위성영상 분석기술을 이용한 시흥갯벌의 지형 및 노출시간 분석

A conceptual model of relationships between mangrove community structure and their physico-chemical environment is developed for point bars and islands in the Tempisque-Bebedero estuarine system, Pacific coast, Costa Rica. The model identifies key variables whose relationships to mangrove forest structure are the focus of extended field and mesocosm studies. Point bars and islands are very dynamic features constantly modified by hydrology and sediment dynamics. In the Tempisque-Bebedero system, they are additionally modified by extensive agricultural activities. High riverine sediment loads, associated with irrigation and seasonal wind-driven resuspension, result in significantly higher sediment deposition in lower intertidal zones; upper intertidal zones are less affected due to their elevation and less frequent flooding. This study shows significant relationships between mangrove forest structure and position along the intertidal gradient. Laguncularia racemosa is the pioneer species colonizing emerging mud banks, and dominates lower intertidal zones in terms of basal area and stem density. Rhizophora racemosa, Avicennia germinans, and A. bicolor dominate basal area of upper intertidal zones. The correlation between forest structure, hydrology and sediment deposition implies that mangroves in this region are distributed according to inter-specific differences in tolerances to inundation and sedimentation dynamics. Soil physico-chemical variables changed significantly across the intertidal gradient, implying that edaphic factors are important explaining the observed mangrove distributional patterns. Laguncularia dominates the lower intertidal zone characterized by lower soil stability and "richer" sods than the upper zone. Riverine source of nutrient-rich, low salinity water and sediments is important and explains the high structural development of these mangrove communities. The effect of hydrology and biotic factors in species distribution are important during the early phases of mangrove development by determining species-specific ability of establishment. Compared to Avicennia, Laguncularia propagules had higher establishment in mud banks, implying that Laguncularia 's specific propagule characteristics are important in determining this species' successful colonization of lower intertidal zones. Intensive crab predation in upper intertidal zones, however, restricts its distribution in upper intertidal zones. Mangrove structure in the Tempisque-Bebedero system is therefore sensitive to a combination of physical and biological factors, which deserve attention considering the impact of further alterations to this estuarine system.

Growth dynamics of the seagrass Zostera japonica at its upper and lower distributional limits in the intertidal zone

Intertidal zonation affects diversity and functional potentials of bacteria in surface sediments: A case study of the Golden Bay mangrove, China

The role of intertidal egg deposition on survival of the puffer, Takifugu niphobles (Jordan et Snyder), embryos

ABSTRACTExperimental field manipulations of artificial substrata were used to examine the mechanisms controlling attached algal zonation down the face of the dam in Lake McConaughy, a large reservoir in western Nabraska. Sets of clay tiles were incubated in the upper (2.5 m depth) and lower (8 m depth) growth zones for two weeks. Five sets tiles were then switched from the upper to the lower growth zone and vice versa. Five additional sets of tiles were switched to the lower zone and artificially disturbed. Diatom cell densities increased rapidly in both the zones; however, wind‐induced turbulence caused dramatic declines (up to 61%) in densities in the upper zone. Consequently, cell densities in the upper and lower growth zones were not significantly different after four weeks, despite the 17–30% higher light levels in the upper zone. Based on cell densities and relative abundances on clay tiles and naturally occurring rocks, 26 of the 32 most common diatom taxa had a significant upper (10) or lower (16) zone preference. Of these, 15 taxa exhibited a consistent response to one or both switching manipulations, confirming a growth zone preference, and two showed a clear preference for disturbed substrata. Diatom growth form appeared to play a major role in determining the vertical zonation of attached communities, since actively motile taxa exhibited a lower zone preference and stalked forms occurred primarily in the upper zone. The present study indicates that light attenuation and wave disturbance are primary mechanisms that control the vertical zonation of freshwater epilithic algae.

This research was conducted to evaluate the gastropods diversity in mangrove forests located in Iranian part of the Govater Gulf in southern border of Iran and Pakistan. Three transects were selected at the water interface vertically to the end of forest stand. In each transect, samples of sediments containing gastropods were taken at the beginning (lower zones), the middle, and the end (upper zone) points during four continued seasons. Biodiversity (Shannon–Wiener index), dominance (Simpson’s dominance index), species evenness (Smith and Wilson evenness index), richness (number of species), and density (number in m3) were calculated for each season in sampling points. Data analysis results showed that biodiversity and richness indices changed significantly among different transects. Shannon–Wiener diversity index in transect one (1.90 ± 0.69) was significantly higher than transect two (1.26 ± 0.67) and three (1.19 ± 0.68). Similarly, richness index was the highest in transect one (7.58 ± 1.53) rather than transect two (4.42 ± 1.15) and three (3.92 ± 0.94). Density index changed differently between lower zone (2318.02 ± 987.76), middle zone (2318.01 ± 605.75) and upper zone (13,420.71 ± 176.50). Species evenness showed significant differences between lower (0.65 ± 0.15) to middle (0.46 ± 0.20) and upper (0.30 ± 0.32) zones. Different seasons had no significant effect on richness, density, diversity, and evenness of gastropod species. Consequently, among the natural factors, it is the intertidal zones which increases the environmental stresses such as salinity and humidity was considered, and surprisingly, weak anthropogenic factors, for example, the effect of the transect was positive due to providing nutrient.

