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We present an overview on different environmental zones within coastal areas and summarise the physical basis behind the three most important methods that are available to date Holocene coastal sediments. Besides radiocarbon and uranium series dating, Optically Stimulated Luminescence (Osl) has increasingly been applied for dating in coastal settings over the past decade. This is illustrated by a number of case studies showing that Osl can be applied to sediments from almost any kind of coastal environment, covering a potential dating range from some years up to several hundred thousand years. Osl dating may hence be the method of choice for deciphering natural environmental change along coasts as well as the presence and the impact of human occupation in such areas. In addition, we briefly show how and where these dating methods could be applied to constrain the palaeo-environmental context of an archaeological site at Vohemar in north-eastern Madagascar. Nous présentons un aperçu sur les différentes zones environnementales dans les secteurs côtiers et proposons de résumer les bases physiques des trois méthodes les plus importantes disponibles à ce jour pour dater les sédiments côtiers de l’holocène. Outre le radiocarbone et la datation série de l’uranium, la luminescence stimulée optiquement (Osl) a été la plus appliquée pour la datation en milieu côtier durant la dernière décennie. Ceci est illustré par un certain nombre d’études de cas montrant que l’Osl peut être appliquée à des sédiments à partir de presque n’importe quel type de milieu côtier, couvrant une datation potentielle de quelques années jusqu’à plusieurs centaines de milliers d’années. La datation par Osl peut donc être une méthode de choix pour décrypter les changements environnementaux naturels le long des côtes ainsi que la présence et l’impact de l’occupation humaine dans ces zones. De plus, nous avons brièvement montré comment et où ces méthodes de datation pourraient être appliquées pour circonscrire le contexte paléo-environnemental d’un site archéologique comme Vohémar, dans le nord-est de Madagascar.

Descriptions are given of the adults and nymphs of 3 new species of Baetis s.I. (B. boussoulius, B. elouardi, B. gambiae) from rivers in West Africa, including the tidal zone of the River Gambia.

In a marine environment, reinforcement corrosion due to chloride attack is the most important degradation process of reinforced concrete. Diffusion models found in the bibliography show opposite results, over or underestimating chloride diffusion coefficient values for tidal zone concretes. In this paper, the chloride penetration rate for tidal zone concretes has been modeled from data collected from a high number of references, covering a wide range of concrete qualities and not considering accelerated test results. Also, this model has been checked with experimental results obtained from five Spanish maritime structures. The basic parameters considered in this model were water-cement ratio (w/c), type, and content of mineral admixtures. Finally, the efficiency factors of fly ash and silica fume (their contribution to chloride permeability) have been calculated.

A large number of ocean and harbor concrete structures have been in service for more than a century. However, the cost associated with repair of these structures damaged by corrosion of steel in concrete is a major maintenance expense for the owners. Due to wave and tidal action of sea water, these structures are divided into atmospheric, tidal, and submerged zones. The most devastating corrosion damage occurs at the splash area which is somewhere between the lower part of the atmospheric zone and upper part of the tidal zone. However, it is generally believed that steel corrosion in the submerged concrete is stifled because the oxygen concentration in the concrete is too low to sustain the corrosion activity. To investigate the corrosion mechanism in partially submerged concrete structures, the corrosion potentials, total corrosion current, and macro-cell corrosion current of the steel in concrete specimens were monitored. The results obtained from the three zones (submerged, tidal, and atmospheric zones) were compared and discussed. (A) For the covering abstract of the conference see IRRD 857776.

Results are presented from a study of the performance of reinforced concrete in a marine environment. Reinforced concrete specimens from three series of concrete mixes of nominal strength grades C25, C35 and C45 and with a range of PFA levels (0–50%) were placed in the tidal zone of the BRE marine exposure site. Measurements of reinforcement weight loss and chloride ion penetration were carried out on the specimens after two years' exposure. The results indicate that chloride ion penetration during early exposure is controlled by sorptivity rather than diffusion, and predictions of diffusion coefficients derived from chloride concentration profiles are not valid. No significant increase in the chloride content at depths below 10 mm were observed between one and two years for concretes containing 30% or more PFA, whereas substantial increases were observed for the OPC control concretes. The PFA concretes were far more resistant to the penetration of chloride ions than the OPC concretes and consequently corrosion of steel reinforcement was reduced in the PFA concrete. It is concluded from results to two years that in marine conditions PFA concrete provides much improved protection to steel reinforcement, compared with OPC concrete of equal strength grade, cementitious content (OPC + PFA) or water–cementitious ratio. Further assessments will be carried out after 5 and 10 years exposure. These results are discussed in the context of current specifications for concrete exposed to marine conditions.

