Effects of size and temperature on mud crab,Panopeus herbstii,predation on hard clams,Mercenaria mercenaria

Predation byPanopeus herbstii onMercenaria mercenaria was significantly affected by temperature, and the size of predators and prey items. LargerP. herbstii opened more clams and preyed more successfully on larger clams than did smaller crabs. Increase in seed clam size and decrease in water temperature significantly reduced predation. Clam size appeared to be more important than crab satiation in reducing predation rate. Planting larger seed clams in cooler months should help to improve clam survival by reducing the impact ofP. herbstii in culture operations.     

Food habits and feeding behavior of the cownose ray,Rhinoptera bonasus,in lower Chesapeake Bay

The most important food item of the cownose ray,Rhinoptera bonasus, in the Virginian tributaries of lower Chesapeake Bay is the soft shell clam,Mya arenaria. The Baltic macoma,Macoma balthica, ranks a distant second. Adult rays feed on deep burrowing mollusks, juveniles on shallow- or non-burrowing bivalves. Foraging schools of rays invade tidal flats during the flood tide. Stirring motions of the pectoral fins combined with suction from the expansive orobranchial chamber are probably used to excavate deep burrowing bivalves.     

Effects of the herbicide alachlor on larval development of the mud crab,Rhithropanopeus harrisii (Gould)

The effects of the herbicide alachlor, in both technical grade and commercial product form (Lasso), were tested for acute toxicity on larvae of the estuarine crabRhithropanopeus harrisii. The generalized effect is a reduction in survival and a lengthening of developmental time with an increase in concentration. The LC₅₀ values were inversely proportional to exposure time and ranged from 10 to 27 mg l^?1. Lasso was slightly more toxic than technical grade alachlor.     

赤泥中的稀土资源:分布、赋存和提取

铝土矿中通常含有一定量的稀土元素(REE),氧化铝生产过程导致矿石中几乎所有的REE都富集到赤泥中,其中喀斯特型铝土矿所产生赤泥中的REE含量相对更高,是潜在的REE二次资源,综合利用赤泥中的REE己成为研究热点之一.已有的研究表明,REE分布于赤泥的各个矿物相,包括铝土矿保留下来的矿物相或新形成的矿物相.类质同象可能是其中REE的主要赋存形式,含Fe或Ti的矿物是其主要载体矿物,存在少量REE独立矿物,硅酸盐矿物相或新形成的矿物相也是REE潜在载体矿物.目前,赤泥中REE回收利用多处于实验室研究阶段,包括直接酸浸、焙烧浸出和生物浸出等方法.对比结果表明,直接酸浸和焙烧浸出是有效的赤泥回收REE的方法,但难点是如何增加浸出的选择性,及简化工艺流程.此外,生物浸出的过程更绿色环保,可能成为未来最具前景的回收REE的方法.在回收过程中,设计和发展多元素回收工艺,将Fe、Al、Na、Ti和REE等元素均纳入提取回收流程,并将有用金属回收后所产生的残渣作为制备建筑装饰、催化支撑材料、吸附剂等的原材料,将是赤泥综合利用未来发展方向.     

Food habits and distribution of wintering canvasbacks,Aythya valisineria,on Chesapeake Bay

Baltic clams (Macoma balthica) were the predominant food items of 323 canvasbacks (Aythya valisineria) collected throughout Chesapeake Bay during 1970–1979. Natural vegetation constituted 4% of the food volume. Widgeongrass (Ruppia maritima) and redhead grass (Potamogeton perfoliatus) constituted the greatest percent volume and frequency of occurrence among the plant species, whereas wild celery (Vallisneria americana) constituted only a trace of the food volume. These results contrast with historical records of food habits of canvasbacks in Chesapeake Bay. Canvasback population estimates during the 1970’s were examined to detect annual and seasonal changes in distribution. Linear regression analyses of winter canvasback populations in the bay showed a significant decline in the upper-bay and middle-bay populations, but no significant changes in the lower-bay and Potomac River populations. The changes in winter distribution and abundance of the canvasback appear related to changes in natural food availability, which is the result of altered environmental conditions.     