While there is already a comprehensive understanding of the effects of environmental variables, such as dissolved oxygen, temperature and salinity, on the structure, biomass and metabolism of aquatic biota in estuarine habitats, the effect of sedimentation, a harmful underlying factor, remains unclear. The aim of this study was to assess the differences in fish assemblages along the freshwater to salt water gradient of a large tropical estuary, and to evaluate the effects on them of habitat disturbance associated with shallow water sedimentation in the intertidal areas. Fish and environmental variables were recorded in the upper, middle and lower salinity zones of the estuary at ebb tide in both the dry and wet seasons. Sediment samples associated with different levels of habitat disturbance were analysed using granulometry, and their organic content and dissolved oxygen levels were quantified. Water temperature, salinity, pH and dissolved oxygen levels were also measured. Habitat disturbance was found to be correlated with the density, biomass and richness of fish assemblages. A total of 77 species were recorded, forming two distinct fish assemblages, with the Eleotridae family dominating in the upper zone, and Gerreidae, Gobiidae and Tetraodontidae the most common in the middle and lower estuary. Changes in the structure of fish assemblages, including reductions in density, biomass and richness, were associated with disturbance to natural features, where muddy sediment was replaced by sandy sediment and the quantity of organic matter fell. Atherinella brasiliensis was the species which showed a preference for the disturbed areas in the middle and lower zones, while Dormitator maculatus showed a preference for them in the upper estuary. They may be taken as indicators of habitat disturbance due to shallow sedimentation.

Diatom distribution along a tidal river in South Korea and trends with elevation and distance along the river

The distribution of the amphipod Corophium arenarium in the Dutch Wadden Sea: relationships with sediment composition and the presence of cockles and lugworms

Littorina brevicula (Philippi) is an abundant herbivorous gastropod species inhabiting intertidal zones of the north‐western Pacific and has internal fertilization with planktonic eggs and a larval stage. A population of L. brevicula on a shore in Amakusa, Japan, splits into an upper and a mid shore sub‐population during the mating season in winter, while all individuals occurred in the upper zone in summer. Transplant and recapture experiments have shown that snails from each sub‐population have a distinct pattern of seasonal migration, suggesting that the snail population consists of two behavioral morphs. To explore the relationship between migration pattern and life history characteristics in the snails of the two migration morphs, monthly quantitative samplings and a mark‐release and recapture survey were carried out for the population of L. brevicula over a 1‐year period. In autumn, some of the adults migrated downward to the mid shore and formed the lower sub‐population from October to April. Migration between the upper and lower sub‐populations was minimal from December to February, when L. brevicula copulate actively. The shell growth rates of the snails in the lower zone were slightly higher than those in the upper zone, but the shell width of females was not a good predictor of the number of mature ova they contained. The number of mature ova was not significantly different between the females of the two migration morphs. In addition, the mortality of marked snails did not differ significantly between the upper and lower zones. Thus, no evidence was obtained to indicate a difference in the reproductive fitness between the two migration morphs.

Using stable isotopes and tritium to delineate groundwater flow systems and their relationship to streams in the Geum River basin, Korea

The effect of variable Zn supply with depth in a soil profile was examined in two wheat genotypes differing in their Zn efficiency. ‘Gatcher’ (Zn-inefficient) and ‘Excalibur’ (Zn-efficient) were grown in a low Zn soil in pots with two treatment zones. The upper zone (10 cm) was supplied with Zn while Zn was either supplied or withheld from the lower zone (25 cm). In both genotypes, withholding Zn from the lower zone had no effect on root growth in either the upper or lower zones; neither did it affect plant appearance prior to booting. However, withholding Zn from the lower zone delayed head emergence in Gatcher by some 10 d and depressed grain yield by 20%. In Excalibur, Zn treatment had no effect on head emergence or grain yield. In Gatcher, withholding Zn from the lower zone depressed water usage by 12% during a 60 d period preceding maturity. No effect of Zn treatment on water usage was seen in Excalibur. Tissue Zn concentrations closely reflected the lower zone Zn treatments in both genotypes. Irrespective of the Zn treatment, Excalibur had higher Zn concentrations in flag leaves but lower concentrations in grain than Gatcher. In whole shoots, genotypic differences in Zn concentration only occurred when Zn was added to the lower zone; Excalibur having almost twice that of Gatcher. Clearly, if Zn is not supplied to the entire root system there is the potential for impaired root function and plant development, and for reduced grain yield. Approaches to managing this problem are discussed.