This paper aimed at the use change of the bay, a dynamic axis-area analysis method was put forward on the basis of the complex and dynamic characteristics of bays. Firstly, a bay was seen as a systematic structure composed of four axes: baymouth, mean low-tide line, coastline, land boundary, and three areas surrounded by these axes, namely alongshore land area, tidal zone, and alongshore sea area, the coastline is the main axis of the structure. Secondly, due to the uncertain structure of bays, the location of axes were explored, a dynamic land range establishing method was brought forward according to the Dynamic Degree of the plantation and construction lands. Thirdly, the monitoring indicators of each component of the bay structure for their use change condition were analyzed. In the end of the paper, the change of Daya Bay in the east of Guangdong province was taken as an example. Multi-source data of 1980s and 2004 were used as data source, the exploitative change characteristics of main axis and each area were analyzed by the method, and the driving forces were also discussed. The dynamic axis-area analysis method can describe the change of bay locally and wholly, and is proved to be a good way to reflect the bay use change.

Marine Streptomyces GB-2, isolated from marine samples collected in the intel tidal zone of Lianyungang, was found to produce antibacterial substance which exhibited significant inhibitory effects on 11 Gram-positive bacteria and 4 Gram-negative bacteria. The antibacterial substance was proved to be neutral and water-soluble according to paper chromatogram analysis, and its production was significantly associated with aritificial seawater. The stability analysis of the fermentation broth of Streptomyces GB-2 showed that it was very stable at pH1 and pH12 under 121 degrees C and changed very little under ultraviolet treatment. The substance produced by strain GB-2 exhibited potential use in the areas of bio-control, food and medical application.

This paper provides an overview of three different instrumentation schemes used to monitor long term performance of FRP repaired piles in tidal waters. These schemes were evaluated in four demonstration projects extending nearly five years. Two of these used linear polarization to estimate the corrosion rate while the third focused on the variation in the corrosion current. Problems associated with selection, installation and monitoring are described and representative results presented from all three systems. The results suggest data from linear polarization is more consistent. Findings indicate FRP wrapping lowers the prevailing corrosion rate.

Within the framework of the evaluation and the prediction of chloride-induced corrosion risks, simple and rapid AgNO3 spray tests can be proposed for various issues. This paper forms the first part of a series. In this first part, the Maultzsch procedure (spraying of 0.1-N AgNO3 solution + K2CrO4) as well as the procedure based on the use of a sole AgNO3 solution have been investigated on a broad range of concretes. These procedures have also been compared to the Collepardi procedure (spraying of 0.1-N AgNO3 + fluoresceine). The feasibility of these colorimetric techniques on saturated specimens cast in laboratory, after non-steady-state diffusion tests carried out in various conditions, is discussed. In addition, the results obtained from applying such spray tests in field conditions on cores drilled out from various RC test specimens exposed to a marine environment (tidal zone) and to a road and cold environment (freezing-thawing cycles and spraying of deicing salts) are presented. Colorimetric methods have in particular been applied here to the assessment of the average chloride penetration depth and of its evolution versus time (kinetics). Moreover, the detection threshold of these techniques has been investigated in various environments. The possible sources of discrepancy on the results have been analysed.

Balıkesir Üniversitesi, Fen Bilimleri Enstitüsü, Biyoloji Eğitimi Ana Bilim Dalı, Bu çalışmada Balıkesir ili sınırları içinde, Manyas ( Kuş ) Gölü’ nün kuzeydoğusunda yer alan, Bandırma ilçesine bağlı Kuş Cenneti Milli Parkı’nın gel-git zonu makrofitleri incelenmiştir. Araştırma alanı, kışın gölün mevsimsel ritmi nedeniyle sular altında olup çalışma yaz aylarındaki vejetasyonu kapsamaktadır. Bitki örnekleri 2002-2005 yıllarında; Haziran-Ağustos ayları arasında toplanmış, herbaryum örnekleri hazırlanmış ve Davis’in “Flora of Turkey and East Aegan Islands” adlı eserinden yararlanılarak teşhis edilmiştir. Çalışma alanında 26 familyaya ait 51 cins ve bu cinslere ait 57 tür ve tür altı taksonun yer aldığı saptanmıştır. Araştırma bölgesinde yer alan tür ve tür altı takson sayısı bakımından en zengin familyanın Asteraceae ( Compositae ) olduğu, onu Poaceae ( Gramineae ) ve Lamiaceae ( Labiatae ) izlemekte olduğu tespit edilmiştir., In this thesis summer season macrophytes of the tidal zone of Manyas Kus Cenneti (Paradise of Bird) National Park, the northwest of Manyas Kus (Bird) Lake which is located in Bandırma within the borders of the city of Balıkesir have been analysed. The study area is under water because of the seasonal rhythm in the Winter season; for this reason this study contains only Summer Season vegetation of the study area. Plant samples have been collected in the time period between the June and August of the years of 2002 and 2005; their herbarium materials have been prepared and plant samples have been identified by using "Flora of Turkey and East Agean Islands" by Davis. In the study area, 51 genus belong to 26 family and 57 species and subspecific taxa relative the these genera were idendified. According to the number of species and subspecific taxa collected from the study area, the richest family in number was Asteraceae (Compositae), followed by Poaceae ( Graminae) and Lamiaceae (Labiatae).