The Influence of Benthic Macrofauna on the Erodibility of Intertidal Sediments with Varying mud Content in Three New Zealand Estuaries

Fine sediment inputs can alter estuarine ecosystem structure and function. However, natural variations in the processes that regulate sediment transport make it difficult to predict their fate. In this study, sediments were sampled at different times (2011–2012) from 45 points across intertidal sandflat transects in three New Zealand estuaries (Whitford, Whangamata, and Kawhia) encompassing a wide range in mud (≤63 μm) content (0–56 %) and macrofaunal community structure. Using a core-based erosion measurement device (EROMES), we calculated three distinct measures of sediment erosion potential: erosion threshold (? _c ; N m^?2), erosion rate (ER; g m^?2 s^?1), and change in erosion rate with increasing bed shear stress (m _e ; g N^?1 s^?1). Collectively, these measures characterized surface (? _c and ER) and sub-surface (m _e ) erosion. Benthic macrofauna were grouped by functional traits (size and motility) and data pooled across estuaries to determine relationships between abiotic (mud content, mean grain size) and biotic (benthic macrofauna, microbial biomass) variables and erosion measures. Results indicated that small bioturbating macrofauna (predominantly freely motile species <5 mm in size) destabilized surface sediments, explaining 23 % of the variation in ? _c (p ≤ 0.01) and 59 % of the variation in ER (p ≤ 0.01). Alternatively, mud content and mean grain size cumulatively explained 61 % of the variation in m _e (p ≤ 0.01), where increasing mud and grain size stabilized sub-surface sediments. These results highlight that the importance of biotic and abiotic predictors vary with erosion stage and that functional group classifications are a useful way to determine the impact of benthic macrofauna on sediment erodibility across communities with different species composition.     

Seasonal abundance and vertical distribution of crab larvae in Delaware Bay

Larvae of 15 species or genera of crabs were collected and identified during a six month (May 26 to October 28, 1978) study in the mouth of Delaware Bay. Seasonal abundance and vertical distribution of each species were investigated. Most species studied had peak abundance in July and August except forCancer irroratus andOvalipes ocellatus which showed peak occurrence in May and June, respectively. Larvae of species strongly dependent on estuarine habitats, such asUca spp.,Pinnixa chaetopterana, andP. sayana, showed a tendency to congregate in near-bottom waters where net flow of water is landward, thus favoring retention within the estuary. Larvae ofOvalipes ocellatus, Cancer irroratus, andCallinectes sapidus were more common at the surface. This vertical distribution suggests that these larvae are flushed out of the estuary. The mechanisms of recruitment and replenishment of adult populations within the estuary would therefore depend on migration of megalopa and juveniles. *** DIRECT SUPPORT *** A01BY019 00006     

Temporal and vertical distribution of crab larvae in a tidal pass

We investigated the vertical and temporal distributions of portunid zoea andCallinectes megalopae in a tidal pass of the Texas coast. Zoea were equally abundant on ebb and flood tide but were more abundant during the day than at night. Megalopae were more abundant during flood tide and at night than during ebb tide or during the day. We examined the evidence for selective tidal stream transport in both life-history stages. Depth of the centers of mass of the larval distributions and the dispersions around those centers were unrelated to temperature, salinity, current velocity, and time of day. Scaling arguments suggest that the absence of pattern in the vertical distributions was not due to turbulent mixing. There was little evidence that either larval stage used these environmental characteristics as cues for changes in behaviour. However, the presence of megalopae in the water column primarily during flood tide does support the tidal transport hypothesis. Megalopae may have difficulty sensing and reacting to environmental cues in wellmixed estuaries with semidiurnal tides.     

