• Journal of Ocean Engineering and Technology
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• v.19 no.4 s.65
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• pp.28-34
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• 2005

In the study application of volcanic scoria concrete to artificial reefs is investigated. Volcanic scoria is a natural volcanic product that shows light weight, mil/i-porous, and far-infrared irradiation characteristics. The properties of volcanic scoria concrete using Jeju scoria aggregate are evaluated by conducting a comprehensive series of tests on strength and void ratio. It is concluded that the volcanic scoria concrete has the sufficient strength of 4MPa-13MPa and adequate void ratio of $12\%-35\%$ to be accepted as artificial reef concrete. The field experiments are performed through observation by scuba diver's at the Seogwipo coast. Porous specimen and plane concrete specimen are prepared for comparison purposes. Seasonal changes of soft coral on the two series of test specimens were have been observed from Apr. 9, 2004 to Mar. 18, 2005. The soft coral is well grown on the porous specimen however there are no significant changes on the conventional plain concrete specimen. Thus it is concluded that the volcanic scoria concrete is highly suitable as artificial reef concrete.

• Fisheries and Aquatic Sciences
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• v.26 no.12
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• pp.738-751
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• 2023

The Sembilan Archipelago is famous for its great biodiversity, in which the humphead wrasse (Cheilinus undulatus) (locally named Napoleon fish) is the primary commodity (economically important), and currently, the environmental degradation occurs due to anthropogenic activities. This study aimed to examine the eco-environmental parameters and assess their influence on the abundance of humphead wrasse and other coral reef fish compositions in the Sembilan Archipelago. Direct field monitoring was performed using a visual census throughout an approximately one km transect. Coral cover data collection and assessment were also carried out. A coastal water quality index (CWQI) was used to assess the water quality status. Furthermore, statistical-based analyses [hierarchical clustering, Pearson's correlation, principal component analysis (PCA), and canonical correspondence analysis (CCA)] were performed to examine the correlation between eco-environmental parameters. The Napoleon fish was only found at stations 1 and 2, with a density of about 3.8 Ind/ha, aligning with the dominant composition of the family Serranidae (covering more than 15% of the total community) and coinciding with the higher coral mortality and lower reef fish abundance. The coral reef conditions were generally ideal for supporting marine life, with a living coral percentage of about > 50% in all stations. Based on CWQI, the study area is categorized as good and excellent water quality. Of the 60 parameter values examined, the phytoplankton abundance, Napoleon fish, and temperature are highly correlated, with a correlation coefficient value greater than 0.7, and statistically significant (F < 0.05). Although the adaptation of reef fish to water quality parameters varies greatly, the most influential parameters in shaping their composition in the study area are living corals, nitrites, ammonia, larval abundance, and temperature.

• ALGAE
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• v.33 no.1
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• pp.85-99
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• 2018

Crustose calcareous algae (CCA) constitute one of the main reef builders on the Abrolhos Bank, Brazil. Once CCA taxonomy is locally understood, differences in growth-forms may be useful for the delimitation of taxa using characteristics such as the presence or absence of surface protuberances. Here, growth-forms were used to identify and quantify the most common CCA taxa on the shallow reefs (3-10 m) of the Abrolhos Bank to determine possible changes in the CCA community over a period of 10 years, and the ecological significance of CCA to local reefs was interpreted. The CCA assemblages were surveyed from 2006-2015 by using fixed photoquadrats at four sites in the inner (10-20 km from the mainland) and mid-shelf reefs (40-75 km from the mainland). The five most common CCA taxa were Pneophyllum conicum, the Lithophyllum kaiserii / Lithophyllum sp. complex, Melyvonnea erubescens, the Hydrolithon boergesenii / Porolithon onkodes complex and Peyssonelia sp. The overall mean CCA cover on the reefs was 20%. A comparison with a previous monitoring study in the same region indicated that the CCA cover nearly doubled from 2003-2008 to 2006-2015. This study reveals that the coral-killing species P. conicum dominated CCA flora on the shallow Abrolhos reefs in the last decade, and the local specific abundance of CCA slightly fluctuated over time and was species- and site-specific. The information obtained in this study contributes to the understanding of the ecology of the key calcifying components of the Abrolhos reefs and provides a useful baseline for exploring the responses of CCA to future environmental changes.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.1
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• pp.101-111
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• 2018

The Korean government has been trying to conserve a marine ecosystem that has been shifting due to climate change. As part of this effort, the government designated seventy-seven marine species that have been disappearing and deserve to be protected as endangered managing them specially. To generate basic data to guide policy for these endangered species, their value must be measured. OOf the species declared endangered, coral is particularly threatened by climate change, and its management is important. Accordingly, understanding the potential value of reefs, can be an effective way of proving the benefits of continuous management to decision makers and the general public alike. To this end, we have applied the contingent valuation method (CVM), an economic technique of for valuing a environmental and non-market goods such as a coral reef. A national face-to-face survey of 1,000 randomly selected households was conducted in order to determine the public's willingness to pay (WTP) for conserving coral reefs. A one-and-one-half-bound (OOHB) model was adopted to interpret WTP responses, and a spike model was employed to deal with zero WTP responses. The results show that the conservation value of a coral reef can be estimated at 3,016 won per household per year, statistically significant at the 1 % level. Expanding values to the national population gives an annual value of 58.9 billion won. We can conclude that the public is willing to pay a significant amount to conserve coral reefs.

