Early Permian xiphosurid trackways from india

Present work is the first report of Early Permian xiphosurid trackways from India. Surface trackways and undertracks, preserved within ice-marginal storm-affected, shoreface sediments of the Talchir Formation, Jayanti coalbasin closely resemble Kouphichnium Nopsca 1923. Trackways reveal distinct heteropody with foliate pusher impressions, paired series of semi-circular, oval, V- or Y-shaped chilate (walking) leg impressions. Varied ventral impressions also include telson drag marks and telson dents; spine drag marks, book -gills impression, genal gouges as well as symmetric, paired lateral genal furrows, partial cubichnial impressions of prosoma and spinose opisthosoma. A tentative early Permian age (Asselian/Sakmarian) and marginal marine facies association points towards a paleolimuloidae affinity for the trace makers, which is in conformity with their inferred widths of exoskeleton, sub-rounded prosoma and subtriangular spinose opisthosoma with predictable movable spines. Flexed pusher impressions and co-dominant pincer impressions as well as, other ventral impressions in abundance, confirm crawling as their dominant mode of locomotion. Inferred presence of juvenile crawlers in the community suggests a probable shoreline or marginal marine ecospace.     

The environments of production and deposition of calcareous sediments on the shelf west of Scotland

The dominant calcareous organisms and sediment characteristics are described for eight different physical settings on the shelf west of Scotland, each having a different depth, substrate and degree of hydrodynamic exposure.

The principal sites of carbonate production are on shallow rocky substrates where barnacles, molluscs, echinoderms and serpulids are the dominant calcareous organisms. In sheltered shallow sandy zones, molluscs, echinoderms and benthic foraminiferans are the active producers, though the sediments are commonly barnacle-rich. Where tidal currents are enhanced between islands and the waves are suppressed, calcareous red algae (Phymatolithon calcareum) and mussel shells build localised banks. In deep, open-shelf water molluscs are the major skeletal contributor to the sediment, though on rocky sea beds bryozoans, serpulids and echinoderms are important.

The major sites of deposition are where persistent hydro- (and aero-) dynamic conditions sweep together grains from active production sites (e.g., sand ribbons or beaches and dunes adjacent to shallow rocky platforms) or in sinks where the physiographic configuration favours the deposition and retention of locally produced sediment or sediment derived from suspension. The well-sorted, cross-bedded, beach and dune sands commonly contain > 75% CaCO₃. In sheltered depressions, bioturbated muds accumulate with up to 30% calcite silt, which is probably the breakdown product of barnacles and benthic foraminiferans.     

Abundance and dispersal potential of horseshoe crab (<Emphasis Type="Italic">Limulus polyphemus</Emphasis>) larvae in the Delaware estuary

The distribution, abundance, and dispersal patterns of horseshoe crab (Limulus polyphemus) trilobite larvae were determined from 671 plankton tows taken near a spawning beach in lower Delaware Bay, New Jersey, in 1998 and 1999. In both years, peaks in larval abundance occurred during periods of rough surf (>30 cm wave heights). Planktonic larvae were significantly more abundant nocturnally than during the day, but there was no evidence of a lunar component to larval abundance. Larvae were strongly concentrated inshore; trilobites were 10–100 times more abundant in the immediate vicinity of the shoreline than they were 100–200 m offshore. The strong tendency ofLimulus larvae to remain close to the beach suggests that their capability for long-range dispersal between estuaries is extremely limited. We suggest that limited larval dispersal potential may help explain previously observed patterns of genetic variation among the Mid-Atlantic horseshoe crab populations.     

