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This datasheet on Monostroma nitidum covers Identity, Overview, Associated Diseases, Pests or Pathogens, Distribution, Environmental Requirements, Impacts, Uses, Management, Genetics and Breeding, Economics, Further Information.

Natural seaweed beds, which play an important role for coastal ecosystems and marine fisheries, have been changing drastically in Japan. Interventions, such as decreasing the over-grazing by sea urchins, are being undertaken to maintain natural seaweed beds. Japan has at least 15 seaweed genera of economic importance utilized either directly as human food, as ingredients in food, or as raw materials for extraction of chemical compounds for various applications. Most species are produced through various cultivation methods that usually start in a land-based facility and are completed when seaweeds are transferred for open-sea cultivation. Cultivation, as well as harvesting, from natural populations, has sustained the Japanese seaweed industry for many years, but recently a downfall in seaweed production has been experienced in some areas for certain species due to warming oceans. Efforts to improve production have led to the development of forced cultivation techniques to reduce the cultivation period for Saccharina japonica while hybridization of different morphological forms of Undaria pinnatifida has resulted in the production of so-called “southern” and “northern types” that have desirable shapes for harvesting and processing. The future of the seaweed industry in Japan is geared towards producing high-grade products from seaweeds grown in land-based tanks using deep-ocean water.

The global climate has been dominated by glacial–interglacial variations since the intensification of Northern Hemisphere glaciation 2.7 million years ago. Although the Atlantic meridional overturning circulation has exerted strong influence on recent climatic changes, there is controversy over its influence on Northern Hemisphere glaciation because its deep limb, North Atlantic Deep Water, was thought to have weakened. Here we show that Northern Hemisphere glaciation was amplified by the intensified Atlantic meridional overturning circulation, based on multi-proxy records from the subpolar North Atlantic. We found that the Iceland–Scotland Overflow Water, contributing North Atlantic Deep Water, significantly increased after 2.7 million years ago and was actively maintained even in early stages of individual glacials, in contrast with late stages when it drastically decreased because of iceberg melting. Probably, the active Nordic Seas overturning during the early stages of glacials facilitated the efficient growth of ice sheets and amplified glacial oscillations. Active overturning in the Nordic seas and strong Atlantic circulation coincided with enhanced glaciation in the Northern Hemisphere after 2.7 Ma, according to a multi-proxy investigation of cores from the IODP site U1314.

Archaeomagnetism is a research area that reconstructs ancient geomagnetic fields mainly using baked samples (especially baked artifacts) containing magnetic minerals such as magnetite and hematite. Archaeomagnetism can be applied to reveal temporal changes in the geomagnetic field related to deep-earth dynamics, and to estimate the age of archaeological remains and artifacts. Reconstruction methods for ancient geomagnetic field intensity (archaeointensity) continue to develop rapidly, with various experimental methods having been proposed since 2000. The Tsunakawa-Shaw method is one of the latest experimental methods. The Tsunakawa-Shaw method was applied to reconstruction of the archaeointensity for a large number of samples of baked clay belonging to different ages from archaeological relics in Osaka Prefecture, Japan, and a new archaeointensity reference curve was constructed. The archaeointensities from 98 specimens belonging to 39 kilns were estimated. These data were screened and compiled for each pottery sequence, and finally 6 mean intensity values for the pottery sequence level were obtained. All of the mean intensity values satisfied the selection criteria, which indicates that they have sufficient reliability. It is notable that these newly estimated archaeointensities are lower than those in previous studies in Japan. On the other hand, new archaeointensity values show a complementary trend in the archaeointensity dataset obtained by the IZZI-Thellier method reported in Korea recently. We combined the dataset for Japan obtained in this study and the dataset for Korea, and drew an interpolation curve to construct an archaeointensity reference curve for East Asia covering from ca. 200 CE to ca. 1100 CE. This reference curve includes events of archaeointensity decrease and increase that occurred around 610 CE and around 950 CE, which are a characteristic pattern of the intensity variation found in this study.