This paper details the planning and installation of two 46 kilovolt submarine cables by the South Carolina Electric and Gas Company in extensive salt marsh environments. Installed approximately two years apart, the circuits are of two different one mile designs (three conductor and three single conductors). The similarities of these projects offer a unique comparison of installation techniques. These projects are reviewed from planning, through permitting, to installation and operation. A discussion of the salt marsh environment is presented. Evaluations of various construction equipment and methods are addressed. In addition, effects of cable construction and operation on marsh grasses and tidal zone life are shown.

An industrial yard owned by the United States Army Corps of Engineers (USACE) is located at the Caven Point peninsula in Jersey City, New Jersey. The yard's berthing waterfront is built in the form of steel a sheet pile bulkhead. The sheet piling, subject to the aggressive salt water environment, has severely corroded since the time of construction in the early 1970s; however, the degree of corrosion of the steel sheeting varied a great deal over the wall height. The most severe corrosion occurred within the tidal zone with its peak being at the Mean Low Water level (MLW). About 15% of the original steel thickness was left at this level. In other zones, where the sheet piling was either permanently dry or permanently submerged, the remaining steel was 80 to 90% of its original thickness. Structural analysis of the bulkhead showed that the maximum bending moment occurs approximately at the level of mudline, where the section loss of the sheet piling due to corrosion was minimal. At the MLW level, where the sheet piling sustained the maximum corrosion loss, the bending moment, on the contrary, was small and the remaining steel thickness was found sufficient to resist it. Consequently, it was determined that the bulkhead in its existing condition was structurally adequate; hence, the goal of its rehabilitation was merely to stop further corrosion and to preserve the sheet piling in its present condition. Protection of the sheet piling has been designed as 20-cm (8-inch) thick precast concrete panels (veneer) installed in front of the existing wall. The space between the sheet piling and the panels would be filled with plain tremie concrete. To make the concrete panels capable of withstanding the lateral pressure of the wet concrete fill, two measures have been proposed: a) use of the lightweight concrete fill, and b) placement of the concrete fill between the sheet piling and panels in several lifts. Each subsequent lift would be placed after concrete in the previous lift has hardened and thus no longer transmits lateral pressure to the panels.

Micropiles and permanent anchors are important elements in geotechnical engineering. To use them successfully under difficult site and soil conditions it is necessary to improve the normal systems in due compliance with project specific specialist measures. Necessary improvements for difficult site and soil conditions are explained by three case histories. The first shows the production of micropiles und permanent anchors in tidal-zone and the improvement of the load bearing zone to guarantee the load bearing capacity through a wharf foundation. In the second example it is described how to protect permanent anchors against lime-attacking carbon dioxide in the groundwater in rock. The concept for the post-foundation under organic soil conditions of the Berlin State Library ”Unter den Linden” is the third case history.

Some products have been proposed which will reduce the adhesion of oil to rocks, and thus diminish the impact of oil spills on shorelines. The products are natural, biodegradable materials (polysaccharides). Experiments conducted in a simulated tidal zone resulted in a 20% to 30% decrease in the adhesion of oil compared with control tests. The products retained their effectiveness for six days after application. In situ tests also showed significant results.

This paper details experiences from in-situ investigations on the effects of different dosages of silica fume and a surface coating system applied to concrete decks on concrete structures in the Persian Gulf Area. The specimens were kept in various placement conditions: fully submerged zone, tidal zone, atmospheric zone, underground zone, and laboratory conditions. The focus is on the ability to prevent or reduce chloride ingress. Test results are compared to numerical results obtained, using the Life-365 model proposed by Thomas and Bentz.