Carbonate sediments in a cool‐water macroalgal environment,Kaikoura, New Zealand

Brown and red, and to a lesser extent green, macroalgae are a hallmark of intertidal rocky coasts and adjacent shallow marine environments swept by stormy seas in middle and high latitudes. Such environments produce carbonate sediment but the sediment factory is neither well‐documented nor well‐understood. This study documents the general marine biology and sedimentology of rocky coastal substrates around Kaikoura Peninsula, a setting that typifies many similar cold‐temperate environments with turbid waters and somewhat elevated trophic resources along the eastern coast of South Island, New Zealand. The macroalgal community extends down to 20 m and generally comprises a phaeophyte canopy beneath which is a prolific rhodophyte community and numerous sessile calcareous invertebrates on rocky substrates. The modern biota is strongly depth zoned and controlled by bottom morphology, variable light penetration, hydrodynamic energy and substrate. Most calcareous organisms live on the lithic substrates beneath macroalgae or on algal holdfasts with only a few growing on macroalgal fronds. A live biota of coralline red algae [geniculate, encrusting and nodular (rhodoliths)], bryozoans, barnacles and molluscs (gastropods and epifaunal bivalves), together with spirorbid and serpulid worms, small benthonic foraminifera and echinoids produce sediments that are mixed with terrigenous clastic particles in this overall siliciclastic depositional system. The resultant sediments within macroalgal rocky substrates at Kaikoura contain bioclasts typified by molluscs, corallines and rhodoliths, barnacles and other calcareous invertebrates. In the geological record, however, the occurrence of macroalgal produced sediments is restricted to unconformity‐related early transgressive systems tract stratigraphic intervals and temporally constrained to a Cenozoic age owing to the timing of the evolution of large brown macroalgae.     

Recruitment of the Crabs Eurypanopeus depressus, Rhithropanopeus harrisii, and Petrolisthes armatus to Oyster Reefs: the Influence of Freshwater Inflow

Oyster reefs provide structural habitat for resident crabs and fishes, most of which have planktonic larvae that are dependent upon transport/retention processes for successful settlement. High rates of freshwater inflow have the potential to disrupt these processes, creating spatial gaps between larval distribution and settlement habitat. To investigate whether inflow can impact subsequent recruitment to oyster reefs, densities of crab larvae and post-settlement juveniles and adults were compared in Estero Bay, Florida, over 22 months (2005–2006). Three species were selected for comparison: Petrolisthes armatus, Eurypanopeus depressus, and Rhithropanopeus harrisii. All are important members of oyster reef communities in Southwest Florida; all exhibit protracted spawning, with larvae present throughout the year; and each is distributed unevenly on reefs in different salinity regimes. Recruitment to oyster reefs was positively correlated with bay-wide larval supply at all five reefs examined. Species-specific larval connectivity to settlement sites was altered by inflow: where connectivity was enhanced by increased inflow, stock–recruitment curves were linear; where connectivity was reduced by high inflows, stock–recruitment curves were asymptotic at higher larval densities. Maximum recruit density varied by an order of magnitude among reefs. Although live oyster density was a good indicator of habitat quality in regard to crab density, it did not account for the high variability in recruit densities. Variation in recruit density at higher levels of larval supply may primarily be caused by inflow-induced variation in larval connectivity, creating an abiotic simulation of what has widely been regarded as density dependence in stock–recruitment curves.     

重庆开县上二叠统长兴组红花生物礁成礁模式

通过对红花生物礁露头的精细解剖和微相分析,研究了礁的内部构成和成礁模式。红花生物礁发育3期礁体旋回：礁A、礁B和礁C。礁A由生屑泥晶灰岩和骨架岩构成;礁B由生屑泥晶灰岩、粘结岩、骨架岩和生屑灰岩构成;礁C由粘结岩、骨架岩和生屑灰岩构成。红花生物礁造礁生物有钙质海绵、钙藻类、苔藓虫和水螅类,附礁生物为有孔虫、腕足类、双壳类、腹足类和棘皮动物等。单个礁体内,由下往上的生物演化为：腕足类+双壳类+有孔虫组合→钙藻类→钙质海绵+水螅类+钙藻类+苔藓虫组合→生物碎屑;岩性演化为：生屑泥晶灰岩→粘结岩→骨架岩→生屑灰岩。礁B的生屑滩内生屑间为泥晶充填,生屑分选、磨圆较好,是由相邻的高能生屑滩侵蚀搬运到礁B侧翼低能区沉积形成。3期礁都发育在碎屑滩上,礁A为低能环境下形成的礁,礁B和礁C在礁A形成的高地上成礁,为高能环境礁;单个礁体的完整成礁模式为：在浅滩之上,钙藻类大量生长、粘结吸附颗粒固结基底,钙质海绵和钙藻类在硬质基底上繁茂生长,形成具有抗浪格架的生物礁,礁体暴露水面死亡后遭波浪、水流改造形成生屑滩。     