Large earthquakes sometimes trigger local seismicity that is distal to their rupture zones. Various mechanisms for this triggered seismicity have been proposed, based on either the static stress change or ground shaking from seismic waves, but local geological structure is rarely studied to discern why this seismicity is remotely induced. We present the results of a joint three-dimensional resistivity and isotopic analysis of the groundwater system surrounding Mount Fuji, Japan, where increased seismicity was observed following the A.D. 2011 Tohoku-Oki megathrust earthquake. An electrically conductive zone and high concentrations of magmatic gases (He and CO2) correspond to the zone of triggered seismicity. In contrast, a contribution of magmatic water is not suggested from 2H (deuterium, D) and 18O isotope ratios. These results suggest that the earthquakes were triggered within a fractured zone through which magmatic gases preferentially migrated. We hypothesize that the upwelling of gas-rich hydrous fluids and/or gas bubbles occurred along this fracture pathway, causing an increase in the pore pressure and triggering the resultant earthquake sequence.

Knowledge of the evolution of North Atlantic Deep Water (NADW) is key to understanding the past evolution of the climatic system. Here we developed a new rock-magnetic method to determine the constituent magnetic minerals of sediments and report on the evolution of NADW during 2.2–2.9 Ma. We measured isothermal remanence acquisition curves of North Atlantic deep-sea sediments drilled at the Gardar Drift and decomposed the first derivatives of these curves into high-coercivity and low-coercivity components. Residuals of the decomposition were sufficiently small throughout the study interval, confirming that the Gardar Drift sediments represent a mixing of the two end-members. Fractional changes of the high-coercivity component represent variation of the Iceland-Scotland Overflow Water, a branch of NADW formed at the Nordic Seas. The high-coercivity component increased significantly during an interglacial period just after ~2.68 Ma, which suggests that NADW formation in the Nordic Seas abruptly intensified at this time.

Continuous monitoring of volcanic gas at Aso volcano using volatile traps from 2002 to 2011 revealed that higher HCl/SO2 ratios are associated with increasing volcanic activities. The HCl/SO2 ratios obtained during the observation period can be categorized into three levels: high (≤ 0.2), intermediate (0.1∼0.2), and low (≤ 0.1). From March 2003 to August 2005, and from December 2008 to August 2011, the HCl/SO2 ratios were generally at intermediate levels, with sporadic high HCl/SO2 ratios associated with small ash emissions. During other periods with no ash emission, the HCl/SO2 ratios were constantly low (∼0.02 in average). The HCl/SO2 ratio and the water level in the crater lake are correlated; the lower the water level in the crater lake, the higher the HCl/SO2 ratio. The reduced scrubbing effect of HCl from the intensely-emitted volcanic gas by a smaller amount of water is likely to generate high HCl/SO2 ratios of volcanic gas. In addition, evaporation of HCl from the water of the crater lake with extreme acidity may contribute to high HCl/SO2 ratios.

Waxing/waning of the ice sheets and the associated change in thermohaline circulation have played an important role in global climate change since major continental ice sheets appeared in the northern hemisphere about 2.75 million years ago. In the earliest glacial stages, however, establishment of the linkage between ice sheet development and ocean circulation remains largely unclear. Here, we show new high-resolution records of marine isotope stage 100 recovered from deep-sea sediments on the Gardar Drift, in the subpolar North Atlantic. Results of a wide range of analyses clearly reveal the influence of millennial-scale variability in iceberg discharge on ocean surface condition and bottom current variability in the subpolar North Atlantic during marine isotope stage 100. We identified eight events of ice-rafted debris, which occurred mostly with decreases in sea surface temperature and in current components indicating North Atlantic Deep Water. These decreases are interpreted by weakened deep water formation linked to iceberg discharge, similarly to observations from the last glacial period. Dolomite fraction of the ice-rafted events in early MIS 100 like the last glacial Heinrich events suggests massive collapse of the Laurentide ice sheet in North America. At the same time, our early glacial data suggest differences from the last glacial period: absence of 1470-year periodicity in the interactions between ice sheets and ocean, and northerly shift of the ice-rafted debris belt. Our high-resolution data largely improve the picture of ice-sheet/ocean interactions on millennial time scales in the early glacial period after major Northern Hemisphere glaciation.