In the early 1980s, an extensive laboratory program was initiated to develop high-strength lightweight concrete for use in offshore and severe marine environments. From results of that development program, 4 mixtures were chosen to be evaluated under field conditions. Large prisms of each mixture were placed in the tidal zone at the U.S. Army Corps of Engineers Severe Weather Exposure Station on the U.S.-Canadian border. An expanded slate aggregate from the U.S. and a pelletized clay aggregate from Japan were used in the mixtures, all of which contained silica fume and had total binder content of 494-556 kg/cu m with water-binder ratios of 0.28 by mass. Concrete density varied from 1800-1990 kg/cu m, with 90-day strength from 60-73 MPa depending on the mixture. The prisms underwent annual visual and nondestructive evaluations. After 10 yrs exposure in the tidal zone, the prisms were removed to the lab and examined for robustness, strength, and chloride ion penetration. Overall performance was deemed very good.

Patterns of tidal microgrowth bands present in acetate peels of shell sections of the Chilean mussel Semimytilus algosus from three tidal levels on a wave-exposed shore were analyzed for the presence of recurring periodicities using numerical tools derived from signal nonlinear analysis. Both chaotic and coherent structure were found within the microgrowth pattern record, with mussels from the middle and lower tidal zones displaying a coherent structure to the patterns, whilst those from the upper tidal level displayed a chaotic banding pattern with a strong tidal component. It is suggested that because mussels in the upper tidal zone are subject to a wider suite of environmental conditions they are influenced by the spring-neap lunar tidal cycle to a greater extent than those growing in the mid to low tidal zone and display deterministic chaotic growth. This allows the mussels to grow continuously in the highly variable conditions that prevail in the upper tidal zone without continuous interruptions to shell deposition.

A seismic refraction survey was conducted at a coastal site in eastern Massachusetts to determine bedrock depth and locate areas where overburden thickness is sufficient for the construction of a replacement stormdrainage system. Since the site is in a tidal zone, the saturated thickness of the overburden is constantly changing. Additionally, the depth to bedrock varies from a few feet to 50 or 60 feet. We use a nonlinear refraction traveltime tomography technique (Zhang et. al., 1996) to evaluate this complex tidal environment and compare the modeled results with those acquired using more conventional processing techniques such as the crossover-distance and iterative ray tracing methods. We find good correlation of the methods along those lines closest to shore and least influenced by tidal changes and organic deposits. However, conventional methods fall short where organics and changing saturation conditions cause abrupt changes in lateral and vertical velocities.

Tidal flow is thought to be an important consideration in the maintenance of fish habitat, particularly nursery habitat. To assess the presence of structures which impede tidal flow in New South Wales, a special project was initiated in mid 1994 which collected anecdotal and field data. The former were collected via a questionnaire sent to Oyster farmers and fisheries officers, while the latter were preceeded by the inspection of 148 1:25000 topographic maps. The presence of bridges, culverts, causeways, fords, weirs and floodgates were noted on the maps. Nearly 4230 structures located in the tidal zone were considered for their remediation potential, and we suggest 1388 are candidates for change. The majority of the candidate structures are floodgates, almost 50% of which occur in three north coast rivers. The information obtained in this inventory has important implications for habitat managers and researchers in NSW and the other Australian states.

From 8 February to 8 June 1995, we investigated aspects of the foraging behavior of northwestern crows (Corvus caurinus) in the intertidal zone relative to various tide heights and invertebrate availability along an urban beach in Seattle, Washington. We directly sampled the density and diversity of invertebrates in the upper, middle, and lower littoral zones to assess their distribution. We recorded the number of steps taken and amount of time spent foraging by crows by tidal zone and tide direction. Worms, crabs, and snails were expected to be exposed to predation at lower tide heights, and some species of worms were only found at low tides (

The Cambrian Chickies Quartzite was produced by a migrating mosaic of subtidal channels, intertidal flats and tidal flat ponds. These tidal zone subenvironments are interpreted from assemblages of physical and biogenic structures, each of which has unique hydrodynamic implications. The highest flow regimes and most persistent currents occur in channels represented by non-burrowed tangentially cross-stratified dune deposits. The range of flow conditions on the intertidal sand flat is represented by burrowed sandstones containing a sequence of physical structures from tangential to avalanche cross-stratification to lower flat bed. The high-energy low flat deposits contain closely spaced Scolithus burrow forms. Lower-energy high flat deposits contain Monocraterion burrow tops in conjunction with widely spaced Scolithus dwelling tubes. Quiet water ponds in abandoned channels on the intertidal flat are represented by lenses of non-burrowed gray clay immediately overlying channel deposits.