Vertical distribution and feeding types of nematodes from Chetumal Bay, Quintana Roo, Mexico

The vertical distribution and feeding type of nematodes in sediments of Chetumal Bay, Mexico, were studied in five intertidal transects along the urbanized zone in June and December 1995. Sediments were collected with a PVC corer to 6-cm sediment depth and cut immediately into three equal 2-cm depth fractions. Nematode density varied from 7.4 × 10³ to 5.3 × 10⁵ m^?2 in June and from 1.7 × 10⁴ to 7.2 × 10⁵ m^?2 in December. In June, the epistrate feederPseudochromadora sp. was the most abundant in the deepest sediment fraction (4–6 cm), whereas epistrate feeders,Neotonchoides sp.,Desmodora sp., and the deposit feederBathylaimus australis were dominant in the top most sediment (0–2 cm). In December, deposit feeders,Desmolaimus zeelandicus, Parodontophora sp., and the epistrate feederOncholaimus oxyuris were the most abundant in the deepest sediment, whereasNeotonchoides sp. andPseudochromadora sp. dominated the first 2 cm of sediments. Highest nematode density was recorded in the uppermost sediment layer (0–2 cm). Feeding types showed different abundance among transects and between months. There was a seasonal change in vertical distribution of nematodes, with the highest abundance in the deepest sediment layer in December, possibly due to the effect of wind waves on sediments of Chetumal Bay. The trophic composition of the nematode fauna in Chetumal Bay showed a dominance of deposit feeders and epistrate feeders, most likely in response to organic enrichment that is typical of eutrophic environments.     

颗粒级配及初始干密度对路基翻浆冒泥特性的影响

重载铁路路基翻浆冒泥病害广泛存在且危害性极大,严重影响了轨道的稳定性和列车运行的安全性。铁路路基土体性质,如颗粒级配、孔隙比等对列车荷载作用下路基翻浆冒泥特性有显著的影响。利用自主研发的试验模型对粉质黏土与不同含量高岭土重塑试样进行翻浆冒泥试验,研究了不同颗粒级配（高岭土含量）、不同初始干密度（孔隙比）对循环荷载作用下试样的轴向应变、超孔隙水压力以及细颗粒迁移特性的影响。研究结果表明：随着高岭土含量以及初始干密度的增加,动荷载作用下试样产生的轴向应变、超孔隙水压力均减小,细颗粒迁移的平均高度降低,路基翻浆冒泥的程度减轻。通过试验发现,动荷载作用下试样内部的超孔隙水压力梯度是驱动路基土体细颗粒迁移的主导因素,试样产生的夹层对路基翻浆冒泥病害的发展具有一定的促进作用。     

Distribution and characters of the mud diapirs and mud volcanoes off southwest Taiwan

In order to identify the mud diapirs and mud volcanoes off SW Taiwan, we have examined ∼1500 km long MCS profiles and related marine geophysical data. Our results show ten quasi-linear mud diapirs, oriented NNE–SSW to N–S directions. Thirteen mud volcanoes are identified from the multibeam bathymetric data. These mud volcanoes generally occur on tops of the diapiric structures. Moreover, the active mud flow tracks out of mud volcanoes MV1, MV3 and MV6 are observed through the high backscatter intensity stripes on the sidescan sonar images. The heights of the cone-shaped mud volcanoes range from 65 m to 345 m, and the diameters at base from 680 m to 4100 m. These mud volcanoes have abrupt slopes between 5.3° and 13.6°, implying the mudflow is active and highly viscous. In contrast, the flat crests of mud volcanoes are due to relative lower-viscosity flows. The larger cone-shaped mud volcanoes located at deeper water depths could be related to a longer eruption history. The formation of mud diapirs and volcanoes in the study area are ascribed to the overpressure in sedimentary layers, compressional tectonic forces and gas-bearing fluids. Especially, the gas-bearing fluid plays an important role in enhancing the intrusion after the diapirism as a large amount of gas expulsions is observed. The morphology of the upper Kaoping Slope is mainly controlled by mud diapiric intrusions.     

Classification,formation, and transport mechanisms of mud clasts

Mud clasts are common in non-marine to marine sedimentary records, however, why lack a widely accepted classification scheme? We propose that it is the relative balance of volumetric abundance, sorting, roundness, and grain size that controls the texture and fabric of mud clasts. Nine distinct types of mud clasts are identified in the study based on quantitatified properties, and fall into two groups coarse-grained and fine-grained. The generation of mud clasts can be assigned to failure, erosion, and/or bioturbation of muddy sediment. These clasts are transported within fluid flows including Newtonian fluids, non-Newtonian fluids, and Bingham plastics (gravity flow and turbidity flow), showing various physical characteristics depended upon the density and viscosity of flows. Newtonian flows with less density and viscosity commonly form mud clasts with mature textures. In non-Newtonian (gravity-driven) flows, mud clasts are normally transported in laminar flows with high density and viscosity, developing matrix-supported mud clasts with immature textures. The study of classification, formation, and transport mechanisms of mud clasts has implications for identifying and interpreting sedimentary environments.     