Warm‐temperate,marine, carbonate sedimentation in an Early Miocene,tide‐influenced,incised valley; Provence,south‐east France

The Saumane‐Venasque compound palaeovalley succession accumulated in a strongly tide‐influenced embayment or estuary. Warm‐temperate normal marine to brackish conditions led to deposition of extensive cross‐bedded biofragmental calcarenites. Echinoids, bryozoans, coralline algae, barnacles and benthic foraminifera were produced in seagrass meadows, on rocky substrates colonized by macroalgae and within subaqueous dune fields. There are two sequences, S1 and S2, the first of which contains three high‐frequency sequences (S1a, S1b and S1c). Sequence 1 is largely confined to the palaeovalley with its upper part covering interfluves. Each of these has a similar upward succession of deposits that includes: (i) a basal erosional surface that is bored and glauconitized; (ii) a discontinuous lagoonal lime mudstone or wackestone; (iii) a thin conglomerate generated by tidal ravinement; (iv) a transgressive systems tract series of cross‐bedded calcarenites; (v) a maximum flooding interval of argillaceous, muddy quartzose, open‐marine limestones; and (vi) a thin highstand systems tract of fine‐grained calcarenite. Tidal currents during stages S1a, S1b and S1c were accentuated by the constricted valley topography, whereas basin‐scale factors enhanced tidal currents during the deposition of S2. The upper part of the succession in all but S1c has been removed by later erosion. There is an overall upward temporal change with quartz, barnacles, encrusting corallines and epifaunal echinoids decreasing but bryozoans, articulated corallines and infaunal echinoids increasing. This trend is interpreted to be the result of changing oceanographic conditions as the valley was filled, bathymetric relief was reduced, rocky substrates were replaced as carbonate factories by seagrass meadows and subaqueous dunes, and the setting became progressively less confined and more open marine. These limestones are characteristic of a suite of similar cool‐water calcareous sand bodies in environments with little siliciclastic or fresh water input during times of high‐amplitude sea‐level change wherein complex inboard antecedent topography was flooded by a rising ocean.     

Stratigraphy and facies development of the marine Late Devonian near the Boulongour Reservoir,northwest Xinjiang,China

Late Devonian to Early Carboniferous stratigraphic units within the ‘Zhulumute’ Formation, Hongguleleng Formation (stratotype), ‘Hebukehe’ Formation and the Heishantou Formation near the Boulongour Reservoir in northwestern Xinjiang are fossil-rich. The Hongguleleng and ‘Hebukehe’ formations are biostratigraphically well constrained by microfossils from the latest Frasnian linguiformis to mid-Famennian trachytera conodont biozones. The Hongguleleng Formation (96.8 m) is characterized by bioclastic argillaceous limestones and marls (the dominant facies) intercalated with green spiculitic calcareous shales. It yields abundant and highly diverse faunas of bryozoans, brachiopods and crinoids with subordinate solitary rugose corals, ostracods, trilobites, conodonts and other fish teeth. The succeeding ‘Hebukehe’ Formation (95.7 m) consists of siltstones, mudstones, arenites and intervals of bioclastic limestone (e.g. ‘Blastoid Hill’) and cherts with radiolarians. A diverse ichnofauna, phacopid trilobites, echinoderms (crinoids and blastoids) together with brachiopods, ostracods, bryozoans and rare cephalopods have been collected from this interval. Analysis of geochemical data, microfacies and especially the distribution of marine organisms, which are not described in detail here, but used for facies analysis, indicate a deepening of the depositional environment at the Boulongour Reservoir section. Results presented here concern mainly the sedimentological and stratigraphical context of the investigated section. Additionally, one Late Devonian palaeo-oceanic and biotic event, the Upper Kellwasser Event is recognized near the section base.     