The development of flowering shoots was studied by daily observation of plants grown in aquaria under controlled conditions. Inflorescences (‘spathes’) of a rhipidium develop and flower one after another, thus elongating the fertile shoot. Rhipidia of the same fertile shoot flower more or less synchronously. The whole course of flowering of one generative shoot is given. There is no peak in flowering in the field, as a consequence of the long time-period over which a fertile shoot flowers. In the tidal zone near Bergen op Zoom (The Netherlands) the production of new shoots increases up until the end of August and then gradually declines. At the beginning of October, the development of new fertile shoots ceases, and at the end of this month nearly all plants have withered or are washed away. In the stagnant water of the Grevelingen (The Netherlands) the production of fertile shoots increases in July, is constant or slightly fluctuating in August and suddenly stops at the beginning of September. The flowering rate is somewhat higher in the Grevelingen than near Bergen op Zoom.

The vertical distribution of flying mosquitoes was investigated in separate experiments in open savanna and over a fallow field system near Keneba Village in the tidal zone of the Gambia using suction traps located at seven levels (0·1, 0·25, 0·5, 1·0, 2·1, 3·9 and 7·9 m) on a scaffolding tower. Mosquito density declined progressively with height forAnopheles melasTheo.,An. pharoensisTheo.,An. squamosusTheo.,An. ziemanniGrünb.,Aedes dalzieli(Theo.),Ae. punctothoracis(Theo.),Culex tritaeniorhynchusGiles andMansoniaspp. Catches ofC. thalassiusTheo. andC. invidiosusTheo. increased with height to around 1 m and then decreased steadily although the 7·9–m trap consistently captured moreC. thalassiusthan the trap below, presenting a bimodal vertical distribution profile. Flight altitudes of the two most abundant species,An. melasandC. thalassius, declined as the night progressed, but wind speed and lunar phase had no clear or consistent effects on flight levels. A functional relationship between flight altitudes and dispersal patterns of mosquitoes is suggested.

Available literature data on the general corrosion of low alloy steels during full immersion in sea water and during exposure in the tidal zone were analysed statistically. The results obtained from tests at various locations lead to similar conclusions regarding the influence of specific alloying elements on the corrosion rate of low alloy steels. The effect of alloying elements depends on the type of exposure. The influence of some important alloying elements is also strongly time dependent. Predictions of the corrosion behaviour of certain low alloy steels based on the results of relatively short exposure tests are therefore unreliable as a basis for the application of such steels in structures that will be exposed to sea water corrosion for a long period.

SynopsisThe coastal zone is being seen increasingly as a major resource requiring the planning of its use to accommodate the many and frequently conflicting demands placed upon it. In the U.K. this planning is complicated by the difficulties arising from the scale, map projection and quality of information provided by the different mapping agencies. These difficulties are compounded because the representation of information concerning the littoral is quickly outdated by the dynamic coastal processes operating in this zone. This paper presents the results of an investigation of the use of digital remote sensing and mapping techniques, using data from a set of LANDSAT MSS scenes corresponding to different tidal states, for mapping within the coastal zone where regular and possibly cyclic map revision is required.

The present paper describes the seasonal variation of constituents such as sterol, hydrocarbon, higher fatty acid, and phytol fractions from Enteromorpha prolifera (MULLER) J. AGARDH (Chlorophyceae) which grow profusely at tidal zone in the Seto Inland Sea of Japan. E. prolifera is characterized by higher contents of 28-isofucosterol (Z-24-ethylidene-cholest-5-en-3β -ol) as the major component in the sterol fraction throughut the year. This content increeased to its maximum level level in the winter months (propagative season) and then gradually decreased to its minimum level in the early spring months when the alga was at the mature stage. The contents of 24-methylenecholesterol (24-methylenecholest-5-en-3β -ol) and cholesterol (cholest-5-en-3β -ol) were consistently low in all seasons. cis-7-Heptadecene was characteristically present in apreciable amounts, along throughout the year with lower contents of n-eicosane and phytol The C18-unsaturated fatty acids were the major components in the higher fatty acid fraction in allseasons. These contents increased to the maximum levels in the early spring months (decay season).

The paper presents some results from a continuing research programme on the marine durability of steel fibre reinforced concrete. A mix of proportions by weight of 1 : 1.5 : 0.86 with a water/cement ratio of 0.4 was reinforced with three types of steel fibres. The cement content of the mix was 590 kg/m3. Uncracked prism specimens were cured under marine splash and tidal zone exposure in the laboratory and at Aberdeen beach. In one batch of prism specimens, flexural cracks of width ranging between 0.07 and 1.08 mm were induced prior to marine exposure. Chloride diffusion characteristics in uncracked and pre-cracked concrete were determined at up to 2000 cycles of marine exposure (1250 days). The results show that Cl− concentrations are significantly greater in laboratory cured specimens relative to those cured on the beach. Most of the Cl− penetration occurs within 150 tidal cycles of exposure at the beach. Cl− concentrations increase with increasing crack widths although the influence of small crack widths of ⩽ 0.2 mm is marginal.