火山、泥火山/泥底辟及含气陷阱与油气运聚关系

火山、泥火山/泥底辟及含气陷阱这些特殊的地质体,不仅是揭示地球深部构造运动的窗口和地球深部流体活动特点的表征,而且其与油气运聚关系密切,具有非常重要的油气地质意义。火山与泥火山/泥底辟的主要差异及区别是所形成的物质基础及源动力不同,前者主要反映地壳深部地球动力学过程,其物资基础来源于火山幔源活动上侵和喷发的岩浆物资;后者则是在结晶基底以上的沉积盆地中,由快速沉积充填的欠压实泥页岩发生塑性流动而产生底辟上拱所形成的产物,其物质基础为巨厚欠压实泥页岩。含气陷阱则为气侵或富含气地层所形成的地震反射畸变之痕迹。火山、泥火山/泥底辟发育演化及展布与油气运聚成藏存在明显的成因联系和耦合关系,且控制和制约了沉积盆地中油气分布与聚集。     

Increased susceptibility to No. 2 fuel oil coincident with initiation of particle feeding in developing mud snails,Ilyanassa obsoleta

Encapsulated embryos and free-living larvae of Ilyanassa obsoleta were exposed to concentrations of No. 2 fuel oil (water-accommodated fraction, WAF) up to 1.0 ppm. Development of velum pigmentation and release of larvae from egg capsules were delayed in the presence of 1.0 ppm WAF, but exposure to the oil did not increase developmental mortality of encapsulated individuals. Individuals which were prematurely removed from egg capsules and exposed to oil directly suffered no mortality until yolk reserves were depleted and feeding on phytoplankton commenced. Feeding, free-living larvae suffer high mortality at 1.0 ppm WAF. The reduced susceptibility of encapsulated embryos to the oil stress may therefore reflect the importance of toxicant uptake by ingestion (as opposed to diffusion) rather than the degree of protection afforded by encapsulation.     

Geochemical and geo-electrical study of mud pools at the Mutnovsky volcano (South Kamchatka,Russia): Behavior of elements,structures of feeding channels and a model of origin

This study presents data on the geochemical composition of boiling mud pools at the Mutnovsky volcano. The physicochemical characteristics of the pools and the concentrations of major, minor and trace elements in pool solutions vary widely. A comparison of the geochemical compositions of host rocks and solutions indicates that leaching from rocks is not the only source of chemicals in thermal solutions. Geophysical studies reveal the inner structure of thermal fields, which reflect the shapes of the underground reservoirs and feed channels. Using geophysical methods (electrical resistivity tomography and frequency domain investigations), it was shown that the vertical structure and complex geochemical zonation of the feed channels leads to a high contrast in the compositions of the mud solutions. These findings answer questions about the origin and composition of surface manifestations. To elucidate the mechanisms of solution formation, an attempt was made to describe the magmatic fluid evolution and the resulting mixing of waters by physical and mathematical models. The model illustrates fluid migration from a magma chamber to the surface. It is shown that the formation of brines corresponding to the mud pool composition is possible during secondary boiling.     

江苏王港潮间带表层沉积物特征及输运趋势

潮滩沉积物粒度参数可以用来反映沉积物沉积的水动力条件和沉积环境。根据对江苏王港潮间带采集的15 4个表层样品的粒度资料进行分析,结果表明,沉积物类型以粉砂为主;随着水动力环境由海向陆的减弱,沉积物粒度参数表现出有规律的变化趋势,即由岸向海粒径具有粗化趋势,分选变好,逐渐正偏并达到近对称。研究区与世界其他地区的潮滩在沉积特征上有较大差异,主要是由于沉积物来源、水动力环境及受生物作用的强弱程度不同所致。沉积物输运趋势分析显示,该地区沉积物输运主要受当地潮波特征、大型人工建筑物、地貌形态及生物作用的影响;在低潮线附近主要向西北方向输运,随着向陆地方向的延伸,沉积物由向西输运逐渐转变为向南输运。     