Drift tube studies of bay-ocean water exchange and implications for larval dispersal

Surface water transport and larval dispersal potential within Mission Bay, San Diego, California and along the southern California coast were studied with drift test tubes. Drift tubes, released once during each season at six sites inside Mission Bay, traveled up to 173 km north and 205 km south of Mission Bay at maximum rates of 36 cm per s (north) and 50 cm per s (south). These findings were used to estimate probability of larval transport out of Mission Bay for the intertidal spionid polychaete Pseudopolydora paucibranchiata (Okuda) which occurred in the back of the bay. Outer coast drift tube returns were used to determine potential for gene flow, via larval exchange, between populations in isolated bays along the California coast. Drift tube recoveries and larval abundances in the plankton indicate that few Pseudopolydora larvae leave Mission Bay, but that longshore currents can carry those which do to other suitable bay habitats.     

Nearshore cool-water carbonate sedimentation and provenance of Holocene calcareous strandline dunes,southeastern Australia

The southeastern coastal plain of South Australia contains a spectacular and world-renowned suite of Quaternary calcareous eolianites. This study is focused on the provenance of components in the Holocene, actively forming sector, of these carbonate eolian deposits. Research was carried out along seven transects across a lateral distance of 120 km from ～30 m water depth offshore across the beach and into the dunes. Offshore sediments were acquired via grab sampling and SCUBA. Results indicate that dunes of the southern Lacepede and Bonney coasts are composed of siliciclastic particles (mainly quartz), relict allochems, Cenozoic and limestone pieces, but dominated by Holocene invertebrate and calcareous algal biofragments. The most numerous grains are from molluscs > benthic foraminifera ≥ coralline algae, > echinoids and > bryozoans. Most of these particles originate in carbonate factories such as macroalgal forests, rocky reefs, seagrass meadows and low-relief sea-floor rockgrounds. Incorporation of Holocene carbonate skeletons into coastal dunes, however, depends on a combination of: (1) the addition of infauna from intertidal and nearshore environments; (2) the physical characteristics of different allochems and their ability to withstand bioerosion, fragmentation and abrasion; (3) the character of the wave and swell climate; and (4) the nature of eolian transport. Most eolian dune sediment is derived from nearshore and intertidal carbonate factories. This is well illustrated by the abundance of robust infaunal bivalves that inhabit the nearshore sands and virtual absence of bryozoans that are common as sediment particles in offshore water depths >15 m. Importantly, the calcareous eolianites in this cool-water, open-platform carbonate setting are not simply an allochthonous reflection of the offshore marine shelf factories, but more a product of autothonous shallow nearshore–intertidal skeletal production and modification. These findings explain the preponderance of mollusc fragments and lack of bryozoans in similar older Pleistocene calcareous eolianites up to ca 1 million years old across ～2000 km of southern Australia with implications for the older rock record.     

Subtidal distribution of barnacles (Cirripedia: Balanidae) in Chesapeake Bay,Maryland

From 1977 to 1980, samples of barnacles were collected (as opportunities arose) from 61 subtidal locations (mostly oyster beds) around Chesapeake Bay, Maryland. Three species were identified from the area.Balanus improvisus dominated, comprising 83% of the 8,231 barnacles identified, and was collected at all locations but one. It occurred over a collection salinity range of 0.8‰ to 17.9‰.Balanus subalbidus (14% of the barnacles identified) was collected over the same salinity range, but mainly in lower salinity waters.Balanus eburneus was scarce (2% of the barnacles identified) and was collected at higher salinities (8.5‰ to 17.1‰).     