Polar constituents of the green alga Cladophora densa HARVEY, which grows in the tidal zone of the Seto Inland Sea, were identified by GC, HPLC, IR, 1H NMR, MS, synthesis, and chemical transformations to known compounds. The methanol extract of the dried algae, from which nonpolar constituents were removed beforehand by n-hexane extraction, consisted of large amouts of monoglycerides with C16-and C18-unsaturated fatty acids and L-alanine, and small amounts of glycerol, L-phenylalanine, Ltyrosine, 2, 3, 5, 6-tetraiodo-DL-tyrosine, and galactoside of β-sitosterol.

The density and size of shrimps on an extensive tidal flat in the western Wadden Sea was followed through 4 successive years. The population consists of juvenile shrimps ( With aid of independant growth data the production of juvenile shrimps in the tidal zone was estimated at 2.35 g ADW·m−2·a−1, of which about 60% is consumed within the area by crabs and fishes. The average food consumption of the juvenile shrimps was estimated at 6.7 g ADW·m−2·a−1, which makes them the most important carnivore population of the Wadden Sea's tidal area.

Annual phytoplankton primary production in the tidal channels of the western Wadden Sea cannot be estimated more precise than 150 ± 50 g C · m −2 · a −1 , because of large spatial and short-term temporal variations. This implies that year-to-year variations and possibly long term trends have to be very pronounced to be measurable even with a weekly sampling program. Short-term temporal variation in primary production of microphytobenthos living on the tidal flats is less pronounced but spatial variation is large. Primary production on high tidal flats is larger than on flats lower in the tidal zone. Year-to-year variation on a tidal flat station occupied now for 12 years is large. This variation cannot be explained by year-to-year variations in nutrients, light or temperature, but probably by year-to-year variations in grazing. Macrophytobenthic primary production plays a subordinate role in the western Wadden Sea. It is difficult to give one figure for annual primary production for an “average” tidal flat for reasons mentioned. Tentatively microphytobenthic plus macrophytobenthic plus phytoplanktonic primary production on and above an average tidal flat is estimated at 150 ± 50 g C · m −2 · a −1 , i.e. the same as given for phytoplankton production in the tidal channels. The western Wadden Sea receives a considerable amount of particulate organic carbon from outside the area, estimated at 240 g C · m −2 · a −1 . Formerly the North Sea was thought to be the only source. New data also indicate an important input from the IJsselmeer. This import of organic carbon, particulate plus dissolved, surpasses in situ primary production. IJsselmeer DOC is probably not used to a considerable extent in the Wadden Sea. IJsselmeer POC, however, consisting for 50% on average of living phytoplankton cells, may form a suitable food source for Wadden Sea invertebrates. Cell counts of the freshwater alga Scenedesmus showed that at least part of the IJsselmeer POC is retained in the western Wadden Sea. The importance of particle size in tidal as well as biological accumulation processes of POC in the Wadden Sea is stressed. There is no indication that POC content of the northern IJsselmeer has changed during the last 30 years.

There is much variation in the form of colony assumed by the common hydroid Clava, and two forms were for long distinguished as separate species, a diffuse one found on stones and rocks in the lower part of the tidal zone and in shallow subtidal depths, with scattered polyps arising from an open hydrorhizal network of creeping stolons, and a clustered one, living on fucoid and other seaweeds in the tidal zone, with densely clustered polyps borne on a compact hydrorhizal base of very short anastomosing stolons. Johnston (1847) did not separate these forms and recognized one species only, named by priority Clava multicornis (Forskal, 1775). It was largely on the authoritative works of Hincks (1868) and Allman (1871–2) that the two forms became accepted as distinct species, the name Clava multicornis (Forskål) being adopted for the diffuse one (though Hincks admitted uncertainty in ascribing Forskål name to this) and Clava squamata (Müller, 1776) for the clustered one. More recently certain authors have considered them to be forms of one species, designated by priority Clava multicornis, but others have continued to treat them as separate species, and the question of their specific identity or distinctness cannot be said to have been resolved. Broch (1916, pp. 38–40), from a study of material from various localities, concluded that there are all transitional conditions between the two forms, rendering specific distinction impossible, and that they are evidently ecologically conditioned forms of one species. He did not, however, adduce any experimental or other evidence in support of his belief.

