Ryuichiro Nishi

MECHANISM AND CALCULATION OF SAND DUNE EROSION BY STORMS

A study of alternatives including a shoreline evolution numerical modelization has been carried out in order to both diagnose the erosion problem at the beaches located between Cambrils Harbour and Pixerota delta (Tarragona, Spain) and select nourishment alternatives.

Purification and identification of a novel primitive secretory enzyme catalyzing the hydrolysis of imidazole-related dipeptides in the jawless vertebrate Lethenteron reissneri

Imidazole-related dipeptides, such as carnosine and anserine, occur widely in skeletal muscles of jawed vertebrates. All of the known enzymes that catalyze the hydrolysis of these dipeptides belong to the M20A metallopeptidase subfamily; two secretory enzymes, serum carnosinase (EC 3.4.13.20) and anserinase (EC 3.4.13.5), and one non-secretory enzyme, cytosolic nonspecific dipeptidase (EC 3.4.13.18). Here we report the enzymatic characterization and molecular identification of an unidentified enzyme, which catalyzes the hydrolysis of these dipeptides, from the skeletal muscle of Far Eastern brook lamprey (Lethenteron reissneri). A 60-kDa subunit protein of the enzyme was purified to near homogeneity. We cloned two M20A genes from the skeletal muscle of Far Eastern brook lamprey; one was a secretory-type gene encoding for the 60-kD protein, and another was a non-secretory-type gene presumably encoding for cytosolic nonspecific dipeptidase. Our findings indicate that the purified enzyme is a N-glycosylated secretory M20A dipeptidase distributed specifically in the jawless vertebrate group, and may be derived from a common ancestor gene between serum carnosinase and anserinase. We propose that this dipeptidase is a novel secretory M20A enzyme and is classified as neither serum carnosinase nor anserinase.

ON THE CHANGE OF VELOCITY FIELD IN NEARSHORE ZONE DUE TO COASTAL DRAIN AND THE CONSEQUENT BEACH TRANSFORMATION

A study of alternatives including a shoreline evolution numerical modelization has been carried out in order to both diagnose the erosion problem at the beaches located between Cambrils Harbour and Pixerota delta (Tarragona, Spain) and select nourishment alternatives.

Purification and identification of two carnosine-cleaving enzymes, carnosine dipeptidase I and Xaa-methyl-His dipeptidase, from Japanese eel (Anguilla japonica)

Three enzymes, carnosine dipeptidase I (EC 3.4.13.20, CNDP1), carnosine dipeptidase II (EC 3.4.13.18, CNDP2), and Xaa-methyl-His dipeptidase (or anserinase: EC 3.4.13.5, ANSN), are known to be capable of catalyzing the hydrolysis of carnosine (β-alanyl-l-histidine), in vertebrates. Here we report the purification and identification of two unidentified carnosine-cleaving enzymes from Japanese eel (Anguilla japonica). Two different dipeptidases were successfully purified to homogeneity from the skeletal muscle; one exhibited a broad substrate specificity, while the other a narrow specificity. N-terminal amino-acid sequencing, deglycosylation analysis, and genetic analysis clearly revealed that the former is a homodimer of glycosylated subunits, encoded by ANSN, and the latter is another homodimer of glycosylated subunits, encoded by CNDP1; that is, Xaa-methyl-His dipeptidase, and carnosine dipeptidase I respectively. This is the first report on the identification of carnosine dipeptidase I from a non-mammal. Database search revealed presence of a CNDP1 ortholog only from salmonid fishes, including Atlantic salmon and rainbow trout, but not from other ray-finned fish species, such as zebrafish, fugu, and medaka whose genomes have been completely sequenced. The mRNAs of CNDP1 and ANSN are strongly expressed in the liver of Japanese eel, compared with other tissues, while that of CNDP2 is widely distributed in all tissues tested.

Short-Term Field Experiments on Beach Transformation under the Operation of a Coastal Drain System

The objective of this study is to add prototype data for estimating the performance of a coastal drain system. Small-scale model experiments aimed at understanding the mechanisms that make coastal drain systems effective were carried out. The model experiments gave us qualitative information on the relevant mechanisms, as well as encougaring results. However, our experiments were done under conditions in which the role of the drain in sediment movement was magnified compared to the effect of wave motion. Some caution is thus advisable when the experimental results are extended to estimate the performance of prototype-scale coastal drain systems. In order to be able to evaluate the performance of a coastal drain system and establish the designing procedures, prototype scale-detailed data that includes information on waves, sediments, beach profiles, drainage and so forth, together with the development of numerical models, is necessary. This paper, firstly briefly discusses where to install drainpipes, then discusses the experimental results.

Compaction Effect on Beach Stabilization

A Laboratory study, on beach stabilization by using artificial compaction control, has been conducted. Erosional and accretional waves were applied to uncompacted, moderately compacted, and densely compacted sandy beaches. Changes in beach profile and cross-shore distribution of compaction were measured, then the net cross-shore sediment transport, the shoreline change, the average size of ripples, and the volumetric change were calculated. The results generally show that the higher the compaction, the lesser the net offshore sediment transport and erosion volume. On the other hand, the effect on the decrease of accretion volume was relatively small. This paper also presents a methodology to estimate a cross-shore distribution of local porosity based on the measured local compaction.