Animal-sediment relationship of the crustaceans and polychaetes in the intertidal zone around Mandvi,Gulf of Kachchh,Western India

Animal-sediment relationships of two benthic communities (Crustaceans and Polychaetes) were studied around Mandvi coast in the Gulf of Kachchh, Western India. This coast consists of many micro-geomorphic landforms in which benthic communities are inhabited and select their niches and produce endemic biogenic structures. Five intertidal subfacies have been described and four types of grounds are identified, based on substrate consistency. 18 species of crustaceans, 15 species of polychaetes and unsegmented worm nemertea have been identified. Crustacean behavioural activities were observed in dunes, beaches and ridge-runnel in the form of burrowing, pellet making, feeding and crawling traces. Pelleted wall lining burrows of the suspension feeder stomatopodean species of Oratosquilla striata are also abundant in runnels. Motile, deposit feeder polychaetes are abundant on the ridges and are occasionally found on the lower reaches of the beaches, while suspension and filter feeders are found in the runnels. Lagoons consist of mainly grouped funnel branched burrows of Oniphus eremita which is identical to ichnogenus Balanoglossites. Nemertea, which are opportunistic algal grazers, have exploited restricted niches for dwelling-feeding purposes and constructed vertical burrow with pentamerous conical mound. The shore platform consists of cemented, calcareous tubes of filter feeder Serpula along with symbiotic encrusters like Ostrea and barnacles. Ichnocoenoses are discussed and three-dimensional ichno-sedimentologic models are reconstructed for Beach, Ridge, Runnel and Lagoon of the Mandvi intertidal zone.     

Miocene bryozoa from the Kachchh Offshore Basin,Western India

The present paper records for the first time the bryozoan fragments from 4 m core of the Godhra Formation (early Miocene) and from 4m core and 5 m core of the Chhasra Formation (early middle Miocene) of the Kachchh Offshore Basin, Western India. The Godhra Formation has presence of three bryozoans, viz., ?Crassimarginatella sp., Thalamoporella sp. and Vincularia sp. while the Chhasra Formation has presence of four bryozoans, namely, ?Margaretta sp., Steginoporella sp., ?Thalamoporella sp. and Vincularia sp.     

New Bivalved Arthropods from the Cambrian (Series 3, Drumian Stage) of Western Hunan,South China

We report two new three-dimensionally phosphatized microfossils, Cambrolongispina reticulata gen. et sp. nov. and Cambrolongispina glabra gen. et sp. nov., from the middle Cambrian （Series 3, Drumian Stage） at Wangcun, Yongshun County, western Hunan, South China. They are bivalved arthropods, with thin, pliable, originally chitinous or chitin-calcareous shields （c. 350-517 I1 m long）. The shields are equipped with a pair of antero-dorsal spines. The spines are internally hollow, varying in length from 1/2 of to as long as the shield length in C. reticulata, and uniformly longer than the shield length in C. glabra. The spines of C. reticulata are ornamented with a longitudinal row of conical or blade-shaped denticles along the posterior edge. Cambrolongispina lacks marginal rims, valve lobation and sulci which are diagnostic of the Bradoriida sensu stricto. It also lacks a donblure/duplicature characteristic of phosphatocopids and some bradoriids. It could be related to the Monasteriidae （which may belong to Bradoriida sensu lato）, both characterized by a pair of antero-dorsal spines. Cambrolongispina may have been meiofaunai detritus feeders that lived on or within sediments. The antero-dorsal spines may have been sensory organs to detect nearby predators. The posterior denticles on these spines might have facilitated the sensory function of the spines.     