This paper reports on the rock-magnetic properties of single zircon crystals, which are essential for future work establishing the reliable paleointensity method using single zircon crystals. Zircon crystals used in this study were sampled from the Nakagawa River, which crosses the Tanzawa tonalitic pluton in central Japan. Rock-magnetic measurements were conducted on 1037 grains of zircons, but many of these measurements are below the limits of the sensitivity of the magnetometers employed. Isothermal remanent magnetizations (IRMs) of 876 zircon crystal are below the practical resolution of this study; we infer that these crystals contain no or only minute quantities of ferromagnetic minerals. The other zircon crystals contain enough magnetic minerals to be measured in the DC SQUID magnetometer. For 81 zircon crystals, IRM intensities (M IRM) are larger than 4 × 10−12 Am2, while natural remanent magnetization (NRM) intensities (M NRM) are below 4 × 10−12 Am2, indicating that these crystals are inappropriate for the paleomagnetic study. For the samples that had values of M NRM ≥ 4 × 10−12 Am2 and M IRM ≥ 4 × 10−12 Am2 (80 zircons), combining the rock-magnetic parameter, we proposed the sample-selection criteria for future study of paleointensity experiments using single zircon crystals. In the case that the samples had high coercivity (B c) values (>10 mT) or high M NRM/M IRM values (>~0.1), main remanence carriers are probably pyrrhotite and these samples are inappropriate for the paleointensity study. In the case that the samples had low B c values (

The relation of magma and crustal activity has been studied from spatial distribution of 3He/4He ratios of gas and/or water samples over the Izu Peninsula, where significant crustal deformation associated with seismic swarm activities has been observed since 1970s. The air-corrected values of 3He/4He ratios ranged from 3.5 to 8.2 RA, where RA is the atmospheric 3He/4He ratio = 1.4 × 10− 6, indicating that helium is mostly of magmatic origin. Among the three pressure sources proposed to explain the crustal deformation, two inflation sources beneath the inland of northeast and the mid east coast of the Izu Peninsula locate in the broad distribution of high 3He/4He ratios, which supports relation of magma to the crustal uplift. In contrast, the distribution of 3He/4He ratios around the tensile fault assumed in the area of seismic swarms appears not to indicate existence of significant amount of magma below the tensile fault. Alternatively, the results suggest magma below a point several kilometers south of the tensile fault. The seismic swarms are explained either by fluid pressurization of thermal water heated by this magma or by intrusion of magma to the tensile fault moved obliquely from the deep magma reservoir.

Variations in fossil diatom assemblages and their relationship with global and Indian monsoon climate changes for the last 600,000 yr were investigated using a core of ancient lake (Paleo-Kathmandu Lake) sediments drilled at the Kathmandu Basin, Nepal Himalaya. Chronological scales of the core were constructed by tuning pollen wet and dry index records to the SPECMAP δ18O stack record. Examinations of biogenic silica contents and fossil diatom assemblages revealed that variations in productivity and compositions of diatom assemblages were closely linked with global and Indian monsoon climate changes on glacial and interglacial time scales. When summer monsoonal rainfall increased during interglacials (interstadials), diatom productivity increased because of increased inputs of terrestrial nutrients into the lake. When summer monsoonal rainfall reduced and/or winter monsoonal aridification enhanced during glacials (stadials), productivity of the diatoms decreased and lake-level falling brought about changes in compositions of diatom assemblages. Monospecific assemblages by uniqueCyclotella kathmanduensisandPuncticulata versiformisappeared during about 590 to 390 ka. This might be attributed to evolutionary fine-tuning of diatom assemblages to specific lake environmental conditions. Additionally, low-amplitude precessional variations in monsoon climate and less lake-level changes may have also allowed both species to dominate over the long periods.

