陕南镇巴筇竹寺期的海绵骨针化石

在陕南镇巴下寒武统西蒿坪段和水井沱组下段的碳酸盐地层中含有大量保存完好、类型多样的海绵骨针化石。基于形态描述法,对海绵骨针化石进行了详细的形态描述及产地与层位判断。结果表明：根据与其共生的小壳化石和三叶虫等生物地层学资料,发现这些海绵骨针化石属于筇竹寺期;该区海绵骨针类型不仅包含有形态规则的二轴四射骨针、三轴六射骨针、三轴五射骨针,而且还有形态不规则的四轴四射骨针、五轴五射骨针、尖头星状骨针、二歧分叉式骨针等;其中的四轴四射骨针、五轴五射骨针、五刺尖头星状骨针、二歧分叉二射式骨针为本次发现的新类型,极大地丰富了海绵骨针的类型。陕南镇巴筇竹寺期海绵骨针化石的数量以及分异度快速增加,充分说明海绵动物在陕南地区寒武纪早期开始大量繁盛并且迅速演化。     

Comparative Morphology, Ecology, and Fatty Acid Composition of West Indian Spheciospongia (Demospongea)

Abstract. The morphological variability of the common West Indian loggerhead sponge, Spheciospongia vesparium, is examined in light of the latest morphological and ecological information and new biochemical criteria, that is, composition and concentration of fatty acids. A typical and a yellow ecophenotypical form are distinguished. Comparing this species with its next relatives in the same zoogeographical region it is found that S. othella, first described from Bermuda, cannot be maintained as a separate species. S. cuspidifera, previously misinterpreted as "Xestospongia tier-neyi", is confirmed as a distinct species of Spheciospongia, whereas "Prianos" tierneyi is considered a morphological variant of S. vesparium.     

Cambrian Reefs in the Western North China Platform, Wuhai, Inner Mongolia

Mid to late Cambrian thrombolites and maze-like maceriate reefs from the western North China Platform, Wuhai, Inner Mongolia, northwestern China, occur in the middle of a succession dominated by thin-bedded lime mudstone-shale/marlstone alternations, and are laterally surrounded by limestone conglomerate and/or grainstone. Thrombolite, characterized by meter-scale lenticular mounds composed of millimeter- to centimeter-scale mesoclots and wackestone matrix, occurs in the lower middle part of the sequence. Thrombolite mesoclots are composed of microstromatolites with alternating dark gray and light gray micritic laminae. The maze-like maceriate reefs occur in the middle to the upper part of the sequence, commonly forming lenticular mounds up to 1 m thick. They are characterized by centimeter- to decimeter-scale branched maze-like structures, whose biogenic portions (maceria) are selectively dolomitized. The maceriae are composed of poorly preserved microstromatolites and siliceous sponges. Inter-macerial sediments consist of lime mud and scattered bioclasts. These Wuhai reefs are generally similar to but older than various other Cambrian reefs previously reported from the Shandong region, northeastern China.     

Temporal dynamics and persistence of sponge assemblages in a Central Pacific atoll lagoon

Sponges are important components of coral reef fauna, although little is known of their temporal dynamics. Sponges dominate the lagoon system at Palmyra Atoll in the Central Pacific, which may not be its natural state. Here we examined the temporal variability and recruitment rates of these sponge assemblages to determine if they are stable and examined the evidence that a recent transition has occurred from a coral‐ to sponge‐dominated system. We found 24 sponge species in permanent quadrats in the lagoon between 2009 and 2011, and 11 species on our recruitment panels. The sponge assemblage composition and abundance did not vary significantly between years and appear stable. Many sponge recruits were found in both years that the panels were examined although higher rates were recorded in the second year of the study. While it seems very possible that a change to a sponge‐dominated lagoon is associated with declining environmental quality at Palmyra as a result of modifications over 70 years ago, without pre‐modification data on reef assemblage composition this remains speculative. Our observations of short‐term temporal stability in the sponge assemblages at Palmyra highlight the potential for sponge‐dominated reef states to be maintained in degraded reef environments that are seemingly unsuitable for coral survival.     

基于流域GIS空间建模的雨洪模拟方法

基于多层次GIS空间分析模型技术,系统地建立了从流域雨洪过程相关影响因子栅格化处理到产汇流过程模型的集成化模拟方法,首次实现了对流域内任意栅格单元内河道断面的径流过程线的可视化测算。同时还对于模型中单元水流长度与河道单元流速率定方法进行了优化改进。实例分析结果表明:模型结构更为严谨、参数设置更为科学,改进的技术方法对于福建汀江十年一遇洪水场次的模拟结果精度有明显提高,能够满足相关海绵城市规划应用需求。     

