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Mandy J. Munro‐Stasiuk T. Kam Manahan Trent Stockton Traci Ardren 《Geoarchaeology》2014,29(2):156-172
This study evaluates the importance of rejolladas to the Ancient Maya in and around the Classic Maya center of Xuenkal, Yucatán State, Mexico. Rejolladas are collapse sinkholes with bases above the local water table. We present a spatial and physical analysis of 186 rejolladas in a 10 × 10 km area centered on Xuenkal. Basal diameters range from ∼22 to 264 m, areas range from 0.04 to 5.48 ha, and depths range from 4 to 12 m. Spatial density ranges from 0 to 8 rejolladas/km2 with higher densities coinciding with known Ancient Maya settlements. Within Xuenkal, residential groups tend to be organized around and focused on the rejolladas. Some rejolladas have modified slopes that may be remnants of terraces or entry paths. High‐resolution satellite imagery analysis demonstrates that rejolladas have denser and healthier vegetation than the surrounding landscape especially in the dry season. Microclimate data demonstrate that the bottom of rejolladas has less extreme diurnal temperature ranges, lower daytime highs, higher atmospheric moisture, and significantly higher and more stable soil moisture. Based on the archaeology at Xuenkal, it appears that the Ancient Maya recognized and actively exploited these environmental microniches for intensive cultivation both locally and regionally. 相似文献
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Baums IB Goodwin KD Kiesling T Wanless D Diaz MR Fell JW 《Marine pollution bulletin》2007,54(5):521-536
Research to understand and remediate coastal pollution is moving toward a multitiered approach in which traditional enumeration of fecal indicators is accompanied by molecular analysis of a variety of targets. Technology that rapidly detects multiple microbial contaminants would benefit from such an approach. The Luminex 100 system is a suspension array that assays multiple analytes rapidly in a single well of a microtiter plate. The ability of the system to simultaneously detect multiple fecal indicating bacteria in environmental samples was tested. Primer/probe sets were designed to simultaneously detect the following fecal indicators: the Bacteroides fragilis group, Enterococcus spp., Escherichia coli and Shigella spp., Bacteroides distasonis, and Ent. faecalis. Specificity and sensitivity of the Luminex probes was tested against laboratory cultures. In addition, sequencing, culture plate testing, and specificity testing with environmental isolates were steps taken to validate the function of the assay with environmental samples. Luminex response to cultures and to environmental samples was consistent with sequencing results, suggesting that the technology has the potential to simultaneously detect multiple targets for coastal water quality applications, particularly as progress is made to efficiently extract DNA from water and sediment matrices. 相似文献
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Spatial and temporal variation of diverse inter‐tidal algal assemblages in Southwest O‘ahu 
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下载免费PDF全文 Spatial and temporal variation in tropical inter‐tidal communities is poorly known, making predictions about the effects of climate change and other anthropogenic disturbances difficult. Along Southwest O‘ahu, Hawai'i, local residents are concerned about the environmental effects of coastal development and the perceived loss of targeted algal species, which are collected for human consumption. To describe the coastal benthic community and better understand the processes that form and maintain it, the abundance and composition of macroalgae were sampled in the region's inter‐tidal zone from 2006 to 2015. Sixty‐six macroalgal species and two broad algal assemblages were identified that corresponded to substrate topography and sand influence at a similar tidal elevation. Along flat carbonate benches with a sand beach, Phaeophyceae and Rhodophytes occurred in almost equal proportions, while shores with slightly more topographic relief and angular substrate were dominated by Rhodophytes. Foliose or turf algal forms were most common. Surveys captured the local invasion of an alga, Avrainvillea sp. and significant declines in abundant macroalgae in 2015 after a period of unseasonably warm, calm water. Temporal changes in algal assemblages were related to maximum water temperature and wave height but not precipitation. Thus, algal assemblages appear to be structured by local beach morphology as they interact with sand and wave activity and episodically by unusual weather events. However, manipulation and continuous monitoring of the algal assemblages coupled to sensing of the localized environment is necessary to confirm factors related to assembly maintenance and recent species shifts. 相似文献
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