. The quality of different vegetated and nonvegetated estuarine and rocky shore habitats in SW Portugal and SW England was evaluated for intertidal C. maenas populations. We estimated population density, size–structure, and potential growth (RNA/DNA ratios) to investigate habitat quality. Vegetated estuarine habitats supported higher crab densities, than nonvegetated estuarine and rocky shore habitats. Investigation of population size–structure revealed that all habitats seem important recruitment and nursery areas although estuarine habitats in SW Portugal appeared to support higher densities of new recruits than equivalent habitats in SW England. Significant variation was found in RNA/DNA ratios among habitats. Ratios were highest in the rocky shore suggesting a high quality habitat where growth potential is high. We speculate that competition from other top-predators (Pachygrapsus spp.) rather than low habitat quality may limit the occurrence of C. maenas in intertidal rocky shore habitats in SW Portugal. In estuarine environments RNA/DNA ratios were significantly higher in the vegetated than in the nonvegetated estuarine habitats in SW Portugal but not in SW England, suggesting geographic differences in the extent to which highly structure habitats represent high quality. Our results challenge the current paradigm that structured habitats are necessarily those of higher quality for C. maenas.  相似文献   

Non-destructive xrf characterization of basaltic artifacts from Truckee,California     

Thomas S. Latham  Paula A. Sutton  Kenneth L. Verosub 《Geoarchaeology》1992,7(2):81-101

We have developed a new approach to the problem of the chemical fingerprinting of artifacts manufactured from volcanic rocks of basaltic and andesitic composition. The method is an adaptation of standard energy-dispersive X-ray fluorescence spectrometry and is based on the observation that for irregularly-shaped rock fragments, the ratios of the intensities of the characteristic X-rays of certain trace elements are proportional to the ratios of the concentrations of those elements. This observation has allowed us to obtain geochemical data about the artifacts in a way that is rapid, inexpensive, and nondestructive, making it particularly suited to archaeological applications. We have used our approach to compare a suite of artifacts from an archaeological site in Martis Valley, near Truckee, California, with a group of lava flows from the surrounding area. Using a numerical measure of the geochemical difference between samples, we have been able to group the artifacts on the basis of their geochemistry, to determine which artifacts were manufactured from material found in Martis Valley and, in at least one case, to identify the lava flow that was the actual source of the lithic material for several of the artifacts.  相似文献   

Correction to: Numerical Analysis of Infiltration in One‑Dimensional Unsaturated Soil–Geotextile Column     

Castro  G. B.  Siacara  A. T.  Nardelli  A.  Lenzi  L.  Futai  M. M. 《Geotechnical and Geological Engineering》2022,40(8):4145-4145

Geotechnical and Geological Engineering -  相似文献   

WSO‐UV project for high‐resolution spectroscopy and imaging     

M. Sachkov  B. Shustov  I. Savanov  A.I. Gmez de Castro 《Astronomische Nachrichten》2014,335(1):46-50

  相似文献