The sediment obtained at Integrated Ocean Drilling Program (IODP) Site U1314 on the Gardar Drift in the eastern flank of the Reykjanes Ridge was analyzed using rock magnetic techniques to study the depositional environment through the mid-Pleistocene climate transition. The study area is under the influence of Iceland–Scotland Overflow Water (ISOW). Consequently, the sedimentary record represents directly ISOW behavior over time. A change in the depositional environment was documented as magnetic property changes that are the result of changes in concentration and grain size of magnetic minerals, both of which decrease upward from around 0.9 Ma. Because these shifts are accompanied by a change in magnetic fabrics, which is interpreted as a change in bottom current directions from E–W to NNE–SSW, it is considered that the sedimentation pattern inferred from magnetic records at the site was modified by a change in the bottom current through the middle Pleistocene.

The geomagnetic field direction during the Gauss-Matuyama (G-M) polarity transition was investigated from a high-accumulation-rate (≥10 cm/kyr) sediment core drilled in the Gardar drift in the North Atlantic at Site U1314 during Expedition 306 of the Integrated Ocean Drilling Program (IODP). A well-defined characteristic remanent magnetization was generally obtained by alternating field demagnetization. The consistency of the results with records from Icelandic lavas confirms that the North Atlantic drift sediments contain a high-fidelity record of the geomagnetic field change. During the G-M transition, the virtual geomagnetic pole (VGP) latitude shows north-south-north-south rebounding, with the three VGP paths falling within different longitudinal bands. Two of the three paths are close to or within the preferred bands in which transitional VGPs are suggested to be longitudinally confined. Three additional loops occur that approach mid-to-low latitudes from the North or South pole regions. In addition, the VGPs show rapid movement (directional jumps) between VGP clusters.

The seaweed industry worldwide uses 7.5–8.0 million tonnes of wet seaweeds annually with a majority of it derived from cultivated farms, as the demand for seaweed based-products exceeds the supply of seaweed raw material from natural stocks. The main advantage of cultivation is that it not only obviates overexploitation of natural populations but also facilitates the selection of germplasm with desired traits. To enhance the economic prospects of seaweed cultivation, varied practices, such as simple and cost effective cultivation methods, use of select germplasm as seed stock coupled with good farm management practices, etc., are adopted. Nevertheless, in vitro cell culture techniques have also been employed as they facilitate development and propagation of genotypes of commercial importance. There are more than 85 species of seaweeds for which tissue culture aspects have been reported. Although the initial aim of these techniques focuses mostly on genetic improvement and clonal propagation of seaweeds for mariculture, recently the scope of these techniques has been extended for use in bioprocess technology for production of high value chemicals of immense importance in the pharmaceutical and nutraceutical sectors. Recently, there has been a phenomenal interest in intensifying seaweed tissue and cell culture research to maximize the add-on value of seaweed resources. This paper deals with the status of seaweed micropropagation techniques and their applications in the context of the marine biotech industry. Further, it also provides an analysis of the problems to be resolved for removing the barriers that are impeding the true realization of potentials offered by these techniques for sustainable development and utilization of seaweed resources.

Aim: Vitamin K2 has been reported to inhibit the growth of human hepatocellular carcinoma (HCC) in vitro and suppress hepatocarcinogenesis in vivo. However, its inhibitory mechanism has not yet been clarified. Methods: Different concentrations of vitamin K2 (30, 10, 1, 0.1 and 0.01 μM) were added to the HCC cell line HepG2 to assess effects on cell growth. The effect of vitamin K2 on cell cycle progression was determined by flow-cytometric analysis. The expression of cell cycle regulatory proteins p21 and p27 was then examined by Western blot. Whether vitamin K2 regulates the gene expression through action on the p21 promoter region was investigated by luciferase assay. Results: Vitamin K2 inhibited the growth of HepG2 cells dose-dependently, and its inhibitory rate reached approximately 50% at the dose of 30 μM after 96 h treatment. After treatment with vitamin K2, the proportion of cells in G0–G1 phase increased, and in S phase decreased. Apoptotic cells were not detected. The expression of cell cycle regulatory protein p21 was induced by vitamin K2 treatment, but p27 was not. By the luciferase assay, vitamin K2 significantly activated the promoter of p21. Knock-down of p21 by siRNA reversed the growth inhibition of HepG2 cells by vitamin K2. Conclusions: The findings suggest that vitamin K2 suppresses the proliferation of HCC cells by blocking the cell cycle G1/S progression through the transcriptional induction of p21.