Aggregations of the filtering archeogastropod Umbonium vestiarium (L.) were investigated in a tropical sand flat on Phuket Island, southern Thailand. Field experiments showed that these assemblages were formed when snail abundance exceeded five individuals per 10 cm2. In these aggregations an average density of 2–3.5 snails per cm2 and a central density of 5–7 snails per cm2 were measured. The biomass ranged from 92 to 148 g/m2 AFDW. The Umbonium aggregations are conspicuous elevations which are generated by the snails fixing sediment with their mucus. During calm weather periods migration of the snail assemblages towards the sublittoral was observed. The formation of aggregations in Umbonium vestiarium prevents deportation from the tidal zone and is interpreted to be advantageous for filter feeding and reproduction.

Corrosion of marine steel constructions may vary to a considerable extent owing to their different locations such as atmosphere, splash zone, tidal zone, immersion zone and mud zone[7, 8]. A rather lengthy hanging steel sample is needed to test its corrosion resistance in various environments. But it is cumbersome to handle and not convenient for frequent observation and maintenance. So an indoor analogue test method is generally adopted for this purpose[1]. This paper is a report of such a test.

Stages in the life cycle of Parvatrema affinis were studied and compared with previous descriptions by Markowski (1937) and Selikman (1953). The cercariae quickly develop into metacercariae and remain within the sporocysts which heavily parasize the intermediate host, Macoma balthica in the tidal zone of the Wadden and North Seas. The adult stage, recovered from experimental infections of Anas platyrhynchos is similar to that described by Jameson & Nicoll (1913) and James (1964). Older, larger clams in the upper littoral zones were most highly infected with P. affinis . These infected clams exhibited surfacing and crawling tracks on the sand, changes in the behaviour of the hosts which may increase risk of predation by birds, the definitive hosts.

Durch elektrochemische Versuche in beluftetem kunstlichem Meerwasser (ASTM-Norm D 1141-75) bei 25,50 und 80°C und durch Auslagerung in einem Meerwasserprufstand auf Helgoland wurden die Korrosionseigenschaften von Auftrags- und Verbindungsschweisungen der Verbundwerkstoffe NiCu30Fe/Stahl im Hinblick auf den Einflus einer Fe-Aufmischung untersucht. Zum Vergleich dienten NiCu30Fe-Bleche mit definierten Fe-Gehalten zwischen 0 und 14%1 . Bei homogener Fe-Verteilung wird in beluftetem KMW von 25°C bis zu einem Fe-Gehalt von 10% kein negativer Einflus des Eisens auf die Lochfrasbestandigkeit gefunden. Mit steigender Temperatur (50 und 80°C) verschlechtert sich die Lochfrasbestandigkeit, und der Fe-Einflus nimmt geringfugig zu. Bei der Beanspruchung in Meerwasser, Helgoland, wird in der Dauertauchzone die Korrosion in erster Linie durch den maritimen Bewuchs bestimmt, der zu muldenformigem Korrosionsangriff fuhrt. In der Wechseltauchzone verursachen bei sehr niedrigen integralen Abtragungsraten Fe-Gehalte deutlich oberhalb 6,7% die Bildung von feinen rosthaltigen Lokalkorrosionsstellen. Die Verbindungsschweisungen lassen leichte Lochfraserscheinungen im Schweisgutbereich erkennen, die wahrscheinlich weniger auf eine Fe-Aufmischung als auf das gegenuber dem Grundwerkstoff leicht abgesenkte freie Korrosionspotential des Schweisgutes zuruckzufuhren sind. Mit integralen Fe-Gehalten in der Decklage zwischen 0,5 und 3% haben die Auftragschweisungen eine gleich gute Korrosionsbestandigkeit wie handelsubliches NiCu30Fe-Blech. In der Wechseltauchzone, dem vorwiegenden Anwendungsbereich, zeigt der nach unterschiedlichen Schweisverfahren geschweiste Werkstoff mit Abtragungsraten < 0,01 mm/a eine gute Bestandigkeit. Dabei haben Fe-Gehalte bis etwa 8% Fe, die mit zweilagigen Schweisungen nach allen bekannten Schweisverfahren eingehalten werden konnen, keinen negativen Einflus auf die Korrosionsbestandigkeit. The influence of iron pick-up on the corrosion properties of NiCu30Fe/steel clad materials The influence of iron pick-up on the corrosion properties of overlay and butt weldings of NiCu30Fe/steel cald materials was investigated by electrochemical tests in aerated artificial sea water (ASTM Standard D 1141-75) at 25, 50 und 80°C and by exposure to sea water in a sea water test rig on Helgoland. NiCu30Fe plates with defined Fe contents between 0% and 14% were used for comparison. On the Fe being distributed homogeneously, no negative influence of the iron on the pitting resistance was noted in aerated artifical sea water of 25°C up to an Fe content of 10%. The pitting resistance increases with rising temperature (50 and 80°C) and the Fe influence increases slightly. On exposure to sea water on Helgoland, the corrosion in the subtidal zone is mainly caused by marine growth resulting in the formation of shallow pits. In the tidal zone, Fe contents of more than 6.7% cause rust pittings at very low integral corrosion rates (≤0.002 mm/a). With integral Fe contents of between 0.5% and 3% in the final pass, the overlay welds have the same good corrosion resistance properties as commercial NiCu30Fe plate material. The compound butt welds exhibit slight pitting in the weld metal and the heat-affected zone which cannot be conclusively attributed to Fe pick-up but is rather due to the different free corrosion potentials of the NiCu30Mn(Ti) weld metal and the NiCu30Fe cladding material. In the tidal zone which is the preferential application of NiCu30Fe corrosion rates are less than 0.01 mm/a for all specimens welded by different welding methods. Iron contents of up to 8% which can be met by all welding methods when welded in two layers have no negative effect on the corrosion properties.

