• Coupled systems mechanics
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• v.2 no.1
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• pp.53-83
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• 2013

Sea waves induce significant pressures on coastal surfaces, especially on rocky vertical cliffs or breakwater structures (Peregrine 2003). In the present work, this hydrodynamic pressure is considered as the excitation acting on a piezoelectric material sheet, installed on a vertical cliff, and connected to an external electric circuit (on land). The whole hydro/piezo/electric system is modeled in the context of linear wave theory. The piezoelectric elements are assumed to be small plates, possibly of stack configuration, under a specific wiring. They are connected with an external circuit, modeled by a complex impedance, as usually happens in preliminary studies (Liang and Liao 2011). The piezoelectric elements are subjected to thickness-mode vibrations under the influence of incident harmonic water waves. Full, kinematic and dynamic, coupling is implemented along the water-solid interface, using propagation and evanescent modes (Athanassoulis and Belibassakis 1999). For most energetically interesting conditions the long-wave theory is valid, making the effect of evanescent modes negligible, and permitting us to calculate a closed-form solution for the efficiency of the energy harvesting system. It is found that the efficiency is dependent on two dimensionless hydro/piezo/electric parameters, and may become significant (as high as 30 - 50%) for appropriate combinations of parameter values, which, however, corresponds to exotically flexible piezoelectric materials. The existence or the possibility of constructing such kind of materials formulates a question to material scientists.

• Journal of the Korean earth science society
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• v.28 no.2
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• pp.248-254
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• 2007

Recently lots of the Early Cambrian fauna were described from the Yunnan Province of China. The fauna occurs from the Maotiangshan shale that dated between 525 and 520 ma, which is about 10-20 million years earlier than the Burgess Shale fauna of Canadian Rocky Mountain and Sirius Passet fauna in North Greenland. The Chengjiang fauna comprises an extremely diverse faunal assembly, and soft body parts of the fauna are well preserved. Such condition probably resulted from repeated rapid burial environment that prevented the bodies from destruction by currents, bioturbation, and biolchemical activities.

• ALGAE
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• v.21 no.3
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• pp.305-310
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• 2006

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.

• ALGAE
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• v.21 no.4
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• pp.463-470
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• 2006

Studies have been made of the species composition and variation of benthic marine algae at subtidal zone of Uljin on the east coast of Korea. Destructive method was employed to measure biomass over four seasons (2000-2002). Of 87 marine algae species identified, 11 were Chlorophyta, 29 were Phaeophyta and 47 were Rhodophyta. Dominant species in biomass were Ulva pertusa, Undaria pinnatifida and Sargassum piluliferum in summer, Laminaria religiosa, Sargassum fulvellum and Gigartina tenella in autumn, Codium fragile, Undaria pinnatifida, Sargassum horneri, S. piluliferum and S. ringgoldianum in winter, and Undaria pinnatifida, Dictyopteris divaricata, Sargassum confusum and S. horneri in spring. In general, green algae (Ulva pertusa, Codium fragile) and brown algae (Undaria pinnatifida, Sargassum fulvellum, S. horneri, S. piluliferum) appeared predominantly in the 3, 6 m depths and red algae (Gelidium amansii, Plocamium telfairiae) in the 9, 12 m depths. The barren ground of the rocky shore might provide the decrease of benthic marine algae biomass and species.

• ALGAE
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• v.31 no.2
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• pp.91-103
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• 2016

A goal of phylogeography is to relate phylogenetic patterns to potential historic and contemporary geographic isolating events. Genetic breaks found in phylogeographic studies may denote boundaries between more generally applicable biogeographic regions. We investigated the distribution of Lessonia variegata, an important habitat forming alga, found on most rocky shores around New Zealand’s main islands, plus related species from surrounding waters. L. variegata has been shown to consist of four distinct cryptic species. Our aim was to compare the distribution of L. variegata with proposed bioregions; and to develop phylogeographic hypotheses to explain its present day distribution. Both a mitochondrial (atp8-sp) and plastid (RuBisCo spacer) marker, with different mutation rates, were used to gain information of the phylogenetic history of Lessonia. The data revealed high phylogeographic structuring and reciprocal endemism for all L. variegata cryptic species. One species (L. variegata / N) is confined to the northern part of the North Island of New Zealand; L. variegata / W is found at the southeast of the North Island and the northern South Island; L. variegata / K is endemic to the northeast South Island; and L. variegata / S is restricted to the southern part of the South Island. No overlapping areas of L. variegata species distribution were found. The data showed that genetic breaks in Lessonia do mostly correlate to bioregions, and highlight the importance of Cape Campbell at the northeast of the South Island and East Cape in the North Island, well known phylogeographic breaks, as a barrier between adjacent species.

