• Ocean and Polar Research
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• v.39 no.1
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• pp.13-21
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• 2017

Temporal changes in the number of zooplankton species are important information for understanding basic characteristics and species diversity in marine ecosystems. The aim of the present study was to estimate the optimal monitoring frequency (OMF) to guarantee and predict the minimum number of species occurrences for studies concerning marine ecosystems. The OMF is estimated using the temporal number of zooplankton species through bi-weekly monitoring of zooplankton species data according to operational taxonomic units in the Tongyoung coastal sea. The optimal model comprises two terms, a constant (optimal mean) and a cosine function with a one-year period. The confidence interval (CI) range of the model with monitoring frequency was estimated using a bootstrap method. The CI range was used as a reference to estimate the optimal monitoring frequency. In general, the minimum monitoring frequency (numbers per year) directly depends on the target (acceptable) estimation error. When the acceptable error (range of the CI) increases, the monitoring frequency decreases because the large acceptable error signals a rough estimation. If the acceptable error (unit: number value) of the number of the zooplankton species is set to 3, the minimum monitoring frequency (times per year) is 24. The residual distribution of the model followed a normal distribution. This model can be applied for the estimation of the minimal monitoring frequency that satisfies the target error bounds, as this model provides an estimation of the error of the zooplankton species numbers with monitoring frequencies.

• Korean Journal of Ecology and Environment
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• v.47 no.4
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• pp.302-311
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• 2014

Global climate change is significant issue in marine ecosystem and fishery market. According to rising of both seawater temperature and sea-level, global fishery environment and marine ecosystem are changing drastically. Moreover, over-exploitation in fishery areas is the most important issue in the marine ecosystem conservation. In analysis and statistics of global network, major fish populations are decreasing very fastly, but fish catch are increasing annually. It means balance between product and consume is not appropriate in the global market. China as emerging new fish consumer in the world is strongly developing fishery industry and technology. In this paper, I try to review a relationship between marine ecosystem and climate change in global scale according to references. I also suggested possibility of sustainable global fishery in changing marine ecosystem by analysis of some related reports of international global fishery.

• Ocean and Polar Research
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• v.44 no.3
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• pp.249-260
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• 2022

This mini review examines the habitat connectivity and effectiveness of Korean Marine Protected Areas (MPAs) in the Yellow Sea Large Marine Ecosystem (YSLME) region. We first reemphasize that the Korean region of the YSLME is a single ecosystem (ecoregion) given the biophysical distribution patterns. The MPAs within the YSLME contribute about 50% to the total MPAs in Korea, accounting for about 10% of the territorial sea waters of Korea and 20% of the waters of YSLME on the Korean side. By area, national parks account for nearly 45% of the MPAs, followed by the wetland protected areas at 25%, with other types of MPA comprising the remaining 30%. Large MPA (> 100 km²) is the dominant type of MPA, accounting for 90% of the total area. We find that MPAs in the region are connected physically and perhaps also genetically. However, the level of protection was found to be low, and a no-take zone is rarely implemented. In addition, interrupted freshwater discharge caused by river-mouth dams poses a major hindrance to the physical connectivity of the MPAs. Restoration of the river-mouth dams and strengthened regulation on MPAs, with further expansion of MPAs in line with the current development of post-2020 global biodiversity frameworks, should be priorities for better management of marine resources. The newly revised law incorporating the concept of "Marine Ecosystem Axis Management" would reinforce the processes, and their effectiveness together with overall management of MPAs in Korea should be evaluated by designing appropriate measurement tools.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.2
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• pp.186-192
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• 2013

Because of the shallow depth of 44 m and large area of wetland in Korea and China, the class I productivity of Yellow Sea is very high (>300 $gC/m^2/year$), which is supporting substantial populations of fish, invertebrates, marine mammals and seabirds. However, the Yellow Sea is a large marine ecosystem which is enclosed by mainland of China and Korean peninsula, so it is vulnerable to external stress such as environmental degradation and overfishing. Recently, since the Fisheries Agreement between Korea and China, overfishing and illegal fishing of China and environmental degradation caused by coastal development in Korea and China have given much stress to the marine ecosystem of Yellow Sea. This article suggests that the major factors of governance are ineffectively responding to the growing demand for exploitation of the Yellow Sea and the international cooperation for establishing network of Yellow Sea governance is urgent.