AnbstractIn the Lublin area of the East European Platform (southeast Poland) sedimentation of the Vendian–Cambrian marine sequence began in Late Vendian times. Vendian and Cambrian strata occur in sedimentary continuity and their features indicate sedimentation in the tidal zone of a shallow epicontinental sea. The Vendian–Cambrian boundary, drawn on the basis of mainly palaeontological data, passes between theVendotaeniaandSabellidites zones.

At higher levels in the tidal zone conspicuous crawling-trails of Macoma balthica are sometimes found. The specimens making these trails turned out to be filled with sporocysts of an as yet unidentified Gymnophallid trematode. It was proved that the parasite does not develop any further in the mollusc, but that in a bird the sexually mature stage is reached within 24 hours. It is supposed that the parasite stimulates the host to crawling behaviour, thus increasing the chance of predation by a bird.

It has generally been assumed that, in tidal zone fucoids, high level species have thicker cell walls and, consequently, a lower desiccation rate than low level species. This turned out to be erroneous: the desiccation rate of high level species is not low at all, in spite of their thick cell walls. When comparing plants of the same species but growing in different environments, it was found that neither the emersion time nor the exposure to sun influences the cell wall thickness of the plants, but exposure to wave action does have such an influence: the more exposed the plant, the thicker the cell walls and the lower the desiccation rate.

A new species, Triglochin gaspense Lieth & D. Löve, is described from a salt marsh between Barachois-Ouest and Coin-du-Banc, Gaspé Peninsula, Quebec, Canada. It is distributed in Quebec, the Canadian Maritime Provinces, and Newfoundland, as well as in at least the northern part of the state of Maine, U.S.A. It is well differentiated from the other American species of the Triglochin maritimum complex, to which it belongs, morphologically (5–20 cm tall, leaves overtopping the short, few-flowered spike), cytologically (2n = 96 chromosomes), and ecologically (confined to the tidal zone of the Atlantic coast below the high-water mark). The type specimen of the new species is preserved in the Marie-Victorin Herbarium, Université de Montréal.

In 1926 a quantitative examination of the fauna of the intertidal sands in the Cumbrae, Firth of Clyde, was begun, and the results proved so interesting that it was decided to extend the survey to other parts of the Scottish coast, the object being to study the variation in density and composition of the fauna, with special reference to the two groups of molluscs and polychætes, from place to place, and at various levels on the beach. During the past two years observations have been made in three widely separated areas, namely, on the Ayrshire coast and Firth of Clyde, on the southern shore of the Moray Firth, and on the east coast of Scotland and in the Firth of Forth. In all, twenty-five bays or stretches of coast have been visited, and over one hundred and fifty quantitative collections worked through.

Summary In sand samples of different beaches of the Gulf of Naples 57 ciliate species have been found. There is no difference between sand-dwelling ciliates of the tidal zone, or deeper along the seashore, when sand granulometry is the same. Further more, it was noticed that the interstitial spaces, which are roughly proportional to the size of the sand grains, limite the distribution of microporal fauna, showing therefore qualificative selection. On the contrary, the water movement and food quantity determine the abundance of species and specimens in certain places.