Interaction of longitudinal surface settlements for twin tunnels in shallow and soft soils: the case of Istanbul Metro

Increasing demands on infrastructures increases the attention on shallow soft ground tunneling methods in urbanized areas. Especially, in metro tunnel excavations, it is important to control the surface settlements observed before and after excavation, which may cause damage to surface structures. To solve this problem, earth pressure balance machines (EPBMs) have widely been used throughout the world. This study focuses on surface settlement measurements, the interaction of twin tunnel surface settlement, and the relationship between shield parameters and surface settlement for parallel tunnels using EPBM shields in clay and sand soils. In this study, the tunnels were excavated using two EPBMs. The tunnels were 6.5 m in diameter, as twin tubes with a 14 m distance from center to center. The EPBM in the first tube followed about 100 m behind the other tube. Segmental lining with 1.4 m of length was employed as a final support. The results from this study showed that (1) the most important parameters for the maximum surface settlements are the face pressure and backfill; (2) in twin tunnel excavation with EPBM for longitudinal profile, the settlement rate reached its peak value when the shield came to the monitoring section and this peak value continued until the shield passed the monitoring section; (3) every shield affected the other tunnel’s longitudinal surface settlement profile by approximately 35–36.8 %; (4) S _A, S _B and S _C values were found to be 38.0, 35.8 and 26.2 %, respectively for an EPBM, and (5) ensuring good construction quality is a very effective way to control face stability and minimize surface settlement.     

The Carbonate Chemistry of the “Fattening Line,” Willapa Bay, 2011–2014

Willapa Bay has received a great deal of attention in the context of rising atmospheric CO₂ and the concomitant effects of changes in bay carbonate chemistry, referred to as ocean acidification, and the potential effects on the bay’s naturalized Pacific oyster (Crassostrea gigas) population and iconic oyster farming industry. Competing environmental stressors, historical variability in the oyster settlement record, and the absence of adequate historical observations of bay-water carbonate chemistry all conspire to cast confusion regarding ocean acidification as the culprit for recent failures in oyster larval settlement. We present the first measurements of the aqueous CO₂ partial pressure (PCO₂) and the total dissolved carbonic acid (TCO₂) at the “fattening line,” a location in the bay that has been previously identified as optimal for both larval oyster retention and growth, and collocated with a long historical time series of larval settlement. Samples were collected from early 2011 through late 2014. These measurements allow the first rigorous characterization of Willapa Bay aragonite mineral saturation state (Ω_ar), which has been shown to be of leading importance in determining the initial shell formation and growth of larval Crassostrea gigas. Observations show that the bay is usually below Ω_ar levels that have been associated with poor oyster hatchery production and with chronic effects noted in experimental work. Bay water only briefly rises to favorable Ω_ar levels and does so out of phase with optimal thermal conditions for spawning. Thermal and carbonate conditions are thus coincidentally favorable for early larval development for only a few weeks at a time each year. The limited concurrent exceedance of thermal and Ω_ar thresholds suggests the likelihood of high variability in settlement success, as seen in the historical record; however, estimates of the impact of elevated atmospheric CO₂ suggest that pre-industrial Ω_ar conditions were more persistently favorable for larval development and more broadly coincident with thermal optima.     

Permian (Leonardian) brachiopods from Paso Hondo Formation,Chiapas, southern Mexico. Paleobiogeographical implications

One of the most important marine sequences of calcareous rocks from the Paleozoic of Mexico outcrops in southern Chiapas. It is composed by different units from Early Permian, being the Paso Hondo Formation the youngest with a Leonardian age. Different groups of marine invertebrates as corals, bivalves, gastropods, bryozoans, brachiopods and crinoids have been previously reported of this unit. Five brachiopod species of the orders Productida, Athyridida, Spiriferida and Spiriferinida from the Barrio Allende section of this unit are herein described. The new species Dyoros (Lissosia) maya and Hustedia shumardi are proposed. Sedimentology and paleoecology of the Paso Hondo Formation, suggest a well-lighted shallow lagoon environment with continuous terrigenous input. The subgenus Dyoros (Lissosia), the genus Paucispinifera and the species Hustedia shumardi, Spiriferella propria and Spiriferellina tricosa are typical taxa from Permian localities of Texas, New Mexico and Coahuila. Their presence in the studied area suggests that during Early Permian there was a geographic connection between the different localities of the biotic Grandian Province (southern USA, northern Mexico and Venezuela) and southeastern Chiapas.     