• ALGAE
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• v.33 no.2
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• pp.167-180
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• 2018

Benthic diatoms are ubiquitous in tidal flats and play major roles in maintaining coastal ecosystems. Spatio-temporal variations in diatom diversity have not been well-studied, mainly because of difficulties in morphological identification and the lack of appropriate genetic tools. To overcome these problems, we used the gene encoding the ribulose bisphosphate carboxylase large-subunit (rbcL) as a molecular marker, and sequenced these genes with the aid of the MiSeq platform. In this manner, we explored the genetic diversity of benthic diatoms in tidal flats of Guenso Bay on the west coast of Korea; differences in the spatial distributions of benthic diatoms were evident. The diatom communities were dominated by Nitzschia, Navicula, and Amphora; their relative distributions were affected by the sand proportion, grain size, and air exposure time. Our results suggest that meta-barcoding of the rbcL gene and next-generation sequencing can be used to explore the diversity of benthic diatoms.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.4
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• pp.389-401
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• 2003

The changes in structure and abundance of taxon or species groups in the East Sea ecosystem were compared between pre- and post-Climatic Regime Shift (CRS) occurred in the mid 1970s using an ECOPATH model. Although the East Sea ecosystem consisted of primary producers, primary consumers, secondary consumers and terminal consumers most species groups were classified as secondary consumers. The mean trophic level between pre- and post-CRS increased from 3.09 during the pre-CRS period to 3.28 during the post-CRS period. Total biomass of the species groups in the East Sea ecosystem increased by $9\%$ due to the CRS, and total catch increased by $48\%.$ The most significant differences between pre- and post-CRS models occurred at the mid/high trophic levels occupied by fishes and cephalopods. Relative contribution of the different species groups to the total energy flow was calculated for the trophic level III. As a result, the status by the dominant species in the East Sea ecosystem shifted from cephalopods to walleye pollock due to the CRS. Relative contribution of 5 species, which were commercially important, such as Pacific saury, Pacific sardine, filefish, walleye pollock and sandfish in trophic level III, were also changed due to the CRS. Finally, the CRS turned out to cause large variations in biomass and catch of fisheries resources as well as the status and role of the major species.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.3
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• pp.193-198
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• 2012

Long term changes in winter time(JFM) sea surface temperature(SST) and marine ecosystem of different Korean waters during last five to six decades were illustrated. Fishing intensity with climate-ocean variability(e.g. SST) have been increasing since 1970s in all of the Korean marine waters. Winter SST around Korean waters went to colder regime in early 1980s and after the late 1980s increased gradually. After 1988/89 CRS all of the waterbody started warmer regime and well coincided with the CRS phenomena. Large predatory, small pelagic and crustacean and mollusks abundance were well coincided by the warmer SST regime after 1988/89 CRS and changed the fishery from demersal fishery to pelagic fishery. Ecosystem parameter of Mean Trophic Level(MTL) showed continuous decreasing trend since mid of 1970s which was mostly affected by the increasing of lower trophic level species. Fishing in balance(FIB) index showed increasing pattern since early 1970s to the late of 1970s and from early 1980s it was almost stable until now. Finally wasp-waist population of anchovy and Japanese sardine have a greater impact to the whole MTL since early 1970s.