不同天然海绵体特征条件下的海绵城市建设适宜性研究

海绵城市建设是近年来城市规划和雨洪管理的重要方向。针对不同的地质环境条件特征,海绵城市建设的适宜性和措施建议各不相同。本文通过对郑州市白沙和高新两个典型地貌单元的海绵城市建设示范区进行研究,在查明区域地质环境条件的基础上,运用层次分析法对两个示范区的天然地质海绵体的适宜性进行评价。评价指标选取地表海绵体中的土地利用现状、地表岩性、地形坡度、土壤环境质量,地下海绵体中的岩性结构组合、厚度。评价结果显示白沙示范区适宜性整体优于高新示范区一个级别。白沙示范区浅层地下水埋深较浅,地层渗透性强,若加大开采力度,其海绵城市建设的蓄水能力会大大增强,海绵城市建设的适宜性也会随之提升;高新示范区虽水位埋藏深,但地层渗透性差,海绵城市建设潜力相对较小。针对不同的天然海绵体条件特征,应辅以相应的LID设施建议。     

Coral colonization by the encrusting excavating Caribbean sponge Cliona delitrix

The Caribbean sponge Cliona delitrix is among the strongest reef space competitors; it is able to overpower entire coral heads by undermining coral polyps. It has become abundant in reefs exposed to organic pollution, such as San Andrés Island, Colombia, SW Caribbean. Forty‐four sponge‐colonized coral colonies were followed‐up for 13 months to establish the circumstances and the speed at which this sponge advances laterally into live coral tissue and the coral tissue retreats. Cliona delitrix presence and abundance was recorded at seven stations to interpret current reef space and coral species colonization trends. The spread of C. delitrix on a coral colony was preceded by a band of dead coral a few millimeters to several centimeters wide. However, the sponge was directly responsible for coral death only when live coral tissue was within about 2 cm distance; coral death became sponge advance‐independent at greater distances, being indirectly dependent on other conditions that tend to accelerate its retreat. Cliona delitrix advanced fastest into recently killed clean coral calices; however, sponge spread slowed down when these became colonized by algae. The lateral advance of C. delitrix was slower than other Cliona spp. encrusting excavating sponges, probably owing to the greater depth of its excavation into the substratum. Cliona delitrix prefers elevated portions of massive corals, apparently settling on recently dead areas. It currently inhabits 6–9% of colonies in reefs bordering San Andrés. It was found more frequently in Siderastrea siderea (the most abundant local massive coral), which is apparently more susceptible to tissue mortality than other corals. Current massive coral mortality caused by C. delitrix could initially change the relative proportions of coral species and in the long‐term favor foliose and branching corals.     

动荷载作用下结构性软土微结构变化的分形研究

为探讨天津滨海新区典型结构性软土的动力特性,采用动三轴试验和压汞试验,对交通荷载作用下结构性软土微观结构变化进行了研究。取原状土和动荷载作用后的土样进行压汞测试,用分形理论对压汞测试数据进行分析,探讨孔隙分布特征,提出孔径划分的方法,给出了卓越频率与土体孔隙变化的规律。研究结果表明：在动荷载作用后,天津滨海新区典型软土的孔隙分布发生改变,可分为3种类型;利用Menger海绵模型研究交通荷载作用下结构性软土的孔隙分布特性是可行的;用孔隙分维数可实现对卓越频率的预测以及路基土体变形行为的机制分析。     

Epibiotic traits of the invasive red seaweed Acanthophora spicifera in La Paz Bay,South Baja California (Eastern Pacific)

The aim of this study was to analyze the interaction of a non‐native macroalga (Acanthophora spicifera) with native macroalgae (Sargassum spp.) and sponge assemblages in a subtropical embayment of the Mexican Pacific. The intensity of A. spicifera epiphytism on the native seaweed Sargassum varied significantly over time and was inversely related to the Sargassum density and size. The higher intensity (up to 28 individuals per host plant) occurred when Sargassum was smaller and was lower in density (senescence period). The lower intensity was recorded during the growth period of Sargassum and the subsequent increase in intensity was attributed to a high fragmentation period of A. spicifera, which was evidenced by a decrease in its average size and biomass and by the presence of larger free‐floating accumulations on the subtidal zone. The facultative interaction between A. spicifera and Sargassum appears to be neutral, as no negative or positive effects were found for epiphytic or basibiont seaweeds. However, this invasive seaweed characteristically monopolizes almost all types of hard substrate, and its effects on other algae and benthic organisms should be investigated. Moreover, A. spicifera was often epizoic on epilithic sponges. This invasive seaweed was found anchored on the sponge tissue by rhizome‐like structures. In addition, free‐floating fronds of A. spicifera were frequently found carrying small pieces of the basibiont sponge in its basis (60% of them with eggs and embryos), which suggests a novel facilitation mechanism for some sponge species, as the A. spicifera epizoism could favor fragmentation, dispersal and recruitment of these invertebrates. This study shows that A. spicifera is not only a species that adapts rapidly to the new conditions of the receiving environment but, due to its epibiotic traits, it can directly interact with and influence the life histories of some native species.