阿拉善沙漠植物钙质根管:形态特征、分类及其环境指示意义

在系统总结前人对植物钙质根管定义及形成机制的基础上,采用形态学方法对阿拉善沙漠26组不同形态的植物钙质根管进行了分类,初步统一了我国植物钙质根管的定义及其分类;通过统计阿拉善沙漠不同类型植物钙质根管在全新世的数量分布,探讨了其分布特征可能蕴含的古环境意义。结果表明,植物钙质根管是陆生植物形成的次生碳酸盐结壳,包括钙质根套、绕根结核、根模具、根导管和根状结核五种类型。其中钙质根套和绕根结核的形成受到植物生长及其根围微生物活动的影响,而根模具、根导管和根状结核的形成则不受上述作用的影响。据此将阿拉善沙漠植物钙质根管分为钙质根套和绕根结核两种类型。这两类植物钙质根管在不同时期的相对数量百分比能够指示植物钙质根管形成时期有效湿度的高低,绕根结核数量百分比较高能够指示较高的有效湿度,而钙质根套数量百分比较高则指示了较低的有效湿度。因此,从植物钙质根管中能够提取丰富的古环境信号,并将其运用于沙漠地区的古环境研究中。     

http://www.sciencedirect.com/science/article/pii/S1674987113000285

Facies characterization of Piacenzian （late Pliocene） carbonate sediments of the Guitar Formation in Car Nicobar Island,India and the subsequent integration of paleoecological data have been applied to interpret the paleoenvironment of the coralline algal-reef deposits.Thin-section analysis reveals that Amphiroa,Corallina and Jania are the dominant geniculate corallines,while Lithothamnion,Mesophyllum,Phymatolithon,Lithophyllum,Spongites and Lithoporella are the major non-geniculate corallines contributing to the sedimentary facies.Numerous small and larger benthic foraminifera also dominate the biogenic assemblages.Corals,barnacle shells,echinoid spines,fragments of bryozoans,mollusks and ostracodes are the subordinate constituents.Grainstones dominate the studied facies while packstones and boundstones （with wackestone elements） are the sub lithofacies showing a fair representation.Six carbonate facies presenting a complete reef complex have been distinguished that were deposited in shallow intertidal,back-reef shelf/lagoon,reef and deeper fore-reef shelf settings.Evidences of coralline algal and benthic foraminiferal assemblages,taphonomic signatures of abrasion and fragmentation,grain size,angularity and encrustation indicate a shallow to relatively deeper bathymetric horizon of approximately 10-60 m that corresponds to a regime of high to moderate hydrodynamic conditions.     

Effect of salinity and temperature on survival and development of young zebra (Dreissena polymorpha) and quagga (Dreissena bugensis) mussels

We reared larval zebra mussels,Dreissena polymorpha, and quagga mussels,D. bugensis, through and beyond metamorphosis (settlement) at salinities of 0–8‰. Juvenile zebra mussels gradually acclimated to 8‰ and 10‰ have been reared at these salinities for over 8 mo. Tolerance to both higher temperatures and higher salinities increases with larval age in both species (though zebra mussel embryos and larvae have a greater degree of salinity tolerance than quagga mussel embryos and larvae). Thus, only 6% of 3-day-old zebra mussel veligers survived after exposure to 4‰ for 8 additional days, whereas there was 22% survival of veligers placed in 4‰ at day 13 and grown to settlement 11 d later. Zebra mussel pediveligers, acclimated to increasing salinity in 2‰ increments beginning at day 23, continued to survive and grow in 8‰ after 5-mo exposure, though the growth rates of these juveniles were significantly less than those of juveniles reared in lower salinities. Quagga mussels did not metamorphose and settle as quickly as zebra mussel pediveligers. No quagga mussel pediveligers had settled before exposure to artificial fresh water (AFW), 2‰ 4‰, 6‰, and 8‰ on day 30. Percent settlement of these quagga mussel juveniles (based on 100% survival at the start of experiments on day 30) was 90% in AFW, 67% at 2‰, 69% at 4‰, 46% at 6‰, and 0.1% at 8‰.