• Journal of Marine Bioscience and Biotechnology
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• v.2 no.1
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• pp.1-10
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• 2007

Coral reefs are among the most dynamic and various ecosystems on tropical ecosystem. They provide a large number of important ecosystem services. Despite their importance, they appear to be one of the most susceptible marine ecosystems. Dramatic decreasing of coral reefs has been reported from every part of the world. Indonesia contains 18% of coral reefs of world's total. Unfortunately the status of coral reefs in Indonesia is already in critical and poor condition. Coral reefs communities in Indonesia are subjected to a variety of environmental disturbance. Threats to Indonesia's coral reefs resources can be divided into two main types: anthropogenic and natural disturbances. The major anthropogenic disturbances on coral reefs in Indonesia are destructive fishing, pollution, coastal development, mining and harvesting live fish and coral, tourism. The natural disturbances such as cyclones, volcanic eruptions, earthquakes, tsunami and predator also contribute to coral reefs destruction in Indonesia. In my paper I tried to compare between natural and anthropogenic disturbances on coral reefs in Indonesia and raised these questions: (i) how the natural disturbances differ from anthropogenic area (ii) which type of disturbances has caused the greatest impact on coral reef ecosystem. My finding is that both of anthropogenic and natural disturbances give major impact on coral reefs in Indonesia. The important issue here is coral reef resilience could be disturbed by synergistic effects between various anthropogenic and natural disturbances. This phenomenon has significant conservation and management implication. The appropriate management should be conducted to protect coral reefs ecosystem in Indonesia. Mangrove management will succeed only when local people are involved and get sustainable benefits from mangrove ecosystem. Community based management and Integrated Coastal Zone Management (ICZM) are type of management that can be applied on coral reef ecosystems in Indonesia.

• ALGAE
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• v.34 no.1
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• pp.57-70
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• 2019

DNA metabarcoding is currently used for large-scale taxonomic identification to understand the community composition in various marine ecosystems. However, before being widely used in this emerging field, this experimental and analytic approach still has several technical challenges to overcome, such as polymerase chain reaction (PCR) bias, and lack of well-established metabarcoding markers, a task which is difficult but not impossible to achieve. In this study, we present an adapted PCR-free small-organelles enriched metagenomics (SoEM) method for marine biodiversity assessment. To avoid PCR bias and random artefacts, we extracted target DNA sequences without PCR amplification from marine environmental samples enriched with small organelles including mitochondria and plastids because their genome sequences provide a valuable source of molecular markers for phylogenetic analysis. To experimentally enrich small organelles, we performed subcellular fractionation using modified differential centrifugation for marine environmental DNA samples. To validate our SoEM method, two marine environmental samples from the coastal waters were tested the taxonomic capturing capacity against that of traditional DNA metabarcoding method. Results showed that, regardless of taxonomic levels, at least 3-fold greater numbers of taxa were identified in our SoEM method, compared to those identified by the conventional multi-locus DNA metabarcoding method. The SoEM method is thus effective and accurate for identifying taxonomic diversity and presents a useful alternative approach for evaluating biodiversity in the marine environment.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.4
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• pp.369-389
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• 2011

Changes in ecosystem risks were evaluated using the ecosystem-based fisheries assessment (EBFA) approach of Zhang et al. (2009, 2010) and the comprehensive ecosystem-based fisheries management (EBFM) plan was made for the southern sea of Korea in this study. The risk assessment of the southern sea ecosystem was conducted by establishing ecosystem management objectives and by estimating risk scores (RS) for indicators. To conduct this analysis a number of indicators and their reference points for assessing these risk scores were developed in this study. The number of indicators in the risk analysis was 28 for the quantitative tier 1 analysis and 30 for the qualitative tier 2 analysis. The objective risk index (ORI), species risk index (SRI) and fisheries risk index (FRI) were calculated from the risk scores. Comparing the past (1988) and the current (2008) status of fisheries resources, management implications were discussed. The fishery risk index (FRI) of large purse seine fishery in the southern sea of Korea decreased substantially from 0.972 in 1988 to 0.883 in 2008, and improvement in the management of fisheries operated in the southern sea of Korea.