FIELD OBSERVATION AND NUMERICAL SIMULATION OF BEACH AND DUNE SCARPS

A special reflecting wall 12 m long and 2.1 m high was built off the beach at Reggio Calabria, and 30 wave gauges were assembled before the wall and were connected to an electronic station on land. It was possible to observe the reflection of wind waves generated by a very stable wind over a fetch of 10 Km. The experiment aimed to verify the general closed solution for the wave group mechanics (Boccotti, 1988, 1989), for the special case of the wave reflection.Significant features on Wadden Sea wave climate are evaluated in respect of the state of the art. Main emphasis was laid on an analysis of the governing boundary conditions of local wave climate in island sheltered Wadden Sea areas with extensions being sufficient for local wind wave growth. Explanatory for significant wave heights a reliable parametrization of local wave climate has been evaluated by using generally available data of water level and wind measurements.

COASTAL EROSION CAUSED BY CONSTRUCTION OF AN ARTIFICIAL ISLAND AND PERFORMANCE OF BEACH NOURISHMENT

Detailed studies have been undertaken to assist in the design of major extensions to the port of Haifa. Both numerical and physical model studies were done to optimise the mooring conditions vis a vis the harbour approach and entrance layout. The adopted layout deviates from the normal straight approach to the harbour entrance. This layout, together with suitable aids to navigation, was found to be nautically acceptable, and generally better with regard to mooring conditions, on the basis of extensive nautical design studies.Hwa-Lian Harbour is located at the north-eastern coast of Taiwan, where is relatively exposed to the threat of typhoon waves from the Pacific Ocean. In the summer season, harbour resonance caused by typhoon waves which generated at the eastern ocean of the Philippine. In order to obtain a better understanding of the existing problem and find out a feasible solution to improve harbour instability. Typhoon waves measurement, wave characteristics analysis, down-time evaluation for harbour operation, hydraulic model tests are carried out in this program. Under the action of typhoon waves, the wave spectra show that inside the harbors short period energy component has been damped by breakwater, but the long period energy increased by resonance hundred times. The hydraulic model test can reproduce the prototype phenomena successfully. The result of model tests indicate that by constructing a jetty at the harbour entrance or building a short groin at the corner of terminal #25, the long period wave height amplification agitated by typhoon waves can be eliminated about 50%. The width of harbour basin 800m is about one half of wave length in the basin for period 140sec which occurs the maximum wave amplification.Two-stage methodology of shoreline prediction for long coastal segments is presented in the study. About 30-km stretch of seaward coast of the Hel Peninsula was selected for the analysis. In 1st stage the shoreline evolution was assessed ignoring local effects of man-made structures. Those calculations allowed the identification of potentially eroding spots and the explanation of causes of erosion. In 2nd stage a 2-km eroding sub-segment of the Peninsula in the vicinity of existing harbour was thoroughly examined including local man-induced effects. The computations properly reproduced the shoreline evolution along this sub-segment over a long period between 1934 and 1997.In connection with the dredging and reclamation works at the Oresund Link Project between Denmark and Sweden carried out by the Contractor, Oresund Marine Joint Venture (OMJV), an intensive spill monitoring campaign has been performed in order to fulfil the environmental requirements set by the Danish and Swedish Authorities. Spill in this context is defined as the overall amount of suspended sediment originating from dredging and reclamation activities leaving the working zone. The maximum spill limit is set to 5% of the dredged material, which has to be monitored, analysed and calculated within 25% accuracy. Velocity data are measured by means of a broad band ADCP and turbidity data by four OBS probes (output in FTU). The FTUs are converted into sediment content in mg/1 by water samples. The analyses carried out, results in high acceptance levels for the conversion to be implemented as a linear relation which can be forced through the origin. Furthermore analyses verifies that the applied setup with a 4-point turbidity profile is a reasonable approximation to the true turbidity profile. Finally the maximum turbidity is on average located at a distance 30-40% from the seabed.

Simple underwater monitoring of shallow water using a spherical camera mounted on a radio-controlled boat

During underwater monitoring observations in shallow water for coastal environmental conservation, the sea is not always clear and waves and current make the observational situation difficult. Underwater monitoring is still conducted mainly by human divers. Therefore, underwater robotics or remotely operated underwater vehicles (ROVs) that can monitor from a human divers perspective are considered as labor-saving equipment. In this study, simple underwater monitoring equipment is developed using a radio-controlled (RC) boat in which a spherical camera is mounted for monitoring underwater conditions at relatively low costs. One purpose of this simple monitoring system is to obtain 360° images for observing sea beds and schools of fish without focus control. To develop the proposed simple monitoring system at a low cost, a commercially marketed spherical camera packed into a waterproof mobile-phone case is mounted on a twin-hulled RC boat. The images obtained include distortions caused by changes in the refractive index. A simple image correction based on a barrel-type image distortion method is provided. Additionally, some demonstrative experiments that were conducted in water tanks of aquariums and in a coastal channel are discussed.

FIELD MEASUREMENTS OF CRITICAL RIP CURRENTS UNDER CALM SEA CONDITION

An investigation team comprised of coastal researchers and engineers carried out field measurements of rip currents and experienced drift by the current on Sagara Sun Beach during August 23-24, 2007 with help of lifesavers and surfers. The waves and rip currents were observed near the breakwaters and the data were analyzed from the viewpoint of the safety of the beach users such as sea bathers and surfers. Various water safety problems related to the rip currents were discussed based on the field data, real experience of the drift and information of the lifesavers. A steady rip current around 0.25 m/s generated along a breakwater under calm sea condition yields dangerous situation to sea bathers and the degree of the dangerousness depends on the water depth as well as current velocity.