Succession of artificial seaweed communities in an artificial iron reef at Ikata, southern Japan was studied based on monthly or bimonthly observations from February 1999 to August 2000. Communities were associated with different substrata (40 cm x 60 cm: steel, concrete, wood and stone) as the cover on artificial iron reefs (4.5 m x 4.1 m x 2.5 m, 45.38 m3 and 3.2 ton), which were placed on a sandy substratum at 8 m depth. Within one month diatoms dominated on all substrata with cover of approximately 100%. Enteromorpha intestinalis and Colpomenia sinuosa dominated on the reef within three months after the placement in the spring. Seaweed communities on the reef decreased during the summer. In the winter, the seaweeds on the reef recovered. Sargassum spp., Ecklonia kurome and Padina arborescens dominated on each substratum after one year. Seaweed communities on the artificial reef were similar to those on the rocky substratum around the artificial reef and also similar on different substrata covering the iron artificial reef. These results indicate that seaweed succession was impacted by season and the recruitment of spores and propagules from mature algae around the artificial reefs.

Anomalous water level changes were observed at two wells associated with seismic swarm activity off Izu Peninsula on March, 1997. These are coseismic water level drops followed by gradual postseismic water level rise at the time of large earthquakes during the swarm activity. The post-seismic water level rises, which can be fitted by an exponential function with a time constant of about six hours, are explained in terms of the horizontal pressure diffusion due to the pressure gradient in the aquifer induced by the coseismic static strain.

The HFE, H ferritin, TFR2, and ferroportin 1 genes of a Japanese patient diagnosed as having hemochromatosis were amplified by PCR and sequenced. A novel mutation in the ferroportin 1 was found in the patient. It was located in the noncoding region of the ferroportin 1; nucleotide 117 adenine was changed to guanine, 7 nucleotides downstream the iron responsive element (IRE) region. This mutation was not found in the patient's son or daughter, or in 50 healthy individuals. It was suggested that the mutation in the ferroportin 1 may be related to hemochromatosis of this patient.

Ulva spp. are common in the intertidal zones of the Philippines, but, at certain times, could over-proliferate producing blooms or `green tide' in some protected bays. In Mactan Island (Cebu), central Philippines, at least two species constitute the Ulva population, either as free-living or attached form. The one referred to in the literature as `Ulva lactuca' mainly consists of free-living population while the species referred to as Ulva reticulata consists mainly of attached population. Based on morphological and physiological characteristics, `U. lactuca' differs much from the descriptions of the species from its type locality in Europe in having a crumpled texture of blade, presence of tooth-like protuberances at the margins, thinner thallus (40–50 μm) and more pyrenoids per cell (two to four). The species referred to as `U. lactuca' in the Philippines therefore is a different species. Two morphotypes consisted the `U. lactuca' population from Mactan – a thick thallus and a thin thallus type. However, both morphotypes cultured under the same condition in the laboratory could transform into the same thin-thallus type observed in the field. `Green tide' caused by `U. lactuca' occur almost regularly in Station 1 of Mactan Island, reaching an average biomass of up to 2.6 kg wet wt m−2 (or 0.5 kg dry wt m−2). Ulva reticulata, although was less abundant in the rocky tidal zone at most times, reaching an average biomass of only up to 0.15 kg wet wt m−2 (or 0.03 kg dry wt m−2) had caused green tide in Station 2 around February–March. Reproductive structures were not observed in both Ulva species during the survey period suggesting that vegetative fragmentation is the main mode of propagation. Vegetative tissues excised from the thallus can be induced to release biflagellated large and small zooids.

Populations of Enteromorpha prolifera collected from four rivers on Shikoku Island in Japan had three different types of life history. One type was the typical sexual life history of Enteromorpha, ...

