九孔鲍担轮幼虫畸形的形态与组织学研究

本文针对九孔鲍人工育苗中担轮幼虫出现的大量畸形现象，采用了组织病理学研究方法，通过石蜡切片的苏木精．曙红、苏木精．苏丹黑和苏木精．品红的染色结果表明：膜内畸形担轮幼虫的游离物质为多糖类，结合透射电子显微镜观察尚未发现病原体，初步推断九孔鲍担轮幼虫的产生并非病原性疾病；本文还阐述了九孔鲍担轮幼虫的基本结构，认为健康成熟的亲鲍和适宜的环境条件是减少九孔鲍畸形幼虫的关键，强调幼虫选育的重要性．     

Quasi-three-dimensional modelling of the morphology of longshore bars

A morphological quasi-three-dimensional (Q3D) area model for barred coasts has been developed. The model combines a two-dimensional depth integrated model for wave-driven currents with a model for undertow circulation currents. The combined model makes a simultaneous simulation of the bar-forming processes associated with the undertow and the horizontal wave-driven circulation currents, which may cause instabilities of the bar and the formation of rip channels. Situations with normal and oblique wave incidence are considered. Compared to the depth integrated approach the Q3D model produces less pronounced alongshore irregularities for obliquely incident waves. For normal incident waves the Q3D model produces a crescentic bar while the depth integrated model predicts almost straight sections of the bar interrupted by rip channels. The sensitivity to variation of wave angle and beach slope is further investigated.     

The influence of particle morphology on microbially induced CaCO3 clogging in granular media

Abstract

Sporosarcina pasteurii (ATCC 11859) is a nitrogen-circulating bacterium capable of precipitating calcium carbonate given a calcium source and urea. This microbially induced carbonate precipitation (MICP) is able to infill inter-granular porosity and act as a biological clogging agent, thus having a wide potential application in strengthening coastal foundations, preventing erosion by seas and rivers and in reducing sand liquefaction potential in coastal areas. A successful MICP application requires the understanding of the primary parameters that influence the microbially mediated process to achieve its engineering goals, such as injection scheme, chemical concentrations, retention times, and injection rates. However, the granular morphology has generally been oversimplified to ideal shape without enough consideration in previous studies. The following explores the critical micro-scale influence of particle morphology on mechanisms of microbially induced clogging. Spherical, non-spherical and angular particles were used as granular aggregates in permeating column experiments with the resulting permeability and calcium carbonate content of the treated aggregates examined. Microscopic examination (SEM) defines the features of the distribution of microbially precipitated calcium carbonate and the forms of clogging. The results show: (1) given a fixed duration of treatment, the calcium carbonate content for the spherical particle aggregate is significantly higher than that for near-spherical and angular particle aggregates; (2) for identical durations of treatment, the maximum permeability reduction occurs for angular particles (rather than for spherical particles with the highest carbonate content). This suggests that the microscopic distribution of calcium carbonate is significantly influenced by particle morphology, exerting a critical control in the effectiveness of clogging. SEM images indicate that the microbial calcium carbonate precipitates encapsulate the spherical particles as a near-uniform shell and occlude the pore space only by increasing the shell thickness. In contrast, the near-spherical and angular particles are only partially coated by a calcium carbonate film with scattered crystals of vaterite and calcite further clogging the void space. The polyhedral nature of the non-spherical particles tends to result in a slot-shaped pore structure which critically defines the hydraulic conductivity of the ensemble medium. As the microbial vaterite and calcite continue to accumulate on the particle surface, these slot-shaped pore structures become increasingly more tortuous – resulting in a noticeable reduction of permeability at a lower calcium carbonate content.     

Quantification of nearshore morphology based on video imaging

The Argus network is a series of video cameras with aerial views of beaches around the world. Intensity contrasts in time exposure images reveal areas of preferential breaking, which are closely tied to underlying bed morphology. This relationship was further investigated, including the effect of tidal elevation and wave height on the presence of wave breaking and its cross-shore position over sand bars. Computerized methods of objectively extracting shoreline and sand bar locations were developed, allowing the vast quantity of data generated by Argus to be more effectively examined. Once features were identified in the images, daily alongshore mean values were taken to create time series of shoreline and sand bar location, which were analyzed for annual cycles and cross-correlated with wave data to investigate environmental forcing and response.These data extraction techniques were applied to images from four of the Argus camera sites. A relationship between wave height and shoreline location was found in which increased wave heights resulted in more landward shoreline positions; given the short lag times over which this correlation was significant, and that the strong annual signal in wave height was not replicated in the shoreline time series, it is likely that this relationship is a result of set-up during periods of large waves. Wave height was also found to have an effect on sand bar location, whereby an increase in wave height resulted in offshore bar migration. This correlation was significant over much longer time lags than the relationship between wave height and shoreline location, and a strong annual signal was found in the location of almost all observed bars, indicating that the sand bars are migrating with changes in wave height. In the case of the site with multiple sand bars, the offshore bars responded more significantly to changes in wave height, whereas the innermost bar seemed to be shielded from incident wave energy by breaking over the other bars. A relationship was also found between a site's mean wave height and inner sand bar location; sites with the highest wave heights tended to have sand bars farther from shore than those with relatively low wave heights.     

Morphodynamic classification of sandy beaches in low energetic marine environment

Morphodynamic classification of beaches has achieved widespread acceptance in both geological and geomorphological literature. In this sense, the present work classifies twelve Mediterranean low energetic beaches according to the dimensionless fall parameter (Ω) parameter in the Island of Mallorca. Propagation of 44 yr of wave data as well as a detailed sediment study allows to provide probabilities for morphodynamical beach state on an annual and seasonal basis. Consequently, beaches in Mallorca fall between three major categories which are (a) truly reflective, (b) reflective skewed to intermediate and (c) intermediate beaches. The Mallorcan beach position in the morphodynamical scheme is close related to the physiographical and geological framework. Comparison of observed values with those obtained in the analysis leads that for gross beach classification there is agreement between predicted and real state. However on a seasonal classification, mainly during summer, there is no agreement between the predicted state and the real one. As the model does not incorporate the role of summer sea breezes, beach reflective states are highlighted. Real beach configurations correspond to more energetic wave dynamic conditions and to intermediate state scenarios.     

一种纤毛虫的分类及形态研究 ——寄生于牙鲆体表溃烂组织中的指状拟舟虫

报道从牙鲆（Paralichthys olivaceus）体表溃烂组织分离的一种纤毛虫，通过活体观察、扫描电镜、蛋白银染色法、银浸法，对其形态学及纤毛图式做了研究。经鉴定，该纤毛虫为指状拟舟虫（Paralembus digitiformis Kahl，1933），隶属于寡膜纲、盾纤目、嗜污科、拟舟虫属。这是指状拟舟虫在牙鲆上兼性寄生的首次报道。     

Ossicle Morphology of four Sea Star Species of the Genus Astropecten (Asteroidea; Echinodermata) and its Bearing on the Investigation of a Predator's Diet

Abstract. The ossicle morphology of four sea star species of the genus Astropecten occurring in Sardinia, Italy, was investigated. Medial inferomarginals are species specific in structure, and readily differentiated by observation at low magnification in the field. Body sizes of ingested sea stars can be assessed from the size of remains such as mouth plates and selected inferomarginals, providing a basis for quantifying predation impact upon those species. We applied this method to Astropecten aranciacus L. which is common in the Mediterranean Sea.