The phenomenon of a dense phase (water) entering through perforations into a stream of a less dense phase (gas or oil) has been examined in a model wellbore. When water entered a gas stream, some of the water fell through the gas stream to occupy a portion of the wellbore below the perforations for all conditions tested and anomalous pressure behavior was observed in the region of the perforations. In the oil-water tests, all of the water was swept upwards by the oil only at the highest oil flow rate (5000 b/d) and lowest water flow rate (50 b/d) with the pipe vertical. The deleterious effect of dense phase fallback on production log interpretation is demonstrated.

Shore platform development and processes are examined for Kaikoura Peninsula on the north‐east coast of the South Island, New Zealand. The environment is exposed to high energy storm and swell waves, is mesotidal (mean range 1.36 m, maximum 2.57 m) and has a temperate climate with moderate rainfall (average 865 mm yr −1 ). Shore platforms range from 40 m to over 200 m wide and are cut in Tertiary mudstones and limestones. Most of the profiles display a prominent low water cliff, an outer rampart and channels developed along lines of structural weakness. The inner margins are extensively mantled in beach, hillslope, and lagoonal sediments which are being rapidly eroded except for three locations where there is an active marine cliff. Net tectonic uplift of the peninsula is thought to be of the order of 108 m during the Quaternary and 2 m during the last 1000 years. The shore platforms are thus clearly polycyclic and contain “inherited” morphological features but are being actively rejuvenated by removal of cover deposits. Data on intertidal platform lowering rates are derived from 31 micro‐erosion meter sites located on seven profiles around the peninsula margin. Each site produces three values per observation and they were measured at two monthly intervals for two years from 1973–1975 yielding 672 values for surface lowering, a 60%measurement repeatability. Mean lowering rate for the two years was 1.53 mm yr −1 (minimum 0.38 mm yr −1 , maximum 7.03 mm yr −1 , standard deviation 1.45 mm yr −1 ) and rates were generally higher on mudstone than on limestone and where eroding cover deposits yield abundant abrasional materials. Backwasting rates were estimated from analysis of air photographs over the period 1942–1974 for 41 sites on the peninsula and ranged up to 1.49 m yr −1 for eroding beach complexes and between 0.24 and 0.33 m yr −1 for active mudstone cliffs. Lowering rates were approximately 3% of backwasting rates. No data was obtained on either recession rates of the low water cliff or block disintegration of platform rock. An approximate minimum littoral sediment budget revealed that the intertidal area of 0.72 km 2 contributes between 4–5000 m 3 of eroded material annually 34% of which is derived from the limited stretches of active marine cliff and 39% of which comes from platform lowering. A parallel retreat model was applied to platform erosion rates with limited success and planation ages of between 10 2 –10 3 years were estimated. Despite the short term nature of the erosion data both the rates and planation times are likely to be of order of magnitude accuracy. Both erosion rates and planation ages lie within the ranges of other studies and are consistent with dated shoreline events on the Kaikoura Peninsula. Four phases of activity are identified for the last 5–6000 years involving changing tectonic‐eustatic levels, platform processes and erosion episodes in the hinterland. The platforms are thus rapidly evolving features which reflect both contemporary processes and recent history. Analysis of variation in lowering rates across the shore revealed upper and lower zones of relatively more intense erosion separated by a central zone of lesser intensity. The upper zone is thought to be essentially sub‐aerial and supra‐littoral in character, while the lower one may be dominated by marine and sub‐littoral processes. There is thus a gradient from sub‐aerial processes to true marine processes across the shore so that it is unlikely that a single dominant mode controls platform development and morphology.

Surf zones, beaches and dunes compose the Littoral Active Zones (LAZ) in coastal areas. Sandy beaches encompass the intertidal-supralittoral interface of LAZ and are characterized by discrete assemblages, tightly related to the physical constrains and habitats where marine, semi-terrestrial and terrestrial organisms live. Crustaceans, molluscs and polychaetes dominate beach communities in intertidal zones, whilst insects become representative in supralittoral. Communities are relatively similar worldwide, being frequently dominated by typical families, with few specificities according to morpho dynamics, latitude and tide regime. Communities are structured mainly by individual responses of species to physical drivers on several spatial dimensions. The Swash Exclusion, Multicausal Environmental Severity and Habitat Harshness hypotheses have been corroborated for explaining the higher richness and density of marine macroinvertebrates on dissipative beaches compared to reflective ones. Nevertheless, supralittoral communities still lack depiction of patterns and processes, since communities of swash and upper zones can be driven by independent factors. For intertidal communities dominated by marine organisms, grain size, beach slope, tide regime, temperature and primary productivity have been considered the main drivers of richness at macroscales. Nevertheless, environmental disturbances, habitat heterogeneity, ecological interactions, and meta-populations connectivity are still neglected in studies on/about community ecology of intertidal and supralittoral zones.