We report the results of paleointensity determination with volcanic rocks of Izu-Oshima and Fuji Volcano, Japan. Samples used for the present study were basaltic rocks from nine lava flow units of Oshima Volcano, which erupted between AD 590 and 1950, and Aokigahara lava flow derived from Fuji Volcano in AD 864. Demagnetization and several rock magnetic experiments show that the samples have stable, single-component remanences, which are carried by magnetite or titanomagnetite with the PSD magnetic domain state. Thellier’s method was used for the paleointensity experiments, and reliable determinations for 10 eruptive units were obtained from 58 samples in total. The unit-mean values generally show good consistency with the previous archaeointensity and paleointensity results, allowing us to construct a reference curve of the field intensity variation for the past 2000 yr in Japan. The reference curve has a general trend of decreasing intensity since AD 500, showing two peaks of the field strength around AD 500 and 1400 and two troughs around AD 1200 and 1700. Since around AD 800, the field intensity predictions for Japan by the inversion spherical harmonic models show good consistency with the reference curve, suggesting that the peak and the troughs in this period have probably been produced mainly by non-dipole sources. The geocentric axial dipole variation extracted from the reference curve with the inversion model shows good agreement with the global averages of the virtual axial dipole moment, except that our reference curve yields a significant peak around AD 500. This suggests that a temporal strengthening of the dipole moment might have occurred over a few hundred years around AD 500.

Although most members of the genus Enteromorpha are important edible green algae, some species are also potentially economically valuable crops. Samples of E. prolifera were obtained from the Yoshino River estuary, Tokushima, Japan and cultured in laboratory conditions at 10°C, a salinity of 20 psu, under white light with 12 h light : 12 h dark cycle and at a photon fluence rate (PFR) of 40 mmol/m 2 per s for 30 days. In the present study, the effect of salinity and PFR on the induction of reproductive cells and rhizoid formation were investigated. Synchronous formation of swarmers by thalli was induced in excised disks of 1.2 mm diameter after 2-5 days incubation. The optimum salinity for maturation of reproductive cells was between 5.0 and 52.0 psu, and between 13.2 and 45.3 psu for swarmer release, although the lower limit for swarmer release was 5.0 psu. Maturation of reproductive cells and swarmer release required a PFR higher than 16 mmol/m 2 per s. The minimum PFR for swarmer release was 8 mmol/m 2 per s. Many rhizoids were formed between 1.6 and 52.0 psu and photon fluence rates between 8 and 320 mmol/m 2 per s. Rhizoids were formed in a polarized manner.

The red seaweed Eucheuma serra is a high yielding source of lectins. The plants were collected from a depth of 5-6 meters and cultured in the laboratory, field and deep seawater. A Daily Growht Rate (DGR) of 3.5% was observed at 18℃ with a low light of 30μmol photon in the laboratory. When the plants were cultured in the field at different depths during winter onths of December and January, best growth was observed at 1 m depth and a DGR of 2.14±0.04% was recorded. The plants grown in the tank with a continuous supply of deep seawater showed a DGR of 8.2% The results indicate that E. serra can be cultivated in large scale both in deep seawater in the tank and in the field for the extraction of lectins at a commercial scale.

In Japan, beverages with higher than ∼67% malt are considered beer. Those with lower are called Happoshu, although the malt ratio in most Happoshu brands is below 25%. Organoleptic tests on aged Happoshu were performed, and the amounts of carbonyl compounds were determined using gas chromatography, HPLC, and liquid chromatography-mass spectrometry. These results led to the selection of 3-methylbutanal as one of the most decisive indices for flavor staleness, which appears as a caramel-like or papery flavor in Happoshu. The brewing trials suggested that the suspended yeast cell concentration at the end of primary fermentation is a decisive factor for the reduction of 3-methylbutanal, as well as the reduction of yeast cell activity. Yeast strains that were preferable for beer conventional brewing were not always suitable for Happoshu fermentation. The fermentation progress was found to be particularly important in stabilizing the flavor of Happoshu. One of the mechanisms proposed is that the yeast plays an important role in decreasing the amount of staling compounds and their precursors.