• The Korean Journal of Malacology
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• v.20 no.2
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• pp.159-164
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• 2004

In the present study we examined latitudinal trend of the number of species and species diversity of rocky subtidal shelled gastropods. Specimens were sampled from four wave-exposed sites along the eastern coast of Korea between Sockcho (38$^{\circ}$14"N_ and Busan (35$^{\circ}$06"N), covering a range of over ca. 440 km and 4$^{\circ}$ of latitude. At a small local scale, the number of species showed a latitudinal trend, decreased with decreasing of latitude, even though no clear trends in species diversity were detected. The present result, consequently, suggest that regulation of small-scale local diversity presumably results from the difference of the local micro-environment.

• Korean Journal of Environmental Biology
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• v.25 no.4
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• pp.297-302
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• 2007

An investigation of fish fauna was conducted based on the specimens from the Taean International Marine Park, off West Coast of Korea in 2005. They were collected by small seine net and stake net. The collected fishes were composed of 27 species belongs to 15 families and 8 orders. The dominant species were gobids of Favonigobius gymmnauchen in the sand area, Chamichthys gulosus and C. dolichognathus in the rocky area. The Korean endemic species were two species of Zoarchias uchidai and Repomucenus koreanus. But Porocottus leptosomus that described as a new species on the basis of specimens collected from this area in 2002 was not collected in this study.

• Animal Systematics, Evolution and Diversity
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• v.32 no.2
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• pp.105-111
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• 2016

The genetic structure of marine animals that inhabit the seashore is affected by numerous factors. Of these, gene flow and natural selection during recruitment have strong influences on the genetic structure of seashore-dwelling species that have larval periods. Relative contributions of these two factors to the genetic structure of marine species would be determined mainly by the duration of larval stage. The relationship between larval period and genetic structure of population has been rarely studied in Korea. In this study, genetic variations of cytochrome oxidase subunit I (COI) were analyzed in two dominant species on rocky shore habitats in the Korean peninsula: periwinkle Littorina brevicula and acorn barnacle Fistulobalanus albicostatus. Both species are not strongly structured and may have experienced recent population expansion. Unlike periwinkle, however, barnacle populations have considerable genetic variation, and show a bimodal pattern of mismatch distribution. These results suggest that barnacle populations are more affected by local adaptation rather than gene flow via larval migration. The bimodal patterns of barnacle populations observed in mismatch distribution plots imply that they may have experienced secondary contact. Further studies on seashore-dwelling species are expected to be useful in understanding the evolution of the coastal ecosystem around Korean waters.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.3
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• pp.266-272
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• 2013

The objective of this study was to monitor and evaluate the schooling characteristics, including the distribution density (volume backscattering strength) and acoustic size (target strength), of commercially valuable species swimming in response to artificial reefs installed at Suyeong Man, Busan, Korea. Fish aggregations at two artificial reef areas and at a nearby natural rocky reef habitat were recorded and analyzed using a 70 kHz split-beam echo sounder and 330 kHz side-scan sonar from August to September, 2006. An underwater CCTV camera system was also used to observe marine organisms in physical contact with and swimming very close to artificial reefs. During the acoustic observations at three reef sites, useful information about schooling characteristics of fish aggregations responding to artificial reefs were obtained, but more trials are needed to confirm significant differences in schooling behavior and geographical distributions in areas containing natural reef structures and artificial reefs.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.3
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• pp.262-269
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• 2010

Seventeen fish species were counted in an underwater visual census, and the most common species, Sebastes inermis and Halichoeres poecilopterus, were released. More than 60% of the released S.inermis occurred near a fish farm 5 days after release, but they moved to a distant rocky area, and decreasing numbers were seen near the farm 90 days after release. In pots, a total of 722 individuals belonging to 43 species occurred, and released S.inermis dominated with 174 individuals recaptured during the study period. The other common fish species were Stephanolepis cirrhifer and Acanthopagrus schlegeli. The percentage of recapture was 0.23%, but declined to 0.12% at 90 days after release. The potential predators of released S.inermis included Lateolabrax japonicus and Sebastes schlegeli.