• Animal Systematics, Evolution and Diversity
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• v.20 no.2
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• pp.109-140
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• 2004

Seven new species of cope pods associated with marine invertebrates are described from the Great Barrier Reef, Australia. They are Panjakus bidentis from the scleractinian Pocillopora verrucosa (Ellis and Solander), Scyphuliger humesi, S. vicinus and S. placidus from the scleractinian Acropora squarrosa (Ehrenberg), Doridicola parapatulus from the nudibranch Glossodoris atromarginata (Cuvier), Ruhtra germinata from an unidentified alcyonacean coral, and Collocheres oribullatus from the crinoid Comanthina belli (Carpenter).

• Ocean and Polar Research
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• v.30 no.3
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• pp.351-359
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• 2008

In an effort to develop high-resolution sea surface temperature (SST) proxies for mid-latitude regions, two massive reef-building coral species, Alveopora and Favia, were collected from Jeju and Tsushima Islands, respectively. Their skeletons were subsequently analyzed for annual growth banding, Sr/Ca and Mg/Ca ratios. Hermatypic corals are thinly distributed in the waters of Jeju Island, where Alveopora japonica was the only dominant coral species. A higher diversity of hermatypic corals were observed in the waters of Tsushima Island, where Favia sp. was the most common coral species and even forming an about 6-m-high reef structure. Both Alveopora and Favia showed annual growth layers consisting of couplets of high- and low-density bands. Sr/Ca ratio of both species and Mg/Ca ratio of Alveopora also showed seasonal variation, likely reflecting SST variation. These results suggest the possibility that Alveopora and Favia species can be used as potential SST proxies. However, this study also highlights the potential growth disturbance of middle latitude corals due to high rainfall during monsoon and low SST during winter. This possibility should be taken into account in the investigation of Sr/Ca(Mg/Ca)-SST relationships.

• Journal of Ocean Engineering and Technology
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• v.35 no.1
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• pp.75-81
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• 2021

Artificial Coral Reefs (ACRs) have been introduced to help solve coastal erosion problems, but their feasibility has not been assessed with field data. This study conducted a feasibility analysis of ACRs on their erosion mitigation effects by performing a case study of Cheonjin-Bongpo beach, South Korea. A numerical-physical combined analysis was carried out using a SWAN model simulation and physical model test with a scale of 1/25 based on field observations of Cheonjin-Bongpo beach. Both Dean's parameter and the surf-scaling parameter were applied to comparative analysis between the absence and presence conditions of the ACR. The results for this combined method indicate that ACR attenuates the wave height significantly (59~71%). Furthermore, ACR helps decrease the mass flux (~50%), undertow (~80%), and maximum wave set up (~61%). The decreases in Dean's parameter (~66%) and the surf-scaling parameter suggest that the wave properties changed from the dissipative type to the reflective type even under high wave conditions. Consequently, an ACR can enhance shoreline stability.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2003.05a
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• pp.393-395
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• 2003

산호충류는 한국을 포함한 전 세계적으로 보호종으로 지정되어 있다. 특히 제주도 해역의 서귀포 문섬, 숲섬 및 범섬 일대가 쿠로시오 난류의 영향으로 조하대 암반기질에 다양한 부착생물이 서식하며, 특히 연산호, 돌산호 등이 군집을 이루고 있어 UNEP의 ICRI(International Coral Reef Initiative)에 이미 보고되었을 뿐만 아니라, 세계 해양보존 지역 위원회에서도 해양보호지역 (Marine Protected Area, MPA)으로 선포하여 보호하려는 계획을 세우고 있다. (중략)

• ALGAE
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• v.25 no.4
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• pp.205-216
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• 2010

The marine red alga Kappaphycus alvarezii is a major source of $\kappa$-carrageenan. It has been introduced in 20 countries including India. Recently, several reports have expressed concerns about Kappaphycus invasion on Acropora corals at Kurusadai Island in the Gulf of Mannar, India, which is part of a marine bioreserve. To understand the extent of the Kappaphycus invasion, 27 randomly selected locations around Kurusadai Island and the mainland coast were surveyed during May-August 2008 and July 2009. Our rigorous sampling revealed that K. alvarezii was confined to two different patches of 105 m $\times$ 55 m and 8 m $\times$ 9 m located at the southeastern part of Kurusadai Island. The actual extent of the K. alvarezii canopy coverage was 76.7 $m^2$, accounting for less than 0.0035% of the total coral reef area. The daily growth rate of the K. alvarezii at Kurusadai was 0.7%. K. alvarezii was not observed in the coral reef area of the adjoining Pullivasal and Poomarichan Islands or the Palk Bay area cultivation sites. The lack of functional reproductive cycle, low spore viability, and the absence of microscopic phases in the life cycle of this alga coupled with the abundance presence of herbivores may restrict the further spread of this alga, so its invasive potential at Kurusadai Island is considered remote.

• Journal of Ecology and Environment
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• v.38 no.2
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• pp.271-279
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• 2015

After the reversion of Okinawa (Ryukyu Islands) to Japan in 1972, extensive urban and agricultural development resulted in a significant increase in sediment discharge to coastal waters. The release of sediment has caused the degradation of freshwater and coastal ecosystems and biodiversity. A consideration for catchment-to-reef continua, as well as agricultural (socioeconomic) factors is necessary to establish proper land-based management plans for the conservation of the island environment. We have set up a framework to integrate biophysics and socioeconomics: 1) setting a conservation target and threshold, 2) identifying the sources and processes, and 3) examining cost-effectiveness and management priorities. The framework may be applicable to other tropical and subtropical islands with similar characteristics.