Artificial reefs for the development of valuable fishery resources wereplaced on sandy substrates at 8, 10 and 13 m depths in Muronohana,Ikata, Japan, and observed monthly or bimonthly from February 1999 to June2001.Enteromorpha intestinalis and Colpomeniasinuosa were the primary dominants in spring. The number of seaweedspecies at all the sites gradually increased in winter. Each reef reached aclimax stage of Sargassum spp., Eckloniakurome and Padina arborescens within 18 months.Overall, 38 seaweed species were found during the study.The settlement of kelp, such as E. kurome, was promoted byreduced sand cover as a result of turbulence. Large-scale surface roughnesscould be important in maintaining the communities after initial establishment.

Algal aquaculture worldwide is estimated to be a $5-6 billion U.S. per year industry. The largest portion of this industry is represented by macroalgal production for human food in Asia, with increasing activity in South America and Africa. The technical foundation for a shift in the last half century from wild harvest to farming of seaweeds lies in scientific research elucidating life histories and growth characteristics of seaweeds with economic interest. In several notable cases, scientific breakthroughs enabling seaweed-aquaculture advances were not motivated by aquaculture needs but rather by fundamental biological or ecological questions. After scientific breakthroughs, development of practical cultivation methods has been accomplished by both scientific and commercial-cultivation interests. Microalgal aquaculture is much smaller in economic impact than seaweed cultivation but is the subject of much research. Microalgae are cultured for direct human consumption and for extractable chemicals, but current use and development of cultured microalgae is increasingly related to their use as feeds in marine animal aquaculture. The history of microalgal culture has followed two main paths, one focused on engineering of culture systems to respond to physical and physiological needs for growing microalgae and the other directed toward understanding the nutritional needs of animals-chiefly invertebrates such as mollusks and crustaceans-that feed upon microalgae. The challenge being addressed in current research on microalgae in aquaculture food chains is to combine engineering and nutritional principles so that effective and economical production of microalgal feed cultures can be accomplished to support an expanding marine animal aquaculture industry.

Because of the importance of seaweed resources for conservation of thecoastal environment, the provision of habitats of commercially importantspecies and because of use as human food, a study was carried out on bedsof Eisenia bicyclis and Ecklonia cava. This included the mostimportant environmental factors and the development of techniques forrestoration and long-term maintenance of the beds. At a site chosen fordetailed study, the Eisenia and Ecklonia bed was influenced bymany factors, including desiccation, rainfall, low salinity, low light intensity,turbidity, accumulation of suspended sediments, cover by adhering animals,wave and current action and grazing pressure. The distribution of suchseaweed beds is also limited locally by the size and hardness of rock on thebottom, and by fluctuations in the sand level at the base of the reefs.The management-free technique of creating Eisenia and Ecklonia beds is based on an understanding of the factors limiting the localdistribution of the beds. Conditions for seaweed growth can then beartificially enhanced by coastal engineering. Suggestions to enhance Eisenia and Ecklonia bed restoration using management-freetechniques include raising the bottom, elevating substrata above the sandybottom, and providing substrata of a shape suitable for the attachment ofkelp.

Observations on the development of seaweed communities on concretepanels suspended at three different slope angles – 0° (horizontal),45° (inclined) and 90° (vertical) – were carried out atUranouchi Inlet, Tosa Bay, southern Japan. Each panel had two opposite20 × 20 cm areas, which were affixed with six pieces of 6 × 9 cmacrylic plate on which algal communities were allowed to colonize. The panelswere suspended 1 m below the sea surface from a floating platform fora period of 6 weeks. The experiments were repeated nine times fromAugust 1996 to October 1997. Young thalli could already be recognized on the panels after 3–4 weeks. Thetype of algal community developing on a panel varied with the slope angleas well as the period of suspension. These were classified into the threedominant green algal genera: Ulva, Enteromorpha and Cladophora. The cover and biomass of particular species were clearlyinfluenced by the slope of the substratum.