莺歌海盆地泥底辟成因、展布特征及其与天然气运聚成藏关系

泥底辟是南海北部边缘西区莺歌海盆地颇具特色的地震地质异常体，具有欠压实异常、高温高压特点及低密低速的地球物理特征，其展布则具有明显分带性且沿盆地北西走向呈近南北向雁行式排列。泥底辟成因及分布，主要受控于盆地快速沉降及高速沉积充填压实与排出流体不均衡所产生的巨大异常高温高压潜能．和区域控盆断裂晚期右旋走滑伸展活动。而晚期泥底辟热流体上侵活动及其他成藏条件的有效配置，则有效地控制了天然气及CO2运聚成藏规律。     

Intertidal foraminifera from the Savitri estuary,west coast,Maharashtra and their implications on the depositional environment

The benthic foraminifera from the Savitri estuary are being reported for the first time. The faunal analyses reveal the occurrence of mixed assemblage. It is observed that Trochammina inflata is the most dominant species and appears to be the indigenous to mangrove environment.     

Ocean distribution of dungeness crab megalopae and recruitment patterns to estuaries in Southern Washington State

We investigated the distribution of meroplankton and water properties off southern Washington and simultaneously measured time series of larval abundance and water properties in two adjacent estuaries, Grays Harbor and Willapa Bay. The cruise period, in late May 1999, coincided with large variation in the alongshore wind stress that caused dynamic change in the position of the Columbia River plume, coastal upelling and downwelling, and offshore phytoplankton production. In the coastal ocean, meroplankton groups responded differently to this wind event and the associated advection of water masses. Dungeness crab (Cancer magister) megalopae were largely indifferent to the wide salinity variation, and were found throughout the surveyed area in both plume and recently upwelled waters. Megalopae of kelp crab (Pugettia producta) and hermit crab (Pagurus spp). were more abundant in upwelled water and low numbers were caught in the plume water. Barnacle cyprids appeared to track the advective transport suggesting that they may be more passively dispersed. Within the estuaries, hydrography responded rapidly and synchronously to variation in wind stress. Intrusions of both plume and newly upwelled waters were detected at estuarine sites, depending on the type of water present at the coast, indicating a tight link between the estuaries and the coastal ocean in this region. A 90-d record ofC. magister megalopae abundance was made at 3 estuarine sites using light traps. The bulk of theC. magister recruitment was limited to a relatively brief period in late May through June. Within this window, megalopae occurred in distinct pulses of 3–5 d interspaced with periods of low or zero abundance.C. magister megalopae recruited to the estuaries over a wide range of wind forcing, and were transported into the estuary within varied water types. There were no periodic patterns indicative of spring-neap tidal variations in the abundance time series. Abundance was only weakly cross-correlated between the adjacent Grays Harbor and Willapa Bay estuaries, which contrasts with the more synchronous estuarine-coastal linkages measured for water properties. These results suggest the interaction of larval aggregation size in the ocean with estuary-ocean exchange processes likely controls patterns of estuarine recruitment.     

江苏王港潮间带表层碳酸盐的沉积特征

利用容量法对江苏王港淤泥质海岸潮间带夏季表层沉积物碳酸盐的含量进行测定。结果表明，碳酸盐含量的空间分布呈现出由岸向海方向递减的大趋势；相关分析表明，总的碳酸盐含量与沉积物的平均粒径有比较显著的相关关系(α=0．01)；沉积物组分及粒径频率曲线对比分析表明王港潮间带表层沉积物碳酸盐主要富集于细颗粒部分，潮水沟系统和生物作用(尤其是有孔虫)加强了碳酸盐在细颗粒部分的富集。沉积物碳酸盐含量可以作为物源分析的一个指标，王港地区沉积物碳酸盐含量表明该地区沉积物主要来源于废黄河三角洲和现代黄河的输入，长江输入的沉积物较少。